U.S. patent application number 15/397488 was filed with the patent office on 2017-05-25 for safety valve control system and method of use.
The applicant listed for this patent is SAFOCO, INC.. Invention is credited to David LYMBEROPOULOS, Benjamin R. MATTHEWS.
Application Number | 20170147012 15/397488 |
Document ID | / |
Family ID | 49624803 |
Filed Date | 2017-05-25 |
United States Patent
Application |
20170147012 |
Kind Code |
A1 |
LYMBEROPOULOS; David ; et
al. |
May 25, 2017 |
SAFETY VALVE CONTROL SYSTEM AND METHOD OF USE
Abstract
A safety valve control system may include a remotely operable
control assembly, a first transducer, a valve assembly, and a
compressor assembly in communication with the control assembly. The
control assembly is operable to actuate the pump and valve
assemblies to supply fluid to actuate the safety valve into open
and closed positions, in response to one or more signals received
from the first transducer. A method of operation may include
maintaining the safety valve in an open or closed position while
sensing a physical property with the control system; communicating
a signal corresponding to the sensed physical property to the
control system; and automatically closing or opening the safety
valve in response to a comparison of the sensed physical property
to a pre-set condition.
Inventors: |
LYMBEROPOULOS; David;
(Houston, TX) ; MATTHEWS; Benjamin R.; (Missouri
City, TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SAFOCO, INC. |
Houston |
TX |
US |
|
|
Family ID: |
49624803 |
Appl. No.: |
15/397488 |
Filed: |
January 3, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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15262642 |
Sep 12, 2016 |
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15397488 |
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13480704 |
May 25, 2012 |
9441453 |
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15262642 |
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13195662 |
Aug 1, 2011 |
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13480704 |
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61551319 |
Oct 25, 2011 |
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61415238 |
Nov 18, 2010 |
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61370721 |
Aug 4, 2010 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F16K 37/0091 20130101;
Y10T 137/7761 20150401; G05D 16/2086 20130101; Y10T 137/2635
20150401; F15B 2211/665 20130101; F15B 20/00 20130101; F16K 31/1262
20130101; E21B 41/0021 20130101; F15B 2211/7052 20130101; E21B
41/00 20130101; F16K 17/00 20130101; Y10T 137/0318 20150401; Y10T
137/7769 20150401; E21B 34/02 20130101; E21B 34/10 20130101; E21B
34/16 20130101; Y10T 137/7762 20150401; E21B 34/06 20130101; Y10T
137/777 20150401; F15B 2211/31576 20130101; F15B 2211/6303
20130101; F16K 3/0254 20130101 |
International
Class: |
G05D 7/06 20060101
G05D007/06; E21B 34/02 20060101 E21B034/02; E21B 41/00 20060101
E21B041/00 |
Claims
1. A control system for controlling fluid flow through a flow line
at a wellsite, the control system comprising: a fluid supply; a
first fluid line in fluid communication with the fluid supply; a
pump in fluid communication with the first fluid line and
configured to pump fluid from the fluid supply to one or more
wellheads through the first fluid line; a second fluid line in
fluid communication with the first fluid line at a location
downstream of the pump and configured to return fluid from the
first fluid line to the fluid supply or another reservoir; a safety
valve in-line with the second fluid line and having a gate normally
maintained in a closed position to close fluid flow through the
second fluid line; a valve actuator configured to move the gate
into the closed position by fluid supplied into the valve actuator
and configured to move the gate into an open position by a biasing
member disposed in the valve actuator; an electronic controller
assembly programmed with a predetermined condition and configured
to receive a signal from a transducer connected to the first fluid
line, wherein the signal corresponds to a measured physical
property; a valve assembly in communication with the controller
assembly; and a fluid drive assembly in communication with the
controller assembly, wherein the controller assembly is operable to
actuate the fluid drive assembly to supply fluid into the valve
actuator to move the gate into the closed position, and wherein the
controller assembly is operable to actuate the valve assembly in
response to a comparison of the measured physical property to the
predetermined condition to release the fluid from the valve
actuator so that the biasing member moves the gate into the open
position, forces the fluid out of the valve actuator, and thereby
opens fluid flow through the second fluid line to return fluid in
the first fluid line back to the fluid supply or another
reservoir.
2. A control system for controlling fluid flow through a flow line
at a wellsite, the control system comprising: a fluid supply; a
first fluid line in fluid communication with the fluid supply; a
pump in fluid communication with the first fluid line and
configured to pump fluid from the fluid supply to one or more
wellheads through the first fluid line; a second fluid line in
fluid communication with the first fluid line at a location
downstream of the pump and configured to relieve fluid from the
first fluid line; a safety valve in-line with the second fluid line
and normally maintained in a closed position to close fluid flow
through the second fluid line; a valve actuator configured to move
the safety valve into the closed position by fluid supplied to the
valve actuator and configured to move the safety valve into an open
position by a biasing member disposed in the valve actuator; an
electronic controller assembly programmed with a predetermined
condition and configured to receive a signal from a transducer
connected to the first fluid line, wherein the signal corresponds
to a measured physical property; a valve assembly in communication
with the controller assembly; and a fluid drive assembly in
communication with the controller assembly, wherein the controller
assembly is operable to actuate the fluid drive assembly to supply
fluid to the valve actuator to move the safety valve into the
closed position, and wherein the controller assembly is operable to
actuate the valve assembly in response to a comparison of the
measured physical property to the predetermined condition to
release fluid from the valve actuator so that the biasing member
moves the safety valve into the open position, forces fluid out of
the valve actuator, and thereby opens fluid flow through the second
fluid line to relieve fluid from the first fluid line.
3. The system of claim 2, further comprising a housing for
supporting the controller assembly, the valve assembly, and the
fluid drive assembly.
4. The system of claim 3, wherein the fluid supplied into the valve
actuator by the fluid drive assembly is supplied from a reservoir
disposed outside of the housing.
5. The system of claim 2, wherein the fluid drive assembly is a
compressor and the fluid is a pneumatic fluid.
6. The system of claim 2, wherein the fluid drive assembly is a
pump and the fluid supplied into the valve actuator by the fluid
drive assembly is a hydraulic fluid.
7. The system of claim 2, further comprising a power source for
supplying power to the controller assembly, the valve assembly, and
the fluid drive assembly.
8. The system of claim 2, further comprising a housing for
supporting the fluid drive assembly, and a filter attached to the
housing for filtering fluid entering the housing by the fluid drive
assembly.
9. The system of claim 2, wherein the fluid supplied into the valve
actuator by the fluid drive assembly is ambient air.
10. The system of claim 2, wherein the controller assembly is
operable to communicate a signal corresponding to the measured
physical property to a remote computer system.
11. The system of claim 2, wherein the controller assembly is a
programmable logic controller.
12. The system of claim 2, wherein the measured physical property
is pressure in the first fluid line.
13. A method for controlling fluid flow through a flow line at a
wellsite, the method comprising: providing a control system
comprising: a fluid supply; a first fluid line in fluid
communication with the fluid supply; a pump in fluid communication
with the first fluid line and configured to pump fluid from the
fluid supply to one or more wellheads through the first fluid line;
a second fluid line in fluid communication with the first fluid
line at a location downstream of the pump and configured to relieve
fluid from the first fluid line; a safety valve in-line with the
second fluid line, a valve actuator configured to actuate the
safety valve, an electronic controller assembly, a fluid drive
assembly, and a valve assembly; supplying fluid to the valve
actuator using the fluid drive assembly to actuate the valve
actuator to move the safety valve into a closed position;
maintaining the safety valve in the closed position to close fluid
flow through the second fluid line; monitoring a physical property
in the first fluid line using the controller assembly; and
actuating the valve assembly using the controller assembly to
release fluid from the valve actuator so that a biasing member
disposed in the valve actuator moves the safety valve into an open
position, forces fluid out of the valve actuator, and thereby opens
fluid flow through the second fluid line based upon a comparison of
the monitored physical property to a predetermined condition to
relieve fluid from the first fluid line.
14. The method of claim 13, wherein the fluid supplied to the valve
actuator by the fluid drive assembly is a pneumatic fluid disposed
external to the housing, and further comprising filtering the
pneumatic fluid as it enters the housing by the fluid drive
assembly.
15. The method of claim 13, wherein the fluid supplied to the valve
actuator by the fluid drive assembly is a hydraulic fluid disposed
in a reservoir within the housing that is in fluid communication
with the fluid drive assembly.
16. The method of claim 13, further comprising measuring the
physical property using a transducer configured to communicate a
signal corresponding to the measured physical property to the
controller assembly.
17. The method of claim 13, wherein the fluid supplied to the valve
actuator by the fluid drive assembly is a pneumatic fluid, and
wherein the fluid drive assembly is a compressor.
18. The method of claim 13, wherein the fluid supplied to the valve
actuator by the fluid drive assembly is a hydraulic fluid, and
wherein the fluid drive assembly is a pump.
19. The method of claim 13, further comprising communicating a
signal from the controller assembly to a remote computer system,
wherein the signal corresponds to an operational characteristic of
the safety valve.
20. The method of claim 13, further comprising actuating the safety
valve by communicating a signal from a remote computer system to
the controller assembly.
21. The method of claim 13, wherein the measured physical property
is pressure in the first fluid line.
22. (canceled)
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 15/262,642, filed Sep. 12, 2016, which claims
benefit of U.S. patent application Ser. No. 13/480,704, filed May
25, 2012, now U.S. Pat. No. 9,441,453, which claims benefit of U.S.
Provisional Patent Application Ser. No. 61/551,319, filed Oct. 25,
2011 and is a continuation-in-part of U.S. patent application Ser.
No. 13/195,662, filed Aug. 1, 2011, which claims benefit of U.S.
Provisional Patent Application Ser. No. 61/415,238, filed Nov. 18,
2010, and U.S. Provisional Patent Application Ser. No. 61/370,721,
filed Aug. 4, 2010, the disclosures of which are herein
incorporated by reference in their entirety.
BACKGROUND OF THE INVENTION
[0002] Field of the Invention
[0003] Embodiments of the invention relate to a wellhead control
system for oil and gas wells. In particular, embodiments of the
invention relate to systems and methods of an emergency shut down
control system for surface and subsurface safety valves.
Embodiments of the invention further relate to systems and methods
of a relief valve control system.
[0004] Description of the Related Art
[0005] A wellhead system may be used to control the flow of fluids
recovered from an oil and gas well in a safe and efficient manner.
The wellhead system may include a variety of flow control devices,
such as valves, which are operable direct fluid flow through a
tubing system connected to the wellhead system. Fluids can be
directed downstream of the wellhead system via the tubing system
for further processing and/or storage.
[0006] The wellhead system may include surface and subsurface
safety valves that are connected to the tubing system and are
operable to shut off fluid flow through the tubing system in the
event of an emergency in the well or at a location downstream of
the wellhead system. Prior art safety valves are generally in fluid
communication with the tubing system, and utilize the fluids
therein for operation. For example, the pressure in the tubing
system may be directly tied into the safety valves to actuate the
valves into an open position, thereby allowing fluid flow through
the system. In the event of an emergency, such as a rupture in the
tubing system downstream of the safety valve or a drop in pressure
in the well, as the pressure in the tubing system drops, so does
the pressure in the safety valves. The safety valves are configured
to move into a closed position after the pressure therein falls
below a minimum pressure, thereby closing fluid flow through the
tubing system and shutting in the wellhead system. Some safety
valves may also be equipped with relief valves that are operable to
block pressure from entering the valve and exhaust the pressure in
the valve, thereby allowing the valve to move into a closed
position.
[0007] There are numerous drawbacks to the prior art safety valve
systems. One drawback includes the reliance of the safety valves on
fluid pressure in the tubing system. These safety valves cannot be
unilaterally operated as desired. Another drawback includes
regular, manual maintenance of the safety valves to ensure that
they are fully operational. Another drawback includes the potential
pollution to the environment when fluid in the safety valves are
exhausted into the atmosphere.
[0008] In some wellbore operations, such as when conducting a
fracking operation, a high volume pressurized fluid is pumped to a
manifold, which directs the fluid to one or more wells for
fracturing the formation below. In the event that flow through the
flow or fluid lines to the manifold and/or in the wells experience
an interruption or become plugged, the highly pressurized fluid
volume can cause catastrophic failure of the fluid lines, the
wells, and any other equipment surrounding the wellsite, which can
even potentially harm workers at the wellsite. Conventional relief
valve systems are inefficient at detecting a failure, have slow
response times, and/or are only one-time use, which require
complete replacement in the event of operation.
[0009] Therefore, there is a need for a new and improved safety
control valve system that is self reliant, can be remotely operated
and monitored real-time, and can automatically shut in and/or
relieve a wellhead system in the event of an emergency or when
desired.
SUMMARY OF THE INVENTION
[0010] In one embodiment, a control system for controlling a safety
valve attached to a flow line at a wellsite is provided. The
control system includes a housing. The control system further
includes a controller assembly disposed within the housing. The
controller assembly is configured to receive a signal from a
transducer connected to the flow line, wherein the signal
corresponds to a measured physical property. Further, the control
system includes a valve assembly disposed within the housing and in
communication with the controller assembly. The control system
further includes a compressor assembly disposed within the housing
and in communication with the controller assembly. Additionally,
the control system includes a power source disposed within the
housing. The power source is configured to supply power to the
controller assembly, the valve assembly, and the compressor
assembly. The controller assembly is operable to cause the
compressor assembly to supply pneumatic fluid to the safety valve
to actuate the safety valve to an open position, wherein the
controller assembly is operable to cause the valve assembly to
actuate the safety valve to a closed position.
[0011] In one embodiment, a method for controlling a safety valve
attached to a flow line at a wellsite is provided. The method
includes the step of positioning a control system adjacent the
safety valve. The control system has a controller assembly, a
compressor assembly, and a power source disposed within a housing
of the control system. The method further includes the step of
supplying pneumatic fluid from the compressor assembly to the
safety valve to open the safety valve. The method also includes the
step of receiving a signal in the controller assembly corresponding
to a sensed physical property in the flow line. Additionally, the
method includes the step of closing the safety valve in response to
a comparison of the sensed physical property to a pre-set
condition.
[0012] In one embodiment, a control system for controlling a safety
valve attached to a flow line at a wellsite may comprise a
controller assembly configured to receive a signal from a
transducer connected to the flow line, wherein the signal
corresponds to a measured physical property; a valve assembly in
communication with the controller assembly; and a fluid drive
assembly in communication with the controller assembly, wherein the
controller assembly is operable to actuate the fluid drive assembly
to supply fluid to the safety valve to actuate the safety valve to
a first position, and wherein the controller assembly is operable
to actuate the valve assembly to actuate the safety valve to a
second position.
[0013] In one embodiment, a method for controlling a safety valve
attached to a flow line at a wellsite may comprise providing a
control system for positioning adjacent to the safety valve,
wherein the control system includes a housing, a controller
assembly, a fluid drive assembly, and a valve assembly; supplying
fluid to the safety valve using the fluid drive assembly to actuate
the safety valve into a first position; monitoring a physical
property in the flow line using the controller assembly; and
actuating the valve assembly using the controller assembly to
actuate the safety valve into a second position based upon a
comparison of the monitored physical property to a predetermined
condition.
[0014] In one embodiment, a method for controlling a safety valve
attached to a flow line at a wellsite may comprise providing a
remotely operable control system for positioning adjacent to the
safety valve; actuating the safety valve into a closed position
using the control system; monitoring fluid pressure in the flow
line using a transducer in communication with the control system
while maintaining the safety valve in the closed position; and
actuating the safety valve into an open position using the control
system when the monitored fluid pressure reaches or exceeds a
predetermined fluid pressure to relieve fluid pressure in the flow
line.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] So that the manner in which the above recited features of
the invention can be understood in detail, a more particular
description of the invention, briefly summarized above, may be had
by reference to embodiments, some of which are illustrated in the
appended drawings. It is to be noted, however, that the appended
drawings illustrate only typical embodiments of this invention and
are therefore not to be considered limiting of its scope, for the
invention may admit to other equally effective embodiments.
[0016] FIG. 1 illustrates a wellhead control system according to
one embodiment.
[0017] FIG. 2 illustrates a safety valve control system according
to one embodiment.
[0018] FIG. 3 illustrates a surface safety valve according to one
embodiment.
[0019] FIG. 4 is a sectional view of a gate valve, an actuator, a
mechanical override, and a safe mode indicator.
[0020] FIG. 5 is a sectional view of the gate valve in an open
position after a manual operation of the mechanical override.
[0021] FIG. 6 is a sectional view of the gate valve in the open
position after an automatic operation of the actuator and with the
safe mode indicator indicating that the gate valve is operating in
a safe mode.
[0022] FIG. 7 is a sectional view of the gate valve in the open
position after the automatic operation of the actuator, the
mechanical override having been partially actuated, and the safe
mode indicator indicating that the gate valve is not operating in
the safe mode.
[0023] FIG. 8 is a cross-sectional view of the mechanical override
along section line 8-8 in FIG. 4.
[0024] FIG. 9 is a sectional view of the gate valve in an open
position after an automatic operation of the actuator.
[0025] FIGS. 10A-10H and 11-11D illustrate a valve assembly
according to one embodiment.
[0026] FIG. 12 is a sectional view of a valve in a fail-safe opened
position.
[0027] FIG. 13 illustrates a safety valve control system according
to one embodiment.
[0028] FIG. 14 illustrates a well control system according to one
embodiment.
[0029] FIG. 15 illustrates the well control system according to one
embodiment.
DETAILED DESCRIPTION
[0030] FIG. 1 illustrates a wellhead control system 100 of an
oil/gas well according to one embodiment. The wellhead control
system 100 is configured to control the recovery of fluids, such as
hydrocarbons, from a reservoir through a primary wellbore 105. The
wellhead control system 100 includes a tree 110 having a series of
valve and flow control devices, a surface safety valve 120 in
communication with the tree 100 via tubing 115, and a subsurface
safety valve 130 in communication with the tree 100 via tubing 125.
The subsurface safety valve 130 may also be in communication with a
well production flow line 145 used to recover oil and/or gas from
the oil/gas well. The surface safety valve 120 may also be in
communication with a surface production flow line 135 used to
direct any recovered fluids to one or more locations downstream of
the wellhead control system 100 for further processing and/or
storage. In one embodiment, the safety valves 120, 130 may include
pneumatically or hydraulically actuated valves. In one embodiment,
the safety valves 120, 130 may include pneumatic valves that are
operated using hydraulic fluid. Each of the safety valves 120, 130
may include a self contained emergency shut down ("ESD") control
system, identified as items 200, 300, and 700, respectively, that
(1) may be operable to automatically close the safety valves 120,
130; (2) may be operable to be continuously monitored and/or
operated (opened and closed) in real-time from a remote location;
and (3) may be operable to verify at all times the operating
condition/characteristics of the safety valves 120, 130, and
various other components of the control system.
[0031] The ESD control systems 200, 300 may be "self-contained,"
which means that they do not depend on any external pneumatic,
hydraulic, mechanical, or electrical sources for their operation to
shut down the oil/gas well. For example, if there is a rupture of a
production flow line downstream from the surface safety valve 120,
and/or if there is a loss of well pressure at the subsurface safety
valve 130, the ESD control systems 200, 300 are operable to
effectively close the safety valves 120, 130, thereby shutting in
the oil/gas well, and alert the appropriate personnel that a
shut-in has occurred without the assistance of any additional
external pneumatic, hydraulic, mechanical, or electrical power
sources. All of the operating fluids and mechanisms necessary to
operate the safety valves 120, 130 are maintained within the ESD
control systems 200, 300 so that there is no pollution of the
environment, and so that any fluids and/or gases from the oil/gas
well may be effectively contained therein without any additional
external dependencies.
[0032] FIG. 2 illustrates the ESD control system 200 according to
one embodiment. Embodiments of the ESD control system 200 described
herein are equally applicable to the ESD control system 300 (and
vice versa). The ESD control system 200 may include a housing 210
for supporting a controller assembly 220, a power source 230, a
pump assembly 240, a fluid reservoir 250, a valve assembly 260, and
a solar panel assembly 270. The ESD control system 200 may also
include one or more transducers/devices 280, 282, 284, 286, and 288
for monitoring and/or measuring one or more physical properties
(further described below). In embodiment, the ESD control system
200 may be configured to control one or more valves, such as flow
control valves or choke valves, that are in communication with the
flow lines of the valves 120, 130 to control fluid flow through the
wellhead control system 100
[0033] The housing 210 may include any structural support member,
such as an explosion-proof container, for protecting the components
stored therein from damage and environmental elements. Appropriate
ventilation of the housing 210 may be provided by ventilation holes
and/or an independent solar powered fan mounted in or through the
housing 210. The housing 210 may further include an access panel or
door for ease of access to the housing's interior, and may be
configured for attachment to the tree 110 or the respective surface
and subsurface safety valve 120, 130. One or more manifold
assembles 212, 214, 216 may be provided on the housing 210 for
fluid and/or electrical connections between the housing 210 (and
the components within the housing 210) and the safety valves 120,
130, the solar panel assembly 270, and the transducer 280. In one
embodiment, the manifold assembly 216 includes a solar converting
charger device. In one embodiment, the structural components of the
ESD control systems 200, 300, to the extent possible, may be made
from stainless steel.
[0034] The controller assembly 220 may be disposed in the housing
210 and may include a microprocessor unit 222, a display screen
224, and a keypad 226. In one embodiment, the controller assembly
220 may be weather-proof, and may be intrinsically safe to provide
power as necessary to one or more components of the ESD control
systems 200, 300. In one embodiment, the controller assembly 220
may be positioned external to and/or adjacent to the housing 210.
The microprocessor unit 222 may include a programmable logic
controller, including a supervisory control and data acquisition
system (SCADA) that is in communication with the one or more
transducers/devices 280, 282, 284, 286, and 288, as well as the
pump and valve assemblies 240, 260. The microprocessor unit 222 may
include a current regulator to provide low current transmission
between the controller assembly 220 and the various components of
the control system. A watchdog sensor 228 may be used to monitor
the operation of the microprocessor unit 222 and provide an alarm
in the event of a failure. The controller assembly 220 may be
operable to send and receive signals with a computer system 150
(such as a desktop computer, laptop computer, or personal digital
assistant (PDA)) at a remote location from the wellhead control
system 100. In one embodiment, the signals may be sent and/or
received between the controller assembly 220 and the computer
system 150 via wired and/or wireless telemetry means, including but
not limited to electrical wires, fiber optical cables, radio
frequency, infrared, microwave, satellite, and/or laser light
communication. In this manner, the ESD control systems 200, 300,
700 can be monitored and operated remotely from one or more
locations on-site or off-site relative to the wellhead control
system 100. In one embodiment, the ESD control systems 200, 300,
700 may be configured for manual and/or remote operation on-site at
the wellhead control system 100. In one embodiment, the controller
assembly 220 may be programmed with one or more trigger points,
such as upstream and/or downstream high and/or lower pressure
points, that will automatically trigger operation of the ESD
control system 200, 700 upon sensing a pressure outside of the
trigger point ranges. In one embodiment, the controller assembly
220 may be configured with a "master/slave" polling protocol or a
"master/master" polling protocol as known in the art to retrieve
and communicate information regarding the ESD control system 200,
700 as desired.
[0035] In one embodiment, the controller assembly 220 may be in
communication with a pressure transducer 280 that is connected to
the surface production flow line 135 as illustrated in FIG. 1. The
pressure transducer 280 can measure the pressure in the flow line
135 and communicate a signal corresponding to the measured pressure
to the controller assembly 220. The pressure transducer 280 can be
connected at various other locations within the wellhead control
system 100, such as at the tree 110 or the tubing 115, 125. In one
embodiment, the transducer 280 can be used to measure fluid flow
rate or detect hydrogen sulfide. In one embodiment, one or more
transducers 280 may be used to measure and/or detect additional
well characteristics at the wellhead control system 100 and
communicate the measured/detected well characteristics to the
controller assembly 220 via a signal corresponding to the
measurement or detection for comparison to one or more
predetermined conditions.
[0036] Regarding the pressure transducer 280, the signal may be
recorded and/or communicated to the computer system 150 via the
controller assembly 220 to provide real-time monitoring of the
pressure in the flow line 135. The measured pressure may be
displayed on the display screen 224 and/or on a display screen of
the computer system 150. In response to the measured pressure, the
controller assembly 220 may be configured to operate the respective
safety valve 120, 130 to which it is connected. For example, the
controller assembly 220 may be used to direct the pump assembly 240
and the valve assembly 260 to supply fluid from the fluid reservoir
250 to the surface safety valve 120 to open the valve. Upon
receiving the signal from the controller assembly 220, the valve
assembly 260 may be configured to open a circuit defined by lines
211, 213, 215 between the surface safety valve 120 and the fluid
reservoir 250 to allow the pump assembly 240 to direct pressurized
fluid from the fluid reservoir 250 to the surface safety valve 120,
thereby opening the surface safety valve 120. The surface safety
valve 120 may be maintained in the open position while the pressure
transducer 280 continuously monitors the pressure in the flow line
135. The controller assembly 220 may be programmed to close the
surface safety valve 120 upon receiving a signal from the pressure
transducer 280 that corresponds to a pressure measurement that is
greater than or less than a predetermined condition, such as a
pre-set pressure range. The pre-set pressure range may be input
into the controller assembly 220 by manual entry using the keypad
226 and the display screen 224. The pre-set pressure range may also
be input into the controller assembly 220 remotely from the
computer system 150. When the signal is received from the pressure
transducer 280 that the pressure in the flow line 135 falls outside
of the pre-set pressure range stored in the microprocessor unit
222, the controller assembly 220 may automatically direct the valve
assembly 260 and/or the pump assembly 240 to return the fluid from
the surface safety valve 120 to the fluid reservoir 250. Upon
receiving the signal from the controller assembly 220, the valve
assembly 260 may be configured to open a circuit defined by lines
211, 217 between the surface safety valve 120 and the fluid
reservoir 250 to allow the pressurized fluid to dump into the fluid
reservoir 250, thereby closing the surface safety valve 120. In one
embodiment, a closing pressure generated by the surface safety
valve 120 may be used to force the fluid into the fluid reservoir
250. Continuous real-time monitoring of the pressure in the flow
line 135 may be used to verify that the surface safety valve 120
has been closed.
[0037] The ESD control systems 200, 300, 700 may be adjusted at
anytime and can be configured to shut in the wellhead control
system 100 at anytime manually and/or remotely. In particular, the
microprocessor unit 222 can be programmed with one or more pre-set
conditions, manually using the display screen 224 and keypad 226
and/or remotely via the computer system 150. The pre-set conditions
may be changed at anytime. And when a signal is received from one
or more of the various transducers/devices and/or the computer
system 150 that conflicts with the pre-set conditions when
compared, the controller assembly 220 may be operable to
automatically close the safety valve 120, 130 to which it is
connected. The controller assembly 220 may be operable when the
signal is above the pre-set condition or when the signal is below
the pre-set condition. Continuous real-time monitoring of the ESD
control systems 200, 300, 700 may be used to verify the operating
condition/characteristics of the wellhead control system 100
components at all times.
[0038] In one embodiment, the ESD control systems 200, 300, 700 may
communicate an auditory, visual, or other similar type of sensory
signal that the wellhead control system 100 has been shut in. In
one embodiment, the controller assembly 220 may send a signal to
the computer system 150 that can be converted into an alarm to
alert an operator of the shut-in. In one embodiment, the controller
assembly 220 may send a signal to trigger an indication device 282,
such as an auditory and/or visual alarm disposed interior or
exterior of the housing 120, to alert an operator within close
proximity of the wellhead control system 100 of the shut-in.
[0039] In one embodiment, the ESD control systems 200, 300, 700 may
include an emergency shutdown device 284 manually and/or remotely
operable to automatically give an alarm and send a signal to the
controller assembly 220 to shut in the wellhead control system 100.
In one embodiment, the ESD control systems 200, 300, 700 may
include a fire device 286 that senses heat, and automatically gives
an alarm and shuts in the wellhead control system 100 via the
controller assembly 220 when the measured heat exceeds a certain
temperature. In one embodiment, the ESD control systems 200, 300,
700 may include an anti-intrusion device 288 that when activated
automatically gives an alarm and shuts in the wellhead control
system 100 via the controller assembly 220, for example when a
theft is attempted or the control system sustains some type of
structural damage. In one embodiment, one or more of the
transducers 282, 284, 286, 288 may be used to detect hydrogen
sulfide (H2S), other gases and vapors, and/or the level of fluid in
one or more storage tanks that are in fluid communication with the
valves 120, 130. Each of the devices 284, 286, 288 may be
continuously monitored real-time using the controller assembly 220
via the computer system 150 to verify operating
conditions/characteristics of the wellhead control system 100.
[0040] Power may be provided to the controller assembly 220 and the
pump assembly 240 from the power source 230. The power source 230
may be operable to provide a low current (amp) stream to the
controller assembly 220 and/or the pump assembly 240. In one
embodiment, the power source 230 may include an intrinsically-safe
battery, such as a 12 or 24 volt, direct current, explosion-proof
power supply. In one embodiment, the power source 230 may include a
watchdog sensor 232 to communicate to the computer system 150 via
the controller assembly 220 a failure of the power source. The
watchdog sensor 232 may also give an auditory or visual alarm to
alert an operator onsite that the power source 230 is low and/or
dead. The controller assembly 220 may be configured to
automatically shut in the wellhead control system 100 upon
receiving a signal from the sensor 232. In one embodiment, the
power source 230 may be a (re-chargeable) power supply that is
supported by the solar panel assembly 270. The solar panel assembly
270 may include one or more solar panels 272 connected to the
exterior of the housing 210 to consume light energy from the sun to
generate electricity. The solar panels 272 may be connected to the
exterior of a housing 730 in the ESD control system 700. An
intrinsically safe voltage controller 274 may deliver electrical
current at an appropriate voltage, 12 or 24 volts for example, to
the power source 230, which in turn supplies power to the
controller assembly 220 and/or pump assembly 240. In one
embodiment, the solar panel assembly 270 may be configured to
provide enough power to the ESD control systems 200, 300, 700 to
open and close the safety valves 120, 130 ten or more times from
about two hours of sunlight per day.
[0041] In one embodiment, the pump (or fluid drive) assembly 240
may include an intrinsically safe motor 242 and a pump 244, which
may each be located in the explosion-proof housing 210. The pump
244 may include a rotary piston pump with about a 100 to 10,000 psi
range. The pump assembly 240 may pump pneumatic and/or hydraulic
fluid from the fluid reservoir 250 to actuate the safety valve 120,
130 to which it is connected.
[0042] In one embodiment, the fluid reservoir 250 may be configured
to store an amount of operating fluid sufficient to actuate the
safety valve 120, 130 to which it is connected. The operating fluid
may include air, water, propylene glycol, and other valve operating
fluids known in the art. In one embodiment, the fluid reservoir 250
may include a level gauge 252, such as a sight glass, to indicate
the level of fluid in the fluid reservoir 250. The fluid reservoir
may also include a level sensor 252 that is in communication with
the controller assembly 220 and is operable to monitor in real-time
the level of fluid in the fluid reservoir 250. In the event that
the level of fluid falls below a pre-set limit, due to evaporation
of the fluid for example, the level sensor 252 may provide an alarm
to alert an operator on-site at the wellhead control system 100
and/or at the remote location via the controller assembly 220 and
the computer system 150. The controller assembly 220 may
automatically shut in the wellhead control system 100 upon
receiving a signal from the level sensor 252.
[0043] In one embodiment, the valve assembly 260 may include one or
more (intrinsically safe) valves 262 to control and direct
communication between the pump assembly 240, the fluid reservoir
250, and the safety valve 120, 130 to which it is connected. The
one or more valves 262 may include solenoid valves, shuttle valves,
and/or any other type of valves operable to open and close the
fluid circuits between the pump assembly 240, the fluid reservoir
250, and the safety valve 120, 130 to which it is connected. The
valve assembly 260 may include an internal relief valve and/or
circuit to rapidly expel the fluid from the safety valves 120, 130
to the fluid reservoir 250 to ensure quick closure of the safety
valves 120, 130. The valve assembly 260 may include one or more
gauges, such as pressure gauge 264, which can be visually inspected
to monitor the pressure in the valve assembly 260 flow lines. In
one embodiment, the pressure gauge 264 may be configured to shut
off the pump assembly 240 when the pressure in the actuator of the
safety valves 120, 130 reaches a pre-determined pressure setting.
The one or more valves 262 may be controlled by the controller
assembly 220 as described above.
[0044] In one embodiment, the display screen 224 and/or one or more
gauges may be mounted through a front panel of the housing 210, 730
to indicate pressure within the various valves and lines in fluid
communication with the ESD control systems 200, 300, 700 and the
wellhead control system 100.
[0045] FIG. 3 illustrates a surface safety valve 120 according to
one embodiment. The surface safety valve 120 may include a valve
actuator 122 for moving a gate valve 124 between an open and closed
position. Pressurized fluid from the fluid reservoir 250 of the ESD
control system 200 or pressurized fluid from the ESD control system
700 may be supplied to a chamber 123 of the valve actuator 122 via
tubing 201 to open the gate valve 124. A biasing member 127, such
as a spring disposed within the valve actuator 122 may be used to
close the gate valve 124 when the force of the biasing member
exceeds the fluid pressure in the valve actuator chamber 123. The
valve actuator 122 may also include a top shaft 126 that can be
used to manually actuate the valve actuator 122 by rotation of a
hand wheel 128 to open and close the gate valve 124. The top shaft
126 may also be used as a visual indication to determine whether
the gate valve 120 is in an open or closed position. For example,
when the top shaft 126 is fully extended outward from the upper end
of the valve actuator 122, the gate valve 124 may be in a closed
position, and when the top shaft 126 is retracted into the upper
end of the valve actuator 122, the gate valve 124 may be in an open
position.
[0046] In one embodiment, the ESD control systems 200, 300, 700 may
include a position indication assembly 290 that is operable to
indicate whether the surface safety valve 120 is in an open or
closed position, including any partial open/closed position
therebetween, based on the location of the top shaft 126. As
illustrated in FIG. 3, when the top shaft 126 is in a fully
extended position, the surface safety valve 120 is in the closed
position. As the surface safety valve 120 begins to open and is
moved either manually or automatically to the open position, the
top shaft 126 will retract into the upper end of the valve actuator
122. The position indication assembly 290 may include one or more
sensors 292 operable to sense the extension and retraction of the
top shaft 126. The sensors 292 may communicate a signal to the
controller assembly 220 corresponding to the measured position,
which may then send a signal to the computer system 150 and display
the measured position on a display screen. In this manner, an
operator can continuously monitor and verify the position of the
surface safety valve 120 at all times. The position indication
assembly 290 can also be used to verify that the surface safety
valve 120 is closed in the event that one of the other ESD control
system 200, 700 components initiated a shut-in of the wellhead
control system 100. In one embodiment, the sensors 292 may include
magnetic sensors operable to sense a magnetic material of the top
shaft 126. For example, one or more sensors 292 may be positioned
at various locations along the longitudinal stroke of the top shaft
160 during opening and closing of the gate valve 124. When the top
shaft 160 is fully extended, all of the sensors 292 may sense the
magnetic material of the shaft, thereby indicating that the gate
valve 124 is closed. However, when the top shaft 160 is fully
retracted, only the sensors 292 closest to the upper end of the
valve actuator 122 may sense the magnetic material of the shaft,
thereby indicating that the gate valve 124 is open. In one
embodiment, the sensors 292 may include other types of position
sensors known in the art to monitor and measure the position of the
top shaft 126.
[0047] In one embodiment, the ESD control system 200, 300, 700 can
be used to partially stroke the safety valves 120, 130. In one
embodiment, the controller assembly 220 may be configured to direct
the pump assembly 240 and valve assembly 260 to supply an amount of
operating fluid to the safety valves 120, 130 to partially open the
safety valves. In one embodiment, the controller assembly 220 may
be configured to direct the pump assembly 240 and valve assembly
260 to return an amount of operating fluid from the safety valves
120, 130 to partially close the safety valves. The controller
assembly 220 may be programmed to automatically conduct a partial
stroke of the safety valves 120, 130 after a pre-set amount of time
or other condition. The controller assembly 220 may be manually
and/or remotely operable to conduct a partial stroking of the
safety valve to which it is connected when desired. The sensors 292
of the position indication assembly 290 can be used to monitor and
verify the partial stroke of the safety valves 120, 130, based on
the position of the top shaft 126. The partial stroking of the
safety valves 120, 130 can assist in preventing/removing build-up
of debris within the valves from the fluids flowing therethrough,
which can potentially prevent complete opening and/or closing of
the valves when necessary.
[0048] In one embodiment, the ESD control systems 200, 300, 700 may
be configured to perform a specific sequential opening and closing
of the safety valves 120, 130 when starting up or shutting in the
wellhead control system 100. In one embodiment, either ESD control
system 200, 300, 700 may initiate closure or opening of the surface
safety valve first 120, and then closure or opening of the
subsurface safety valve 130. In one embodiment, either ESD control
system 200, 300, 700 may initiate closure or opening of the
subsurface safety valve first 130, and then closure or opening of
the surface safety valve 120. In one embodiment, if one of the ESD
control system 200, 700 components initiates a shut-in, the
controller assembly 220 may automatically send a signal to the
computer system 150, which may then automatically send a signal to
the controller assembly of the ESD system 300 to initiate closing
of the subsurface safety valve 130. After closure of the subsurface
safety valve 130 is verified by the ESD control system 300 via the
computer system 150, another signal may be sent to the ESD control
system 200, 700 to then initiate closing of the surface safety
valve 120. The reverse process may be performed beginning with the
ESD control system 300 if closure of the surface safety valve 120
is required prior to closure of the subsurface safety valve
130.
[0049] In one embodiment, a method for controlling a wellhead
control system having a plurality of valves, including a surface
safety valve and a subsurface safety valve, may include producing
power with solar panel assembly and delivering the produced power
to a controller assembly and to a pump assembly that supplies
operating fluid to the valves, the control assembly operable to
monitor a variety of conditions in an oil/gas well and at the
wellhead control system. The controller assembly may be used to
control the operation of the pump assembly and the valves manually,
remotely, automatically, and/or in response to one or more pre-set
conditions programmed in the controller assembly. The solar panel
assembly may provide to a power source or directly to a pump
assembly to operate a motor of the pump assembly, which in turn
operates a pump of the pump assembly. The motor may be controlled
by the controller assembly. The controller assembly may include a
microprocessor and its related apparatuses, circuits, devices,
switches, etc. The power produced by the solar panel assembly may
be stored in a power source, such as in one or more battery
apparatuses for use on demand. The use and flow of the stored power
may be controlled and/or monitored by the controller assembly. The
pump assembly may supply operating fluid (hydraulic and/or
pneumatic) at a low or high pressure to operate either of both of
the safety valves as directed by the controller assembly. The
pre-set condition may include a fluid flow parameter, a flow line
condition, an alarm, an emergency condition, and/or an intrusion of
the components of the wellhead control system, including the valves
and the controller assembly.
[0050] The voltages of power from the solar panel assembly may be
controlled with a voltage controller having a sensor provide an
alert signal, an alarm signal, and/or a shut-off signal if a
pre-set voltage is exceeded or is not provided. One or more sensors
may be provided to sense an amount and/or pressure of available
operating fluid in any or all of the flow lines used and/or in a
fluid reservoir, the sensor(s) providing a signal to indicate fluid
volume and/or fluid pressure to the controller assembly. In
response to the signal, the controller assembly may operate one or
more of the valves and/or shut in the wellhead control system. The
controller assembly may signal other devices, such as the pump
assembly or a valve assembly to increase fluid pressure and/or
fluid amount in some or all of the flow lines. A sensor may signal
the controller assembly when a fire is detected and provide a fire
alarm. The controller assembly may provide a fire alarm signal to a
remote location and/or operate the valves to shut in the wellhead
control system. The signals of alarm, intrusion, etc. may be
provided at the immediate area of the wellhead control system and
to a remote location via known transmission methods.
[0051] The controller assembly may be operable to monitor the
various components of the wellhead control system and employing
intrinsically safe components. A single controller assembly may be
operable to control a surface safety valve, a subsurface safety
valve, as well as one or more additional valves in communication
with the wellhead control system. The controller assembly may be
operable to control the subsurface safety valve with an electric
submersible pump. The controller assembly may be operable to
remotely shut in the wellhead control system using switches
interconnected therewith, telephone, radio, SCADA, DCS and/or
satellite signals. One or more sensors may be use to detect
dangerous gases in the oil/gas well and/or at the wellhead control
system and producing an alarm signal in response. A thermoelectric
generator may be used instead of or in addition to a solar panel
assembly. The pre-set condition(s) may include one or more of the
following: the presence of fire or dangerous gases, intrusion by
unwanted humans or animals, vandalism, damage, or destruction of
equipment used in the wellhead control system, or too low to too
high fluid pressures, fluid volumes, power amperages, or power
voltages. In one embodiment, that various components of the control
system may be weather proof and "intrinsically safe," i.e. that
they require vastly reduced power levels and therefore minimize the
risk of sparks and explosions, e.g. less than 100 milliamps.
[0052] FIG. 4 is a sectional view of a mechanical override 400, an
actuator 401, a gate valve 402, and a safe mode indicator 403. The
actuator 401 couples to a valve body 404 of the gate valve 402. A
bonnet assembly can provide an interface between the gate valve 402
and the actuator 401. During an automatic operation of the gate
valve 402, hydraulic or pneumatic pressure enters a chamber 406 of
the actuator 401 defined by a cover 408 of the actuator 401 and a
diaphragm 410 positioned over an operator member 412. The operator
member 412 moves in response to the hydraulic or pneumatic pressure
within the chamber 406 and against a biasing force supplied by a
spring 418. A valve stem 414 coupled to a sliding gate 416 of the
gate valve 402 moves in response to the movement of the operator
member 412. In this manner, the automatic operation of the actuator
401 moves the sliding gate 416 of the gate valve 402 between a
closed position shown in FIG. 4 and an open position as shown in
FIG. 6.
[0053] In one embodiment, the actuator 401 may be selected from the
pneumatic and hydraulic actuators described in detail in U.S. Pat.
No. 6,450,477 which is herein incorporated by reference in its
entirety. The actuator 401 may be selected from any other actuator
known in the industry for moving the sliding gate 416 of the gate
valve 402 between the open and closed positions by automatic
operation.
[0054] When using the automatic operation of the actuator 401, the
biasing force of the spring 418 is configured to act as a fail-safe
mechanism. When the pressure in the actuator 401 is removed,
inadvertently or otherwise, the spring 418 will move the gate valve
402 into a fail-safe closed position illustrated in FIG. 4 or a
fail-safe opened position illustrated in FIG. 12. Although the
mechanical override 400 may provide an additional means to actuate
the gate valve 402 in the event of a failure, such as a loss of
pressure, it may also override the fail-safe mechanism. The
mechanical override 400 may prevent the spring 418 from moving the
gate valve 402 into the fail-safe closed position or the fail-safe
opened position. The gate valve 402 is operating in a safe mode
when the fail-safe mechanism has not been overridden by the
mechanical override and is not prevented or inhibited from moving
into the fail-safe closed position or the fail-safe opened
position. Therefore, the safe mode indicator 403 is configured to
provide a signal, such as a visual indication, communicating to a
valve operator that the valve is or is not operating in the safe
mode. The signal from the safe mode indicator 403 may also
communicate that (1) the valve will move to the fail-safe closed
position or the fail-safe opened position in the event of a
pressure loss in the actuator, (2) the valve has been automatically
actuated into the open position, and/or (3) the mechanical override
will not disable or interfere with the fail-safe mechanism.
[0055] As illustrated in FIG. 4, the mechanical override 400 is
connected to the actuator 401 to provide a manual operation for
moving the sliding gate 416 between open and closed positions. The
mechanical override 400 includes a top shaft 460, a lever for
manual rotation of the top shaft 460, such as a handwheel 500, a
housing 450 having a longitudinal bore therethrough, a drive sleeve
504 rotationally locked to the housing 450, and a top seal
cartridge 550. The housing 450 passes through an aperture 452 in
the cover 408 of the actuator 401. A shoulder 454 formed by a
portion of the housing 450 with an increased outer diameter
provides a stop for positioning the housing 450 in the aperture 452
of the cover 408. The housing 450 may be secured to the cover 408
by any known means such as a thread or by welding.
[0056] The housing 450 includes an upper bore 509, an inner
shoulder 511, a top bore 510, and a bottom bore 512. The inner
shoulder 511 is disposed below the upper bore 509, the top bore 510
is disposed below the inner shoulder 511, and the bottom bore 512
is disposed below the top bore 510. The bottom bore 512 has an
inner diameter greater than the top bore 510. A tapered shoulder
515 is located at the interface between the top bore 510 and the
bottom bore 512.
[0057] The top seal cartridge 550 is disposed in the upper bore 509
and can be removed for replacement as a single unit without
disassembling the actuator 401 or the mechanical override 400. The
top seal cartridge 550 is preferably formed of a plastic-like
material such as Delrin and is held in place by at least one
retainer ring 552 which is preferably stainless steel.
Accessibility to the retainer ring 552 without disassembly of the
actuator 401 permits removal of the retainer ring 552 from the top
of the housing 450, thereby allowing removal and replacement of the
top seal cartridge 550. The top seal cartridge 550 contains dual
reciprocating top shaft seals 556 and dual static seals 558 to
ensure seal integrity and long life. The top seal cartridge 550
incorporates rod wiper 554 to keep a shaft sealing region
therebelow clean of dirt, grease, and other contaminants for longer
life of the top shaft seals 556. The rod wiper 554 is preferably
made from Molythane 90. These and other seals may be T-seals or
other substantially elastomeric seals, such as O-ring seals.
[0058] The top shaft 460 extends through the longitudinal bore of
the housing 450, the top seal cartridge 550, and the drive sleeve
504. The inner diameter of the inner shoulder 511 is greater than
the outer diameter of the top shaft 460, but smaller than the outer
diameter of the drive sleeve 504. The inner shoulder 511 permits
axial movement of the top shaft 460 therethrough while providing a
backstop for the drive sleeve 504. The top shaft 460 may also
include a shoulder configured to engage an upper shoulder of the
drive sleeve 504 to prevent removal of the top shaft 460 from the
upper end of the drive sleeve 504.
[0059] The drive sleeve 504 is disposed in the housing 450 and is
movable within the top bore 510 and the bottom bore 512. The drive
sleeve 504 includes a threaded bore 516 that corresponds with a
drive thread 514 on an outside surface of the top shaft 460. In one
embodiment, the drive thread 514 is an Acme thread capable of
functioning under loads and includes a small number of threads per
inch, such as five, in order to decrease the work required to
manually operate the actuator 401. The drive thread 514 permits
unassisted rotation of the top shaft 460 with the handwheel 500.
The threaded engagement permits relative axial movement between the
top shaft 460 and the drive sleeve 504 within the housing 450. The
outer diameter of the upper portion of the drive sleeve 504 is
substantially the same as the inner diameter of the top bore 510 of
the housing 450. One or more seals 518, such as o-rings, are
provided on the outer diameter of the upper portion of the drive
sleeve 504 to form a sealed engagement with the top bore 510 of the
housing 450. One or more seals 519, such as o-rings, are provided
on the inner diameter of the upper portion of the drive sleeve 504
to form a sealed engagement with the top shaft 460.
[0060] In one embodiment, the lower end of the drive sleeve 504 is
configured to move axially relative to the bottom bore 512 of the
housing 450 while being rotationally locked relative to the housing
450. Any known rotational locking assembly that prevents rotation
of the drive sleeve 504 while permitting the drive sleeve 504 (and
the top shaft 460) to move axially within the housing 450 during
the automatic operation of the actuator 401 may be used. FIG. 8
illustrates a new rotational locking assembly by showing one
embodiment of a cross-section at sectional line 8-8 in FIG. 4. FIG.
8 illustrates the outer diameter of the lower end of the drive
sleeve 504 having an oval shape that corresponds to an oval shape
of the inner diameter of the housing 450. The oval shaped diameters
provide a physical interference that rotationally locks the drive
sleeve 504 to the housing 450 without inhibiting axial movement of
the drive sleeve 504 relative to the housing 450. The outer
diameter of the drive sleeve 504 and the bore of the housing 450
may be formed in a number of ways known by one of ordinary skill in
the art to prevent relative rotational movement while permitting
relative axial movement. In one embodiment, the lower portion of
the drive sleeve 504 may have one or more splines that extend into
one or more corresponding longitudinal grooves formed in the bottom
bore 512 of the housing 450 to permit relative axial movement but
prevent relative rotational movement. In one embodiment, the lower
portion of the drive sleeve 504 may be keyed to the bottom bore 512
with a pin that extends through corresponding longitudinal grooves
in the drive sleeve 504 and the bottom bore 512.
[0061] A coupling assembly 458 prevents longitudinal separation
between a retaining nut 462 secured to the operator member 412 and
the top shaft 460 while isolating rotational movement of the top
shaft 460 from the actuator 401 and the gate valve 402. The
coupling assembly 458 includes a female coupler 464 and ball
bearings 468. The lower end of the top shaft 460 rotates around the
upper end of the retaining nut 462 and against the ball bearings
468. A bottom shoulder 472 on the top shaft 460 is secured against
the ball bearings 468, which are positioned on the upper end of the
retaining nut 462, by the female coupler 464. The female coupler
464 is connected to the upper end of the retaining nut 462 and
includes an upper shoulder that engages the bottom shoulder 472 of
the top shaft 460 to prevent separation of the shaft from the
retaining nut 462 and thus the actuator 401 and the gate valve 402.
The top shaft 460 freely rotates relative to the retaining nut 462
and eliminates the transmission of torque to the valve stem 414,
the sliding gate 416, and/or components of the actuator 401 when
using the mechanical override 400.
[0062] Embodiments of the invention do not require the coupling
assembly connecting the top shaft 460 with the operator member 412.
The top shaft 460 of the mechanical override 400 may contact and
apply force directly to a portion of the actuator 401, such as the
retaining nut 462 or the operator member 412 depending on the type
of actuator used. For example, the end of the top shaft 460 may
directly contact the upper end of the retaining nut 462. The solid
retaining nut 462 may include a separate locking device to prevent
the retaining nut 462 from unthreading from the operator member 412
since the top shaft 460 rotates during the manual operation of the
mechanical override 400. Alternatively, other known rotation
isolation means may be provided to prevent transference of the
rotation of the top shaft 460 to other components within the
actuator 401 and the gate valve 402.
[0063] Referring to FIG. 6, a chamber 610 is formed within the
housing 450 between the top seal cartridge 550 and the drive sleeve
504. The chamber 610 is sealed at an upper end by the engagement
between the top seal cartridge 550, the upper bore 509, and the top
shaft 460, and at a lower end by the engagement between the drive
sleeve 504, the top bore 510, and the top shaft 460. Fluid
communication may be established between the chamber 610 and the
actuator 401 when the drive sleeve 504 is moved into the bottom
bore 512, as shown in FIG. 6. In particular, the seals 518 of the
drive sleeve 504 are moved across the tapered shoulder 515 into the
bottom bore 512, thereby releasing the sealed engagement with the
top bore 510. When the drive sleeve 504 is located in the bottom
bore 512 and fluid communication is established between the chamber
610 and the actuator 401, the gate valve 402 is operating in the
safe mode. When the gate valve 402 is operating in the safe mode,
the valve may be moved to the fail-safe closed position (shown in
FIG. 4) or the fail-safe opened position (shown in FIG. 12) by the
fail-safe mechanism without interference from the mechanical
override 400.
[0064] The safe mode indicator 403 communicates to a valve operator
when the valve is operating in the safe mode. The safe mode
indicator 403 includes an indication device 600, such as a sensor,
that is connected to the housing 450. The indication device 600 is
in fluid communication with the chamber 610 via an orifice 615
located through the housing 450. The pressure in the chamber 610
may be used to actuate the indication device 600 to communicate a
signal to the valve operator.
[0065] In one embodiment, when the chamber 610 is at a first
pressure, the indication device 600 may communicate a first signal
to the valve operator to indicate that the valve is not operating
in the safe mode. When the chamber 610 is at a second pressure that
is different than the first pressure, the indication device 600 may
communicate a second signal that is different than the first signal
to the valve operator to indicate that the valve is operating in
the safe mode. The pressure in the chamber 610 may be the pressure
directed into the actuator 401 when fluid communication is
established between the chamber 610 and the actuator 401, as shown
in FIG. 6. The pressure in the chamber 610 is communicated to the
indication device 600 through the orifice 615 to actuate the
indication device 600. In one embodiment, the first and/or second
pressures may be in a range from about 0 PSI to about 80 PSI, 150
PSI, or greater. In one embodiment, the first and/or second signals
may be a visual indication, such as a colored light or marker, an
auditory indication, and any other type of signal known to one of
ordinary skill.
[0066] In one embodiment, the indication device 600 may be any
commercial sensor, such as a pressure sensor, that can be used to
indicate a pressure change in the chamber 610. In one embodiment,
the indication device 600 may be a Rotowink Indicator, commercially
available through Norgen Ltd. The Rotowink Indicator is a
spring-loaded device actuated by air pressure for use in visual
monitoring of pneumatic or fluidic circuits. The device uses two
contrasting colors (e.g. black, red, yellow, green) on a rotating
ball that can be viewed from any angle to indicate the presence or
absence of pressure.
[0067] The operation of the invention illustrated in FIGS. 4, 5, 6,
7, 12 will now be described. FIG. 4 illustrates the gate valve 402
in the fail-safe closed position. The spring 418 provides a force
configured to bias the valve stem 414, the operator member 412, the
top shaft 460, and the drive sleeve 504 in an upward direction,
thereby positioning the sliding gate 416 in the closed position.
Seating of the sliding gate 416 in the closed position limits the
upward axial movement of the top shaft 460 and the drive sleeve
504. The mechanical override 400 is in an un-actuated position and
does not interfere with the closing of the gate valve 402. The bias
of the spring 418 raises the top shaft 460 to an extended position
providing a visual indication that the gate valve 402 is in the
closed position. The safe mode indicator 403 may provide a first
visual indication that the gate valve 402 is not automatically
actuated into the operating safe mode and/or the chamber 610 is not
pressurized or has experienced a pressure change.
[0068] FIG. 12 illustrates the gate valve 402 in the fail-safe
opened position. The spring 418 provides a force configured to bias
the valve stem 414, the operator member 412, the top shaft 460, and
the drive sleeve 504 in an upward direction, thereby positioning
the sliding gate 416 in the opened position. Seating of the sliding
gate 416 in the opened position limits the upward axial movement of
the top shaft 460 and the drive sleeve 504. The mechanical override
400 is in an un-actuated position and does not interfere with the
opening of the gate valve 402. The bias of the spring 418 raises
the top shaft 460 to an extended position providing a visual
indication that the gate valve 402 is in the opened position. The
safe mode indicator 403 may provide a first visual indication that
the gate valve 402 is not automatically actuated into the operating
safe mode and/or the chamber 610 is not pressurized or has
experienced a pressure change.
[0069] FIG. 5 illustrates the gate valve 402 in an open position
after a manual operation of the actuator 401 using the mechanical
override 400. To move the sliding gate 416 to the open position
using the mechanical override 400, the valve operator manually
turns the handwheel 500 to provide rotation to the top shaft 460.
Rotation of the handwheel 500 rotates the top shaft 460 to advance
the top shaft 460 through the drive sleeve 504 across the length of
the drive thread 514. As the top shaft 460 rotates, the top shaft
460 advances through the drive sleeve 504 until the upper portion
of the drive thread 514 is located at the lower portion of the
threaded bore 516 of the drive sleeve 504. During the manual
operation, the inner shoulder 511 provides the backstop that
prevents the drive sleeve 504 from moving relative to the housing
450. The manual rotation of the handwheel 500 mechanically advances
the top shaft 460 through the housing 450 to either directly or
indirectly axially move the valve stem 414 to place the gate valve
402 in the open position. The top shaft 460 is mechanically driven
against the bias of the spring 418, thereby compressing the spring
418. The top shaft 460 lowers during the manual operation to a
retracted position and provides a visual indication that the gate
valve 402 is in the open position. The valve operator may also
check the safe mode indicator 403 to determine whether the gate
valve 402 is operating in the safe mode. The pressure in the
chamber 610 should not have significantly changed between the
operation of the gate valve 402 from the fail-safe closed position,
shown in FIG. 4, to the open position by manual operation, shown in
FIG. 5. Thus, the safe mode indicator 403 communicates the same
first visual indication to the valve operator, which has not
changed by the mechanical operation of the gate valve 402. The safe
mode indicator 403 may therefore indicate that the gate valve 402
is not operating in the safe mode, has not been automatically
actuated, has been actuated (at least partially) using the
mechanical override 400, and/or may be prevented from moving into
the fail-safe closed position or the fail-safe opened position.
[0070] FIG. 6 illustrates the gate valve 402 in the open position
after an automatic operation of the actuator 401. Pressure is
directed into the chamber 406 of the actuator 401 to overcome the
bias of spring 418 and advance the top shaft 460, the drive sleeve
504, the operator member 412, and the valve stem 414 in a downward
direction to position the sliding gate 416 into the open position.
The top shaft 460 and the drive sleeve 504 are moved together
axially within the bore of the housing 450 until the seals 518 on
the drive sleeve 504 are moved across the tapered shoulder 515 and
into the bottom bore 512. Fluid communication is established
between the chamber 610 and the chamber 406. The pressure in the
chamber 406 is communicated to the indication device 600 via the
orifice 615, thereby actuating the indication device 600. The
pressure change in the chamber 610 actuates the safe mode indicator
403 to communicate a second visual indication that is different
than the first visual indication. Since the top shaft 460 also
lowers during the automatic operation to the retracted position and
provides a visual indication that the gate valve 402 is in the open
position, the valve operator may use the safe mode indicator 403 to
determine whether the gate valve 402 is operating in the safe mode.
The second visual indication may therefore indicate that the gate
valve 402 is operating in the safe mode, has not been mechanically
actuated, has been automatically actuated, and/or will move into
the fail-safe closed position or the fail-safe opened position upon
release of pressure in the actuator 401. When operating in the safe
mode, the upper end of the drive sleeve 504 is located at least a
distance X from the inner shoulder 511 of the housing 450. In this
position, the mechanical override 400 will not disable or interfere
with the fail safe mechanism. When the pressure in the actuator 401
is released, the drive sleeve 504 is located a sufficient distance
from the inner shoulder 511 so as not to limit upward axial
movement of the top shaft 460 and thus the valve stem 414 and the
sliding gate 416. In this manner, the sliding gate 416 may move
into the fail-safe closed position or the fail-safe opened
position.
[0071] FIG. 7 illustrates the gate valve 402 in an open position
after an automatic operation of the actuator 401 and a partial
operation of the mechanical override 400. Before and/or after
automatic actuation of the gate valve 402, the mechanical override
400 may be actuated at least partially, inadvertently or otherwise.
If the handwheel 500 has been rotated one or more times, the top
shaft 460 and the drive sleeve 504 will move relative to each other
in an offset position illustrated in FIG. 7. When in the offset
position and if the valve is automatically actuated, then the upper
end of the drive sleeve 504 may be positioned a distance Y from the
inner shoulder 511, which would prevent the gate valve 402 from
moving to the fail-safe closed position or the fail-safe opened
position. In one embodiment, the distance Y may be any distance
that is less than the distance X identified in FIG. 6. When the
pressure in the actuator 401 is released, the upper end of the
drive sleeve 504 would backstop on the inner shoulder 511 before
the sliding gate 416 closes, and limit the upward axial movement
necessary to move the sliding gate 416 into the fail-safe closed
position or the fail-safe opened position. Depending on the amount
of offset between the drive sleeve 504 and the top shaft 460, the
sliding gate 416 may be located in a partially open/closed
position. Also, when in the gate valve 402 is automatically
actuated and the drive sleeve 504 is located the distance Y from
the inner shoulder 511, the chamber 610 remains isolated from fluid
communication with the chamber 406 by the seals 518 and 519. Any
slight actuation of the mechanical override 400 may offset the top
shaft 460 and the drive sleeve 504 enough to prevent the seals 518
from moving across the tapered shoulder 515 during automatic
actuation.
[0072] Since the top shaft 460 may still visually indicate that the
valve 402 is in the open position in FIG. 7, the valve operator may
also check the safe mode indicator 403 to determine whether the
gate valve 402 is operating in the safe mode. The pressure in the
chamber 610 should not have significantly changed since it is
isolated from the chamber 406 by the seals 518 and 519. Thus, the
safe mode indicator 403 communicates the same first visual
indication to the valve operator, which has not changed by the
automatic actuation of the gate valve 402. The safe mode indicator
403 may therefore indicate that the gate valve 402 is not operating
in the safe mode, has been actuated (at least partially) using the
mechanical override 400, and/or may be prevented from moving into
the fail-safe closed position or the fail-safe opened position.
While the actuator 401 is pressurized, the valve operator may
rotate the handwheel 500 to advance the drive sleeve 504 into the
bottom bore 512 until the gate valve 402 is operating in the safe
mode. The valve operator may rotate the handwheel 500 until the
safe mode indicator 403 changes from the first visual indication to
the second visual indication, e.g. when fluid communication is
established between the chamber 406 and the chamber 610, to ensure
that the gate valve 402 is operating in the safe mode.
Alternatively, the valve operator may release the pressure in the
actuator 401 to permit the drive sleeve 504 to backstop against the
inner shoulder 511, and then rotate the handwheel 500 to move the
mechanical override 400 into the un-actuated position so that the
top shaft 460 and the drive sleeve 504 are not in an offset
position as described above. The actuator 401 may be re-actuated
automatically so that the safe mode indicator 403 indicates that
the valve is operating in the safe mode.
[0073] FIG. 9 illustrates the gate valve 402 in an open position
after an automatic operation of the actuator 401 according to one
embodiment. The gate valve 402, the actuator 401, and the
mechanical override 400 illustrated in FIG. 9 may each include the
embodiments described above with respect to FIGS. 4-8. FIG. 9
further illustrates a bore 462 disposed through the top shaft 460,
a check valve 464 disposed in a lower end of the top shaft 460 and
in communication with the bore 462, and a retaining member 466
coupled to the top shaft 460 to support the check valve 464 in the
lower end of the top shaft 460. In one embodiment, the bore 462 may
be disposed through the top shaft 460 in any manner known by one of
ordinary skill in the art to allow fluid communication between the
chamber 610 and the chamber 406. In one embodiment, the check valve
464 may be any type of valve known by one of ordinary skill in the
art, such as a one-way valve, that is operable to control the flow
of fluid through the bore 462 in either direction. In one
embodiment, the retaining member 466 may be any type of member
known by one of ordinary skill in the art, such as a retainer ring,
that is operable to maintain the check valve 462 in engagement with
the top shaft 460 and/or the bore 462. The top shaft 460
illustrated in FIG. 9 may be used in any of the embodiments
described with respect to FIG. 4-8.
[0074] In operation, the bore 462 may be configured to relieve any
fluid pressure that is located in the chamber 610, which may cause
a pressure lock and prevent the fail-safe mechanism from closing
the gate valve 402. For example, when the gate valve 402 is
operating in the safe mode as illustrated in FIG. 9, the chamber
610 is in fluid communication with the chamber 406 of the actuator
401 and is filled with pressurized fluid. As the pressure in the
chamber 406 is reduced, the spring 418 begins to move the gate
valve 402 into the closed position, as illustrated in FIG. 4, and
the chamber 610 is sealed upon engagement of the seals 518 with the
inner surface of the top bore 510. Any fluid that may be retained
in the chamber 610 is relieved through the bore 462 into the
chamber 460. In one embodiment, the fluid may be forced through the
bore 462 and the check valve 464 under its own pressure and/or as
it is pressurized as the volume of the chamber 610 is reduced by
movement of the drive sleeve 504 toward the shoulder 511 via the
spring 418. The check valve 464 may allow fluid to flow from the
upper end of the top shaft 460, through the bore 462 and into the
chamber 406, and prevent fluid from flowing into the bore 462 and
thus into the chamber 610 from the lower end of the top shaft 460.
In one embodiment, the top shaft 460 may include one or more ports
468 located adjacent to the outlet of the check valve 464 to assist
with venting fluid pressure into the chamber 406. In one
embodiment, one or more seals 519 may be situated between the top
shaft 460 and the drive member 504 to prevent any unintended leak
paths from communicating fluid to the bore 462 during operation of
the gate valve 402.
[0075] In one embodiment, the ESD Control Systems 200, 300, 700
described herein with respect to FIGS. 1-3 and 13 may be used in
combination with the mechanical override 400, the actuator 401, the
gate valve 402, and/or the safe mode indicator 403 as described
herein with respect to FIGS. 4-9. In one embodiment, the pressure
transducer 280 illustrated in FIG. 2 can be connected to the
housing 450, similar to the indication device 600 illustrated in
FIGS. 6, 7, and 9. The pressure transducer 280 may be operable to
measure the pressure in the chamber 610 via the orifice 615 and
send a signal to the controller assembly 220 corresponding to the
measured pressure. The controller assembly 220 may then send a
signal to the computer system 150 via wired or wireless telemetry
for monitoring and display of the measured pressure in real time.
In this manner, the ESD control systems 200, 300, 700 can be used
to remotely monitor and verify whether the gate valve 402 is
operating in the safe mode as described above.
[0076] FIGS. 10A-10H and 11-11D illustrate a valve assembly 1000
according to one embodiment. FIGS. 10A-10H illustrate a top
perspective view, a left side view, a bottom perspective view, a
front view, a top view, a right side view, a bottom view, and a
rear view, respectively, of the valve assembly 1000. FIG. 11
illustrates a top view of the valve assembly 1000, and FIGS.
11A-11D illustrate cross sectional views A-A, B-B, C-C, and D-D,
respectively, of the valve assembly 1000. The valve assembly 1000
may be used as the valve assembly 260 described above. The valve
assembly 1000 includes a first body portion 1010, a second body
portion 1015, a first seat 1020, and a second seat 1030. The first
and second body portions 1010, 1015 may be formed from a single
piece of material, or may include two separate pieces of material
that are connected together. The first and/or second seats 1020,
1030 may be removably secured to the first body portion 1010 for
accessing a gate 1055 that is movably disposed in the first body
portion 1010 to control fluid communication therethrough. The first
and second body portions 1010, 1015 may be provided with one or
more mounting holes 1011, 1012, 1013 for securing the valve
assembly 1000 within the housing 210 and/or to one or more
components of the ESD control systems 200, 300. The first body
portion 1010 may include a first fluid inlet 1040 for receiving
fluid from the pump assembly 240. The first fluid inlet 1040 may
include a fluid path 1041 disposed through the first body portion
1010 from a first end to a second end, adjacent to the first seat
1020. Second and third fluid inlets 1042, 1045 (the third fluid
inlet 1045 being disposed through the first seat 1020) may
optionally be provided to receive fluid from the pump assembly 240.
As illustrated, the optional second and third fluid inlets 1042,
1045 are plugged with one or more sealing members, but include
fluid paths that are in communication with the fluid path 1041 of
the first fluid inlet 1040. The first body portion 1010 may also
include a first fluid outlet 1050 for directing fluid to the
actuator of the surface and/or subsurface safety valves 120, 130 to
actuate the valves. The first fluid outlet 1050 may also include a
fluid path 1051 disposed through the first body portion 1010 from a
first end to a second end, adjacent to the second seat 1030. The
first body portion 1010 may further include a fluid path 1052 that
extends from the first seat 1020 to the second seat 1030 to provide
fluid communication between the first fluid inlet 1040 and the
first fluid outlet 1050. The gate 1055 may be disposed in the fluid
path 1052 between the first and second seats 1020, 1030 to control
fluid communication between the first fluid inlet 1040, the first
fluid outlet 1050, and a first relief outlet 1060 of the second
seat 1030 as described below. One or more machining holes 1051,
1052 (illustrated as being plugged) may be formed in the first body
portion 1010 to form the fluid paths disposed through the body as
described herein.
[0077] During operation, fluid may flow through at least one of the
fluid inlets 1040, 1042, 1045 past the gate 1055 that is disposed
within the fluid path 1052 of the first body portion 1010 between
the first and second seats 1020, 1030, and then through the fluid
outlet 1050. While fluid is flowing through the valve assembly 1000
to the actuators of the valves 120 and/or 130, the pressure in the
first body portion 1010 forces the gate 1055 to seal off
communication with the first relief outlet 1060. The first relief
outlet 1060 provides fluid communication to the fluid reservoir
250, to dump the fluid in the first body portion 1010 and the valve
actuators when desired during operation. A second relief outlet
1070 may also be provided to quickly release fluid from the first
body portion 1010 and the valve actuators. The second relief outlet
1070 may include a fluid path 1071 that intersects the fluid path
1041 of the first fluid inlet 1040, but which includes an in-line
relief valve to release fluid from the fluid paths to the fluid
reservoir 250 in the event that the pressure in the first body
portion 1010 exceeds a pre-determined pressure. A pressure switch
port 1019 may be disposed through the first body portion 1010 that
intersects the fluid path 1051 of the first fluid outlet 1050. The
pressure switch port 1019 may be used as a means to communicate the
pressure in the first body portion 1010 to one or more
sensors/transducers that are in communication with the ESD control
systems 200, 300 and/or the controller assemblies 220, 320. Using
the pressure measured by the sensors/transducers via the pressure
switch port 1019, the controller assemblies 220, 320 may
selectively control, e.g. turn on and off, the pump assemblies 240,
340 to actuate the valves 120, 130 as described herein.
[0078] The second body portion 1015 may include a fluid control
outlet 1090 that directs flow from the fluid path 1041 of the first
fluid inlet 1040 via a fluid path 1091 to a control valve assembly,
such as a solenoid valve assembly. The solenoid valve assembly may
also be in communication with the controller assemblies 220, 320 to
control operation (e.g. open and close) of the valve assembly 1000
to thereby control actuation of the valves 120, 130 as desired. The
second body portion 1015 may further include a second fluid control
outlet 1080 to release fluid from the fluid paths in the second
body portion 1015 via a fluid path 1081 and the control valve
assembly to the fluid reservoir 250. When the control valve
assembly is actuated to dump fluid pressure to the fluid reservoir
250, the pressure release in the fluid path 1041 of the first fluid
inlet 1040 and the back pressure in the fluid path 1051 of the
first fluid outlet 1050 may move the gate 1055 to a position within
the first body portion 1010 where the fluid in the first body
portion 1010 and the valve actuators is quickly released to the
fluid reservoir 250 via the first relief outlet 1060, the second
relief outlet 1070, and/or the second fluid control outlet 1080. In
this manner, the valve assembly 1000 may be selectively used to
supply and maintain fluid in one or more valve actuators of the
valves 120, 130, and to selectively release and dump fluid from the
valve actuators to the fluid reservoir 250.
[0079] FIG. 13 illustrates the ESD control system 700 according to
one embodiment. Embodiments of the ESD control system 700 described
herein may be applicable to the ESD control system 300. For
convenience, the components in the ESD control system 700 that are
similar to the components in the ESD control system 200 will be
labeled with the same number indicator. The ESD control system 200
may include the housing 730 for supporting the controller assembly
220, the power source 230, a compressor (or fluid drive) assembly
740, a check valve 715, a pressure switch 710, a filter/dryer
assembly 705, and the solar panel assembly 270. In one embodiment,
the controller assembly 220 and/or any of the other components may
be disposed external to and/or adjacent to the housing 730.
[0080] The ESD control system 700 may be "self-contained" or
"stand-alone unit," which means that the ESD control system 700
does not depend on any external pneumatic, hydraulic, mechanical,
or electrical sources for its operation to shut down the oil/gas
well. In other words, the power source 230, the compressor assembly
740 and other components are within the housing 730 and thus the
ESD control unit 700 is an integral portable unit. For example, if
there is a rupture of a production flow line downstream from the
surface safety valve 120, and/or if there is a loss of well
pressure at the subsurface safety valve 130, the ESD control system
700 is operable to effectively close the safety valves 120, 130,
thereby shutting in the oil/gas well, and alert the appropriate
personnel that a shut-in has occurred without the assistance of any
additional external power sources, such as external compressors or
motors.
[0081] The ESD control system 700 may also include one or more
transducers/devices 280, 282, 284, 286, and 288 for monitoring
and/or measuring one or more physical properties as described
herein. The ESD control system 700 may be configured to control one
or more valves, such as flow control valves or choke valves that
are in communication with the flow lines of the valves 120, 130 to
control fluid flow through the wellhead control system 100. The ESD
control system 700 may also include a quick dump valve 725 in line
211. The quick dump valve 725 is a manual valve that is configured
to exhaust pneumatic fluid to an area outside of the housing 730.
Additionally, the check valve 715 may be located in the line 211.
The check valve 715 is a valve that allows fluid flow in one
direction, from the compressor assembly 744 to the valve 120, and
restricts fluid flow in the opposite direction.
[0082] The housing 730 may include any structural support member,
such as an explosion-proof container, for protecting the components
stored therein from damage and environmental elements. Appropriate
ventilation of the housing 730 may be provided by ventilation holes
and/or an independent solar powered fan mounted in or through the
housing 730. The housing 730 may further include an access panel or
door for ease of access to the housing's interior, and may be
configured for attachment to the tree 110 or the respective surface
and subsurface safety valve 120, 130. In one embodiment, the
structural components of the ESD control system 700, to the extent
possible, may be made from stainless steel. The controller assembly
220 may be disposed in the housing 730 and may include a
microprocessor unit 222, a display screen 224, and a keypad 226. In
one embodiment, the controller assembly 220 may be weather-proof,
and may be intrinsically safe to provide power as necessary to one
or more components of the ESD control system 700. The
microprocessor unit 222 may include a programmable logic
controller, including a supervisory control and data acquisition
system (SCADA) that is in communication with the one or more
transducers/devices 280, 282, 284, 286, and 288, as well as the
compressor assembly 740 and valve assemblies 710, 720.
[0083] In one embodiment, the compressor assembly 740 may include
an intrinsically safe motor 742 and a compressor 744, which may
each be located in the explosion-proof housing 730. As set forth
herein, the compressor assembly 740 may supply pneumatic fluid from
a location outside the housing 730 to actuate the safety valve 120,
130 to which it is connected. The pneumatic fluid may be ambient
fluid, such as air, outside the housing 730. In one embodiment, the
compressor assembly 740 may have multiple compressors and/or motors
in parallel.
[0084] In one embodiment, the pneumatic fluid may be supplied from
an optional reservoir 735 located outside of the housing 730. The
reservoir 735 may be connected to the filter/dryer assembly 705 for
supplying fluid to the compressor assembly 740. The reservoir may
also be connected to the valve assembly 720 and/or valve 725 for
receiving fluid exhausted from the system. The reservoir 735 may
include a level gauge, such as a sight glass, to indicate the level
of fluid in the reservoir 735. The reservoir 735 may also include a
level sensor that is in communication with the controller assembly
220 and is operable to monitor in real-time the level of fluid in
the reservoir 735. In the event that the level of fluid falls below
a predetermined limit (e.g. pre-set limit), due to evaporation of
the fluid for example, the level sensor may provide an alarm to
alert an operator on-site at the wellhead control system 100 and/or
at the remote location via the controller assembly 220 and the
computer system 150. The controller assembly 220 may automatically
shut in the wellhead control system 100 upon receiving a signal
from the level sensor.
[0085] As set forth herein, the signal from the pressure transducer
280 may be recorded and/or communicated to the computer system 150
via the controller assembly 220 to provide real-time monitoring of
the pressure in the flow line 135. The measured pressure may be
displayed on the display screen 224 and/or on a display screen of
the computer system 150. In response to the comparison of the
measured pressure to one or more predetermined conditions, the
controller assembly 220 may be configured to operate the respective
safety valve 120, 130 to which it is connected. For example, the
controller assembly 220 may be used to direct the compressor
assembly 740 to supply pneumatic fluid, such as ambient air, to the
surface safety valve 120 to open the valve. Upon receiving the
signal from the controller assembly 220, the valve assembly 720 may
be configured to open a circuit defined by lines 211, 215 between
the surface safety valve 120 and the filter/dryer assembly 705 to
allow the compressor assembly 740 to direct fluid from the fluid
entering the filter/dryer assembly 705 to the surface safety valve
120, thereby opening the surface safety valve 120. The surface
safety valve 120 may be maintained in the open position while the
pressure transducer 280 continuously monitors the pressure in the
flow line 135. The controller assembly 220 may be programmed to
close the surface safety valve 120 upon receiving a signal from the
pressure transducer 280 that corresponds to a pressure measurement
that is greater than or less than a pre-set pressure range. The
pre-set pressure range may be input into the controller assembly
220 by manual entry using the keypad 226 and the display screen
224. The pre-set pressure range may also be input into the
controller assembly 220 remotely from the computer system 150. When
the signal is received from the pressure transducer 280 that the
pressure in the flow line 135 falls outside of the pre-set pressure
range stored in the microprocessor unit 222, the controller
assembly 220 may automatically direct the compressor assembly 740
to stop supplying pressurized fluid to the surface safety valve 120
and/or allowing the valve assembly 720 to exhaust the pneumatic
fluid, thereby closing the surface safety valve 120. Continuous
real-time monitoring of the pressure in the flow line 135 may be
used to verify that the surface safety valve 120 has been
closed.
[0086] Power may be provided to the controller assembly 220 and the
compressor assembly 740 from the power source 230. The power source
230 may be operable to provide a low current (amp) stream to the
controller assembly 220 and/or the compressor assembly 740. The
controller assembly 220 is configured to control the pressure
switch 710, which can be visually inspected to monitor the pressure
in the line 211. In one embodiment, the pressure switch 710 may be
configured to shut off the compressor assembly 740 when the
pressure in the actuator of the safety valves 120, 130 reaches a
predetermined pressure setting.
[0087] FIG. 14 illustrates a well control system 800 at a wellsite
for conducting a wellbore operation, such as a fracturing
operation. The well control system 800 may be configured with one
or more of the control systems 200, 300, 700 as described herein.
The well control system 800 includes a fluid supply 810, such as a
reservoir or tank, or a vehicle comprising a storage tank for
storing fluid. A pump 820, or other fluid drive assembly, is
provided for pumping fluid from the fluid supply 810 to a well. In
particular, fluid from the fluid supply 810 is pumped through flow
or fluid line 811 to a manifold 830, which directs the pressurized
fluid to one or more wellheads 840, 841, 842, 843 via fluid lines
831, 832, 833, 834, respectively. As illustrated, the wellhead 840
may control the pressurized fluid flow into a well 850 that
intersects a formation 860 for conducting a fracturing operation as
conventionally known in the art.
[0088] A fluid line 812 is in fluid communication with the fluid
line 811 at a location downstream of the pump 820. The fluid line
812 may also be in fluid communication with the fluid supply 810 or
with any other fluid reservoir type assembly. The safety valve 120
is in-line with the fluid line 812 for controlling fluid flow from
the fluid line 811 to the fluid supply 810. The safety valve 120
may be configured as a fail-safe open relief valve or a fail-safe
close safety valve, and is operable using one or more of the
control systems 200, 300, 700. The safety valve 120 is operable
using a pneumatic/hydraulic working fluid, which may be supplied
from a fluid reservoir internal or external of the control systems
200, 300, 700 (as described herein) and/or from the fluid supply
812 directly or via one of the fluid lines. The transducer 280,
such as a pressure transducer, measures the pressure in the fluid
line 812 and communicates the measured characteristic to the
controller assemblies of the control systems 200, 300, 700, which
compare the measured characteristic to one or more predetermined
conditions. The computer system 150 enables remote monitoring,
control and operation of the safety valve 120 using the control
systems 200, 300, 700 as described herein.
[0089] In one embodiment, one or more fluid lines 812 may be
provided for fluid communication between fluid lines 811, 831, 832,
833, 834 (including the manifold and/or wellheads) and the fluid
supply 810 or other fluid reservoir. In one embodiment one or more
safety valves 120 and/or control systems 200, 300, 700 may provided
in-line with one or more of the fluid lines 811, 831, 832, 833, 834
(including the manifold and/or wellheads). In one embodiment, one
or more transducers 280 may be provided for measuring physical
properties (e.g. pressure, temperature, flow rate, flow volume,
etc.) of one or more of the fluid lines 811, 831, 832, 833, 834
(including the manifold and/or wellheads).
[0090] In operation, the pump 820 may be actuated to pump fluid
from the fluid supply 810 to the manifold 830 via fluid line 811.
The safety valve 120 may be actuated into a closed position using a
working fluid as directed by the control systems 200, 300, 700 to
prevent or substantially restrict fluid flow through fluid line
812. The pressurized fluid may therefore be directed from the
manifold 830 to the wellheads 840, 841 842, 843 via fluid lines
831, 832, 833, 834 for conducting a fracturing operation, such as
in well formation 860. The safety valve 120 may be continuously
monitored remotely using the computer system 150. The transducer
280 may also continuously monitor and measure physical properties,
such as fluid pressure, in fluid line 811 and communicate the
measured physical properties to the control system 200, 300, 700
for comparing to one or more predetermined conditions. In the event
that the pressure in the fluid line 811 exceeds a predetermined
condition (as programmed into the controller assembly of the
control system), the control system is operable to release the
working fluid from maintaining the safety valve 120 in the closed
position, and the safety valve 120 is operable to automatically
move into the open position (such as by spring 418 or other biasing
member) to relieve the pressure in the fluid line 811 and dump the
pressurized fluid back into the fluid supply 810 or other reservoir
via fluid line 812. The well control system 800 is therefore
operable to prevent over pressurization or other conditions of the
fluid lines 811, 831, 832, 833, 834 (including the manifold and/or
wellheads) that can lead to failure.
[0091] After any remedial operations necessary to remove any
restriction to flow to the wellheads, the control system 200, 300,
700 may be operable to actuate the safety valve 120 into the closed
position to continue with one or more wellbore operations.
Advantages of the well control system 800 include the ability to
relieve high fluid volume, flow, and pressure quickly, efficiently,
and repeatedly to prevent failure of the wellbore system.
Additional advantages include the ability to remotely monitor and
control the system 800.
[0092] In one embodiment, the control system 200, 300, 700 may be
configured to actuate the safety valve 120 at a predetermined
condition, such as a set pressure, which is below the rated working
pressure of one or more of the fluid lines, manifolds, and/or
wellheads. In the event that the pressure in the fluid lines reach
or exceed the predetermined set pressure (as measured by the
transducer 280), the control system 200, 300, 700 will actuate the
safety valve 120 into the open position to relieve the excessive
fluid pressure. In one embodiment, the control system 200, 300, 700
may be configured with a predetermined condition, such as a reset
pressure. For example, in the event of actuation of the safety
valve 120 due to a failure, the control system 200, 300, 700 may
prevent operation of the safety valve 120 back into the closed
position until the transducer 280 measures the predetermined reset
pressure in the fluid lines.
[0093] In one embodiment, the control system 200, 300, 700 may be
configured to actuate the safety valve 120 in anticipation of a
failure. For example, the control system 200, 300, 700 may include
an electronic wave generator for generating a wave signal that
corresponds to fluid flow volume, rate, pressure, etc., and which
is monitored by the controller assembly for any changes or
fluctuations that indicate a failure at one or more points in the
well control system 800. In the event of an indication of failure,
the control system 200, 300, 700 can operate the safety valve 120
for actuation into the open position.
[0094] In one embodiment, the control system 200, 300, 700 can
monitor, track, and record the operation of the safety valve 120
and/or the transducer 280 measurements. In one embodiment, the
control system 200, 300, 700 may be configured with one or more
mechanical and/or electrical overrides for independent, manual, or
direct operation of the safety valve 120. In one embodiment, a
transducer 280 may be coupled to the safety valve 120 to monitor
the working pressure within the valve actuator, which can help
determine life of the valve, force required to actuate, and whether
maintenance is required.
[0095] In one embodiment, the control system 200, 300, 700 may be
configured to trigger or actuate one or more alarms or alerts
(audio/visual) to indicate a potential or actual failure; that the
safety valve 120 has been actuated; and/or one or more other
conditions have been detected, such as H2S (or other harmful
gases), fire, and/or damage to the control system. In one
embodiment, the alarms or alerts may be communicated through the
computer system 150. In one embodiment, the control system 200,
300, 700 may be configured to prevent remote operation in the event
that the safety valve 120 has been actuated, and may require manual
re-setting of the system.
[0096] In one embodiment, the control system 200, 300, 700 may
include a geographical positioning system for tracking the location
of the control system and the safety valves, which may be
displayed, monitored, and tracked using the computer system 100. In
one embodiment, the control system 200, 300, 700 may store
information related to a particular wellbore operation, including
maintenance and operational history, employee contact information,
and/or status of the safety valve. In one embodiment, the control
system 200, 300, 700 may be configured to open and/or close the
safety valve 120 within a predetermined time frame. In one
embodiment, the control system 200, 300, 700 may be configured to
actuate the safety valve 120 at one or more predetermined time
intervals.
[0097] FIG. 15 illustrates the well control system 800 according to
one embodiment. The well control system 800 includes a gate valve
402 and a valve actuator 401, the operations of which are described
above with respect to at least FIGS. 4-12. A pilot valve 870 (or
other functionally similar type of mechanical, electrical, and/or
hydraulic sensor) may be coupled to the valve actuator 401, and may
be operable to control fluid communication between the valve
actuator 401 and a fluid reservoir 875 via fluid line 872. A pump
876 may be provided to pump actuator fluid from the reservoir 875
to the valve actuator 401 to actuate the valve 402 into the closed
position.
[0098] Upon actuation of the pilot valve 870, the actuator fluid
may be released from the valve actuator 401 back to the reservoir
875, such that the valve 402 may be automatically biased into the
open position. The pilot valve 870 may be actuated by fluid
pressure via fluid line 871, which is in communication with fluid
line 811. In the event that fluid pressure directed to the
wellheads 840-843 exceeds a predetermined amount, the fluid
pressure will actuate the pilot valve 870 (via fluid line 871) to
release the actuator fluid from the valve actuator 401 to the
reservoir 875 (via fluid line 872), and thereby automatically bias
the valve 402 into the fail safe open position to release the
excessive fluid pressure back to the fluid supply 810 (via fluid
line 812) as described above.
[0099] In one embodiment, the pilot valve 870 may operate as a
check valve or one-way valve when in an un-actuated or first
position, to allow actuator fluid to be pumped into the valve
actuator 401 while preventing actuator fluid flow out of the valve
actuator 401. When the pilot valve 870 is in an actuated or second
position, actuator fluid may flow out of the valve actuator 401 to
the reservoir 875. The pilot valve 870 may monitor and be in
communication with the fluid pressure in any one of the flow lines
811 and 830-834. In one embodiment, the actuator fluid may be
forced into the reservoir 875 by the biasing member 418 acting on
the operating member 412 as described above.
[0100] While the foregoing is directed to embodiments of the
invention, other and further embodiments of the invention may be
devised without departing from the basic scope thereof, and the
scope thereof is determined by the claims that follow.
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