U.S. patent application number 16/990695 was filed with the patent office on 2020-11-26 for hydrostatic pressure test method and apparatus.
This patent application is currently assigned to Engip, LLC. The applicant listed for this patent is Engip, LLC. Invention is credited to Lewis Jackson Dutel, Clifford Lee Hilpert, Jeffrey Lee Hilpert, Laura Tufts Meyer.
Application Number | 20200370987 16/990695 |
Document ID | / |
Family ID | 1000005008431 |
Filed Date | 2020-11-26 |
United States Patent
Application |
20200370987 |
Kind Code |
A1 |
Hilpert; Clifford Lee ; et
al. |
November 26, 2020 |
Hydrostatic Pressure Test Method and Apparatus
Abstract
A method of pressure testing a closed hydraulic system for leaks
includes heating or cooling pressure intensification fluid before
it enters the closed hydraulic system under pressure. The closed
hydraulic system may be for example a blowout preventer for an
oil/gas well, a manifold system or tubulars. The intensification
fluid is heated or cooled to a temperature at or near the
temperature of the fluid within the closed hydraulic system.
Inventors: |
Hilpert; Clifford Lee;
(Conroe, TX) ; Hilpert; Jeffrey Lee; (Conroe,
TX) ; Dutel; Lewis Jackson; (Houston, TX) ;
Meyer; Laura Tufts; (Sealy, TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Engip, LLC |
Conroe |
TX |
US |
|
|
Assignee: |
Engip, LLC
Conroe
TX
|
Family ID: |
1000005008431 |
Appl. No.: |
16/990695 |
Filed: |
August 11, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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16162121 |
Oct 16, 2018 |
10739223 |
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16990695 |
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15151309 |
May 10, 2016 |
10161824 |
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16162121 |
|
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62159426 |
May 11, 2015 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
E21B 33/06 20130101;
G01M 3/02 20130101; F28F 27/00 20130101; E21B 36/00 20130101; F28F
9/26 20130101; G01M 3/2892 20130101 |
International
Class: |
G01M 3/02 20060101
G01M003/02; E21B 33/06 20060101 E21B033/06; G01M 3/28 20060101
G01M003/28; F28F 9/26 20060101 F28F009/26; F28F 27/00 20060101
F28F027/00; E21B 36/00 20060101 E21B036/00 |
Claims
1. A method of pressure testing a closed hydraulic system for leaks
comprising: a. initiating a flow of intensification fluid under
pressure to the closed hydraulic system to establish a first
pressure level within the closed hydraulic system, b. cooling or
heating the intensification fluid to a level corresponding to the
temperature of the closed hydraulic system, c. isolating the closed
hydraulic system from a pressurized testing fluid, and d. measuring
any pressure changes within the closed hydraulic system, wherein
the intensification fluid is pressurized by an intensification
pump, and further wherein the intensification fluid is heated
inside an electrical heater unit after exiting the intensification
pump.
2. The method of claim 1, wherein the closed hydraulic system is a
blowout preventer positioned on a subsea oil/gas well.
3. The method of claim 1, wherein the closed hydraulic system is a
blowout preventer for a surface oil/gas well.
4. The method of claim 1, wherein the closed hydraulic system is a
blowout preventer for an oil/gas well which includes a drill string
and the intensification fluid is cooled or heated to be at or near
the ambient temperature of the drilling fluid within the drill
string and the blowout preventer.
5. The method according to claim 1, wherein the intensification
fluid is introduced into the electrical heater unit through the
intensification pump.
6. The method according to claim 1, wherein the intensification
fluid is cooled inside the electrical heater unit after making
contact with cooling fluid and prior to entering the drill string
and the blowout preventer.
7. The method according to claim 1, wherein the cooling fluid
enters into the electrical heater unit through a fluid intake
nozzle.
8. The method according to claim 7, wherein the cooling fluid is
sea water.
9. The method according to claim 1, wherein a heat coil within the
electrical heater unit can be used to further heat the
intensification fluid.
10. A method of pressure testing a closed hydraulic system for
leaks comprising: a. initiating a flow of intensification fluid
under pressure to the closed hydraulic system to establish a first
pressure level within the closed hydraulic system, b. cooling or
heating the intensification fluid to a level corresponding to the
temperature of the closed hydraulic system, c. isolating the closed
hydraulic system from the pressurized testing fluid, and d.
measuring any pressure changes within the closed hydraulic system,
wherein an electrical heater unit comprises two units.
11. The method of claim 10 wherein the closed hydraulic system is a
blowout preventer positioned on a subsea oil/gas well.
12. The method of claim 10 wherein the closed hydraulic system is
the blowout preventer for a surface oil/gas well.
13. The method of claim 10 wherein the closed hydraulic system is
the blowout preventer for an oil/gas well which includes a drill
string and the intensification fluid is cooled or heated to be at
or near the ambient temperature of the drilling fluid within the
drill string and the blowout preventer.
14. The method according to claim 10, wherein the intensification
fluid is introduced into the electrical heater unit through a fluid
intake nozzle.
15. The method according to claim 10, wherein the intensification
fluid is heated or cooled by the electrical heater unit prior to
entering the drill string and the blowout preventer.
16. The method according to claim 10, wherein cooling fluid enters
into the electrical heater unit through a fluid intake nozzle.
17. The method according to claim 10, wherein the two units of the
electrical heater unit may each have heat transfer coils within
them to heat the intensification fluid.
18. The method according to claim 10, wherein connectors attach the
two units to each other.
19. The method according to claim 18, wherein one of the connectors
is an upper connector, which is located between the two units
allowing for the intensification fluid to be cooled.
20. The method according to claim 18, wherein one of the connectors
is a lower connector located between the two units allowing for the
cooling fluid in the cooling coils.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. application Ser.
No. 16/162,121 filed Oct. 16, 2018, which is a continuation of U.S.
Pat. No. 10,161,824 filed on May 10, 2016, which is a
non-provisional that claims the benefit of provisional application
Ser. No. 62/159,426 filed May 11, 2015, the entire contents of
which is expressly incorporated herein by reference thereto.
I. BACKGROUND OF THE INVENTION
1. Field of the Invention
[0002] This invention is directed toward a method of testing
blowout preventers (BOP) located at a well head to prevent
unrestricted flow of gas and or oil from a well during an emergency
situation.
[0003] Oil and Gas Exploration risk management includes the ability
to control subsurface pressures which may be encounter during
drilling operation. The primary mechanism utilized by operators to
control downhole pressures is the hydrostatic pressure as a result
of the drilling fluid contained within the wellbore. The drilling
fluid is engineered and formulated to a density that provides a
hydrostatic pressure inside of the wellbore that is greater than
the formation pressure being drilled. In the majority of drilling
operations, the hydrostatic control of wellbore pressure is
adequate. However, from time-to-time the operator may encounter a
higher than expected formation pressure where there is not adequate
hydrostatic pressure to control the wellbore pressure. During these
times the operator relies on a series of mechanical controls to
stabilize the wellbore and prevent a "Blow Out". A blow out is the
uncontrolled release of fluid or gas from the wellbore. This event
is extremely dangerous and therefore must be avoided if at all
possible. The primary mechanical control device utilized by
operators to control wellbore pressure is the Blowout Preventer
(BOP) assembly. The BOP assembly consists of multiple sealing and
shearing devices that are hydraulically actuated to provide various
means of sealing around the drill string or shearing it off
entirely, completely sealing the wellbore. It is essential that the
BOP assembly operate as designed during these critical operations.
Therefore it is a regulatory requirement to test the functionality
and the integrity of the BOP assembly before starting drilling
operations and at specific events during the drilling
operations.
2. Description of Related Arts Invention
[0004] The BOP assembly test is a series of pressure tests
typically at a minimum of two pressure levels, low pressure and
high pressure. During the pressure test, intensification fluid from
a high pressure intensification pump is introduced into the closed
BOP assembly in a volume sufficient to cause the internal pressure
within the closed BOP assembly to rise to the first pressure test
level. Once the first pressure test level is established the high
pressure intensification pump is isolated from the closed BOP
assembly and the pressure is monitored for a specified time period.
During the monitoring phase the pressure decay is determined and
compared to the pressure decay specification. A typical
specification for compliance allows for a pressure decay rate of no
more than 5 psi/minute or 25 psi total over the entirety of the
five minute test.
[0005] Measuring leak rate utilizing the indirect result of
pressure decay, while widely accepted, is problematic. This is
especially apparent when performing BOP assembly tests offshore in
deeper waters. In a typical offshore configuration the BOP assembly
will be located at the sea floor. The distant between the BOP
assembly and the drilling platform at the surface can reach upwards
of 10,000 feet. The BOP assembly is connected to the drilling
platform via tubular pipe sections typically referred to as the
"riser assembly". The drill string is a series of tubular pipes
attached to the drilling platform at one end and the drill bit or
service assembly at the opposite end. The drill string is
positioned within the riser assembly. During a typical BOP
hydrostatic test the drill string and riser assembly are filled
with drilling fluid. The BOP is configured for the applicable
hydrostatic test which acts to close off or seal the drill string.
A high pressure intensification pump, typically the cement pump, is
aligned so as to add additional drilling fluid, or other suitable
intensification fluid, via the open end of the drill string drill
string at the drilling platform, in a volume sufficient to cause
the pressure within both the BOP assembly and the drill string to
rise to the appropriate test pressure. The volume of drilling fluid
required to raise the pressure within the BOP assembly and the
drill string to the applicable level is related to the
compressibility of the drilling fluid within the BOP assembly and
drill string as well as the intensification fluid. For example: a
typical offshore BOP assembly and the drill string might require
approximately 100 bbls of drilling fluid to completely fill the
area between the BOP assembly and the drilling platform. Typical
drilling fluids used in offshore drilling have a compressibility
factor of approximately 0.0035/1000 psi. A typical BOP assembly
test pressure might be 5,000 PSI. Therefore in this example the
additional volume of intensification fluid required to raise the
internal pressure of the BOP assembly and the drill string is 1.75
bbls. If the required test pressure of the BOP assembly is 10,000
psi, the additional volume of intensification fluid required to
raise the internal pressure of the BOP assembly and the drill
string is 3.5 bbls.
[0006] In most cases a high pressure reciprocating intensification
pump is utilized to pump the required additional drilling fluid
into the BOP assembly and drill string. The action of pumping
intensification fluid from an ambient pressure to a significantly
high pressure, sometimes in excess of 20,000 psi creates heat. The
heat is principally generated by mechanical inefficiencies of the
intensification pump and the compressive strain of the drilling
fluid. The temperature rise subsequent to the intensification pump
is a function of the pressure differential and the volume of
drilling fluid pumped. In some cases the temperature of the
intensification fluid can rise as much as 40 deg F. The temperature
rise has a significant effect on the volume/pressure relationship
within the BOP assembly and the drill string due to the thermal
coefficient of expansion of the intensification fluid. The thermal
coefficient of expansion of intensification fluids and drilling
fluids varies greatly but a typically might have a thermal
coefficient of expansion of approximately 0.0003 per degree
Fahrenheit. Therefore if during the pressurization phase of the BOP
pressure test, the intensification fluid temperature is raised
approximately 30 degrees F. by the intensification pump, the volume
will increase approximately 0.009 or approximately 1%.
[0007] Referring to the previous example above where approximately
3.5 bbls of intensification fluid was added to the BOP assembly and
the drill string to raise the pressure to approximately 10,000 psi
will equate to a pressure increase slope of approximately 2850
psi/bbl of intensification fluid added. Referring to the previous
example above where a 30 degree F. increase in intensification
fluid temperature results in approximately a 1% increase in volume
will further equate to 0.035 bbls (3.5.times.0.01=0.035).
[0008] Subsequent to pumping, the heated intensification fluid will
cool at a rate defined by the general thermal conductivity of the
surrounding environment. As the intensification fluid cools there
is a corresponding reduction in volume equal to the previous
thermally induced volume increase. The reduction in volume causes
the pressure to decrease at a rate approximately equal to the
pressure slope previously described. In this example the decrease
in pressure would be approximately 100 psi over the period of time
necessary for the temperature of the intensification fluid to
return to ambient. This period of time can be as little as 5
minutes to as much as 20 minutes. During this time the pressure
decay rate exceeds the limit of 5 psi/minute. Therefore the
pressure test of the BOP assembly cannot begin until the pressure
decay has stabilized at a rate less than 5 psi/minute. This period
of time is known within the industry as "waiting on a flat line".
Once the pressure decay stabilizes at or below 5 psi/minute the BOP
pressure test can begin.
[0009] It would be desirable to eliminate the affects of the
temperature increase in the pressurizing fluid. This would increase
the accuracy of the test and also reduce the amount of time
required for each test segment. This would greatly decrease the
cost of BOP testing.
[0010] Additionally, in certain environments where the ambient
temperature is cold, it may be necessary to further heat rather
than cool the intensification fluid so that it is approximately
equal to the temperature of the BOP assembly or other closed
hydraulic systems. In certain testing situations the BOP assembly
may not contain fluid or it may be partially or completely filled
with fluids.
[0011] In any case the temperature of the BOP assembly is measured
and the intensification fluid is heated or cooled as necessary to
match the temperature of the BOP assembly or other closed hydraulic
system.
II. BRIEF SUMMARY OF THE INVENTION
[0012] The present invention overcomes the above noted problems by
cooling or heating the intensification fluid prior to pressurizing
the BOP or other closed hydraulic systems to the test pressures.
This may be accomplished by the use of a heat exchanger which is
positioned either upstream or downstream of the intensification
pump. In the case of a subsea oil well, sea water may be utilized
as the heat exchange fluid for the heat exchanger. The
intensification fluid is either heated or cooled to match the
temperature of the BOP assembly.
III. BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS
[0013] For a detailed description of the preferred embodiments of
the invention, reference will now be made to the accompanying
drawings in which:
[0014] FIG. 1 illustrates the pressure verses time curve for a test
cycle of the prior art.
[0015] FIG. 2 illustrates a time the pressure verses time curve for
a test cycle according to an embodiment of the invention.
[0016] FIG. 3 illustrates apparatus according to a first embodiment
of the invention
[0017] FIG. 4 illustrates apparatus according to second embodiment
of the invention.
IV. DETAILED DESCRIPTION OF THE INVENTION
[0018] FIG. 1 depicts a pressure recording chart from a typical BOP
assembly hydrostatic pressure test method. It is defined by four
distinct phases. The period between point 1 and point 2 is the
pressurization phase. The period between point 2 and point 3 is the
first step of the monitoring phase. The period between point 3 and
point 4 is the second step of the monitoring phase. The period
between point 4 and point 5 is the dump phase where pressure is
released to complete the hydrostatic test process. The first phase,
the pressurization phase, is the period where intensification fluid
is added to the drilling fluid within the closed BOP assembly and
the drill string to increase the pressure to a level sufficiently
above the applicable test pressure to allow for the pressure decay
associated with temperature decay while remaining above the
applicable hydrostatic test level. It is during this pressurization
phase that the intensification fluid added is also heated from the
inefficiencies of the intensification pump and the compressive
strain of the drilling fluid.
[0019] Immediately subsequent to the pressurization phase, the
first step of the monitoring phase begins. It is during this step
of the monitoring phase that the intensification fluid added by the
intensification pump is cooling. As time passes the intensification
fluid continues to cool until it is very near the temperature of
the sounding environment. Subsequently the next step, step 2, of
the monitoring phase begins. It is during this phase that a
determination about the integrity of the BOP assembly (leak-no
leak) based on the pressure decay rate will be made. The BOP
assembly is considered to be safe to use if the pressure decay rate
is less than 5 psi/min. Subsequent to the monitoring phase the
pressure is released during the dump phase from point 4 to point
5.
[0020] The first step of the monitoring phase can be as little as
five minutes to as much as twenty minutes depending on how long it
takes the pressurizing fluid to cool to ambient conditions.
[0021] FIG. 2 depicts a pressure recording chart of the new and
improved BOP assembly hydrostatic pressure test method. It is
defined by three distinct phases. The period between point 1 and
point 2 is the pressurization phase. The period between point 2 and
point 3 is the monitoring phase. The period between point 3 and
point 4 is the dump phase where pressure is released to complete
the hydrostatic test process. The first phase, the pressurization
phase, is the period where intensification fluid is added to the
drilling fluid within the closed BOP assembly and the drill string
to increase the pressure within the BOP assembly and the drill
string to applicable test pressure. It is during this
pressurization phase that the intensification fluid added is also
heated from the inefficiencies of the intensification pump and the
compressive strain of the drilling fluid. However unlike typical
BOP hydrostatic test methods, the new and improved hydrostatic test
method provides a means of reducing or eliminating the temperature
rise within the intensification fluid experienced during
pressurization normally associated with hydrostatic testing.
Immediately subsequent to the pressurization phase, the monitoring
phase begins. It is during this phase that a determination about
the integrity (leak-no leak) based on the pressure decay rate is
made. The BOP assembly is considered to be safe to use if the
pressure decay rate is less than 5 psi/min.
[0022] Subsequent to the monitoring phase the pressure is released
during the dump phase. It is important to note that it is not
necessary to include a step of the monitoring phase that would
allow time for the temperature of the added intensification fluid
to stabilize at or near the ambient temperature of the drilling
fluid within the BOP assembly and drill string. Therefore, BOP
hydrostatic test method with temperature stabilization will save a
substantial amount of test time and money when compared to typical
hydrostatic testing without temperature stabilization.
[0023] FIG. 3 depicts an embodiment of the improved hydrostatic
test method which includes heat exchange system 10 downstream of
the intensification pump and before the drill string connection.
Heat laden intensification fluid received at fluid intake nozzle 20
from the intensification pump would pass through heat exchanger 30
exiting out of fluid discharge nozzle 60. Cold sea water introduced
at fluid nozzle 40 will pass through heat exchanger 30 exiting
fluid discharge nozzle 50. As a function of heat exchanger 30 the
heat induced into the intensification fluid by the intensification
pump 65 will be transferred to the cooler sea water as both fluids
come in contact with the heat transfer medium of heat exchanger 30.
An alternate embodiment to the method might utilize a chilled water
loop to replace of the cool sea water as the cooling liquid. Heat
exchange system 10 may be manually operated or with the inclusion
of optional temperature sensor 70 automatically operated to
regulate the heat transfer rate. Cooled intensification fluid is
then directed to BOP assembly 80.
[0024] Heat exchanger 30 may include two units 31 and 32 each
having heat transfer coils within them. A connector 33 connects
units 31 and 32 for the intensification fluid to be cooled while
connectors 34 and 35 may be used for the cooling fluid in the
cooling coils. Any well-known heat exchange unit may be employed to
cool the intensification fluid.
[0025] In this embodiment inlet 20 is connected to the intensifying
pump 65 and outlet 60 is connected to the drill string and blowout
preventer assembly 80. The intensification fluid is cooled to a
temperature approximately equal to the temperature of the BOP
assembly.
[0026] FIG. 4 depicts a second embodiment of heat exchange system
10 which includes heat exchanger 30 prior to the fluid inlet of the
intensification pump 65. In this second embodiment intensification
fluid is introduced into heat exchanger 30 via fluid intake nozzle
20. Intensification fluid received at intake nozzle 20 will pass
though heat exchanger 30 exiting via fluid discharge nozzle 60.
Chilled water introduced into heat exchanger 30 via fluid intake
nozzle 40 will pass through heat exchanger 30 exiting fluid
discharge nozzle 50. The chilled water will be sufficiently cool to
reduce the intensification fluid temperature to a temperature
approximately equal to the temperature of the BOP assembly. The
reduction of the intensification fluid temperature is a function of
heat exchanger 30 as the intensification fluid and the chilled
water come into contact with each other across the heat transfer
medium of heat exchanger 30. Heat exchange system 10 may be
manually operated or with the inclusion of optional temperature
sensor 70 automatically operated to regulate the heat transfer
rate. Fluid from outlet 60 in this embodiment is directed to the
inlet of the intensifying pump 65 and then to BOP assembly 80. In
this embodiment heat exchanger 30 may be of the same type as
described above with respect to FIG. 3.
[0027] In the situation where it is desirable to further heat the
intensification fluid, heat exchange 30 would be of the type that
raised the temperature of the intensification fluid such as an
electrical fluid heater unit.
[0028] In either situation the temperature of the BOP assembly is
measured and the heat exchange unit is controlled so that the
temperature of the intensification fluid matches that of the BOP
assembly.
[0029] The principles, preferred embodiment, and mode of operation
of the present invention have been described in the foregoing
specification. It will be obvious to those skilled in the art that
variations may be utilized for similar closed vessel hydrostatic
testing such as well heads, tubulars, and manifolds. This invention
is not to be construed as limited to the particular forms
disclosed, since these are regarded as illustrative rather than
restrictive. Moreover, variations and changes may be made by those
skilled in the art without departing from the spirit of the
invention.
[0030] The above detailed description of the related embodiments of
the improved BOP hydrostatic test method is intended as an
exemplification of the principals of the invention and not intended
to limit the invention to any specific embodiment. The improved BOP
hydrostatic test method provides for a means of cooling or heating
the intensification fluid either before or after the
intensification pump so that subsequent to the pressurization phase
the intensification fluid added to cause the pressure increase is
at or near the ambient temperature of the BOP assembly. This method
of stabilizing the intensification fluid temperature at or near the
ambient temperature of the BOP assembly will mitigate the effects
of the temperature decay and associated pressure decay immediately
subsequent to the pressurization phase of the hydrostatic test.
[0031] Although the present invention and its advantages have been
described in detail, it should be understood that various changes,
substitutions and alterations may be made herein without departing
from the spirit and scope of the invention as defined by the
appended claims.
* * * * *