Pump system

Claim 2

In a down hole well pumping system, the improvement comprising: pump structure for positioning in a well bore down hole in contact with a well reservoir, said pump structure defining a first fluid confining chamber for receiving displacing fluid, a second fluid confining chamber for receiving well fluid and a fluid conducting passage interconnecting said fluid confining chambers in communication with each other, said second chamber having an inlet and outlet port defined therein, said inlet port being defined to communicate with the well reservoir in which said pump structure is positioned, said passage extending upwardly from its point of communication with said second chamber to define an upwardly extending channel of predetermined length in which displacing fluid and well fluid may interface, at least a portion of said first cHamber defining a plunger chamber; inlet valve means mounted in said inlet port for conducting well fluid into said second chamber; outlet valve means mounted in said outlet port for discharging fluid from said second chamber; means for expanding and contracting the effective volume of said first chamber, each expansion and contraction of the effective volume of said first chamber being defined as a pump stroke, said means for expanding and contracting the effective volume of said first chamber being a plunger means mounted for reciprocal motion in said plunger chamber; means for supplying displacing fluid to said pump structure on each stroke of said pump at a controllable rate to maintain the moving interface region between displacing fluid and well fluid within said upwardly extending channel and said second chamber, said displacing fluid supply means being operable to supply displacing fluid to said pump structure in time coincidence with the expansion of the effective volume of said first chamber; said displacing fluid supply means comprising: reservoir means for displacing fluid defined as a continuation of said plunger chamber, said plunger means sealing said first chamber from said reservoir means whereby movement of said plunger means to contract and expand the effective volume of said first chamber, respectively, expands and contracts the volume of said reservoir means; means connected to said reservoir means for transferring displacing fluid thereto at a controlled rate; and valve means mounted in said plunger means for controlling the flow of displacing fluid between said reservoir means and said first chamber, said valve means being operated by the pressure differential developed between said first chamber and said reservoir means to open and close, respectively, during the expansion and contraction of the effective volume of said first chamber; and means for conducting fluid pumped from said outlet valve means to well surface.

Claim 3

In a down hole well pumping system, the improvement comprising: pump structure for positioning in a well bore down hole in contact with a well reservoir, said pump structure defining a first fluid confining chamber for receiving displacing fluid, a second fluid confining chamber for receiving well fluid and a fluid conducting passage interconnecting said fluid confining chambers in communication with each other, said second chamber having an inlet and outlet port defined therein, said inlet port being defined to communicate with the well reservoir in which said pump structure is positioned, said passage extending upwardly from its point of communication with said second chamber to define an upwardly extending channel of predetermined length in which displacing fluid and well fluid may interface, at least a portion of said first chamber defining a vertically extending plunger chamber; inlet valve means mounted in said inlet port for conducting well fluid into said second chamber; outlet valve means mounted in said outlet port for discharging fluid from said second chamber; means for expanding and contracting the effective volume of said first chamber, said means for expanding and contracting the effective volume of said first chamber is a plunger means mounted for up and down reciprocal motion in said plunger chamber; means for supplying displacing fluid to said pump structure at a controllable rate to maintain the moving interface region between displacing fluid and well fluid within said upwardly extending channel and said second chamber, said displacing fluid supply means being operable to supply displacing fluid to said pump structure in time coincidence with the expansion of the effective volume of said first chamber; said displacing fluid supply means comprising: reservoir means for displacing fluid defined as a continuation of said plunger chamber, said plunger chamber being positioned above said reservoir means, said plunger means sealing said first chamber from said reservoir means whereby movement of said plunger means to contract and expand the effective volume of said first chamber, respectively, expands and contracts the volume of said reservoir means; means connected to said reservoir means for transferring displacing fluid thereto at a controlled rate; and valve means mounted in said plunger means for controlling the flow of displacing fluid between said reservoir means and said first chamber, said valve means being operated by the pressure differential developed between said first chamber and said reservoir means to open and close, respectively, during the expansion and contraction of the effective volume of said first chamber; and means for conducting fluid pumped from said outlet valve means to well surface.

Claim 4

In a down hole well pumping system, the improvement comprising: pump structure for positioning in a well bore down hole in contact with a well reservoir, said pump structure defining a first fluid confining chamber for receiving displacing fluid, a second fluid confining chamber for receiving well fluid and a fluid conducting passage interconnecting said fluid confining chambers in communication with each other, said second chamber having an inlet and outlet port defined therein, said inlet port being defined to communicate with the well reservoir in which said pump structure is positioned, said passage extending upwardly from its point of communication with said second chamber to define an upwardly extending channel of predetermined length in which displacing fluid and well fluid may interface, at least a portion of said first chamber defining a vertically extending plunger chamber; inlet valve means mounted in said inlet port for conducting well fluid into said second chamber; outlet valve means mounted in said outlet port for discharging fluid from said second chamber; means for expanding and contracting the effective volume of said first chamber, said means for expanding and contracting the effective volume of said first chamber is a plunger means mounted for up and down reciprocal motion in said plunger chamber; means for supplying displacing fluid to said pump structure at a controllable rate to maintain the moving interface region between displacing fluid and well fluid within said upwardly extending channel and said second chamber, said displacing fluid supply means being operable to supply displacing fluid to said pump structure in time coincidence with the expansion of the effective volume of said first chamber; said displacing fluid supply means comprising: reservoir means for displacing fluid defined as a continuation of said plunger chamber, said plunger chamber being positioned above said reservoir means, said plunger means sealing said first chamber from said reservoir means whereby movement of said plunger means to contract and expand the effective volume of said first chamber, respectively, expands and contracts the volume of said reservoir means; means connected to said reservoir means for transferring displacing fluid thereto at a controlled rate; and valve means mounted in said plunger means for controlling the flow of displacing fluid between said reservoir means and said first chamber, said valve means being operated by the pressure differential developed between said first chamber and said reservoir means to open and close, respectively, during the expansion and contraction of the effective volume of said first chamber; and means for conducting fluid pumped from said outlet valve means to well surface.

Claim 5

The invention defined in claim 2, including a string of sucker rods for reciprocating said plunger means up and down, said sucker rods being connected to said plunger means and extending therefrom to well surface, said sucker rods being hollow and defining a conduit for conducting displacing fluid from well surface to said plunger means, said plunger means having a fluid conducting path defined therethrough for conducting displacing fluid from said sucker rods to said reservoir means.

Claim 6

A well pumping system, comprising: a sucker rod string; a fluid sealed string of tubing for positioning in a well to extend from the bottom portion of a well to well surface, said sucker rod string being mounted in said string of tubing for reciprocation up and down therein whereby said tubing functions as a housing to isolate said sucker rod string from well fluid thereby up and down reciprocal movement of said sucker rod string is not inhibited by well fluid; pump structure mounted on the lower end of said string of tubing to depend therefrom into the reservoir of well fluid to be pumped, said pump structure defining a first fluid confining chamber in communication with a second fluid confining chamber through a fluid conducting passage, said first and second chambers being for holding, respectively, a displacing fluid and a well fluid, said passage extending upwardly from its point of communication with said second chamber to define an upwardly extending channel in which displacing fluid and well fluid may interface, said second chamber having inlet and outlet port means operable only to receive and discharge fluid, respectively; plunger means mounted for up and down reciprocal motion in said first chamber for expanding and contracting the effective volume of said first chamber to displace up and down in said channel the region of interface between the displacing fluid and the well fluid whereby the displacing fluid functions as a piston to pump well fluid in said inlet port means and out said discharge port means; means for isolating the discharge point of said outlet port means of said pump structure from the well fluid reservoir and connecting said outlet port means in communication with well surface so that well fluid discharged from said outlet port means is pumped to well surface; means for connecting said plunger means to said sucker rod string whereby said plunger means may be driven through said sucker rod string; displacing fluid supply means connected to said first chamber for supplying displacing fluid thereto at a controllable rate to maintain the moving region of interface between the displacing fluid and the well fluid within said upwardly extending channel and said second chamber, said displacing fluid supply means being operable to supply displacing fluid to said pump structure in time coincidence with the expansion of the effective volume of said first chamber; said displacing fluid supply means comprising: structure defining a reservoir for displacing fluid, said displacing fluid reservoir being defined by a downwardly extending continuation of said first chamber and being in alignment with said plunger means; means connected to said displacing fluid reservoir for Transferring displacing fluid thereto at a controlled rate; and valve means connecting said displacing fluid reservoir in communication with said first chamber for controlling the flow of displacing fluid between said displacing fluid reservoir and said first chamber, said valve means being operable to open and close, respectively, in time coincidence with the expansion and contraction of the effective volume of said first chamber, said valve means being operated by the pressure differential developed between said first chamber and said displacing fluid reservoir during the expansion and contraction of the effective volume of said first chamber; said plunger means sealing said first chamber from said displacing fluid reservoir whereby the up and down reciprocal movement of said plunger means to contract and expand the effective volume of said first chamber, respectively, expands and contracts the volume of said reservoir means, said valve means being carried by said plunger means; and prime mover means connected to said sucker rod string for driving said sucker rod string in up and down reciprocal motion thereby to drive said plunger means.

Claim 7

A well pumping system, comprising: a sucker rod string; a fluid sealed string of tubing for positioning in a well to extend from the bottom portion of a well to well surface, said sucker rod string being mounted in said string of tubing for reciprocation up and down therein whereby said tubing functions as a housing to isolate said sucker rod string from well fluid thereby up and down reciprocal movement of said sucker rod string is not inhibited by well fluid; pump structure mounted on the lower end of said string of tubing to depend therefrom into the reservoir of well fluid to be pumped, said pump structure defining a first fluid confining chamber in communication with a second fluid confining chamber through a fluid conducting passage, said first and second chambers being for holding, respectively, a displacing fluid and a well fluid, said passage extending upwardly from its point of communication with said second chamber to define an upwardly extending channel in which displacing fluid and well fluid may interface, said second chamber having inlet and outlet port means operable only to receive and discharge fluid, respectively; plunger means mounted for up and down reciprocal motion in said first chamber for expanding and contracting the effective volume of said first chamber to displace up and down in said channel the region of interface between the displacing fluid and the well fluid whereby the displacing fluid functions as a piston to pump well fluid in said inlet port means and out said discharge port means; means for isolating the discharge point of said outlet port means of said pump structure from the well fluid reservoir and connecting said outlet port means in communication with well surface so that well fluid discharged from said outlet port means is pumped to well surface; means for connecting said plunger means to said sucker rod string whereby said plunger means may be driven through said sucker rod string; displacing fluid supply means connected to said first chamber for supplying displacing fluid thereto at a controllable rate to maintain the moving region of interface between the displacing fluid and the well fluid within said upwardly extending channel and said second chamber, said displacing fluid supply means being operable to supply displacing fluid to said pump structure in time coincidence with the expansion of the effective volume of said first chamber; said displacing fluid supply means comprising: structure defining a reservoir for displacing fluid, said displacing fluid reservoir being defined by a downwardly extending continuation of said first chamber and being in alignment with said plunger means; means connected to said displacing fluid reservoir for Transferring displacing fluid thereto at a controlled rate; and valve means connecting said displacing fluid reservoir in communication with said first chamber for controlling the flow of displacing fluid between said displacing fluid reservoir and said first chamber, said valve means being operable to open and close, respectively, in time coincidence with the expansion and contraction of the effective volume of said first chamber, said valve means being operated by the pressure differential developed between said first chamber and said displacing fluid reservoir during the expansion and contraction of the effective volume of said first chamber; said plunger means sealing said first chamber from said displacing fluid reservoir whereby the up and down reciprocal movement of said plunger means to contract and expand the effective volume of said first chamber, respectively, expands and contracts the volume of said reservoir means, said valve means being carried by said plunger means; and prime mover means connected to said sucker rod string for driving said sucker rod string in up and down reciprocal motion thereby to drive said plunger means.

Claim 8

The invention defined in claim 4, wherein: said sucker rods are hollow and define a conduit for conducting displacing fluid from well surface to said plunger means; and said plunger means has a fluid conducting path defined therethrough for conducting displacing fluid from said sucker rods to said displacing fluid reservoir.

Claim 9

The invention defined in claim 4, wherein said means for isolating the discharge point of said outlet port means of said pump structure from the well fluid reservoir and connecting said outlet port means in communication with well surface is a string of production tubing detachably coupled to said outlet port means.

Claim 10

The invention defined in claim 4, wherein: said sucker rod string defines a conduit for conducting displacing fluid from well surface to said plunger means; and said plunger means has a fluid conducting path defined therethrough for conducting displacing fluid from said sucker rod string to said reservoir means.

Claim 11

The invention defined in claim 7, wherein said means for isolating the discharge point of said outlet port means of said pump structure from the well fluid reservoir and connecting said outlet port means in communication with well surface is a string of production tubing detachably coupled to said outlet port means.

Claim 12

A pump for down hole use, comprising: structure defining a first fluid confining chamber for receiving displacing fluid, a second fluid confining chamber for receiving well fluid and a fluid conducting passage interconnecting said fluid confining chambers in communication with each other, said second chamber having an inlet and outlet port defined therein, said inlet port being defined to communicate with a well reservoir, said passage extending upwardly from its point of communication with said second chamber to define an upwardly extending channel of predetermined length in which displacing fluid and well fluid may interface, at least a portion of said first chamber defining a plunger chamber; inlet valve means mounted in said inlet port for conducting well fluid into said second chamber; outlet valve means mounted in said outlet port for discharging fluid from said second chamber; reservoir means defined as a continuation of said plunger chamber, said reservoir means being arranged for connection to a displacing fluid supply so that displacing fluid may be selectively supplied thereto; plunger means mounted for reciprocal motion in said plunger chamber for expanding and contracting the effective volume of said first chamber, said plunger means sealing said first chamber from said reservoir means whereby movement of said plunger means to contract and expand the effective volume of said first chamber, respectively, expands and contracts the volume of said reservoir means; and valve means moUnted in said plunger means for controlling the flow of displacing fluid between said reservoir means and said first chamber, said valve means being operated by the pressure differential developed between said first chamber and reservoir means to open and close, respectively, during the expansion and contraction of the effective volume of said first chamber.

Claim 13

A pump for down hole use, comprising: structure defining a first fluid confining chamber for receiving displacing fluid, a second fluid confining chamber for receiving well fluid and a fluid conducting passage interconnecting said fluid confining chambers in communication with each other, said second chamber having an inlet and outlet port defined therein, said inlet port being defined to communicate with a well reservoir, said passage extending upwardly from its point of communication with said second chamber to define an upwardly extending channel of predetermined length in which displacing fluid and well fluid may interface, at least a portion of said first chamber defining a plunger chamber; inlet valve means mounted in said inlet port for conducting well fluid into said second chamber; outlet valve means mounted in said outlet port for discharging fluid from said second chamber; reservoir means defined as a continuation of said plunger chamber, said reservoir means being arranged for connection to a displacing fluid supply so that displacing fluid may be selectively supplied thereto; plunger means mounted for reciprocal motion in said plunger chamber for expanding and contracting the effective volume of said first chamber, said plunger means sealing said first chamber from said reservoir means whereby movement of said plunger means to contract and expand the effective volume of said first chamber, respectively, expands and contracts the volume of said reservoir means; and valve means moUnted in said plunger means for controlling the flow of displacing fluid between said reservoir means and said first chamber, said valve means being operated by the pressure differential developed between said first chamber and reservoir means to open and close, respectively, during the expansion and contraction of the effective volume of said first chamber.

Claim 14

The invention defined in claim 9, wherein: said plunger chamber is defined to be substantially vertically extending; and said reservoir means is defined as a downward continuation of said plunger chamber.

Claim 15

The invention defined in claim 10, wherein: said plunger means is arranged for connection to a string of upwardly extending hollow sucker rods whereby sand plunger means may be driven up and down and displacing fluid may be conducted from well surface to said plunger means through a string of hollow sucker rods connected thereto; and said plunger means has a fluid conducting path defined therethrough for conducting displacing fluid to said reservoir means from the point of connection of a string of hollow sucker rods thereto.

Claim 16

The invention defined in claim 11, wherein said outlet port is arranged for being detachably coupled to a string of production tubing.

Claim 17

The invention defined in claim 9, wherein said outlet port is arranged for being detachably coupled to a string of production tubing.

Claim 18

A pump for downhole use to pump well fluid from a well, said pump comprising: structure defining a first fluid confining chamber in communication with a second fluid confining chamber through a fluid conducting passage, said first and second chambers being for holding, respectively, a displacing fluid and a well fluid, said passage extending upwardly from its point of communication with said second chamber to define an upwardly extending channel in which displacing fluid and well fluid may interface, said second chamber having inlet and outlet port means operable only to receive and discharge fluid, respectively, said pump structure having a gas trap defined therein above and in communication with the upper end of said channel to trap gas evolved from the well fluid, and including valve controlled conduit means connected for conducting trapped gas from said gas trap to a point in said second chamber adjacent said outlet port means so that the gas is pumped out of said second chamber with well fluid, said valve controlled conduit means being operable to control the flow of gas therethrough as a function of the pressure level of gas being conducted therethrough and the pressure levels within said gas trap and said second chamber; means for injecting displacing fluid at a controlled rate into said first chamber, said means arranged for connection to a source of displacing fluid; means for expanding and contracting the effective volume of said first chamber to displace up and down in said channel the region of interface between the displacing fluid and the well fluid whereby the displacing fluid functions as a piston to pump well fluid in said inlet port means and out said discharge port means, said means being constructed for connection with a prime mover; and means for conducting fluid pumped from said outlet port means to well surface.

Claim 19

A pump for downhole use to pump well fluid from a well, said pump comprising: structure defining a first fluid confining chamber in communication with a second fluid confining chamber through a fluid conducting passage, said first and second chambers being for holding, respectively, a displacing fluid and a well fluid, said passage extending upwardly from its point of communication with said second chamber to define an upwardly extending channel in which displacing fluid and well fluid may interface, said second chamber having inlet and outlet port means operable only to receive and discharge fluid, respectively, said pump structure having a gas trap defined therein above and in communication with the upper end of said channel to trap gas evolved from the well fluid, and including valve controlled conduit means connected for conducting trapped gas from said gas trap to a point in said second chamber adjacent said outlet port means so that the gas is pumped out of said second chamber with well fluid, said valve controlled conduit means being operable to control the flow of gas therethrough as a function of the pressure level of gas being conducted therethrough and the pressure levels within said gas trap and said second chamber; means for injecting displacing fluid at a controlled rate into said first chamber, said means arranged for connection to a source of displacing fluid; means for expanding and contracting the effective volume of said first chamber to displace up and down in said channel the region of interface between the displacing fluid and the well fluid whereby the displacing fluid functions as a piston to pump well fluid in said inlet port means and out said discharge port means, said means being constructed for connection with a prime mover; and means for conducting fluid pumped from said outlet port means to well surface.

Claim 20

The invention recited in claim 14, wherein said inlet port means includes a check valve operative to prevent fluid flow therethrough out from said second chamber and said outlet port means includes a check valve operative to prevent fluid flow therethrough into said second chamber.

Claim 21

The invention recited in claim 14, including means for supplying displacing fluid, said displacing fluid supply means being connected to said fluid injecting means to maintain the region of interface between the displacing fluid and the displaced fluid within said channel and second chamber.

Claim 22

The invention recited in claim 14, wherein said means for expanding and contracting the effective volume of said first chaMber is a plunger means mounted therein for up and down reciprocal motion, said plunger means being adapted for connection through a string of sucker rods to a prime mover.

Claim 23

The invention recited in claim 14, including fluid injection means associated with said structure to extend into well fluid being pumped for injecting controlled quantities of a diluent fluid into the well fluid to be pumped whereby to dilute and thereby reduce the viscosity of the well fluid.

Claim 24

The invention recited in claim 14, wherein said means for expanding and contracting the effective volume of said first chamber is a plunger means mounted therein for reciprocal motion.

Claim 25

The invention recited in claim 19, including prime mover means connected to said plunger means for driving said plunger means in its reciprocal path of motion.

Claim 26

A well pumping system, comprising: a sucker rod string; a fluid sealed string of tubing for positioning in a well to extend from the bottom portion of a well to well surface, said sucker rod string being mounted in said string of tubing for reciprocation up and down therein whereby said tubing functions as a housing to isolate said sucker rod string from well fluid thereby up and down reciprocal movement of said sucker rod string is not inhibited by well fluid; pump structure mounted on the lower end of said string of tubing to depend therefrom into the reservoir of well fluid to be pumped, said pump structure defining a first fluid confining chamber in communication with a second fluid confining chamber through a fluid conducting passage, said first and second chambers being for holding, respectively, a displacing fluid and a well fluid, said passage extending upwardly from its point of communication with said second chamber to define an upwardly extending channel in which displacing fluid and well fluid may interface, said second chamber having inlet and outlet port means operable only to receive and discharge fluid, respectively, said pump structure having a gas trap defined therein above and in communication with the upper end of said channel to trap gas evolved from the well fluid, and including valve controlled conduit means connected for conducting trapped gas from said gas trap to a point in said second chamber adjacent said outlet port means so that the gas is pumped out of said second chamber with well fluid, said valve controlled conduit means being operable to control the flow of gas therethrough as a function of the pressure level of gas being conducted therethrough and the pressure levels within said gas trap and said second chamber; plunger means mounted for up and down reciprocal motion in said first chamber for expanding and contracting the effective volume of said first chamber to displace up and down in said channel the region of interface between the displacing fluid and the well fluid whereby the displacing fluid functions as a piston to pump well fluid in said inlet port means and out said outlet port means; means for isolating the discharge point of said outlet port means of said pump structure from the well fluid reservoir and connecting said outlet port means in communication with well surface so that well fluid discharged from said outlet port means is pumped to well surface; means for connecting said plunger means to said sucker rod string whereby said plunger means may be driven through said sucker rod string; displacing fluid supply means connected to said first chamber for supplying displacing fluid thereto at a controllable rate to maintain the moving region of interface between the displacing fluid and the well fluid within said upwardly extending channel and said second chamber; and prime mover means connected to said sucker rod string for driving said sucker rod string in up and down reciprocal motion thereby to drive said plunger means.

Claim 27

A well pumping system, comprising: a sucker rod string; a fluid sealed string of tubing for positioning in a well to extend from the bottom portion of a well to well surface, said sucker rod string being mounted in said string of tubing for reciprocation up and down therein whereby said tubing functions as a housing to isolate said sucker rod string from well fluid thereby up and down reciprocal movement of said sucker rod string is not inhibited by well fluid; pump structure mounted on the lower end of said string of tubing to depend therefrom into the reservoir of well fluid to be pumped, said pump structure defining a first fluid confining chamber in communication with a second fluid confining chamber through a fluid conducting passage, said first and second chambers being for holding, respectively, a displacing fluid and a well fluid, said passage extending upwardly from its point of communication with said second chamber to define an upwardly extending channel in which displacing fluid and well fluid may interface, said second chamber having inlet and outlet port means operable only to receive and discharge fluid, respectively, said pump structure having a gas trap defined therein above and in communication with the upper end of said channel to trap gas evolved from the well fluid, and including valve controlled conduit means connected for conducting trapped gas from said gas trap to a point in said second chamber adjacent said outlet port means so that the gas is pumped out of said second chamber with well fluid, said valve controlled conduit means being operable to control the flow of gas therethrough as a function of the pressure level of gas being conducted therethrough and the pressure levels within said gas trap and said second chamber; plunger means mounted for up and down reciprocal motion in said first chamber for expanding and contracting the effective volume of said first chamber to displace up and down in said channel the region of interface between the displacing fluid and the well fluid whereby the displacing fluid functions as a piston to pump well fluid in said inlet port means and out said outlet port means; means for isolating the discharge point of said outlet port means of said pump structure from the well fluid reservoir and connecting said outlet port means in communication with well surface so that well fluid discharged from said outlet port means is pumped to well surface; means for connecting said plunger means to said sucker rod string whereby said plunger means may be driven through said sucker rod string; displacing fluid supply means connected to said first chamber for supplying displacing fluid thereto at a controllable rate to maintain the moving region of interface between the displacing fluid and the well fluid within said upwardly extending channel and said second chamber; and prime mover means connected to said sucker rod string for driving said sucker rod string in up and down reciprocal motion thereby to drive said plunger means.

Claim 28

The invention recited in claim 21, wherein the well fluid is of an offensive nature and the displacing fluid is of an inoffensive nature.

Claim 29

The invention defined in claim 21, including lubricating fluid within said fluid sealed string of tubing to provide a lubricated path through which said sucker rod string may reciprocate with minimum wear and substantially free fall velocity.

Claim 30

The invention recited in claim 21, wherein the well fluid is a high viscosity crude oil, the displacing fluid is kerosene, and including fluid injection means associated with said pump structure to extend into the crude oil being pumped for injecting controlled quantities of a diluent fluid into the high viscosity crude oil whereby to dilute the crude oil and reduce its viscosity.

Claim 31

The invention recited in claim 24, wherein the diluent fluid is kerosene.

Claim 32

The invention defined in claim 21, wherein said means for isolating the discharge point of said outlet port means from the well fluid reservoir and connecting said outlet port means in communication with well surface is a fluid sealed string of production tubing.

Claim 33

The invention defined in claim 26, wherein said string of production tubing is detachably coupled to said pump structure.

Claim 34

The invention defined in claim 21, wherein said displacing fluid supply means is operable to supply displacing fluid to said pump structure in time coincidence with the expansion of the effective volume of said first chamber.

Claim 35

The invention defined in claim 28, wherein said displacing fluid supply means comprises: structure defining a reservoir for displacing fluid; means connected to said displacing fluid reservoir for transferring displacing fluid thereto at a controlled rate; and valve means connecting said displacing fluid reservoir in communication with said first chamber for controlling the flow of displacing fluid between said displacing fluid reservoir and said first chamber, said valve means being operable to open and close, respectively, in time coincidence with the expansion and contraction of the effective volume of said first chamber.

Claim 36

The invention defined in claim 29, wherein said valve means is operated by the pressure differential developed between said first chamber and said displacing fluid reservoir during the expansion and contraction of the effective volume of said first chamber.

Claim 37

The invention defined in claim 30, wherein: said displacing fluid reservoir is defined by a downwardly extending continuation of said first chamber, said displacing fluid reservoir being in alignment with said plunger means; and said plunger means seals said first chamber from said displacing fluid reservoir whereby the up and down reciprocal movement of said plunger means to contract and expand the effective volume of said first chamber, respectively, expands and contracts the volume of said reservoir means; and said valve means is carried by said plunger means.