Background Art There are a variety of prior art well pumps in use. One of the most popular types of prior art well pumps comprises a reciprocating rod system which is primarily used for low volume flow rates. If higher volume flow rates are required, electrical submersible pumps are more appropriate. Another type of prior art well pump is the progressive cavity pump which utilizes a rotating helical rod within an elastomeric sleeve to move fluids.

Disclosure of Invention A subsurface well system contains well bore fluid and a pumping system which is lowered into the well bore on a conduit. The pumping system is supplied with electrical power through an insulated conductor which extends from the surface. The pumping system has an outer chamber, a discharge valve, and an intake valve for admitting the well bore fluid into the chamber. The chamber contains a reservoir or bladder. The reservoir is filled with an environmentally reactive polymer gel that undergoes a significant change in volume in response to environmental changes, such as an electrical or magnetic stimulus.

In one embodiment, the conductor is in electrical contact with the gel. Passing electrical current through the gel causes it to expand in volume significantly. When the gel is stimulated by the electrical current, the gel and the reservoir expand, thereby forcibly expelling the well bore fluid within the chamber through the discharge valve. When the gel is not stimulated, the gel and the reservoir contract or collapse, thereby drawing fluid into

the chamber through the intake valve. When electrical current is oscillated through the gel, the expansions and contractions are repeated so that a pumping action of well bore fluid is achieved.

In an alternate embodiment, the gel is formulated to react to the presence of an AC or DC electromagnetic field. The gel of this embodiment contains metallic particles which increase in temperature when exposed to the magnetic field. The temperature increase significantly increases the volume of the gel. A length of the lower end of the conductor is formed into a coil which surrounds the reservoir. Applying electrical current to the coil causes a magnetic field to pass through the gel, thereby increasing its volume. When electrical current is oscillated through the coil, the gel expands and contracts so that a pumping action of well bore fluid is achieved.

Brief Description of Drawings Figure I is a schematic drawing of an apparatus constructed in accordance with the invention.

Figure 2 is a schematic sectional view of a pump of the apparatus of Figure 1.

Figure 3 is a schematic sectional view of an alternate embodiment of a pump of the apparatus of Figure 1.

Best Mode for Carrying Out the Invention Referring to Figure 1, a subsurface well system 11 having a well bore 13 containing well bore fluid 15 and a pumping system 17 is shown. Pumping system 17 is lowered into well bore 13 on a conduit 21. Pumping system 17 is supplied with electrical power through an insulated conductor 23 which extends from the surface. Conductor 23 is secured and sealed to pumping system 17 at an upper end. A power supply 25 and a switch 27 control the electricity and are located at the surface. Power supply 25 may be DC or AC, and is

preferably single phase. Switch 27 is an automatically timed on/off switch which preferably variable.

Referring to Figure 2, pumping system 17 comprises an outer chamber 31, a discharge valve 33, and an intake valve 35 for admitting well bore fluid 15 into chamber 31.

The interior of chamber 31 communicates with an interior of conduit 21 through discharge valve 33. Intake valve 35 is located on a lower end 37 of chamber 31. In the preferred embodiment, valves 33,35 comprise check valves.

Chamber 31 contains an inner, variable volume reservoir 41 which is secured to lower end 37 of chamber 31. In the embodiment shown, reservoir 41 is an elastomeric bellows or bladder. Reservoir 41 is filled with an environmentally reactive polymer gel 43 that undergoes a significant change in volume in response to environmental changes, such as an electrical or magnetic stimulus. In the preferred embodiment, gel 43 is a mixture of N-isopropylacrylamide, water, an appropriate polymerization initiator and an accelerator.

Gel 43 of this nature is commercially available through Gel Sciences, Bedford, Massachusetts. Reservoir 41 protects gel 43 from contact with well fluid 15.

In the embodiment of Figure 2, a short length of the lower end of conductor 23 is formed into a flexible insulated lead 45. Lead 45 extends downward from the upper end of chamber 31 and extends sealingly into an upper end of reservoir 41 in electrical contact with gel 43. Chamber 31 is fabricated from an electrically conductive metal. Lower end 37 of chamber 31 is also in contact with gel 43 and acts as a ground. Passing electrical current through gel 43 causes it to expand in volume significantly. Gel 43 and, thus, reservoir 41 have two states: an unstimulated, contracted state wherein a relatively small volume of chamber 31 is filled, and a stimulated, expanded state wherein a relatively large volume of chamber 31 is filled.

In operation, power supply 25 alternatively passes electricity through gel 43 from conductor 23 to the ground at lower end 37. When gel 43 is stimulated by the electrical

current, gel 43 and reservoir 41 expand, thereby forcibly expelling the well bore fluid 15 within chamber 31 through discharge valve 33. Intake valve 35 is in a closed position and discharge valve 33 is in an open position while gel 43 and reservoir 41 are expanding. When gel 43 is not stimulated, gel 43 and reservoir 41 contract or collapse, thereby drawing fluid 15 into chamber 31 through intake valve 35. Intake valve 35 is in an open position and discharge valve 33 is in a closed position while gel 43 and reservoir 41 are contracting. When the electricity is oscillated through gel 43, the expansions and contractions are repeated so that a pumping action of well bore fluid 15 is achieved.

An alternate embodiment of the invention is shown in Figure 3. In this embodiment, the gel is formulated to react to the presence of an AC or DC electromagnetic field. A pumping system 47 is similar to pumping system 17. Pumping system 47 comprises an outer chamber 51, a discharge valve 53, and an intake valve 55 for admitting well bore fluid 15 into chamber 51. The interior of chamber 51 communicates with an interior of a conduit 49 through discharge valve 53. Intake valve 55 is located on a lower end 57 of chamber 51. ln the preferred embodiment, valves 53,55 comprise check valves.

Chamber 51 contains an inner, variable volume bladder or reservoir 61 which is secured to lower end 57 of chamber 51. Reservoir 61 is filled with an environmentally reactive polymer gel 63 that undergoes a significant change in volume in response to a magnetic field stimulus. In the preferred embodiment, reservoir 61 is a thin flexible bladder.

Gel 63 contains metallic particles which increase in temperature when exposed to the magnetic field. The temperature increase significantly increases the volume of gel 63. Gel 63 does not come into contact with well bore fluid 15. An insulated electrical conductor 64 extends downward from the surface to chamber 51. A length of the lower end of conductor 64 is formed into a coil 65 with an outer diameter that is approximately equal to an inner diameter of chamber 51. Coil 65 extends downward from the upper end of

chamber 51 to the lower end 57 of chamber 51 and surrounds reservoir 61. Applying electrical current to coil 65 causes a magnetic field to pass through gel 63, thereby increasing its volume. Gel 63 and, thus, reservoir 61 have two states: an unstimulated, contracted state wherein a relatively small volume of chamber 51 is filled, and a stimulated, expanded state wherein a relatively large volume of chamber 51 is filled.

In operation, a power supply (not shown) selectively passes electrical current through conductor 64 to produce a magnetic field by coil 65. When gel 63 is stimulated by the magnetic field, gel 63 and reservoir 61 expand, thereby forcibly expelling the well bore fluid 15 within chamber 51 through discharge valve 53. Intake valve 55 is in a closed position and discharge valve 53 is in an open position while gel 63 and reservoir 61 are expanding. When gel 63 is not stimulated, gel 63 and reservoir 61 contract or collapse, thereby drawing fluid 15 into chamber 51 through intake valve 55. Intake valve 55 is in an open position and discharge valve 53 is in a closed position while gel 63 and reservoir 61 are contracting. When the electricity is oscillated through coil 65, the expansions and contractions are repeated so that a pumping action of well bore fluid 15 is achieved.

The invention has several advantages. This pump system has no submerged reciprocating seals, no moving components exposed to the well casing, and much simpler surface equipment than all other forms of lift. Because of its simplicity, this pump system should be more reliable and less expensive than prior art low volume pump alternatives.

While the invention has been shown in only two of its forms, it should be apparent to those skilled in the art that it is not so limited, but is susceptible to various changes without departing from the scope of the invention. For example, if the interior of chamber 31 must be protected from well bore fluid 15, a simple seal section chamber (not shown) comprising a bag type or labyrinth chamber of commercial types used with electrical centrifugal submersible pumps can be located above it. The expansion and contraction of gel 43 would cycle the oil contained within the seal section in and out similar to a motor thermal cycle. The well bore fluid 15 discharged into the seal section head as the gel expands would pass through a check valve. The seal section chamber drain valve would be left open and contain another check valve. Well bore fluid would be drawn into this check valve as the gel contracts. The seal section would have no dynamic seals.