U.S. patent application number 12/098447 was filed with the patent office on 2009-10-01 for top hold down rod pump with hydraulically activated drain and method of use.
Invention is credited to Blaine Michael Wicentovich.
Application Number | 20090242195 12/098447 |
Document ID | / |
Family ID | 41060223 |
Filed Date | 2009-10-01 |
United States Patent
Application |
20090242195 |
Kind Code |
A1 |
Wicentovich; Blaine
Michael |
October 1, 2009 |
Top Hold Down Rod Pump with Hydraulically Activated Drain and
Method of Use
Abstract
The present invention relates to a top hold-down pump having a
barrel drain operatively connected to the pump beneath a seating
nipple. The design of the pump provides specific advantages over
past systems by improving the efficiency of re-setting the barrel
drain and the required work over costs after the drain has been
activated.
Inventors: |
Wicentovich; Blaine Michael;
(Calgary, CA) |
Correspondence
Address: |
Nixon Peabody LLP
200 Page Mill Road, Suite 200
Palo Alto
CA
94306
US
|
Family ID: |
41060223 |
Appl. No.: |
12/098447 |
Filed: |
April 6, 2008 |
Current U.S.
Class: |
166/244.1 ;
166/68 |
Current CPC
Class: |
E21B 43/127
20130101 |
Class at
Publication: |
166/244.1 ;
166/68 |
International
Class: |
E21B 43/00 20060101
E21B043/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 31, 2008 |
CA |
2,627,822 |
Claims
1) In a top hold-down pump for pumping fluids from a well to the
surface through production tubing, the top hold-down pump having an
upper end for sealing engagement with a seating nipple within the
production tubing and a positive displacement pumping system
operatively retained within a barrel for allowing fluid within the
barrel to be displaced to the surface by a reciprocating or
rotating rod operatively connected to the positive displacement
pumping system, the improvement comprising a barrel drain between
the upper end and the lower end for draining fluid from the
production tubing to the exterior of the barrel beneath the seating
nipple.
2) A top hold-down pump comprising: a barrel having a top section
for sealing engagement with a seating nipple within the production
tubing and a bottom section operatively retaining positive
displacement pumping equipment; a barrel drain operatively
connected to the barrel between the top section and the bottom
section for releasing hydrostatic fluid pressure from the
production tubing to the exterior of the barrel beneath the seating
nipple.
3) A top hold-down pump as in claim 2 wherein the barrel drain
includes at least one barrel drain port and a barrel sleeve
operatively retaining a drain sleeve between a closed position
where the at least one barrel drain port is closed and an open
position where the at least one barrel drain port is open, the
drain sleeve and barrel sleeve retaining a shear pin for holding
the drain sleeve in the closed position wherein an increase in
hydraulic pressure on the interior of the barrel drain will cause
the shear pin to shear at a threshold pressure causing the drain
sleeve to move to the open position.
4) A top hold-down pump as in claim 2 wherein the barrel drain
includes at least one barrel drain port for operatively retaining a
corresponding rupture disk for scaling the at least one drain port
and rupturing at a threshold pressure to open the at least one
barrel drain port.
5) A top hold-down pump as in claim 2 wherein the barrel drain
includes a precision slot having a specific thickness.
6) A top hold-down pump as in claim 2 where the top hold-down pump
is a reciprocating rod pump.
7) A top hold-down pump as in claim 2 where the top hold-down pump
is a progressive cavity pump.
8) A top hold-down pump as in claim 2 further comprising a
secondary check valve operatively connected to the barrel between
the barrel drain and the bottom section.
9) A method of releasing hydrostatic pressure in production tubing
in a well having a lop hold-down pump as described in claim 2,
comprising the step of: applying a hydraulic pressure to the
interior of the production tubing at sufficient pressure to open
the barrel drain to permit fluid within the production tubing to
flow to an annular space between the barrel and production tubing
beneath the seating nipple.
10) A top hold-down pump drain for operative connection to a top
hold-down pump barrel secured within a hold-down seating nipple
within production tubing, the top hold-down pump drain for
operative connection to the pump barrel between the hold-down
seating nipple and positive displacement pumping equipment retained
within the pump barrel, the top hold-down pump drain for releasing
hydrostatic fluid pressure from the production tubing and interior
of the pump barrel to the exterior of the pump barrel beneath the
hold-down seating nipple.
11) A top hold-down pump system comprising: a barrel having a top
section for sealing engagement with a seating nipple within the
production tubing and a bottom section operatively retaining
positive displacement pumping equipment, wherein the bottom section
extends beneath the seating nipple within the production tubing; a
barrel drain operatively connected to the barrel between the top
section and the bottom section for releasing hydrostatic fluid
pressure from the production tubing to the exterior of the barrel
beneath the seating nipple above a threshold pressure; and, at
least one production tubing opening operatively connected to the
production tubing beneath the seating nipple and adjacent the
barrel drain for allowing fluid flow between the annular space
between the barrel and production tubing.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to top hold-down pump systems
having a barrel drain operatively connected to the pump positioned
beneath a pump seating nipple. The design of the pump provides
specific advantages over past systems by improving the efficiency
of re-setting the barrel drain and the required work over costs
after the drain has been activated.
BACKGROUND OF THE INVENTION
[0002] As is well known, oil is often pumped from a production well
using various designs of reciprocating pump and pump jack.
Generally, the pump jack includes a reciprocating rod (i.e. a
polish rod) that passes through the wellhead that is connected to a
series of sucker rods which provides the reciprocating pumping
action to draw oil from the well. The down-hole pump is seated
within a tubing string in the production zone of the well. The pump
includes a pump barrel through which a pump piston operates to lift
oil to the surface through the production tubing. This general
style of pump has been in operation for over 100 years.
[0003] More specifically, the primary components of this type of
pump consist of a pump barrel, a plunger and two valves; a
traveling valve and a standing valve. Sucker rods which reciprocate
within the tubing string of the well are connected to the plunger
such that fluids are brought to the surface.
[0004] Over time, as various designs of pump have evolved, two hold
down positions of rod pumps have been utilized; namely, the top
hold down rod pump and the bottom hold down rod pump both of which
are sealed within a seating nipple within the production tubing.
The top hold down rod pump (where the pump is below the seating
nipple) is more commonly used as it is resistant to sand sticking
and is typically easier to remove from the well when removal is
required. The bottom hold down rod pump (where the pump is above
the seating nipple) is less commonly used.
[0005] Similarly, top hold down insert progressive cavity pumps
(PCPs) are becoming more available worldwide. A PCP includes a
rotor and a stator and, as with reciprocating rod pumps, a pump
barrel or stator is operatively sealed within a seating nipple
secured to the production tubing. A rotor rotates within the stator
within a helical chamber so as to positively lift fluids from the
lower end of the stator into the production tubing.
[0006] For both top and bottom hold down rod pumps and top hold
down PCPs, when problems arise in the wellbore and the hydrostatic
pressure above the pump is desired to be released for reasons such
as to assist in killing a well or to avoid pulling a wet tubing
string to the surface if the pump cannot be unseated, engineers may
choose to incorporate a tubing drain. As a part of the tubing
string, the tubing drain is located towards the bottom of the
production tubing and slightly spaced above the pump seating
nipple. The tubing drain will open at a threshold pressure and
cause the discharged fluid above the pump to drain to the wellbore.
As such, the pressure differential between the inside of the
production tubing and the annulus between the well-bore and
production tubing will equalize. The pressure equalization may then
enable the tubing string to be withdrawn without the trapped fluid
within the production tubing or alternatively may enable the pump
to be unseated and withdrawn from within the production tubing to
surface. Additionally, the tubing drain can be used as a safety
feature to protect the production system from over-pressuring while
in operation.
[0007] If the tubing drain (which in the past has always been
located on the production tubing string above the pump) is opened,
regardless of the problem being solved or for the reason the tubing
drain was opened, the opened drain requires that the production
tubing string be returned to the surface in order to reset the
tubing drain. Self-resetting tubing drains have not been employed
due to the difficulty in automatically resetting such systems in
the very dirty downhole environment. Withdrawing the entire tubing
string to the surface is expensive and inefficient if the problem
being solved does not relate to the tubing string.
[0008] More specifically, as the tubing drain is located slightly
above the hold down seating nipple in the production tubing this
means that when opened, the tubing drain allows the discharge fluid
to drain to the annulus between the wellbore and the production
tubing (usually by hydraulic over-pressure).
[0009] In summary therefore, there are many reasons for including a
tubing drain as part of the production tubing with the top hold
down rod pump. These include: [0010] 1) The tubing drain is a
safety feature for preventing over pressuring of all equipment
downstream of the pump discharge; [0011] 2) The activation of the
tubing drain can be invoked intentionally to assist in releasing a
rod pump from the hold down seating nipple by removing both the
fluid within the production tubing and its hydrostatic head; or to
avoid pulling a wet tubing string if the pump will not release from
the seating nipple; [0012] 3) A tubing drain can also be activated
in an effort to kill the surface pressure on a wellhead by pumping
kill fluid down the tubing and entering the wellbore from the
bottom of the production string via the tubing drain and cycling to
the top.
[0013] However, in each case when the tubing drain of these past
systems is activated, the production tubing must be removed from
the wellbore to replace/reset the opened tubing drain and then
returned downhole in order to resume production. This will result
in significant cost increases, as service equipment and time is
required to complete the work over.
[0014] Accordingly, there has been a need for a pump system that
does not require that the production tubing be removed from the
well in the event that it is required that the hydrostatic pressure
within the production tubing is released.
[0015] A review of the prior art reveals that while limited
hydraulic drain systems and various mechanically operated drains
have been incorporated into various downhole pump designs, no such
solution has been provided to a top hold down rod pump.
[0016] For example, U.S. Pat. No. 3,994,338 discloses a hydrostatic
pressure release for bottom hold down rod pumps. This system
provides a sub-joint having a release port that will drain oil from
the production tubing into the borehole. The sub-joint is located
between the standing valve and bottom hold down seal assembly on
the pump. This system is limited by virtue of the bottom hold down
drain being located in an area where sand commonly bridges off in
the static fluid area adjacent the exterior of the pump barrel. As
a result, the normal settling of sand in many wells would make this
drain inoperable in many wells. Moreover, trapped sand commonly
causes the pump to become stuck in the pump seating nipple.
[0017] U.S. Pat. No. 3,150,605 describes a casing pump drain
incorporating a pressure release valve beneath the casing seal that
incorporates channels and a mechanical valve system to convey
liquid from above the pump seal to below the pump seal.
[0018] Other examples of various pump systems include U.S. Pat. No.
6,857,477 which discloses a reciprocating pump vent-dump valve
using a mechanical valve system; US Publication 2004/0055743 which
discloses a reciprocating pump dump valve using a mechanical
dumping system; US Publication 2004/0216867 and U.S. Pat. No.
6,752,212 which disclose dump valves for use with tubing; U.S. Pat.
No. 4,273,520 which discloses a deep well pump incorporating a
mechanical valve system; U.S. Pat. No. 4,909,326 which discloses a
tubing unloader incorporating a mechanical valve system and seals;
U.S. Pat. No. 4,166,715 which discloses a tubing drain device that
is mechanically operated; U.S. Pat. No. 4,157,117 which discloses a
tube draining system that is mechanically operated; and, U.S. Pat.
No. 5,005,651 which discloses a downhole pump unseating
apparatus.
SUMMARY OF THE INVENTION
[0019] The present invention provides a pump system that overcomes
the primary shortcomings of prior art in not requiring the
withdrawal of production tubing from the wellbore in the event of
releasing the hydrostatic pressure within the production
tubing.
[0020] More specifically, the invention utilizes the discharged
fluid space within the interior of a top hold down pump body as a
conduit for the discharge fluid within the tubing string to reverse
flow through a pressure activated barrel drain integral to the pump
body. The fluid drain path continues through the micro-annulus
between the exterior of the barrel and inner tubing below the
seating nipple. The barrel drain duplicates every function of a
past tubing drain, but with the significant advantage of not
requiring the withdrawal of the production tubing from the
wellbore.
[0021] More specifically, the invention provides in a top hold-down
pump for pumping fluids from a well to the surface through
production tubing, the top hold-down pump having an upper end for
sealing engagement with a seating nipple within the production
tubing and a positive displacement pumping system operatively
retained within a barrel for allowing fluid within the barrel to be
displaced to the surface by a reciprocating or rotating rod
operatively connected to the positive displacement pumping system,
the improvement comprising a barrel drain between the upper end and
the lower end for draining fluid from the production tubing to the
exterior of the barrel beneath the seating nipple.
[0022] In a further embodiment, the invention provides a top
hold-down pump comprising: [0023] a barrel having a top section for
sealing engagement with a seating nipple within the production
tubing and a bottom section operatively retaining positive
displacement pumping equipment; [0024] a barrel drain operatively
connected to the barrel between the top section and the bottom
section for releasing hydrostatic fluid pressure from the
production tubing to the exterior of the barrel beneath the seating
nipple.
[0025] In a further embodiment, the barrel drain includes at least
one barrel drain port and a barrel sleeve operatively retaining a
drain sleeve between a closed position where the at least one
barrel drain port is closed and an open position where the at least
one barrel drain port is open, the drain sleeve and barrel sleeve
retaining a shear pin for holding the drain sleeve in the closed
position wherein an increase in hydraulic pressure on the interior
of the barrel drain will cause the shear pin to shear at a
threshold pressure causing the drain sleeve to move to the open
position.
[0026] In another embodiment, the barrel drain includes at least
one barrel drain port for operatively retaining a corresponding
rupture disk for sealing the at least one drain port and rupturing
at a threshold pressure to open the at least one barrel drain
port.
[0027] In yet another embodiment, the barrel drain includes a
precision slot having a specific thickness that will rupture at a
threshold pressure.
[0028] In another aspect, the invention provides a method of
releasing hydrostatic pressure in production tubing in a well
having a top hold-down pump having a barrel drain, comprising the
step of: applying a hydraulic pressure to the interior of the
production tubing at sufficient pressure to open the barrel drain
to permit fluid within the production tubing to flow to an annular
space between the barrel and production tubing beneath the seating
nipple.
[0029] In another aspect of the invention, the invention provides a
top hold-down pump drain for operative connection to a top
hold-down pump barrel secured within a hold-down seating nipple
within production tubing, the top hold-down pump drain for
operative connection to the pump barrel between the hold-down
seating nipple and positive displacement pumping equipment retained
within the pump barrel, the top hold-down pump drain for releasing
hydrostatic fluid pressure from the production tubing and interior
of the pump barrel to the exterior of the pump barrel beneath the
hold-down seating nipple.
[0030] In a further embodiment, the invention provides a top
hold-down pump system comprising: [0031] a barrel having a top
section for sealing engagement with a seating nipple within the
production tubing and a bottom section operatively retaining
positive displacement pumping equipment, wherein the bottom section
extends beneath the seating nipple within the production tubing;
[0032] a barrel drain operatively connected to the barrel between
the top section and the bottom section for releasing hydrostatic
fluid pressure from the production tubing to the exterior of the
barrel beneath the seating nipple above a threshold pressure; and,
[0033] at least one production tubing opening operatively connected
to the production tubing beneath the seating nipple and adjacent
the barrel drain for allowing fluid flow from the annular space
between the barrel and the exterior of the production tubing.
BRIEF DESCRIPTION OF THE FIGURES
[0034] The invention is described with reference to the
accompanying figures in which:
[0035] FIG. 1 is a cross-sectional view of a top hold-down rod pump
having a hydraulic drain in accordance with the prior art;
[0036] FIG. 2A is a cross-sectional view of a top hold-down rod
pump having a hydraulic drain in accordance with the invention;
[0037] FIG. 2B is a cross-sectional view of a top hold-down rod
pump having a hydraulic drain in accordance with the invention and
a secondary check valve;
[0038] FIG. 3A is a side and cross-sectional view of a hydraulic
drain in accordance with one embodiment of the invention;
[0039] FIG. 3B is a side and cross-sectional view of a hydraulic
drain in accordance with one embodiment of the invention;
[0040] FIG. 3C is a side and cross-sectional view of a hydraulic
drain in accordance with one embodiment of the invention; and,
[0041] FIG. 4 is a cross-sectional view of a secondary check valve
in accordance with one embodiment of the invention.
DETAILED DESCRIPTION
[0042] With reference to the Figures, top hold-down pumps are
described to include a hydraulic drain within a pump barrel. The
design of the system promotes the efficiency of maintenance in the
event that the hydraulic drain has been activated in that the
system does not require that the production tubing string be
withdrawn from the well to re-set the hydraulic drain.
[0043] With reference to FIG. 1, a typical top hold-down rod pump
10 in accordance with the prior art is described. The pump is set
within a wellbore 12 having casing 13 and casing perforations 13a
adjacent to or near the bottom of production tubing 14. The
production tubing includes a seating nipple 16 for receiving a
seating mandrel 18, seating cup 18a and seating cup ring 18b on the
pump and for securing the pump at its upper end within the
production tubing 14. The pump 10 is connected to the surface via
sucker rod 20.
[0044] The pump 10 further includes a barrel 22 and plunger/piston
24 together with traveling valve 26 and standing valve 28. The
traveling valve 26 is secured within the plunger 24 whereas the
standing valve 28 is secured to the lower end of the barrel 22.
[0045] In operation, the sucker rod 20 is made to reciprocate such
that the plunger 24 moves up and down within the barrel. Upward
motion of the plunger causes the traveling valve 24 to close
causing fluid above the plunger to be displaced upwardly. This
fluid passes through the seating mandrel 18 wherein it is expelled
to the interior 14a of the production tubing 14 towards the
surface. At the same time, the standing valve 28 will open allowing
fluid to enter the lower region of the barrel 22 to fill the volume
22a created by the upwardly moving plunger.
[0046] Subsequent downward motion of the plunger 24 causes the
traveling valve 26 to open and the standing valve 28 to close such
that the plunger 24 moves downwardly through the barrel 22 so as to
retain hydrostatic pressure within the production tubing 14.
[0047] As is well known, repetition of the cycle enables fluid to
be drawn from the well.
[0048] FIG. 1 also shows the location of a tubing drain 30 in
accordance with the prior art above the seating nipple 16 in the
production tubing 14. As is known, in the event of the need to
relieve the hydrostatic pressure in the production tubing (for all
reasons including production, maintenance and safety), by
increasing the hydraulic pressure within the production tubing 14a
will cause tubing drain 30 to open allowing the fluid within the
production tubing 14a to flow into the annular space 32 between the
casing 13 and production tubing 14. Once opened, this system then
requires that the entire tubing string 14 be removed from the well
to replace the tubing drain 30.
[0049] As known to those skilled in the art, the pump 10 may be
assembled in sections so as to facilitate maintenance of the
various sub-components of a pump.
[0050] As shown in FIGS. 2A and 2B and in accordance with the
invention, a pump 50 is described in which a barrel drain 52 is
configured to the pump beneath the pump seating nipple 16 as a
section of the barrel 22 and above the traveling 26 and standing
valves 28. As such, in the event that the hydrostatic pressure
within the production tubing 14 must be relieved, an increase in
hydraulic pressure within the production tubing 14 will cause the
barrel drain 52 to open. In the subject design, as the barrel drain
52 is located beneath the seating nipple 16 and in the barrel 22,
hydrostatic pressure will equalize between the production tubing
volume 14a and annular space 32 through micro-annular space 32a and
the bottom of the production tubing 14. Importantly, this design
will not require that the production tubing 14 be withdrawn from
the well to reset the system but rather only requires that the pump
50 be returned to surface to be reset. In a further embodiment, the
production tubing beneath the seating nipple 16 may also be
provided with one or more slots 56 adjacent the barrel drain 52
such that in the event that the barrel drain 52 is opened, the
fluid within the production will more rapidly flow into the well
bore as fluid drag through the micro-annular space would be
reduced. This may be especially advantageous in the event that
surface pressure must be quickly killed within the well.
[0051] As is readily understood by those skilled in the art,
removal of the pump 50 is considerably more cost efficient than
removing both the pump 50 and production tubing 14.
[0052] In a further embodiment, as shown in FIG. 2B and FIG. 4, a
secondary check valve 54 may be incorporated beneath the barrel
drain 52 to replace any secondary check valve above the seating
mandrel on select pump configurations. The secondary check valve is
used to assist in opening the travelling valve when the plunger
moves downward as the check valve relieves the travelling valve of
the weight of the hydrostatic head. As shown the secondary check
valve 54 includes a valve sleeve 54a that is engaged around valve
rod 16a between retaining cage 54b and check valve seat 54c. The
secondary check valve does not interfere with the normal operation
of the plunger and standing and traveling valves.
[0053] FIGS. 3A, 3B, and 3C show different embodiments of a barrel
drain. In FIG. 3A, a barrel drain 70 includes a drain sleeve 72
around drain mandrel 74 having drain ports 75. Seal rings 76a and
76b provide a seal between the interior of the drain mandrel 74 and
the exterior. Drain sleeve 72 is retained in a closed position as
shown in the Figure by shear pin 78. In operation, by increasing
the hydraulic pressure within the drain mandrel 74 will, at a
desired pressure threshold, cause the shear pin 78 to shear thereby
causing the drain sleeve to move to an open position where the
drain ports 75 are opened. The barrel drain 70 may be configured to
the pump barrel by an appropriate connection system such as
threads.
[0054] In FIG. 3B, a barrel drain 80 is similar to the barrel drain
70 shown in FIG. 3A with respect to a barrel sleeve 82 and a drain
port 84. The drain port 84 is fitted with a rupture plug 86
designed to rupture at a desired pressure threshold.
[0055] In FIG. 3C a barrel drain 90 includes a precision slot
vertically milled into the joint. An increase in pressure above a
threshold causes the precision slot to rupture at the precision
slot based on the specific thickness of the slot material.
[0056] Progressive Cavity Pump
[0057] The technology may be similarly applied to top hold down
insertable progressive cavity pump (PCP) which could use any of the
barrel drains described above. In a progressive cavity pump system,
the barrel drain would be configured to an upper section of a PCP
stator beneath a top hold-down seating nipple and above the PCP
rotor.
[0058] Although the present invention has been described and
illustrated with respect to preferred embodiments and preferred
uses thereof, it is not to be so limited since modifications and
changes can be made therein which are within the full, intended
scope of the invention.
* * * * *