CA1249965A - Downhole well pump - Google Patents
Downhole well pumpInfo
- Publication number
- CA1249965A CA1249965A CA000556180A CA556180A CA1249965A CA 1249965 A CA1249965 A CA 1249965A CA 000556180 A CA000556180 A CA 000556180A CA 556180 A CA556180 A CA 556180A CA 1249965 A CA1249965 A CA 1249965A
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- pump
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- chamber
- valve
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- Details Of Reciprocating Pumps (AREA)
Abstract
Abstract of the Invention Methods and means wherein a downhole reciprocating oil well pump powered by a source of pressurized fluid located at the wellhead receives fluid power via one tubing string and pumps liquid from the well through another tubing string, the downhole pump having internal means to vent gas and vapor from the pump chamber and to cause a pump stroke only when the pump chamber becomes filled with liquid. Means are provided to expel sediment from the pump chamber prior to a pump stroke and a method to independently vary the speed of the pump and return strokes and disclosed so as to conserve energy and reduce maintenance.
Description
~2~`3~?~i5 Downhole Well Pum~
Technical Field This invention relates generally to methods and means 05 for pumping oil and water from deep wells and more particularly to the use of reciprocating pumps powered by pressurized fluids such as gas, oil or water. Although fluld power has long been used to power such pumps, severe difficulties still exist in the pumps now available such as sand cutting, sand fouling, vapor locking, excessive use of energy, excessive downtime, excessive replacement of downhole tubing and other e~uipment, pumping at too fast a rate, pumping at too slow a rate, damage to producing formations, to name a few.
Although the use of sucker rods to operate a downhole reciprocating pump is the oldest and most wide spread method, the well known high first cost and endless maintenance problems inherent in sucker rod systems have almost become accepted by many operators as inevitable which unfortunately, drives up the cost of oil and gas and many "crooked holes" cannot be pumped at all with the use of suc.~er rods. The practice of "gaslifting" liquids from wells by injecting pressurized gas into a column of liquid within a tubing is well known to be an inefficient system when compressors are required to compress the gas before injection, and it cannot be used at all in most deep wells of today.
Therefore, particularly with regard to such wells as offshore wells which are generally both deep and directionally drilled, a more reliable and efficient method and means for pumping is needed by the industry to gain many millions of barrels of oil and billions of cubic feet of gas, as the present invention provides.
Bac.~round Art US Patents 2,362,777 and 3,123,007 disclose early systems for hydraulically driving a reciprocating well ~7¢
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pump by hydrostatic and elevated pressures respectively but neither have bearing on the present invention. Many similar patents e~ist, some having fluid motors for attachment to conventional pumps or to operate a string of sucker rods which in turn operate a conventional downhole pump.
Coberly U.S. Patent 2,952,212 issued Se?t~er 13, 1960 operates by co-mingling spent power fluid with produced liquid from the well which requires separation and purification of the power fluid before recirculation to the downhole pump.
~ later Coberly U.S. patent 3,C05,414 issued October 24, 1961 employs a power fluid s~ring and a separate string to return spent power fluid and a production string to convey produced liquid to the surface so as to maintain the power fluid clean, in a closed circuit. The present invention may be operated by either method or by a reciprocation of power fluid within one string, the production tubing being used only for produced liquid and other conduit such as an annulus being used to convey gas to the wellhead, as disclosed by the first mentioned patent.
Roeder U.S. patent 4,268,227 issued May 19, 1981 provides a "free type" pump that may be removed from the well without removal of the tubing. Copending Canadian Patent application 414,084 filed October 25, 1982, bears the closest physical resemblence to the apparatus of the present invention.
The above referenced application provides highly desirable features such as the venting of gas and vapor from the pump chamber before start of a pump stroke and filling of the pump chamber with liquid before start of the pump stroke but controlled from the well head. For some well conditions, it may cause considerable difficulties to cr/`
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communicate between the pump and the power unit at the well-head and therefore, the present invention comprises all intelligence in the downhole pump, to thereby eliminate the need for communication with the wellhead in orde- to function.
Whereas the referenced application requires a reci?rocating column OL fluid to power the downhole pump, the present invention may be operated by a reciprocating column or a non-reciprocating column of fluid. The above application provides a float valve to trigger a pump cycle whereas the present invention uses a flow restrictor sensitive to a difference in mass flow rate of a vapor as compared to a liquid. Also, the present invention may operate without a pressure buildup of power fluid above the normal operating pressure to cause a return stroke of the plunger, which therefore allows the use of lower pressure rated equipment and even further reduction of power usage.
All of the prior art known to the inventor, takes for granted: sand cutting of the pump and early replacement thereof; the pumping of all sediment that enters the pump chamber; no difference in speed between the pump and return strokes which often requires excessive energy usage because of a pump stroke faster than is required to pump at the rate that the well will produce. Said prior art has no provision within the downhole pump to sense when the pump chamber is full of liquid and to trigger a pump or return stroke but requires extensive communication equipment with the surface or worse still, it must often operate with an empty or partially empty pump chamber which wastes energy and causes premature pump failure because enough liquid is not present to carry heat of friction from the pump. Said prior art has no provision to make sliding seals resistant or immune to sand cutting and has no provision to prevent the pumping of sediment that enters the pump chamber which may cause excessive wear of standing valves or may fill the production tubing s sufficiently to stop flow to the wellhead. Therefore, it is clear that the industry is in need of novel features afforded by the present invention.
DISCLOSURE _ TUE INVENTION
The present application is a division of commonly owned Canadian Patent Application No~ 434,704 filed August 16, 1983.
The present invention provides novel methods and means within a downhole well pump to accept a pressurized power fluid from an external source and to operate the downhole pump such that: no pump stroke occurs until gas is vented from the pump chamber and the pump chamber is filled with liquid to be pumped; the pump chamber is sensed to be filled with liquid by a flow sensitive flow restrictor which monitors the venting of gas and vapor from the pump chamber and causes the vent to close when liquid flows past the restrictor; and a power valve may be caused to open when the vent is closed, so as to allow the flow of power fluid as required to cause a pump stroke.
All necessary intelligence is within a downhole pump constructed and installed in accord with the present invention such that the pump may automatically in sequence:
receive liquid, gas an vapor into the pump chamber; vent gas and vapor from the pump chamber and up the well bore;
sense when the pump chamber is filled with liquid; admit power fluid to the pump as required to cause a pump stroke at a predetermined speed best suited to the particular well conditions; stop the flow of power fluid to the pump near LCM:mls ~24~ 5 the end of the pump stroke; allow return of spent power fluid from the pump so as to allow a return stroke; use stored energy to cause a return stroke at an optimum predetermined speed; position all members of the pump as required to begin a subsequent pump cycle. The present invention may provide within the downhole pump: a lower wall of the pump chamber contoured so as to direct sediment out of the pump chamber prior to the pump chamber being pressured so as to begin a pump stroke; sliding sealing surfaces wetted by the produced liquid that are harder than sand particles entrained in the produced liquid; means to power a return stroke of the pump comprising a compressed gas-over-oil system with provision to bleed gas from the chambers requiring the presence of oil; quick acting valve means for controlling the flow of power fluid to and from the pump.
In summary, therefore, the present invention broadly provides a downhole well pump comprising means within the pump to: receive pressurized power fluid into the pump from an external sOurce sufficient to operate the pump; receive well liquid, gas and vapor from the well bore into a pump chamber; vent gas and vapor from the pump chamber; sense when the pump chamber is substantially filled with liquid and close the vent; automatically admit power fluid into such operating chambers as is necessary to operate the pump.
Other features and advantages of my invention will become obvious to those skilled in the art after LCM:mls - 5a -review of these disclosures and review of the attached drawings.
BRIEF DESCRIPTION OF DRAWINGS
Figure 1 depicts a downhole pump constructed in accord with the present invention, assembled and suspended in liquid to be pumped.
Figures 2 and 5 illustrate an arrangement for cooperation with a reciprocating column of power fluid and are vertical sections of Figure 1, taken 90 degrees apart.
Figures 3 and 4, when placed below Figure 2, illustrate a vertical sectional view of Figure 1 in the same plane as Figure 2.
LCM:mls 1'~4'.'3~ti5 (6~
Figure 5 is a vertical sectional view ta.~en along line 5-5 of Figure 2.
Figure 6 is a horizontal sectional view taken along line 6-6 of Figure 2.
05 Figure 7 is a horizontal sec'ional view ta~en along line 7-7 of Figure 4.
Figur~ 8 ill~strates an alter~ate arrangement to that shown in Figure 2, wherein fully automatic operations of the pump is effected without need to reciprocate the column of power fluid.
Figure 9 is a sectional view taken along line 9-9 of Figure 8.
Best Mode For Carryinq_Out the Invention The assembled pump depicted generally by 20 in Figure 1 is shown suspended in the liquid to be pumped, such that intake ports 22 are below the liquid surface 24 and such that the upper end 26 of vent pipe 28 is above surface 24.
The pump 20 is shown suspended from tubing 30 which conveys produced liquid to the wellhead, and from tubing 32 which conveys power fluid from the wellhead to the pump. Surge chamber 34 may be attached at its lower end with tubing 30 for communications therewith, as at 36. At its upper end, head 38 is sealably attached with tubing 30, tubing 32 and vent pipe 28 for communication with each as is later described. Other major members attached in sequence below head 38 are tubular upper jacket 40, tubular middle jacket 42, connector 44, tubular lower jacket 46 and foot 48, all preferably having the same outside diameter as the head.
Now referring to Figures 2 and 3, the upper end of centrally disposed tube 50 may be sealably connected with the lower end of head 38 so as to form annular pump chamber 52 between jacket 40 and tube 50, the lower end of head 38 defining the upper wall of chamber 52. The lower 3s end of jacket 40 may be bored to receive seal rings 56 alternately with spacer rings 58 for purposes to be s (7) described below. Lantern ring 60 may retain rings 56 and 58 against downward axial movement and mav be aligned such that ports 62 formed through the wall of ring 60, allow communication through ports 2Z and 62, between chamber 52 05 and the producing formation.
The periphery of rings 58 and 60 may be formed to receive seal rings as at 64 suitable to maintain a seal with the end bore or jacket 40. The end surfaces of rings 56 and 58 are formed flat and smooth such that an effective seal is maintained between said surfaces when held in contact by ring 60. Threaded t~be 66 may cooperate with mating threads formed within jac~et 40 to move rings 56, 58 and 60 into intimate sealing contact with one another, being retained against upward movement by shoulder 69 fonmed within jacket 40. Cooperating threads within the upper end of jacket 42 may be attached to threaded tube 66 so as to cause jac.~et 42 to abut jacket 40 and firmly secure the jackets together. The lower end of tube 50 may be sealably attached to fixed piston 68 having a maximum diameter greater than that of tube 50.
Tube 70, having a maximum diameter less than that of piston 68 may be attached to the lower end thereof and pr~ject downwardly through connector 44 as shown in Figures 3 and 4 so as to allow for nut 72 to be tightened on the lower threaded end of tube 70 against connector 44 through gland 140 and thereby preload tube 50, tube 70 and piston 68 in tension so as to preclude buckling of tubes 50 and 70. Annular plunger shown generally at 74, may be formed with bore 76 for slidable sealing cooperation with seals 78 positioned around fixed piston 68 to prevent flow around piston 68 within bore 76. Plunger 74 may be provided with end caps 80 which have end bores as at 82 so as to position seals 84 for slidable sealing cooperation against the perlphery of tubes 50 and 70. Bore 86 of tube 50 may convey power fluid to ports 88 through the wall of ;5 (8) tube 50 just above piston 68 to act within chamber 89 upwardly against the upper cap 80 and cause plunger 74 to move upwardly. Bore 90 of tube 70 mav convey return oil to ports 92 and within chamber 93 to act downwardly against 05 the lower cap and tend to cause plunger 74 to move downwardly~
The outer cylindrical surface 94 of plunger 74 may be of material harder than sand or foreign particles that may be entrained in the liquid to be pumped and the inner surace 96 of seal rings 56 may be sufficiently harder than surface 94 such that both sand cutting and gauling of the surfaces is precluded. For instance, surface 94 may be of chromium oxide and surface 96 may be of tungsten carbide which will provide such hardnesses and will also preclude corrosion of the seals.
The vertical motion of plunger 74 is limited when the lower cap abuts connector 44 and when the upper cap abuts head 38. Lateral mavement of plunger 74 is limited by the sliding fit between surface 94 and surfaces 96 as well as by the contact of bores 82 with the outer surface of tubes 50 and 70. Surfaces 96 guide the portion of the plunger near piston 68 while tubes 50 and 70 guide the ends of plunger 74 near head 38 or connector 44, such that surface 94 is not allowed to contact the inner wall of jackets 40 or 42, even under normal flexing of the jackets during transport or operation of the pump.
The top of upper cap 80 is contoured so as to direct any sediment from chamber 52 outwardly through ports 22 when plunger 74 is near the lowermost position as shown in Figure 3.
Rings 98 may be provided within the ends of caps 80 so as to scrape t~bes 50 and 70 and thereby preclude sand from entering bore 82 and cause eYcessive wear of seals 84. The outer surface of tubes 50 and 70 may be made similar to surface 94 and the inner surface of ring 98 may 1~4~i5 ( g ) be made similar to surface 96 for reasons already described.
The lowermost ring 56 positioned immediately above member 66, prevents sediment from passing from chamber 52 05 into jacket 42 which if allowed to collect, could settle on the upper end of connector 44 and prevent movement of plunger 74 to its lowermost position. Ports 100 positioned within connector 44 to drain fluid from within jacket 42 may be provided with check valves so as to prevent inflow of fluid from the well bore upon upstroke of the plungerO
Referring now to Figure 4, jacket 46, the lower end of connector 44 and the upper end of foot 48 define gas chamber 102 for containing pressurized gas such as nitrogen for use as a spring to store energy so as to power a return stroke or the plunger. Near the lower end of the gas chamber, oil surface 104 is maintained above the lcwer end of snorkle tube 106 so as to prevent entry of gas into tube 106. Durins a return stroke of the plunger, the compressed gas in chamber 102 acts on surface 104 and forces pressurized oil up tube 106, through ports 92 to act within the lower portion of plunger 74 against fixed piston 68 and against lower cap 80 to thereby force plunger 74 downwardly. Surface 104 is lowered during a return stroke and is raised during a pump stroke as shown at 105, to again further compress the gas within chamber 102 which in turn stores energy for the ne~t return stroke. Should gas enter tube 106 or plunger 74 through ports 92 sized for oil, the plunger action may become less controllable and there~ore means to bleed gas is desirable. Tube 108 may be mounted within tube 106, tube 108 having an open upper end positioned near the upper end of tube 106 and having its lower end connected with conventional vent valve 110 such that when valve 110 is opened, gas acting on surface 104 forces oil up tube 106 which in turn forces gas trapped in the upper end of tube 106, into the top of tube 108 and out valve 110. To ~2~3~i5 (10 ) prevent gas from entering tube 106 during transport of the pump, oil valve 112 may be provided to seal the lower end of tube 106. Rotation of valve 112 within foot 48 may advance valve 112 by means of cooperating sc~ew thre~ds as 05 at 114 until seal 116 mounted around the upper circumference of valve 112 engages the inner diameter 118 of the lower end of tube 106 and effects a seal between them. With valve 112 closed, the pump may be laid horizontally without gas entering tube 106. To prevent leakage around valve 112 to atmosphere, annular seal 120 may be provided around the lower end of valve 120 for sealing cooperation with bore 122 of foot 48. Should it be desired to add or remove oil from chamber 102, conventional valve 124 may be provided within foot 48.
Should it be desired to add or remove gas from chamber 102, conventional valve 126 may be provided within connector 44. Figure 7 illustrates a configuration for both valves 124 and i26 wherein plug 128 may be replaced with a pressure connection to a pump or to a bleed line, after which needle 130 is partially screwed out to allow fluid to pass seat 132 from or to chamber 102 while no flow is allowed to pass by seal 134 positioned around needle 130.
Pac~ing 136 is retained in centrally disposed bore 138 25 within connector 44 by gland 140 so as to slidably seal between tube 70 and connector 44 such that nut 72 may be sufficiently tightened on tube 70 and against gland 140 so as to preload tubes 50 and 70 against buckling and reversal of stresses during operation of the pump.
Now referring to Figure 2, tubing 30 is sealably connected with the upper end of head 38 and in communication with production flow path 142 from pump chamber 52. Located within path 142 are conventional standing valves 144 which allow upward flow from chamber 52 into tubing 30 but allow no return. Power fluid tubing 32 is sealably connected with the upper end of head 38 and 1~4~i5 (111 in communication with power fluid flow path 146 between tubing 32 and cham~er 89, in which power ~-a]ve 148 is positioned to control the flow. Differential piston 150 has: on its large end a first pressure area 152; on its 05 small end, a second pressure area 154; on the annular surface between said first pressure area and said second pressure area, a th~rd pressure area 15Z; around the cylindrical surface toward of the small end of piston 150, a fourth pressure area 158. Area 154 is exposed to the 10 power fluid pressure within tubing 32; area 158 is exposed to the fluid pressure within path 146 which is always in communication with tube 50; area 156 is always in communication with open vent 158 shown in Figure 6; area 152 is in communication with flow path 160 which is opened 15 and closed by valve 162 shown in Figure 5 and Figure 6.
Piston 150 is shown in its uppermost position for closure of flow path 146 but may be moved downwardly such that seal 164 around pressure area 154 disengages cooperating sealing surface on annular piston 166 to allow flow 20 between areas 154 and 158. Annular piston 166 may be provided with a sliding seal 167 around its periphery for cooperating with bore 168 within which it is mounted such that a pressure below, will cause piston 166 to move upwardly, compressing spring 170 and allow flow between 25 area 158 and area 154. When pressure above piston 166 is equal or greater than the pressure below it, piston 166 will remain in its lowermost position as shown, to allow for sealing contact with seal 164 when piston 150 is in an uppermost position and thereby stop flow between areas 154 30 and 158.
Differential piston 150 will remain in the closed upward position as shown as long as the force on area 152 exceeds the force on area 154 and conversely, it will move to the open lower position when the force on area 152 is less than the force on area 154.
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(12) As best viewed in Figure 5, vent valve 162 may comprise recess 174 formed around stem 176 slidablv mounted within bore 178 formed axially within valve body 180. In the lowermost position shown, recess 174 provides 05 for communication between flow path 172 which is in communication with power fluid tubing 32, and flow path 160 ln communication with pressure are 152; vent 182 the~
being closed by the upper portion of stem 176 when in the position shown. In such position, it is clear that power fluid pressure from tubing 3Z acts on both ends of piston 150 which causes pi~ton 150 to close power valve 148 because area 152 is greater than area 154, resulting in a net upward force on piston 150.
Flow restrictor 184 may comprise disc 186 mounted on the lower portion of stem 176, disc 186 being of such diameter and configuration as required to cause a suitable differential pressure across the disc when gas, vapor or liquid flows around the disc within vent path 188, formed axially within and through head 38. Compression coil spring 190 may be mounted around stem 176 below body 180 such that nut 186 may be adjusted along a threaded portion of stem 176 so as to create a desired compression load upon spring 190 and thereby prevent upward movement of stem 176 until a predetermined upward force on stem 176 is exceeded. The predetermined force must be greater than the differential force created across disc 184 by anticipated flowing gas through vent path 188 but less than the force caused by anticipated flowing liquid. Thus, as gas and vapor are vented from pump chamber 52 through path 188, stem 176 remains in the lower position but when chamber 52 becomes filled with liquid, liquid then flows upward through path 188 around disc 186 and creates an upward 3S force on stem 176 sufficient to overcome the preload on spring 190 which in turn, causes stem 176 to move upwardly. As an alternate, selected weights may be used in place of spring 190 to provide the desired force. Plug 194 ~2'~3~i5 (13) may be mounted on the upper end of stem 176 for cooperation with vent valve seat 196 formed concentrically within body 180, such that the contact of plug 194 with seat 196 limits the upward movement of stem 176 and closes 05 vent path 188. The spacing of flow paths 160, 172 and 182, together with the length of recess 174, are such that when stem 176 is in the lowermost position, paths 160 and 172 communicate and path 182 is closed and when st~m 176 is in the uppermcst position, paths 160 and 182 communicate and path 172 is closed. Cylindrical body 180 may have flats cut on opposite sides as shown in Figure 6 from the lowermost end of body 180 up to just below the level of seat 196 so as to allow the flow of gas and vapor to flow through seat 196 and out vent pipe 28 to the wellhead, when stem 176 is in the lower position. Body 180 has no flats above seat 196 so as to form a seal around body 180 against the bore of path 188.
It can now be understood that a downward acting preload suitable for a given well condition may be provided such that stem 176 remains in the lower position during venting of gas and vapor from chamber 52, maintaining vent path 188 open and maintaining pressure area 152 in communication with power fluid tubing 32 which in turn maintains power valve 148 closed as previously explained. It can also now be understood that when pump chamber 52 fills with liquid, liquid begins to flow around disc 186 to create the differential force required to overcome the downwardly acting preload and thereby move stem 176 to its uppermost position which in turn, closes vent path 188 and flow path 172 while allowing pressure area 152 to vent through paths 160 and 182 which in turn causes power valve 148 to move down to the open posltion.
After assembly and installation of the invention as illustrated in Figure 1, operation may be described as follows. Beginning with the configuration as depicted in ~2~ 5 (14) the drawings, power fluid is maintained under pressure within tubing 32 by a suitable fluid power source near the wellhead (not shown) as is well ~nown in the ar'. Because the downhole pump is suspended below the liquid level 24 05 in the well bore, the liquid together with entrained gas and vapor may flow into pump chamber 52 through intake ports 22, the liquid level rising in chamber 52 while gas and vapor escape through vent path 188, through open seat 196 and up vent pipe 28 toward the wellhead. Immediately after chamber 52 becomes filled with liquld, liquid flows around disc 186 which causes stem 176 to rise and move plug 194 against seat 196 to thereby close vent path 188 as before explained. The upward movement of stem 176 also vents pressure area 152, allowing power valve 148 to open and admit a flow of pressurized power fluid from tubing 32 through pressure area 158, flow path 146, tube 50, ports 88 and into chamber ~9 to act against upper cap 80 in sufficient force to move plunger 74 upwardly against the force of liquid within chamber 52 and against the oil pressure within chamber 93 so as to cause liquid from chamber 52 to rise through path 142 past conventional standing valves 144 and upwardly to the wellhead through tubing 30. As upper cap 80 rises to contact the lower wall of head 38, the upward movement of plunger 74 is stopped which causes an increase of pressure within tubing 32 above the pressure necessary to raise the plunger. Upon a conventional pressure switch mounted with tubing 32 at the wellhead sensing such pressure increase, the pressure within tubing 32 may be automatically vented by a motor valve which serves to reduce the pressure within chamber 89 to hydrostatic pressure only. Gas within chamber 102 having been precharged to a pressure suitable for given well conditions, is further compressed as plunger 74 moves upwardly, forcing oil from chamber 93, through ports 92, tube 70 and into the bottom of chamber 102 to cause liquid surface 104 to rise.
(15) Now, after reduction of pressure within chamber 89 to hydrostatic only, the oil pressure within chamber 93 driven by compressed gas within chamber 102 is suf~icient to overcome hydrostatic pressure within chamber 89 and 05 return plunger 74 to the lowermost position which in turn reverses the flow of the power fluid and returns gas pressure within chamber 102 to the precharge pressure.
Power fluid returning upwardly through power valve 148 will move annular piston 166 upwardly against spring 170 to allow free return of power fluid regardless of the position of piston 150, until pressures above and below piston 166 are substantially equal, at which time, spring 170 will force piston 166 to a lowermost position and thereby allow sealing contact with piston 150 to allow closure of valve 148.
As plunger 74 begins to descend from the uppermost position, a partial vacuum is created within chamber 52 which causes a downward differential pressure across plug 194 which acts together with said downwardly acting force to move stem 176 to its lowermost position and thereby reopen vent path 188, close vent 182 and admit power fluid from tubing 32 through paths 172 and 160 to act against pressure area 152 to move piston 150 upwardly to effect closure of valve 148 and thereby return the pump to the first configuration, ready to begin another pump cycle.
A conventional flow sensor mounted with tubing 32 at the wellhead may be used to signal the motor valve to close and to cause repressurization of tubing 32, after return of the power fluid upon the return stroke of plunger 74.
As the pump stroke begins, sealing surface 94 of plunger 74 is not in contact with any of the seal rings 56 that serve to seal chamber 52 from the well bore. Sediment that may settle from the liquid while chamber 52 is being filled will fall on the contoured upper surface of cap 80 to be directed towards ports 62. As plunger 74 begins to rise, a predetermined amount of liquid is forced out 9~1~S
(16) through ports 62 so as to return such sediment to the well bore and down below the pump. Upon surface 94 rising high enough to contact the seal ring immediately above lantern ring 60, such flow through ports 60 ceases and liquid 05 within chamber 52 becomes pressurized sufficiently to force it toward the wellhead. Surface 96 of seal rings 56 may be of a slightly smaller diameter than surface 94 so as to maintain sealing contact, rings 56 being cut at one part of its periphery so as to allow minute expansion of the ring and intimate contact of sealing surfaces 94 and 96. Because both surfaces are harder than sand, no sand cutting will occur, causing a higher efficiency and longer operating life of the pump.
In some installations the pump may be operatin~ with such a fast pump stroke that an excessive pressure buildup tends to occur within the pump chamber before flow to the surface within the production tubing begins 9 due to the inertia of liquid within the production tubing. To prevent such a pressure buildup and to maintain a more constant rate of flow within the production tubing, surge chamber 34 may be provided, being suitably precharged with gas above piston 35, to a pressure near the hydrostatic pressure within the production tubing. Then as a pump stroke starts and a pressure surge tends to build up before the column of liquid begins to rise, liquid flows into conduit 36 to act upwardly on piston 35 and further compress the gas above it. As the column of liquid begins to rise, the pressure surge reduces and the compressed gas forces piston 35 back down to help continue the flow, even after standing valves 144 have closed. Surge chamber 34 may be rotated inwardly from the position shown so as to pass within the same size pipe that the downhole pump will pass. Surge chamber 35 may be assembled from conventional oilwell tubing such that any required length may be readily assembled.
~9'~?~;5 tl7) For slow stroking pump ins~allations, surge cont_ol may be accomplished by controlling the pu-np stroke speed as described below, so as to star~ slow and inc-ease the stro~e speed as the column of liquid begins to rise.
oS Wells bored into the earth have infinite combinations of conditions such as depth, pipe diameter, pressures, fluid characteristics, temperature, pressure ratings of tubing joints and other equipment. Therefore, it may be desirable under some well conditions to furnish fluid power to the downhole pump at a constant pressure and to return spent power fluid from the pump up the production string, tubing 30, or up a separate return string, tubing 200 as depicted in Figure 9, both methods of return well known in the art. To operate the present inven~ion by such a method, alternate head 202 may be provided to replace head 38.
Referring to Figure 8, conventional standing valves 144 are positioned to recieve produced liquid from pump chamber 52, through flow path 122 and to convey it to tubing 30 as described above for Figure 2. Tubing 32 is sealably attached to the upper end of head 202 so as to supply power fluid at a substantially constant pressure to flow path 204 formed axially within head 202 concentric with and below tubing 32. Now referring to Figure 9, switching valve 206 may be positioned within bore 208 ~ormed axially within head 202 and parallel to flow path 204 so as to protrude into chamber 52 as shown at 210 when in the lowermost position, and reversably movable to an uppermost position 212 as depicted by solid lines. When valve 206 is in the upper.nost position, recess 214 formed around a portion of valve stem 216 is positioned such that spent power fluid may return from tube 50 up through axially disposed flow path 218, through laterally disposed flow path 220 into path 208 via recess 214~ thence into flow path 222 in communication with return tubing 200.
Should it be desired to return power fluid through ti5 (18) production tubing 30, flow path 222 may be furnished with a suitable chec.~ valve not shown, and connected so as to communicate with tubing 30 instead of with tubing 200 to thereby allow flow from path 222 into tubing 30 but no 05 return flow. While chamber 52 is filling with liquid, valve 206 is held in the uppermost position by the hydrostatic pressure of spent power fluid acting against an upper enlarged end of st~m 216 as at shoulder 224, the top end 226 of stem 216 being vented at that time. When fluid force acting against end 226 exceeds the fluid force acting against shoulder 224, valve 206 must move to the lowermost position such that shoulder 224 abuts shoulder 228 and recess 214 connects flow path 230 with path 220 and path 222 is sealed by stem 216 above recess 214.
~alve 232 is constructed the same as valve 162 previously described except that valve 232 vents pressure when in the lowermost position and repressures when in the uppermost position. When valve 232 is in the lowermost position as depicted in Figure 9, fluid pressure acting against end 226 may be vented through lateral flow path 234 into valve 232 through recess 236 and thence out vent 238 to the well bore. A check valve may be installed in vent 238 to prevent well fluid from entering the vent path. When valve 232 is shifted to the uppermost position, vent path 238 is closed by the valve stem and recess 236 places flow path 234 in communication with flow path 240 which in turn is in communication with pressurized fluid flow path 204.
Operation of alternate head 202 may now be described, the remainder of the pump operating as described above. As gas and vapor are vented through valve 232, liquid rises within pump chamber 52 until it is filled whereupon it causes valve 232 to move to the uppermost position as described above for valve 162, thence causing power fluid to flow from path 204 through path 240, recess 236 and path 234 into chamber 225 to act against end 226 of valve 1'~4~`3~;5 (13) stem 216 to overcome hydros~atic pressure against shoulder 224 and to cause stem 216 to move to the lowermost position such that path 222 is sealed by stem 216 and simultaneously paths 220 and 23û are placed in OS communication via recess 214. Then pressurized power fluid may flow from path 204 into tube 50 so as to actuate the plunger as described above. As upper cap 80 approaches the top of the stroke, the cap contacts the lower end of stem 216 as at 210 and pushes the stem to the uppermost position as at 212, whereupon, power fluid is allowed to return from tube 50 through recess 214 and path 222 and up the tubing to the wellhead. As the plunger starts to descend, a vacuum is created in chamber 52 which causes valve 232 to return to the lowermost position which causes recess 236 to vent pressure from chamber 225 through paths 234 and 238 such that hydrostatic pressure of spent power fluid may once again act on shoulder 224 to maintain valve 206 in the uppermost position in preparation for a subsequent pump cycle. Because the pressure area against cap 80 is far greater than the pressure area against end 226 of stem 206, plunger 74 will easily move stem 216 upwardly and expel fluid from chamber 225 through path 234, recess 236, path 240 and back into path 204.
The return stroke speed of the plunger may be adjusted to the fastest reasonable speed consistant with proper operation by sizing ports 92 to restrict the flow of oil or by regulating the return flow of spent power fluid as by sizing ports 88 or by placing a flow restrictor at any point along the spent power fluid return path including placing flow restrictors at the source of pressurized power fluid. For some well conditions it may be desired to use only a gas chamber with no oil, for powering the return stroke of the plunger. Any suitable conventional flow restrictors may be utilized, depending upon the position of installation and the flow and fluid ;5 (20) requirements. The pump stroke speed may be independently regulated by adjusting the volume output at the source of fluid pressure mounted ne~r the we:Llhead. The pump s~roke need be no faster than is necessary to pump liquid from 05 the well at the rate the well is capable of producing to thereby reduce the size of the power unit required and to reduce the amount of power consumed to pump the well. It may therefore be understood how to regulate the pump and return strokes independently of one another so as to use the minimum energy required to pump a given well.
New and timely methods, means and apparatus for pumping liquids from deep oil wells and the like may now be understood by study of these disclosures and review of the attached drawings.
It is now obvious that the present invention is well suited to attain the desired objectives and provide novel advantages ~or pumping oil and water from deep wells so as to conserve energy, to reduce maintenance requirements, to reduce costs, to extend e~uipment life and to recover hydrocarbon deposits otherwise not feasible to recover.
Technical Field This invention relates generally to methods and means 05 for pumping oil and water from deep wells and more particularly to the use of reciprocating pumps powered by pressurized fluids such as gas, oil or water. Although fluld power has long been used to power such pumps, severe difficulties still exist in the pumps now available such as sand cutting, sand fouling, vapor locking, excessive use of energy, excessive downtime, excessive replacement of downhole tubing and other e~uipment, pumping at too fast a rate, pumping at too slow a rate, damage to producing formations, to name a few.
Although the use of sucker rods to operate a downhole reciprocating pump is the oldest and most wide spread method, the well known high first cost and endless maintenance problems inherent in sucker rod systems have almost become accepted by many operators as inevitable which unfortunately, drives up the cost of oil and gas and many "crooked holes" cannot be pumped at all with the use of suc.~er rods. The practice of "gaslifting" liquids from wells by injecting pressurized gas into a column of liquid within a tubing is well known to be an inefficient system when compressors are required to compress the gas before injection, and it cannot be used at all in most deep wells of today.
Therefore, particularly with regard to such wells as offshore wells which are generally both deep and directionally drilled, a more reliable and efficient method and means for pumping is needed by the industry to gain many millions of barrels of oil and billions of cubic feet of gas, as the present invention provides.
Bac.~round Art US Patents 2,362,777 and 3,123,007 disclose early systems for hydraulically driving a reciprocating well ~7¢
1~4~t;S
pump by hydrostatic and elevated pressures respectively but neither have bearing on the present invention. Many similar patents e~ist, some having fluid motors for attachment to conventional pumps or to operate a string of sucker rods which in turn operate a conventional downhole pump.
Coberly U.S. Patent 2,952,212 issued Se?t~er 13, 1960 operates by co-mingling spent power fluid with produced liquid from the well which requires separation and purification of the power fluid before recirculation to the downhole pump.
~ later Coberly U.S. patent 3,C05,414 issued October 24, 1961 employs a power fluid s~ring and a separate string to return spent power fluid and a production string to convey produced liquid to the surface so as to maintain the power fluid clean, in a closed circuit. The present invention may be operated by either method or by a reciprocation of power fluid within one string, the production tubing being used only for produced liquid and other conduit such as an annulus being used to convey gas to the wellhead, as disclosed by the first mentioned patent.
Roeder U.S. patent 4,268,227 issued May 19, 1981 provides a "free type" pump that may be removed from the well without removal of the tubing. Copending Canadian Patent application 414,084 filed October 25, 1982, bears the closest physical resemblence to the apparatus of the present invention.
The above referenced application provides highly desirable features such as the venting of gas and vapor from the pump chamber before start of a pump stroke and filling of the pump chamber with liquid before start of the pump stroke but controlled from the well head. For some well conditions, it may cause considerable difficulties to cr/`
lZ~'?~iS
communicate between the pump and the power unit at the well-head and therefore, the present invention comprises all intelligence in the downhole pump, to thereby eliminate the need for communication with the wellhead in orde- to function.
Whereas the referenced application requires a reci?rocating column OL fluid to power the downhole pump, the present invention may be operated by a reciprocating column or a non-reciprocating column of fluid. The above application provides a float valve to trigger a pump cycle whereas the present invention uses a flow restrictor sensitive to a difference in mass flow rate of a vapor as compared to a liquid. Also, the present invention may operate without a pressure buildup of power fluid above the normal operating pressure to cause a return stroke of the plunger, which therefore allows the use of lower pressure rated equipment and even further reduction of power usage.
All of the prior art known to the inventor, takes for granted: sand cutting of the pump and early replacement thereof; the pumping of all sediment that enters the pump chamber; no difference in speed between the pump and return strokes which often requires excessive energy usage because of a pump stroke faster than is required to pump at the rate that the well will produce. Said prior art has no provision within the downhole pump to sense when the pump chamber is full of liquid and to trigger a pump or return stroke but requires extensive communication equipment with the surface or worse still, it must often operate with an empty or partially empty pump chamber which wastes energy and causes premature pump failure because enough liquid is not present to carry heat of friction from the pump. Said prior art has no provision to make sliding seals resistant or immune to sand cutting and has no provision to prevent the pumping of sediment that enters the pump chamber which may cause excessive wear of standing valves or may fill the production tubing s sufficiently to stop flow to the wellhead. Therefore, it is clear that the industry is in need of novel features afforded by the present invention.
DISCLOSURE _ TUE INVENTION
The present application is a division of commonly owned Canadian Patent Application No~ 434,704 filed August 16, 1983.
The present invention provides novel methods and means within a downhole well pump to accept a pressurized power fluid from an external source and to operate the downhole pump such that: no pump stroke occurs until gas is vented from the pump chamber and the pump chamber is filled with liquid to be pumped; the pump chamber is sensed to be filled with liquid by a flow sensitive flow restrictor which monitors the venting of gas and vapor from the pump chamber and causes the vent to close when liquid flows past the restrictor; and a power valve may be caused to open when the vent is closed, so as to allow the flow of power fluid as required to cause a pump stroke.
All necessary intelligence is within a downhole pump constructed and installed in accord with the present invention such that the pump may automatically in sequence:
receive liquid, gas an vapor into the pump chamber; vent gas and vapor from the pump chamber and up the well bore;
sense when the pump chamber is filled with liquid; admit power fluid to the pump as required to cause a pump stroke at a predetermined speed best suited to the particular well conditions; stop the flow of power fluid to the pump near LCM:mls ~24~ 5 the end of the pump stroke; allow return of spent power fluid from the pump so as to allow a return stroke; use stored energy to cause a return stroke at an optimum predetermined speed; position all members of the pump as required to begin a subsequent pump cycle. The present invention may provide within the downhole pump: a lower wall of the pump chamber contoured so as to direct sediment out of the pump chamber prior to the pump chamber being pressured so as to begin a pump stroke; sliding sealing surfaces wetted by the produced liquid that are harder than sand particles entrained in the produced liquid; means to power a return stroke of the pump comprising a compressed gas-over-oil system with provision to bleed gas from the chambers requiring the presence of oil; quick acting valve means for controlling the flow of power fluid to and from the pump.
In summary, therefore, the present invention broadly provides a downhole well pump comprising means within the pump to: receive pressurized power fluid into the pump from an external sOurce sufficient to operate the pump; receive well liquid, gas and vapor from the well bore into a pump chamber; vent gas and vapor from the pump chamber; sense when the pump chamber is substantially filled with liquid and close the vent; automatically admit power fluid into such operating chambers as is necessary to operate the pump.
Other features and advantages of my invention will become obvious to those skilled in the art after LCM:mls - 5a -review of these disclosures and review of the attached drawings.
BRIEF DESCRIPTION OF DRAWINGS
Figure 1 depicts a downhole pump constructed in accord with the present invention, assembled and suspended in liquid to be pumped.
Figures 2 and 5 illustrate an arrangement for cooperation with a reciprocating column of power fluid and are vertical sections of Figure 1, taken 90 degrees apart.
Figures 3 and 4, when placed below Figure 2, illustrate a vertical sectional view of Figure 1 in the same plane as Figure 2.
LCM:mls 1'~4'.'3~ti5 (6~
Figure 5 is a vertical sectional view ta.~en along line 5-5 of Figure 2.
Figure 6 is a horizontal sectional view taken along line 6-6 of Figure 2.
05 Figure 7 is a horizontal sec'ional view ta~en along line 7-7 of Figure 4.
Figur~ 8 ill~strates an alter~ate arrangement to that shown in Figure 2, wherein fully automatic operations of the pump is effected without need to reciprocate the column of power fluid.
Figure 9 is a sectional view taken along line 9-9 of Figure 8.
Best Mode For Carryinq_Out the Invention The assembled pump depicted generally by 20 in Figure 1 is shown suspended in the liquid to be pumped, such that intake ports 22 are below the liquid surface 24 and such that the upper end 26 of vent pipe 28 is above surface 24.
The pump 20 is shown suspended from tubing 30 which conveys produced liquid to the wellhead, and from tubing 32 which conveys power fluid from the wellhead to the pump. Surge chamber 34 may be attached at its lower end with tubing 30 for communications therewith, as at 36. At its upper end, head 38 is sealably attached with tubing 30, tubing 32 and vent pipe 28 for communication with each as is later described. Other major members attached in sequence below head 38 are tubular upper jacket 40, tubular middle jacket 42, connector 44, tubular lower jacket 46 and foot 48, all preferably having the same outside diameter as the head.
Now referring to Figures 2 and 3, the upper end of centrally disposed tube 50 may be sealably connected with the lower end of head 38 so as to form annular pump chamber 52 between jacket 40 and tube 50, the lower end of head 38 defining the upper wall of chamber 52. The lower 3s end of jacket 40 may be bored to receive seal rings 56 alternately with spacer rings 58 for purposes to be s (7) described below. Lantern ring 60 may retain rings 56 and 58 against downward axial movement and mav be aligned such that ports 62 formed through the wall of ring 60, allow communication through ports 2Z and 62, between chamber 52 05 and the producing formation.
The periphery of rings 58 and 60 may be formed to receive seal rings as at 64 suitable to maintain a seal with the end bore or jacket 40. The end surfaces of rings 56 and 58 are formed flat and smooth such that an effective seal is maintained between said surfaces when held in contact by ring 60. Threaded t~be 66 may cooperate with mating threads formed within jac~et 40 to move rings 56, 58 and 60 into intimate sealing contact with one another, being retained against upward movement by shoulder 69 fonmed within jacket 40. Cooperating threads within the upper end of jacket 42 may be attached to threaded tube 66 so as to cause jac.~et 42 to abut jacket 40 and firmly secure the jackets together. The lower end of tube 50 may be sealably attached to fixed piston 68 having a maximum diameter greater than that of tube 50.
Tube 70, having a maximum diameter less than that of piston 68 may be attached to the lower end thereof and pr~ject downwardly through connector 44 as shown in Figures 3 and 4 so as to allow for nut 72 to be tightened on the lower threaded end of tube 70 against connector 44 through gland 140 and thereby preload tube 50, tube 70 and piston 68 in tension so as to preclude buckling of tubes 50 and 70. Annular plunger shown generally at 74, may be formed with bore 76 for slidable sealing cooperation with seals 78 positioned around fixed piston 68 to prevent flow around piston 68 within bore 76. Plunger 74 may be provided with end caps 80 which have end bores as at 82 so as to position seals 84 for slidable sealing cooperation against the perlphery of tubes 50 and 70. Bore 86 of tube 50 may convey power fluid to ports 88 through the wall of ;5 (8) tube 50 just above piston 68 to act within chamber 89 upwardly against the upper cap 80 and cause plunger 74 to move upwardly. Bore 90 of tube 70 mav convey return oil to ports 92 and within chamber 93 to act downwardly against 05 the lower cap and tend to cause plunger 74 to move downwardly~
The outer cylindrical surface 94 of plunger 74 may be of material harder than sand or foreign particles that may be entrained in the liquid to be pumped and the inner surace 96 of seal rings 56 may be sufficiently harder than surface 94 such that both sand cutting and gauling of the surfaces is precluded. For instance, surface 94 may be of chromium oxide and surface 96 may be of tungsten carbide which will provide such hardnesses and will also preclude corrosion of the seals.
The vertical motion of plunger 74 is limited when the lower cap abuts connector 44 and when the upper cap abuts head 38. Lateral mavement of plunger 74 is limited by the sliding fit between surface 94 and surfaces 96 as well as by the contact of bores 82 with the outer surface of tubes 50 and 70. Surfaces 96 guide the portion of the plunger near piston 68 while tubes 50 and 70 guide the ends of plunger 74 near head 38 or connector 44, such that surface 94 is not allowed to contact the inner wall of jackets 40 or 42, even under normal flexing of the jackets during transport or operation of the pump.
The top of upper cap 80 is contoured so as to direct any sediment from chamber 52 outwardly through ports 22 when plunger 74 is near the lowermost position as shown in Figure 3.
Rings 98 may be provided within the ends of caps 80 so as to scrape t~bes 50 and 70 and thereby preclude sand from entering bore 82 and cause eYcessive wear of seals 84. The outer surface of tubes 50 and 70 may be made similar to surface 94 and the inner surface of ring 98 may 1~4~i5 ( g ) be made similar to surface 96 for reasons already described.
The lowermost ring 56 positioned immediately above member 66, prevents sediment from passing from chamber 52 05 into jacket 42 which if allowed to collect, could settle on the upper end of connector 44 and prevent movement of plunger 74 to its lowermost position. Ports 100 positioned within connector 44 to drain fluid from within jacket 42 may be provided with check valves so as to prevent inflow of fluid from the well bore upon upstroke of the plungerO
Referring now to Figure 4, jacket 46, the lower end of connector 44 and the upper end of foot 48 define gas chamber 102 for containing pressurized gas such as nitrogen for use as a spring to store energy so as to power a return stroke or the plunger. Near the lower end of the gas chamber, oil surface 104 is maintained above the lcwer end of snorkle tube 106 so as to prevent entry of gas into tube 106. Durins a return stroke of the plunger, the compressed gas in chamber 102 acts on surface 104 and forces pressurized oil up tube 106, through ports 92 to act within the lower portion of plunger 74 against fixed piston 68 and against lower cap 80 to thereby force plunger 74 downwardly. Surface 104 is lowered during a return stroke and is raised during a pump stroke as shown at 105, to again further compress the gas within chamber 102 which in turn stores energy for the ne~t return stroke. Should gas enter tube 106 or plunger 74 through ports 92 sized for oil, the plunger action may become less controllable and there~ore means to bleed gas is desirable. Tube 108 may be mounted within tube 106, tube 108 having an open upper end positioned near the upper end of tube 106 and having its lower end connected with conventional vent valve 110 such that when valve 110 is opened, gas acting on surface 104 forces oil up tube 106 which in turn forces gas trapped in the upper end of tube 106, into the top of tube 108 and out valve 110. To ~2~3~i5 (10 ) prevent gas from entering tube 106 during transport of the pump, oil valve 112 may be provided to seal the lower end of tube 106. Rotation of valve 112 within foot 48 may advance valve 112 by means of cooperating sc~ew thre~ds as 05 at 114 until seal 116 mounted around the upper circumference of valve 112 engages the inner diameter 118 of the lower end of tube 106 and effects a seal between them. With valve 112 closed, the pump may be laid horizontally without gas entering tube 106. To prevent leakage around valve 112 to atmosphere, annular seal 120 may be provided around the lower end of valve 120 for sealing cooperation with bore 122 of foot 48. Should it be desired to add or remove oil from chamber 102, conventional valve 124 may be provided within foot 48.
Should it be desired to add or remove gas from chamber 102, conventional valve 126 may be provided within connector 44. Figure 7 illustrates a configuration for both valves 124 and i26 wherein plug 128 may be replaced with a pressure connection to a pump or to a bleed line, after which needle 130 is partially screwed out to allow fluid to pass seat 132 from or to chamber 102 while no flow is allowed to pass by seal 134 positioned around needle 130.
Pac~ing 136 is retained in centrally disposed bore 138 25 within connector 44 by gland 140 so as to slidably seal between tube 70 and connector 44 such that nut 72 may be sufficiently tightened on tube 70 and against gland 140 so as to preload tubes 50 and 70 against buckling and reversal of stresses during operation of the pump.
Now referring to Figure 2, tubing 30 is sealably connected with the upper end of head 38 and in communication with production flow path 142 from pump chamber 52. Located within path 142 are conventional standing valves 144 which allow upward flow from chamber 52 into tubing 30 but allow no return. Power fluid tubing 32 is sealably connected with the upper end of head 38 and 1~4~i5 (111 in communication with power fluid flow path 146 between tubing 32 and cham~er 89, in which power ~-a]ve 148 is positioned to control the flow. Differential piston 150 has: on its large end a first pressure area 152; on its 05 small end, a second pressure area 154; on the annular surface between said first pressure area and said second pressure area, a th~rd pressure area 15Z; around the cylindrical surface toward of the small end of piston 150, a fourth pressure area 158. Area 154 is exposed to the 10 power fluid pressure within tubing 32; area 158 is exposed to the fluid pressure within path 146 which is always in communication with tube 50; area 156 is always in communication with open vent 158 shown in Figure 6; area 152 is in communication with flow path 160 which is opened 15 and closed by valve 162 shown in Figure 5 and Figure 6.
Piston 150 is shown in its uppermost position for closure of flow path 146 but may be moved downwardly such that seal 164 around pressure area 154 disengages cooperating sealing surface on annular piston 166 to allow flow 20 between areas 154 and 158. Annular piston 166 may be provided with a sliding seal 167 around its periphery for cooperating with bore 168 within which it is mounted such that a pressure below, will cause piston 166 to move upwardly, compressing spring 170 and allow flow between 25 area 158 and area 154. When pressure above piston 166 is equal or greater than the pressure below it, piston 166 will remain in its lowermost position as shown, to allow for sealing contact with seal 164 when piston 150 is in an uppermost position and thereby stop flow between areas 154 30 and 158.
Differential piston 150 will remain in the closed upward position as shown as long as the force on area 152 exceeds the force on area 154 and conversely, it will move to the open lower position when the force on area 152 is less than the force on area 154.
~2~ S
(12) As best viewed in Figure 5, vent valve 162 may comprise recess 174 formed around stem 176 slidablv mounted within bore 178 formed axially within valve body 180. In the lowermost position shown, recess 174 provides 05 for communication between flow path 172 which is in communication with power fluid tubing 32, and flow path 160 ln communication with pressure are 152; vent 182 the~
being closed by the upper portion of stem 176 when in the position shown. In such position, it is clear that power fluid pressure from tubing 3Z acts on both ends of piston 150 which causes pi~ton 150 to close power valve 148 because area 152 is greater than area 154, resulting in a net upward force on piston 150.
Flow restrictor 184 may comprise disc 186 mounted on the lower portion of stem 176, disc 186 being of such diameter and configuration as required to cause a suitable differential pressure across the disc when gas, vapor or liquid flows around the disc within vent path 188, formed axially within and through head 38. Compression coil spring 190 may be mounted around stem 176 below body 180 such that nut 186 may be adjusted along a threaded portion of stem 176 so as to create a desired compression load upon spring 190 and thereby prevent upward movement of stem 176 until a predetermined upward force on stem 176 is exceeded. The predetermined force must be greater than the differential force created across disc 184 by anticipated flowing gas through vent path 188 but less than the force caused by anticipated flowing liquid. Thus, as gas and vapor are vented from pump chamber 52 through path 188, stem 176 remains in the lower position but when chamber 52 becomes filled with liquid, liquid then flows upward through path 188 around disc 186 and creates an upward 3S force on stem 176 sufficient to overcome the preload on spring 190 which in turn, causes stem 176 to move upwardly. As an alternate, selected weights may be used in place of spring 190 to provide the desired force. Plug 194 ~2'~3~i5 (13) may be mounted on the upper end of stem 176 for cooperation with vent valve seat 196 formed concentrically within body 180, such that the contact of plug 194 with seat 196 limits the upward movement of stem 176 and closes 05 vent path 188. The spacing of flow paths 160, 172 and 182, together with the length of recess 174, are such that when stem 176 is in the lowermost position, paths 160 and 172 communicate and path 182 is closed and when st~m 176 is in the uppermcst position, paths 160 and 182 communicate and path 172 is closed. Cylindrical body 180 may have flats cut on opposite sides as shown in Figure 6 from the lowermost end of body 180 up to just below the level of seat 196 so as to allow the flow of gas and vapor to flow through seat 196 and out vent pipe 28 to the wellhead, when stem 176 is in the lower position. Body 180 has no flats above seat 196 so as to form a seal around body 180 against the bore of path 188.
It can now be understood that a downward acting preload suitable for a given well condition may be provided such that stem 176 remains in the lower position during venting of gas and vapor from chamber 52, maintaining vent path 188 open and maintaining pressure area 152 in communication with power fluid tubing 32 which in turn maintains power valve 148 closed as previously explained. It can also now be understood that when pump chamber 52 fills with liquid, liquid begins to flow around disc 186 to create the differential force required to overcome the downwardly acting preload and thereby move stem 176 to its uppermost position which in turn, closes vent path 188 and flow path 172 while allowing pressure area 152 to vent through paths 160 and 182 which in turn causes power valve 148 to move down to the open posltion.
After assembly and installation of the invention as illustrated in Figure 1, operation may be described as follows. Beginning with the configuration as depicted in ~2~ 5 (14) the drawings, power fluid is maintained under pressure within tubing 32 by a suitable fluid power source near the wellhead (not shown) as is well ~nown in the ar'. Because the downhole pump is suspended below the liquid level 24 05 in the well bore, the liquid together with entrained gas and vapor may flow into pump chamber 52 through intake ports 22, the liquid level rising in chamber 52 while gas and vapor escape through vent path 188, through open seat 196 and up vent pipe 28 toward the wellhead. Immediately after chamber 52 becomes filled with liquld, liquid flows around disc 186 which causes stem 176 to rise and move plug 194 against seat 196 to thereby close vent path 188 as before explained. The upward movement of stem 176 also vents pressure area 152, allowing power valve 148 to open and admit a flow of pressurized power fluid from tubing 32 through pressure area 158, flow path 146, tube 50, ports 88 and into chamber ~9 to act against upper cap 80 in sufficient force to move plunger 74 upwardly against the force of liquid within chamber 52 and against the oil pressure within chamber 93 so as to cause liquid from chamber 52 to rise through path 142 past conventional standing valves 144 and upwardly to the wellhead through tubing 30. As upper cap 80 rises to contact the lower wall of head 38, the upward movement of plunger 74 is stopped which causes an increase of pressure within tubing 32 above the pressure necessary to raise the plunger. Upon a conventional pressure switch mounted with tubing 32 at the wellhead sensing such pressure increase, the pressure within tubing 32 may be automatically vented by a motor valve which serves to reduce the pressure within chamber 89 to hydrostatic pressure only. Gas within chamber 102 having been precharged to a pressure suitable for given well conditions, is further compressed as plunger 74 moves upwardly, forcing oil from chamber 93, through ports 92, tube 70 and into the bottom of chamber 102 to cause liquid surface 104 to rise.
(15) Now, after reduction of pressure within chamber 89 to hydrostatic only, the oil pressure within chamber 93 driven by compressed gas within chamber 102 is suf~icient to overcome hydrostatic pressure within chamber 89 and 05 return plunger 74 to the lowermost position which in turn reverses the flow of the power fluid and returns gas pressure within chamber 102 to the precharge pressure.
Power fluid returning upwardly through power valve 148 will move annular piston 166 upwardly against spring 170 to allow free return of power fluid regardless of the position of piston 150, until pressures above and below piston 166 are substantially equal, at which time, spring 170 will force piston 166 to a lowermost position and thereby allow sealing contact with piston 150 to allow closure of valve 148.
As plunger 74 begins to descend from the uppermost position, a partial vacuum is created within chamber 52 which causes a downward differential pressure across plug 194 which acts together with said downwardly acting force to move stem 176 to its lowermost position and thereby reopen vent path 188, close vent 182 and admit power fluid from tubing 32 through paths 172 and 160 to act against pressure area 152 to move piston 150 upwardly to effect closure of valve 148 and thereby return the pump to the first configuration, ready to begin another pump cycle.
A conventional flow sensor mounted with tubing 32 at the wellhead may be used to signal the motor valve to close and to cause repressurization of tubing 32, after return of the power fluid upon the return stroke of plunger 74.
As the pump stroke begins, sealing surface 94 of plunger 74 is not in contact with any of the seal rings 56 that serve to seal chamber 52 from the well bore. Sediment that may settle from the liquid while chamber 52 is being filled will fall on the contoured upper surface of cap 80 to be directed towards ports 62. As plunger 74 begins to rise, a predetermined amount of liquid is forced out 9~1~S
(16) through ports 62 so as to return such sediment to the well bore and down below the pump. Upon surface 94 rising high enough to contact the seal ring immediately above lantern ring 60, such flow through ports 60 ceases and liquid 05 within chamber 52 becomes pressurized sufficiently to force it toward the wellhead. Surface 96 of seal rings 56 may be of a slightly smaller diameter than surface 94 so as to maintain sealing contact, rings 56 being cut at one part of its periphery so as to allow minute expansion of the ring and intimate contact of sealing surfaces 94 and 96. Because both surfaces are harder than sand, no sand cutting will occur, causing a higher efficiency and longer operating life of the pump.
In some installations the pump may be operatin~ with such a fast pump stroke that an excessive pressure buildup tends to occur within the pump chamber before flow to the surface within the production tubing begins 9 due to the inertia of liquid within the production tubing. To prevent such a pressure buildup and to maintain a more constant rate of flow within the production tubing, surge chamber 34 may be provided, being suitably precharged with gas above piston 35, to a pressure near the hydrostatic pressure within the production tubing. Then as a pump stroke starts and a pressure surge tends to build up before the column of liquid begins to rise, liquid flows into conduit 36 to act upwardly on piston 35 and further compress the gas above it. As the column of liquid begins to rise, the pressure surge reduces and the compressed gas forces piston 35 back down to help continue the flow, even after standing valves 144 have closed. Surge chamber 34 may be rotated inwardly from the position shown so as to pass within the same size pipe that the downhole pump will pass. Surge chamber 35 may be assembled from conventional oilwell tubing such that any required length may be readily assembled.
~9'~?~;5 tl7) For slow stroking pump ins~allations, surge cont_ol may be accomplished by controlling the pu-np stroke speed as described below, so as to star~ slow and inc-ease the stro~e speed as the column of liquid begins to rise.
oS Wells bored into the earth have infinite combinations of conditions such as depth, pipe diameter, pressures, fluid characteristics, temperature, pressure ratings of tubing joints and other equipment. Therefore, it may be desirable under some well conditions to furnish fluid power to the downhole pump at a constant pressure and to return spent power fluid from the pump up the production string, tubing 30, or up a separate return string, tubing 200 as depicted in Figure 9, both methods of return well known in the art. To operate the present inven~ion by such a method, alternate head 202 may be provided to replace head 38.
Referring to Figure 8, conventional standing valves 144 are positioned to recieve produced liquid from pump chamber 52, through flow path 122 and to convey it to tubing 30 as described above for Figure 2. Tubing 32 is sealably attached to the upper end of head 202 so as to supply power fluid at a substantially constant pressure to flow path 204 formed axially within head 202 concentric with and below tubing 32. Now referring to Figure 9, switching valve 206 may be positioned within bore 208 ~ormed axially within head 202 and parallel to flow path 204 so as to protrude into chamber 52 as shown at 210 when in the lowermost position, and reversably movable to an uppermost position 212 as depicted by solid lines. When valve 206 is in the upper.nost position, recess 214 formed around a portion of valve stem 216 is positioned such that spent power fluid may return from tube 50 up through axially disposed flow path 218, through laterally disposed flow path 220 into path 208 via recess 214~ thence into flow path 222 in communication with return tubing 200.
Should it be desired to return power fluid through ti5 (18) production tubing 30, flow path 222 may be furnished with a suitable chec.~ valve not shown, and connected so as to communicate with tubing 30 instead of with tubing 200 to thereby allow flow from path 222 into tubing 30 but no 05 return flow. While chamber 52 is filling with liquid, valve 206 is held in the uppermost position by the hydrostatic pressure of spent power fluid acting against an upper enlarged end of st~m 216 as at shoulder 224, the top end 226 of stem 216 being vented at that time. When fluid force acting against end 226 exceeds the fluid force acting against shoulder 224, valve 206 must move to the lowermost position such that shoulder 224 abuts shoulder 228 and recess 214 connects flow path 230 with path 220 and path 222 is sealed by stem 216 above recess 214.
~alve 232 is constructed the same as valve 162 previously described except that valve 232 vents pressure when in the lowermost position and repressures when in the uppermost position. When valve 232 is in the lowermost position as depicted in Figure 9, fluid pressure acting against end 226 may be vented through lateral flow path 234 into valve 232 through recess 236 and thence out vent 238 to the well bore. A check valve may be installed in vent 238 to prevent well fluid from entering the vent path. When valve 232 is shifted to the uppermost position, vent path 238 is closed by the valve stem and recess 236 places flow path 234 in communication with flow path 240 which in turn is in communication with pressurized fluid flow path 204.
Operation of alternate head 202 may now be described, the remainder of the pump operating as described above. As gas and vapor are vented through valve 232, liquid rises within pump chamber 52 until it is filled whereupon it causes valve 232 to move to the uppermost position as described above for valve 162, thence causing power fluid to flow from path 204 through path 240, recess 236 and path 234 into chamber 225 to act against end 226 of valve 1'~4~`3~;5 (13) stem 216 to overcome hydros~atic pressure against shoulder 224 and to cause stem 216 to move to the lowermost position such that path 222 is sealed by stem 216 and simultaneously paths 220 and 23û are placed in OS communication via recess 214. Then pressurized power fluid may flow from path 204 into tube 50 so as to actuate the plunger as described above. As upper cap 80 approaches the top of the stroke, the cap contacts the lower end of stem 216 as at 210 and pushes the stem to the uppermost position as at 212, whereupon, power fluid is allowed to return from tube 50 through recess 214 and path 222 and up the tubing to the wellhead. As the plunger starts to descend, a vacuum is created in chamber 52 which causes valve 232 to return to the lowermost position which causes recess 236 to vent pressure from chamber 225 through paths 234 and 238 such that hydrostatic pressure of spent power fluid may once again act on shoulder 224 to maintain valve 206 in the uppermost position in preparation for a subsequent pump cycle. Because the pressure area against cap 80 is far greater than the pressure area against end 226 of stem 206, plunger 74 will easily move stem 216 upwardly and expel fluid from chamber 225 through path 234, recess 236, path 240 and back into path 204.
The return stroke speed of the plunger may be adjusted to the fastest reasonable speed consistant with proper operation by sizing ports 92 to restrict the flow of oil or by regulating the return flow of spent power fluid as by sizing ports 88 or by placing a flow restrictor at any point along the spent power fluid return path including placing flow restrictors at the source of pressurized power fluid. For some well conditions it may be desired to use only a gas chamber with no oil, for powering the return stroke of the plunger. Any suitable conventional flow restrictors may be utilized, depending upon the position of installation and the flow and fluid ;5 (20) requirements. The pump stroke speed may be independently regulated by adjusting the volume output at the source of fluid pressure mounted ne~r the we:Llhead. The pump s~roke need be no faster than is necessary to pump liquid from 05 the well at the rate the well is capable of producing to thereby reduce the size of the power unit required and to reduce the amount of power consumed to pump the well. It may therefore be understood how to regulate the pump and return strokes independently of one another so as to use the minimum energy required to pump a given well.
New and timely methods, means and apparatus for pumping liquids from deep oil wells and the like may now be understood by study of these disclosures and review of the attached drawings.
It is now obvious that the present invention is well suited to attain the desired objectives and provide novel advantages ~or pumping oil and water from deep wells so as to conserve energy, to reduce maintenance requirements, to reduce costs, to extend e~uipment life and to recover hydrocarbon deposits otherwise not feasible to recover.
Claims (12)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A downhole well pump comprising means within the pump to: receive pressurized power fluid into the pump from an external source sufficient to operate the pump;
receive well liquid, gas and vapor from the well bore into a pump chamber; vent gas and vapor from the pump chamber;
sense when the pump chamber is substantially filled with liquid and close the vent; automatically admit power fluid into such operating chambers as is necessary to operate the pump.
receive well liquid, gas and vapor from the well bore into a pump chamber; vent gas and vapor from the pump chamber;
sense when the pump chamber is substantially filled with liquid and close the vent; automatically admit power fluid into such operating chambers as is necessary to operate the pump.
2. The invention of Claim 1 further comprising:
a gas chamber for retaining a compressed gas as required to cause a return stroke of the pump; the power fluid being of sufficient pressure and volume to power the pump stroke and to further compress said compressed gas so as to store sufficient energy as required to cause a return stroke of the pump powered by expansion of the gas to the degree of compression as before the pump stroke began.
a gas chamber for retaining a compressed gas as required to cause a return stroke of the pump; the power fluid being of sufficient pressure and volume to power the pump stroke and to further compress said compressed gas so as to store sufficient energy as required to cause a return stroke of the pump powered by expansion of the gas to the degree of compression as before the pump stroke began.
3. The invention of Claim 2 wherein: flow of the return fluid is restricted so as to limit the speed of the stroke as may be desired.
4. The invention of Claim 1 wherein: the flow of the power oil is restricted so as to limit the speed of the stroke as may be desired.
5. The invention of Claim 2 further comprising:
a gas chamber for retaining a compressed gas as required to drive a return stroke of the pump; the power fluid being of sufficient pressure and volume to power the pump stroke and to further compress said compressed gas so as to store sufficient energy as required to drive a return stroke of the pump by expansion of the gas to the degree of compression as before the pump stroke began.
a gas chamber for retaining a compressed gas as required to drive a return stroke of the pump; the power fluid being of sufficient pressure and volume to power the pump stroke and to further compress said compressed gas so as to store sufficient energy as required to drive a return stroke of the pump by expansion of the gas to the degree of compression as before the pump stroke began.
6. The invention of Claim 1 further comprising means within the downhole pump to cause an automatic return stroke of the pump sufficient to allow for successive cycles.
7. The invention of Claim 1 wherein means to automatically admit power fluid comprises a hydraulically operated power valve positioned so as to control flow within a power fluid conduit connected with such chambers as is necessary to operate the pump.
8. The invention of Claim 7 further comprising:
means to cause the power valve to open when the vent is closed; means to cause the power valve to close when the vent is open.
means to cause the power valve to open when the vent is closed; means to cause the power valve to close when the vent is open.
9. The invention of Claim 1 wherein the power fluid reciprocates in a conduit connected between the external power source and the pump, during operation of the pump.
10. The invention of Claim 1 wherein the power fluid flows in a conduit connected between the external power source and the pump, without reciprocation of the power fluid.
11. The invention of Claim 1 further comprising means to return power fluid from the pump to the external power source, separate from the power fluid conduit.
12. The invention of Claim 11 wherein means to return the power fluid comprise: an outlet valve positioned in a conduit for connecting the operating chambers with a power valve; the power valve being positioned so as to selectively admit power fluid to the operating chambers; means to open the outlet valve and close the power valve as the power stroke substantially ends; means to close the outlet valve and open the power valve as the pump chamber becomes substantially filled with liquid.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000556180A CA1249965A (en) | 1982-09-22 | 1988-01-08 | Downhole well pump |
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US42150382A | 1982-09-22 | 1982-09-22 | |
| US06/421,503 | 1982-09-22 | ||
| CA000434704A CA1232194A (en) | 1982-09-22 | 1983-08-16 | Downhole well pump |
| CA000556180A CA1249965A (en) | 1982-09-22 | 1988-01-08 | Downhole well pump |
Related Parent Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000556180A Division CA1249965A (en) | 1982-09-22 | 1988-01-08 | Downhole well pump |
Related Child Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000556180A Division CA1249965A (en) | 1982-09-22 | 1988-01-08 | Downhole well pump |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1249965A true CA1249965A (en) | 1989-02-14 |
Family
ID=25670125
Family Applications (2)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000556180A Expired CA1249965A (en) | 1982-09-22 | 1988-01-08 | Downhole well pump |
| CA000556179A Expired CA1249964A (en) | 1982-09-22 | 1988-01-08 | Downhole well pump |
Family Applications After (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000556179A Expired CA1249964A (en) | 1982-09-22 | 1988-01-08 | Downhole well pump |
Country Status (1)
| Country | Link |
|---|---|
| CA (2) | CA1249965A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114152783A (en) * | 2021-11-12 | 2022-03-08 | 环维电子(上海)有限公司 | Micro-needle floating test tool and test module |
-
1988
- 1988-01-08 CA CA000556180A patent/CA1249965A/en not_active Expired
- 1988-01-08 CA CA000556179A patent/CA1249964A/en not_active Expired
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114152783A (en) * | 2021-11-12 | 2022-03-08 | 环维电子(上海)有限公司 | Micro-needle floating test tool and test module |
| CN114152783B (en) * | 2021-11-12 | 2023-06-16 | 环维电子(上海)有限公司 | Microneedle floating test tool and test module |
Also Published As
| Publication number | Publication date |
|---|---|
| CA1249964A (en) | 1989-02-14 |
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| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |