초록 ▼

Liquid is accumulated above fluid displacement device which is moveable and sealed within a production chamber defined by a production tubing, and upward movement of the fluid displacement device is initiated to pump liquid and gas from a well, by different magnitudes of differential pressure create

Liquid is accumulated above fluid displacement device which is moveable and sealed within a production chamber defined by a production tubing, and upward movement of the fluid displacement device is initiated to pump liquid and gas from a well, by different magnitudes of differential pressure created at the well bottom. Preferably the different magnitudes of differential pressure are created by fluid passageways having different cross-sectional areas.

대표청구항 ▼

The invention claimed is: 1. A skirt apparatus for use with a fluid displacement device which is moveable and sealed within a production chamber defined by a production tubing which extends between a surface of the earth and a bottom of a well in a subterranean zone which contains liquid and gas, t

The invention claimed is: 1. A skirt apparatus for use with a fluid displacement device which is moveable and sealed within a production chamber defined by a production tubing which extends between a surface of the earth and a bottom of a well in a subterranean zone which contains liquid and gas, the skirt apparatus responding to different magnitudes of differential pressure between the exterior of the skirt apparatus at the well bottom and within the production chamber to accumulate liquid above the fluid displacement device and to initiate upward movement of the fluid displacement device within the production chamber, the skirt apparatus comprising: a structure adapted to be attached to the production tubing at the well bottom to continue the production chamber sufficiently to receive the fluid displacement device when moved to a lowermost position within the production chamber; a first fluid passageway extending from the exterior of the structure into the production chamber above the fluid displacement device when the fluid displacement device is in the lowermost position to communicate liquid and gas from the well bottom into the production chamber above the fluid displacement device, the first fluid passageway presenting a first predetermined cross-sectional size for communicating the liquid and gas; and a second fluid passageway extending from the exterior of the structure to below the fluid displacement device when the fluid displacement device is in the lowermost position to communicate liquid and gas from the well bottom to a location below the fluid displacement device, the second fluid passageway presenting a second predetermined cross-sectional size for communicating the liquid and gas; and wherein: the second predetermined cross-sectional size is greater than the first predetermined cross-sectional size; the greater second predetermined cross-sectional size relative to the first predetermined cross-sectional size enabling a relatively greater pressure differential between the exterior of the structure and within the production chamber to initiate upward movement of the fluid displacement device from relatively greater pressure communicated through the second fluid passageway to below the fluid displacement device compared to the pressure communicated through the first fluid passageway to above the fluid displacement device; and the lesser first predetermined cross-sectional size relative to the second predetermined cross-sectional size enabling a relatively lesser pressure differential between the exterior of the structure and within the production chamber to transfer liquid and gas into the production chamber above the fluid displacement device without creating sufficient force below the fluid displacement device to initiate upward movement of the fluid displacement device from the lowermost position. 2. A skirt apparatus as defined in claim 1, wherein: the first and second fluid passageways each include an inlet through which liquid and gas is communicated from the well bottom into the fluid passageways; and the inlet to the first fluid passageway is located at a position below the inlet to the second fluid passageway at the well bottom. 3. A skirt apparatus as defined in claim 1, wherein: the structure includes a bottom opening; and the second fluid passageway includes the bottom opening. 4. A skirt apparatus as defined in claim 1, wherein: the structure comprises an extension of the production tubing. 5. A skirt apparatus as defined in claim 4, wherein: the fluid displacement device maintains the seal against the extension when the fluid displacement device is at the lowermost position. 6. A skin apparatus as defined in claim 1, wherein: the first and second fluid passageways each include an inlet and an outlet; the inlet to the first fluid passageway is located at a position below the inlet to the second fluid passageway at the well bottom; the outlet of the second fluid passageway is located below the fluid displacement device; and the outlet of the first fluid passageway is located above the fluid displacement device at a predetermined distance where the initial upward movement of the fluid displacement device from the lowermost position closes the outlet to the first fluid passageway. 7. A skirt apparatus as defined in claim 1, wherein the well includes a casing which extends from the earth surface to the well bottom, the production tubing extends within the casing, a casing chamber is defined between the production tubing and the casing, the structure is located within the casing at the well bottom, and the pressure differentials to initiate upward movement of the fluid displacement device and to transfer liquid and gas into the production chamber above the fluid displacement device are established by relative pressures within the casing chamber and the production chamber. 8. A skirt apparatus for use with a fluid displacement device which is moveable and sealed within production chamber defined by production tubing which extends between a surface of the earth and a bottom of a well in a subterranean zone which contains liquid and gas, the skirt apparatus responding to different magnitudes of differential pressure between the exterior of the skirt apparatus at the well bottom and within the production chamber to accumulate liquid above the fluid displacement device and to initiate upward movement of the fluid displacement device within the production chamber, the skirt apparatus comprising: a structure adapted to be attached to the production tubing at the well bottom to continue the production chamber sufficiently to receive the fluid displacement device when moved to a lowermost position within the production chamber; a first fluid passageway extending from the exterior of the structure into the production chamber above the fluid displacement device when the fluid displacement device is in the lowermost position to communicate liquid and gas from the well bottom into the production chamber above the fluid displacement device, the first fluid to passageway presenting a first predetermined cross-sectional size for communicating the liquid and gas; and a second fluid passageway extending from the exterior of the structure to below the fluid displacement device when the fluid displacement device is in the lowermost position to communicate liquid and gas from the well bottom to a location below the fluid displacement device, the second fluid passageway presenting a second predetermined cross-sectional size for communicating the liquid and gas; and wherein: the second predetermined cross-sectional size is greater than the first predetermined cross-sectional size; the greater second predetermined cross-sectional size relative to the first predetermined cross-sectional size enabling a relatively greater pressure differential between the exterior of the structure and within the production chamber to initiate upward movement of the fluid displacement device from relatively greater pressure communicated through the second fluid passageway to below the fluid displacement device compared to the pressure communicated through the first fluid passageway to above the fluid displacement device; and the lesser first predetermined cross-sectional size relative to the second predetermined cross-sectional size enabling a relatively lesser pressure differential between the exterior of the structure and within the production chamber to transfer liquid and gas into the production chamber above the fluid displacement device without creating sufficient force below the fluid displacement device to initiate upward movement of the fluid displacement device from the lowermost position, wherein: the structure includes a bottom opening; the second fluid passageway includes the bottom opening; and the structure includes a shoulder surrounding the bottom opening upon which the fluid displacement device rests when in the lowermost position. 9. A skirt apparatus for use with a fluid displacement device which is moveable and sealed within a production chamber defined by a production tubing which extends between a surface of the earth and a bottom of a well in a subterranean zone which contains liquid and gas, the skirt apparatus responding to different magnitudes of differential pressure between the exterior of the skirt apparatus at the well bottom and within the production chamber to accumulate liquid above the fluid displacement device and to initiate upward movement of the fluid displacement device within the production chamber, the skirt apparatus comprising: a structure adapted to be attached to the production tubing at the well bottom to continue the production chamber sufficiently to receive the fluid displacement device when moved to a lowermost position within the production chamber; a first fluid passageway extending from the exterior of the structure into the production chamber above the fluid displacement device when the fluid displacement device is in the lowermost position to communicate liquid and gas from the well bottom into the production chamber above the fluid displacement device, the first fluid passageway presenting a first predetermined cross-sectional size for communicating the liquid and gas; and a second fluid passageway extending from the exterior of the structure to below the fluid displacement device when the fluid displacement device is in the lowermost position to communicate liquid and gas from the well bottom to a location below the fluid displacement device, the second fluid passageway presenting a second predetermined cross-sectional size for communicating the liquid and gas; and wherein: the second predetermined cross-sectional size is greater than the first predetermined cross-sectional size; the greater second predetermined cross-sectional size relative to the first predetermined cross-sectional size enabling a relatively greater pressure differential between the exterior of the structure and within the production chamber to initiate upward movement of the fluid displacement device from relatively greater pressure communicated through the second fluid passageway to below the fluid displacement device compared to the pressure communicated through the first fluid passageway to above the fluid displacement device; and the lesser first predetermined cross-sectional size relative to the second predetermined cross-sectional size enabling a relatively lesser pressure differential between the exterior of the structure and within the production chamber to transfer liquid and gas into the production chamber above the fluid displacement device without creating sufficient force below the fluid displacement device to initiate upward movement of the fluid displacement device from the lowermost position, wherein: the structure comprises an extension of the production tubing; and the extension of the production tubing includes a bottom opening; the second fluid passageway includes the bottom opening of the extension; the structure defines a hollow concentric chamber surrounding the extension; the hollow concentric chamber is closed at a top end; the first fluid passageway comprises at least one perforation through the extension into the hollow concentric chamber at a position below the closed top end of the hollow concentric chamber and above the bottom opening of the extension; the cumulative cross-sectional size of all perforations defines the first cross-sectional size of the first fluid passageway; and the cross-sectional size of the bottom opening of the extension contributes to the cross-sectional size of the second fluid passageway. 10. A skirt apparatus as defined in claim 6, wherein: the hollow concentric chamber extends downward to the level of the bottom opening. 11. A skirt apparatus as defined in claim 7, wherein: the second fluid passageway further comprises transverse passageways extending from the exterior of the structure through the hollow concentric chamber and the extension of the production tubing, the transverse passageways located above the bottom opening and below each perforation and below the fluid displacement device when the fluid displacement device is in the lowermost position; and each transverse passageway is isolated from communication with the hollow concentric chamber. 12. A skirt apparatus in combination with a fluid displacement device which is moveable and sealed within a production chamber defined by a production tubing which extends between a surface of the earth and a bottom of a well in a subterranean zone which contains liquid and gas, the skirt apparatus responding to different magnitudes of differential pressure between the exterior of the skirt apparatus at the well bottom and within the production chamber to accumulate liquid above the fluid displacement device and to initiate upward movement of the fluid displacement device within the production chamber, the skirt apparatus comprising: a structure adapted to be attached to the production tubing at the well bottom to continue the production chamber sufficiently to receive the fluid displacement device when moved to a lowermost position within the production chamber; a first fluid passageway extending from the exterior of the structure into the production chamber above the fluid displacement device when the fluid displacement device is in the lowermost position to communicate liquid and gas from the well bottom into the production chamber above the fluid displacement device, the first fluid passageway presenting a first predetermined cross-sectional size for communicating the liquid and gas; and a second fluid passageway extending from the exterior of the structure to below the fluid displacement device when the fluid displacement device is in the lowermost position to communicate liquid and gas from the well bottom to a location below the fluid displacement device, the second fluid passageway presenting a wherein: the second predetermined cross-sectional size is greater than the first predetermined cross-sectional size; the greater second predetermined cross-sectional size relative to the first predetermined cross-sectional size enabling a relatively greater pressure differential between the exterior of the structure and within the production chamber to initiate upward movement of the fluid displacement device from relatively greater pressure communicated through the second fluid passageway to below the fluid displacement device compared to the pressure communicated through the first fluid passageway to above the fluid displacement device; and the lesser first predetermined cross-sectional size relative to the second predetermined cross-sectional size enabling a relatively lesser pressure differential between the exterior of the structure and within the production chamber to transfer liquid and gas into the production chamber above the fluid displacement device without creating sufficient force below the fluid displacement device to initiate upward movement of the fluid displacement device from the lowermost position; and wherein the fluid displacement device comprises a toroid shaped structure having an exterior elastomeric skin defining a cavity within which a viscous material is confined, an outside surface of the toroid shaped structure is compressed against the production tubing and the structure, an inside surface of the toroid shaped structure is compressed against itself, and the toroid shaped structure moves within the production chamber by rolling the outside surface in contact with the production tubing and by rolling the inside surface in contact with itself, and the seal of the fluid displacement device is maintained by contacting the outside surface of the toroid shaped structure while the inside surface contacts itself. 13. A method of accumulating liquid above a fluid displacement device which is moveable and sealed within a production chamber defined by a production tubing which extends between a surface of the earth and a bottom of a well in a subterranean zone which contains liquid and gas, and of initiating upward movement of the fluid displacement device within the production chamber from a lowermost position at which liquid is accumulated above the fluid displacement device, the method comprising: moving the fiuld displacement device to the lowermost position within the production chamber; creating first and second pressure differentials between the exterior of the production tubing and the production chamber at the well bottom from relative fluid pressure between the exterior of the production tubing and the production chamber, the second pressure differential being greater than the first pressure differential; transferring liquid and gas through a first fluid passageway which communicates from the well bottom into the production chamber above the fluid displacement device when the fluid displacement device is at the lowermost position by applying the first pressure differential; initiating upward movement of the fluid displacement device in the production chamber from the lowermost position by applying the second pressure differential through a second fluid passageway which communicates from the well bottom with the bottom of the fluid displacement device; applying the first and second pressure differentials simultaneously through both the first and second fluid passageways; establishing the first pressure differential applied through the second fluid passageway to be insufficient to initiate upward movement of the fluid displacement device from the lowermost position; and restricting the amount of the second pressure differential applied through the first fluid passageway to be insufficient to prevent initiation of upward movement of the fluid displacement device from the lowermost position in response to the second pressure differential applied through the second fluid passageway. 14. A method as defined in claim 13, further comprising: restricting the amount of the second pressure differential applied through the first fluid passageway above the fluid displacement device by a cross-sectional size of the first fluid passageway which is smaller than a larger cross-sectional size of the second fluid passageway. 15. A method as defined in claim 13, further comprising: establishing an inlet for each of the first and second fluid passageways; and locating the inlet of the first fluid passageway at a position within the well bottom no higher than the inlet of the second fluid passageway. 16. A method as defined in claim 13, further comprising: establishing an inlet for each of the first and second fluid passageways; and locating the inlet of the first fluid passageway at a lower position within the well bottom than the inlet of the second fluid passageway. 17. A method as defined in claim 16, further comprising: transferring liquid from the well bottom through the first fluid passageway into the production chamber above the fluid displacement device until the liquid within the well bottom is below the inlet to the second fluid passageway; and thereafter applying the second pressure differential. 18. A method as defined in claim 13, further comprising: maintaining the seal of the fluid displacement device against the production tubing while the fluid displacement device is in the lowermost position. 19. A method as defined in claim 13, further comprising: closing the first fluid passageway by the initial upward movement of the fluid displacement device from the lowermost position during application of the second pressure differential. 20. A method as defined in claim 13, further comprising: obtaining the pressure for the first and second pressure differentials from gas supplied by the well at natural formation pressure. 21. A method as defined in claim 13, wherein the well includes a casing which extends from the earth surface to the well bottom, the production tubing extends within the casing, and a casing chamber is defined between the production tubing and the casing, and the method further comprises: communicating pressure between the production chamber and the casing chamber at the well bottom; and creating the first and second pressure differentials between the production and casing chambers. 22. A method as defined in claim 21, further comprising: creating the first and second pressure differentials between the production and casing chambers by natural formation pressure of gas supplied into the casing chamber. 23. A method as defined in claim 22, further comprising: accumulating gas supplied from the well at the earth surface at a pressure established by natural formation pressure; and moving the fluid displacement device downward within the production chamber by applying the accumulated gas above the fluid displacement device at the pressure of the accumulated gas established by natural formation pressure. 24. A method of accumulating liquid above a fluid displacement device which is moveable and sealed within a production chamber defined by a production tubing which extends between a surface of the earth and a bottom of a well in a subterranean zone which contains liquid and gas, and of initiating upward movement of the fluid displacement device within the production chamber from a lowermost position at which liquid is accumulated above the fluid displacement device, the method comprising: moving the fluid displacement device to the lowermost position within the production chamber; creating first and second pressure differentials between the exterior of the production tubing and the production chamber, the second pressure differential being greater than the first pressure differential; transferring liquid and gas through a first fluid passageway from the well bottom into the production chamber above the fluid displacement device when at the lowermost position by applying the first pressure differential; initiating upward movement of the fluid displacement device from the lowermost position by applying the second pressure differential through a second fluid passageway which communicates with the bottom of the fluid displacement device; and obtaining the pressure for the first and second pressure differentials from gas supplied by the well at natural formation pressure. 25. A method as defined in claim 24, further comprising: accumulating gas supplied from the well at the earth surface at a pressure established by natural formation pressure; and moving the fluid displacement device downward within the production chamber by applying the accumulated gas to the production tubing above the fluid displacement device at the pressure of the accumulated gas established by natural formation pressure. 26. A method of accumulating liquid above a fluid displacement device which is moveable and sealed wtthin a production chamber defined by a production tubing which extends between a surface of the earth and a bottom of a well in a subterranean zone which contains liquid and gas, and of initiating upward movement of the fluid displacement device within the production chamber from a lowermost position at which liquid is accumulated above the fluid displacement device, the method comprising: moving the fluid displacement device to the lowermost position within the production chamber; creating first and second pressure differentials between the exterior of the production tubing and the production chamber, the second pressure differential being greater than the first pressure differential; transferring liquid and gas through a first fluid passageway from the well bottom into the production chamber above the fluid displacement device when at the lowermost position by applying the first pressure differential; initiating upward movement of the fluid displacement device from the lowermost position by applying the second pressure differential through a second fluid passageway which communicates with the bottom of the fluid displacement device; and maintaining the sealed relationship of the fluid displacement device within the production chamber during the initial upward movement by rolling the fluid displacement device upward within the production chamber. 27. A method as defined in claim 26, further comprising: substantially eliminating relative movement between the fluid displacement device and the production tubing during movement within the production chamber. 28. A method as defined in claim 26, further comprising: compressing a portion of the fluid displacement device against the production tubing during the initial upward movement. 29. A method of accumulating liquid above a fluid displacement device which is moveable and sealed within a production chamber defined by a production tubing which extends between a surface of the earth and a bottom of a well in a subterranean zone which contains liquid and gas, and of initiating upward movement of the fluid displacement device within the production chamber from a lowermost position at which liquid is accumulated above the fluid displacement device, the method comprising: moving the fluid displacement device to the lowermost position within the production chamber; creating first and second pressure differentials between the exterior of the production tubing and the production chamber, the second pressure differential being greater than the first pressure differential; transferring liquid and gas through a first fluid passageway from the well bottom into the production chamber above the fluid displacement device when at the lowermost position by applying the first pressure differential; initiating upward movement of the fluid displacement device from the lowermost position by applying the second pressure differential through a second fluid passageway which communicates with the bottom of the fluid displacement device; using as the fluid displacement device a torold shaped structure having an exterior elastomeric skin defining a cavity within which a viscous material is confined; contacting an outside surface of the toroid shaped structure with an inner sidewall of the production chamber; contacting an inside surface of the torold shaped structure with itself; rolling the toroid shaped structure within the production chamber with the outside surface contacting the inner sidewall and the inside surface contacting itself; and maintaining the sealed relationship of the fluid displacement device within the production chamber by compressing the outside surface of the toroid shaped structure against the inner sidewall and by compressing the inside surface of the toroid shaped structure against itself while rolling the toroid shaped structure within the production chamber. 30. A method of accumulating liquid above a fluid displacement device which is moveable and sealed within a production chamber defined by a production tubing which extends between a surface of the earth and a bottom of a well in a subterranean zone which contains liquid and gas, and of initiating upward movement of the fluid displacement device within the production chamber from a lowermost position at which liquid is accumulated above the fluid displacement device, the well including a casing which extends from the earth surface to the well bottom, the production tubing extending within the casing, and a casing chamber is defined between the production tubing and the casing, the method comprising: moving the fluid displacement device to the lowermost position within the production chamber; creating first and second pressure differentials between the exterior of the production tubing and the production chamber, the second pressure differential being greater than the first pressure differential; transferring liquid and gas through a first fluid passageway from the well bottom into the production chamber above the fluid displacement device when at the lowermost position by applying the first pressure differential; initiating upward movement of the fluid displacement device from the lowermost position by applying the second pressure differential through a second fluid passageway which communicates with the bottom of the fluid displacement device; communicating pressure between the production chamber and the casing chamber at the well bottom; creating the first and second pressure differentials between the production and casing chambers; and creating the first and second pressure differentials between the production and casing chambers by natural formation pressure of gas supplied into the casing chamber. 31. A method as defined in claim 30, further comprising: accumulating gas supplied from the well at the earth surface at a pressure established by natural formation pressure; and moving the fluid displacement device downward within the production chamber by applying the accumulated gas above the fluid displacement device at the pressure of the accumulated gas established by natural formation pressure.