Patent ID: 7328749

Claim:
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.