U.S. patent application number 11/283334 was filed with the patent office on 2007-05-24 for well production by fluid lifting.
Invention is credited to Danny Kent Daniels, Vernon Dale Daniels.
Application Number | 20070114038 11/283334 |
Document ID | / |
Family ID | 38052355 |
Filed Date | 2007-05-24 |
United States Patent
Application |
20070114038 |
Kind Code |
A1 |
Daniels; Vernon Dale ; et
al. |
May 24, 2007 |
Well production by fluid lifting
Abstract
Oil production from formerly producing wells may be restored
without removing a preexisting production tube by perforating the
production tube above the tubing packer and charging the casing
annulus at the surface with a pressurized charging fluid fluid,
preferably deoxygenated air, that is lighter than water. The
pressurized charging of the casing annulus with charging fluid is
continued to purge the production tube flow bore of a static water
column and reduce the tubing column head pressure against the
formation production zone.
Inventors: |
Daniels; Vernon Dale;
(Tishomingo, OK) ; Daniels; Danny Kent;
(Tishomingo, OK) |
Correspondence
Address: |
W. ALLEN MARCONTELL
P.O. BOX 800149
HOUSTON
TX
77280-0149
US
|
Family ID: |
38052355 |
Appl. No.: |
11/283334 |
Filed: |
November 18, 2005 |
Current U.S.
Class: |
166/372 ;
166/105; 166/369 |
Current CPC
Class: |
E21B 43/122
20130101 |
Class at
Publication: |
166/372 ;
166/369; 166/105 |
International
Class: |
E21B 43/00 20060101
E21B043/00 |
Claims
1. A method of extracting earth formation fluid comprising the
steps of: a. drilling a borehole into an earth formation containing
formation fluid; b. positioning a production tube within said
borehole, said production tube having a flow bore extending from a
formation fluid production zone to a surface discharge zone, said
flow bore being confined within a surrounding tube wall; c. at a
point above said formation fluid production zone, sealing a well
annulus between an internal wall within said borehole and an
external surface of said tube wall; d. in situ perforating said
tube wall above said annulus seal; and, e. delivering a pressurized
charging fluid into said well annulus above said tube wall
perforations to drive substantially all fluids present in said flow
bore up said flow bore into said surface discharge zone.
2. A method as described by claim 1 wherein said borehole is lined
with a casing pipe and said internal wall within said borehole is
an internal diameter surface of said casing pipe.
3. A method as described by claim 1 wherein said tube wall is
perforated from within said tube flow bore while positioned within
said borehole.
4. A method as described by claim 1 wherein said borehole is
plugged below said fluid production zone.
5. A method as described by claim 1 wherein said charging fluid is
non-cryogenic nitrogen.
6. A method as described by claim 1 wherein said charging fluid is
oxygen depleted air.
7. A method as described by claim 1 further comprising the steps
of: a. positioning a jet pump within said flow bore above said well
annulus seal, said jet pump having a fluid flow passage between a
suction end and a discharge end, an aspirating nozzle within said
flow passage between said suction and discharge ends and a nozzle
supply orifice externally of said flow passage between said suction
and discharge ends; b. sealing said tube flow bore around said jet
pump suction end below said tube wall perforation; c. sealing said
tube flow bore around said jet pump discharge end above said tube
wall perforation to position said nozzle supply orifice between
said jet pump suction and discharge end seals.
8. A method as described by claim 7 wherein tube flow bore space
around said jet pump between said seals respective to said suction
and discharge ends provides a fluid supply plenum for said
aspirating nozzle.
9. A method as described by claim 7 wherein at least one gas lift
valve is positioned in said production tube above said jet
pump.
10. A method of enhancing the fluid production of a petroleum well
having a production tube disposed within a wellbore between a
formation fluid production zone and a surface discharge zone, said
method comprising the following steps: a. sealing a first
cross-sectional zone between and inside surface of said wellbore
and an outside surface of said production tube at a point above
said production zone; b. in situ perforating said production tube
at a point above said first cross-sectional zone; c. positioning a
jet pump within a flow bore of said production tube proximate of
said production tube perforation, said pump having a housing around
a formation fluid flow channel sealed to an internal flow bore of
said production tube above and below said tube perforation to
provide an aspirating fluid supply plenum between said above and
below seals; and, d. supplying aspirating fluid to an annulus space
between said inside surface of said wellbore and said outside
surface of said production tube above said first cross-sectional
zone.
11. A method of enhancing the fluid production of a petroleum well
as described by claim 10 wherein the supply of aspirating fluid
opens and closes at least one gas lift valve in said production
tube above said jet pump.
12. A method of enhancing the fluid production of a petroleum well
as described by claim 10 wherein a plurality of gas lift valves are
sequentially opened and closed prior to aspirating fluid entering
said jet pump.
13. A method of enhancing the fluid production of a petroleum well
as described by claim 10 wherein said aspirating fluid is
non-cryogenic nitrogen.
14. A method of enhancing the fluid production of a petroleum well
as described by claim 10 wherein said aspirating fluid is oxygen
depleted air.
15. An earthen fluid production well comprising: a borehole
penetrating a fluid bearing earth formation; a fluid production
tube comprising a tube wall around a tube flow bore, said
production tube disposed within said borehole between a fluid
production zone proximate of said formation and a fluid discharge
zone proximate of the earth's surface; a first fluid flow seal
between said tube wall and an internal wall surface within said
borehole surrounding said tube wall, said fluid seal disposed above
said production zone; perforations of said tube wall above said
first fluid flow seal; a jet pump having a housing, said housing
having a suction flow end, a discharge flow end and an aspirating
fluid inlet orifice in said housing between said suction and
discharge flow ends, said jet pump disposed between a second fluid
seal of said tube flow bore around said housing proximate of said
suction flow end and a third fluid seal of said tube flow bore
around said housing proximate of said discharge flow end whereby
said fluid inlet orifice is open to borehole space surrounding said
tube wall; and, at least one gas lift valve in said production tube
above said third fluid seal.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to methods and apparatus for
enhancing the extractive flow of crude petroleum from production
wells.
[0003] 2. Description of Related Art
[0004] When a petroleum extraction well is first completed, in situ
formation pressure is often sufficient to drive the formation fluid
(crude oil) to the surface. Over time, with the continued
extraction of the in situ fluid, the original formation pressure
declines to the point of insufficient internal energy to drive a
flow of fluid to the surface. This circumstance is exacerbated by
the frequent invasion of water and other contaminating fluids into
the formation interstices vacated by the original formation fluid.
These contaminating fluids ultimately find their way into the
production flow stream and into the well production tube. Due to a
greater specific gravity of water than oil, the well production
tube slowly fills with water to prevent all fluid extraction
flow.
[0005] Unfortunately, natural production flow cessation may occur
before even half of the in situ petroleum is drained. By some
geological theories, the "depleted" fields of the world still
contain at least as much petroleum as was originally extracted.
[0006] If the affected well is sufficiently shallow and
sufficiently perpendicular to the earth's center, fluid production
of a well originally produced by natural drive force may be
continued by pumping. In such cases, the original production tube
is withdrawn from the well and replaced by a sucker rod assembly.
Sucker rod assemblies are mechanical lifts comprising a
reciprocating rod disposed coaxially within a specialized
production tube. The reciprocating rod supports a plurality of
annular piston elements having opposite faces linked by pressure
differentially operated check valves. The upper or surface end of
the reciprocation rod is mechanically manipulated in a
reciprocating motion to lift the formation fluid to the surface
along the rod tube in successive increments. As with most
reciprocating machines, sucker rod assemblies are expensive to
position and to maintain.
[0007] Production inducements for deviated well bores and extremely
deep wells are more difficult. In some of these examples,
production has been enhanced by a process known to the art as "gas
lifting". Gas lifting includes the step of positioning a
specialized formation fluid production tube within the well having
one or more gas--lift valves strategically positioned along the
length of the tube. The open, lower end of the production tube
extends into the formation production zone. The well casing annulus
between the external tubing wall and the internal casing wall at a
point above the production zone is sealed by a packer to isolate
the well production zone from the casing annulus above the
zone.
[0008] The gas-lift valves are essentially pressure differentially
controlled valves that link the internal flow bore of the fluid
production tube with the external annulus volume between the
production tube exterior and the well casing interior. A
non-oxidizing gas such as methane, natural gas, or cryogenic
nitrogen is charged under pressure into the casing annulus. When
the designated pressure differential between the casing annulus and
the tubing flow bore is attained, the lift valve opens to admit the
gas into the flow bore. The higher pressure gas entrains the
non-flowing fluid in the tubing flow bore with liquid displacing
bubbles that enlarge as they rise to the surface of the production
tube. This rising bubble expansion pushes the previously static
flow bore fluid up and out of the tube at the surface.
Additionally, the gas bubble entrainment reduces the density of the
standing fluid column thereby reducing the positive, bottomhole
head pressure that has prevented production flow in the first
place. Fresh formation fluid is allowed to drain into the
production zone of the well and into the production tube flow
bore.
[0009] This process is continued with a continuing injection of gas
into the well casing annulus at the wellhead. As the fluid pressure
gradient within the tubing flow bore declines, additional lift
valves open down the length of the production tube to further
reduce the formation zone pressure until a net flow of new
formation fluid is produced at the surface end of the production
tube.
[0010] Although operationally effective, in many cases the process
is economically marginal or negative due to the cost of the gas to
drive the process. If low cost natural gas is available, the
process may be profitable. If not, compressed methane or cryogenic
nitrogen is the usual alternative. Production by means of the
alternative gases is rarely profitable.
[0011] It is, therefore, an object of the present invention to
teach a more economical process for fluid lifting the production of
crude oil from a well.
[0012] It is also and object of the present invention to disclose a
combination of well production equipment that economically
facilitates the practice of the present invention process.
[0013] Another object of the present invention is to teach a method
of opening the flow of a shut-in well without removing a
pre-positioned production tube.
SUMMARY OF THE INVENTION
[0014] These and other objects of the invention are accomplished by
one preferred embodiment in which a pre-positioned production tube
is wire-line or slick-line perforated at a point above the
production zone packer and, preferably, below or proximate of an
oil-water interface standing in the production tube flow bore. A
suitable fluid having a density less than water such as gaseous
nitrogen, oxygen depleted air (non-cryogenic nitrogen) or carbon
dioxide is charged into the well casing annulus above the
production zone packer.
[0015] Pressure of the charging fluid bears against the surface of
any fluid standing the casing annulus to force it into the tubing
flow bore through the perforations. Initially, the pressure induced
casing fluid flow will translate in both directions, up and down
the tubing bore. However, the tubing down-flow capacity is limited.
Hence, the flow is forced upward and out of the tubing flow bore at
the surface. Continued charging expunges all of the static
overburden fluid from the tubing and replaces it with a fluid that
is lighter than water.
[0016] With the overburden fluid removed from the tubing flow bore,
the overburden fluid being replaced by the lighter charging fluid,
the charging fluid pressure may, in some cases, be reduced to
permit a flow resumption of formation fluid into the production
zone and up the production tube.
[0017] Another preferred embodiment of the invention also includes
wire-line or slick-line perforation of the pre-existing production
tube at a point above the tubing bottom packer. Internally of the
tubing flow bore, a wire-line set tubing stop is positioned below
the perforation. The landing nipple of a jet pump is positioned
within the tubing stop to project a flow bore opening below the
tubing stop. The outside surface (OD) of the jet pump upper end is
sealed to the inside wall of the tubing flow bore by a top
hold-down packer. The nozzle inlet orifices for the jet pump
driving fluid flow are positioned within an annulus volume between
the outside surface of the jet pump and the inside wall surface of
the production tube. This annulus volume is axially delineated
between the top hold-down packer and the bottom tubing stop.
[0018] As with the first embodiment of the invention, charging
fluid enters the casing annulus at or near the wellhead to bear
against the standing fluid surface thereby driving any standing
annulus fluid through the preset tubing perforations and into the
aspirator nozzle inlets. Discharge of fluid flow from the nozzle is
channeled through an aspirator orifice to induce a low pressure
zone within the jet pump body upstream of the orifice. This low
pressure zone is flow line linked with the well production zone
thereby inducing a formation fluid drainage into the jet pump
landing nipple and up the production tube.
[0019] A third embodiment of the invention entails one or more
gas-lift valves in side-pocket mandrels. These side pocket mandrels
are flow carrier increments in production tubing string. Below the
bottom-most gas-lift valve but above tubing packer a jet pump sub
is positioned in the mandrel tubing string.
[0020] As charging gas sequentially opens the gas-lift valves
starting from the top and advancing downwardly, the overburden
fluid is removed up the tubing string. As the tubing flow bore
back-pressure declines due to fluid extraction above the open lift
valve, the open valve closes and the next lower valve opens.
[0021] This sequence continues until all lift valves have opened
and closed. Only the jet pump remains open to continue aspirating
the production zone.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] Relative to the drawings wherein like reference characters
designate like or similar elements throughout the several figures
of the drawings:
[0023] FIG. 1 is a typical prior art well schematic shown in axial
cross section;
[0024] FIG. 2 is an axial cross-section representing the first
embodiment of the invention;
[0025] FIG. 3 is an axial cross-section representing the second
embodiment of the invention;
[0026] FIG. 4 is sectioned detail of the jet pump section of the
second embodiment;
[0027] FIG. 5 is an elevation view of jet pump sub embodiment of
the invention
[0028] FIG. 6 is a schematic view of the invention embodiment that
combines a gas-lift valve in the jet pump tubing string.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0029] The environment of utility for the present invention is
generally represented by FIG. 1 as a Prior Art schematic of an oil
well. The well comprises a raw borehole 12 drilled through the
earth formations 10 into a productive formation 13. In many cases,
a casing pipe 14 is extended along the borehole for a predetermined
portion of the borehole depth and secured in place by an annular
collar of cement 16.
[0030] At a depth corresponding with the production formation 13,
the casing 14 and cement 16, if present, is perforated by numerous
apertures and fissures 18. The perforations 18 facilitate the
drainage flow of formation fluid into a production zone 20 within
the casing interior.
[0031] Often, the borehole 12 continues past the production
formation. In these circumstances, the borehole 12, or if cased 14,
may be obstructed with a plug packer 22 secured below the
production zone 20.
[0032] A well with sufficient pressure in the production formation
13 to drive the drainage fluid to the surface may be produced
through the open flow bore of a production tube 24. The O.D.
surface of the bottomhole end of the production tube 24 is sealed
to the interior wall face of the casing 14 or borehole wall by
means of a tubing packer 26. The open end 25 of the production tube
flow bore below the packer 26 extends into the well production zone
28. Although the inflow end 25 of the production tube 24 flow bore
is graphically represented here by FIG. 1 as an axially biased
cross-cut, in normal practice, however, the inflow end of a
production tube is a screened opening into the interior production
tube flow bore.
[0033] As the production formation 13 is drained of in situ
petroleum, water may seep into the formation to fill the formation
interstices vacated by the extracted petroleum. Such migrant water
also finds its way into production zone flow and up the production
tube 24. Over time and continued production, the oil/water ratio of
the production tube flow stream decreases with a consequent
increase in the tubing flow column density. Eventually, the
standing fluid head within the column exerts a bottomhole pressure
that equals the in situ formation pressure. At that point the
production flow at the surface stops and the fluid column within
the production tube 24 is static.
[0034] Standing statically in the tubing flow bore, fluids of
different specific weights will separate, more or less, into
respective strata. For example, the top or upper strata 30, being
the less dense fluid, may be predominately oil. Below the oil is a
heavier water column 32. Although described herein by the term
"water", the aqueous well bore fluid usually comprises a mixture of
water, acid and emulsified petroleum. The two immiscible fluid
columns meet at a contiguous interface 34. Although the originally
mixed fluids separate in the tubing column, the total head pressure
above the production zone 20 remains the same; substantially equal
to the in situ formation pressure.
[0035] Depending on the integrity of the packer 26 and/or the
continuity of the casing 14 wall, a column of water 36 may also
accumulate in the borehole or casing annulus 15.
[0036] In a first embodiment of the invention, represented by FIG.
2, for example, restoration of productive flow from a "depleted"
well includes the preparatory step of securing an injection flow
connection 42 proximate of the wellhead 40 for injecting
pressurized charging fluid into the casing annulus 15. The charging
fluid is preferably oxygen depleted air such as non-cryogenic
nitrogen. However, other non oxidizing fluids such as natural gas,
methane, carbon dioxide may also be suitable depending on the well
site economics.
[0037] Further to the charging fluid connection, 42, the
preexisting production tube 24 is in situ perforated at a strategic
point 44 above the packer 26. Usually, in situ production tube
perforations are executed by a "slick line" or wire-line operation
that includes a small diameter perforating gun suspended from the
surface at the end of a wire-line. The depth of tubing perforation
is selected to sufficiently reduce the tubing column overburden
pressure sufficient to restore production flow.
[0038] Compressed charging fluid 50 enters the well casing annulus
15 through the injection flow connection 42 to bear upon the
surface 38 of any fluid column that may be standing in the annulus.
With the surface discharge end 46 of the tubing 24 flow bore open
into a discharge zone, annulus fluid is driven through the
perforations 44. There being no volumetric accommodation for flow
displacement downwardly, the top pressure driven annulus fluid
escapes up the tubing flow bore pushing the static fluid column in
the tubing flow bore ahead and out of the tube at the surface.
[0039] When the surface 38 of the annulus fluid column 36 is driven
below the tubing perforations 44, the remaining fluid column in the
tubing flow bore begins entrainment by the lighter charging fluid.
As the rising charging fluid displaces the flow bore liquid from
the surface discharge zone 46 of the tube, the overburden pressure
on the production zone begins to decline. At this point, residual
in situ formation pressure begins to push additional formation
fluid into the production zone 20 and up the tubing 24 flow bore
where it joins the charging fluid mixture zone proximate of the
perforations 44.
[0040] Usually, the resumed flow of formation fluid comprises the
same mixture of oil and water that originally terminated the well
production. Consequently, it is frequently necessary to continue
injection of the charging fluid to sustain the production fluid
flow. However, a reduction of the charging fluid flow rate and
pressure may be permitted after the original water head is
discharged. Moreover, the majority of charging fluid is normally
recyclable. Hence, sustained production flow is economically
burdened only by the cost of charging fluid compression and loss
replenishment.
[0041] Except for the charging fluid compression apparatus, which
is normally surface positioned and operated, the process includes
no dynamic machine elements subject to wear or structural
failure.
[0042] A second embodiment of the invention is represented by the
schematic of FIG. 3 and detail of FIG. 4. As with the first
embodiment, a preexisting production tube 24 stands within the
casing 14. The tube 24 supports a static head of production fluid
that may have gravimetrically separated into lighter and heavier
liquid elements. The production tube O.D. is sealed to the casing
l.D. wall by means of a packer 26.
[0043] This FIG. 3 invention embodiment also includes in situ
perforations 44 of the preexisting tubing. Additionally, however, a
tubing stop 52 is secured, for example, by wire-line manipulation
to the l.D. wall of the tubing 24 below the perforations 44 as best
illustrated by FIG. 4. The jet pump assembly 55 includes a landing
nipple 54 that is seated within an axial aperture of the tubing
stop 52. The upper end of the jet pump 55 is aligned and secured by
a top hold-down packer 56 that is strategically positioned above
the tubing apertures 44. This alignment of elements creates an
aspirator nozzle supply plenum 58 around the jet pump 55 linked by
the tube perforation apertures 44 to the casing annulus 15. The
nozzle supply plenum 58 serves as a fluid supply reservoir for
charging fluid flow into the aspirator nozzle inlet orifice 62.
[0044] Operationally, the second invention embodiment is similar to
the first embodiment in that the charging fluid is channeled into
the casing annulus 15 via an injection flow fitting 42 to pressure
load a standing fluid column 36 in the casing annulus 15. Casing
annulus fluid 36 is displaced under the pressure load through the
tubing apertures 44 into the nozzle supply plenum 58. From the
nozzle supply plenum 58, fluid is driven through the orifice 62 for
high velocity jet discharge from the nozzle 60. The high velocity
jet discharge is directed through a larger diameter aspirator
nozzle 64 to generate a low pressure flow induction zone at the jet
pump inlet 66.
[0045] Referring to the detail of FIG. 4, attention is directed to
the check valve 70 in the nozzle 60. This illustrated embodiment of
a check valve comprises a ball 72 caged between a ball valve seat
and a gage- pin 74. Fluid flow entering the nozzle inlet 66 lifts
the ball 72 off the valve seat. The cage-pin 74 prevents the ball
72 from flowing out of the nozzle flow bore while the drive fluid
flows around the valve ball 72.
[0046] In the event that natural production flow is restored by
removal of the tube 24 overburden fluid, it may be tolerable to
eliminate the charging fluid flow. In such a case, the pressure
differential between the tubing 24 flow bore and the jet pump
secondary annulus 58 would reverse and the check valve ball 72
would pressure differentially seat to close the nozzle bore.
[0047] Although the jet pump aspirating principles are effective
with a liquid charging fluid discharged from the nozzle 64, the
flow induction efficiency is considerably greater when the charging
fluid is a compressed gas. When the compressed gas is released into
the liquid filled tubing bore, the gas nucleates into numerous
small bubbles, each containing a fixed, finite weight of gas. In
conformance with Boyle's Law, as the bubbles rise in the tubing
flow bore column, the fluid environment pressure declines. As the
environment pressure declines, the fixed weight of gas charging
fluid in each bubble volumetrically expands to accelerate the
displacement of surrounding liquid.
[0048] FIGS. 5 and 6 illustrate a third embodiment of the invention
that comprises a jet pump sub 80 that is line coupled in a straight
tubing string 24 or below a side pocket mandrel tube 82.
[0049] The jet pump sub 80 essentially conforms to the jet pump
body 55 illustrated by FIG. 4 with the exception that the nozzle
inlet 62 is protected by a slotted screen 84, for example.
[0050] Unless the original production tube is installed with the
jet pump sub 80 in-line, which it may be, it will be necessary to
withdraw the tubing 24 to insert the pump sub 80. However, no
wire-line or perforating procedures are necessary. The entire
casing annulus becomes the charging fluid plenum for the pump sub
80.
[0051] In the case of the FIG. 6 embodiment, a gas-lift valve
string 28 comprises several lift valves 90, 92 and 94, for example.
The valve orifices and mechanisms are disposed in side-pocket
mandrel joints 82 above the jet pump 80.
[0052] Operatively, the casing annulus 15 is charged with an
opening pressure that, for example, may be 2000 psi for a
lift-valve at 3000 ft. depth. If the flow bore head pressure is
1500 psi at that point, a 500 psi differential opening pressure may
be necessary to open the first lift valve 90.
[0053] Once lifting flow begins, the opening pressure differential
declines. For example, is valve 94 is at 3500 ft., the internal
flow bore head pressure may have declined to 1200 psi and only a
250 psi differential is required to open valve 94. Hence, the
casing annulus pressure may be reduced to 1450 psi.
[0054] At the same time that valve 94 is opening to 250 psi
differential, this differential is insufficient to hold the valve
90 open. Hence, valve 90 closes at the approximate pressure
differential that valve 92 opens considering the respective depth
i.e. head, differential between valves 90 and 92.
[0055] This sequence continues down the tubing string until all
lift valves in the string 28 have opened and closed leaving only
the jet pump 80 as transferring charging fluid from the casing
annulus 15 into the production tube flow bore.
[0056] As is often the case with deep, gas drive well, the presence
of excess water in the production flow stream may be intermittent.
Consequently, the flow bore of a production tube may be purged of a
stagnating water head and resume an unassisted production of
petroleum for an indeterminate period. Eventually, however, another
water flow will invade the production to stagnate the production.
Advantageously, the invention embodiment of FIG. 6 may be
positioned as the original well completion and continued
indefinitely by intermittently purging the flow bore of accumulated
water and thereafter stopping the flow of external lifting gas to
permit the natural drive production.
[0057] As used herein, the terms "up" and "down", "upper" and
"lower", "upwardly" and "downwardly", "upstream" and "downstream",
"above" and "below" and other like terms indicating relative
positions above or below a given point or element are used in this
description to more clearly describe some embodiments of the
invention. However, when applied to equipment and methods for use
in wells that are deviated or horizontal, such terms may refer to a
left-to-right or right-to-left or other relationship as
appropriate. Moreover, in this specification and appended claims,
the terms "pipe", "tube"; "tubular", "casing", "liner" and/or
"other tubular goods" are to be interpreted and defined generically
to mean any and all of such elements without limitation of industry
usage.
[0058] Having fully described the presently known preferred
embodiments of our invention, those of skill in the art will
understand other obvious permutations and modifications of the
invention. As definition of our invention, therefore,
* * * * *