| Popis: |
Abstract This paper describes the development and field testing of a wireline-retrievable, subsurface safety valve tailored for jet pump production systems. An examination of earlier safety system components adapted to hydraulic pump enhanced production systems is provided to show the evolution of design features involved in this new valve. From conceptual design stages to the actual field implementation and operation, a versatile pump power fluid-operated safety valve specifically designed for jet pumps is presented. Introduction Marathon's Steelhead Platform, located in Cook Inlet, Alaska, was installed in 1986 primarily to develop gas zones in the McArthur River field. The platform design also provided oil production and water injection capability to allow further development of secondary oil reservoirs in the field. Facilities included a gas lift compressor sized to service up to ten oil producing wells. Since gas development was given priority, the low number of oil producers and water injection wells drilled during the early years could not be serviced efficiently with facility design based on ultimate development. Evaluation of artificial lift methods demonstrated that jet pump lift using existing excess waterflood injection capacity as power fluid was the most economical means of producing the oil wells. It was also apparent that gas lift would become more economical as the number of oil producers increased and excess capacity of the water injection facilities diminished. The high cost of workovers in Alaska led Marathon to complete oil wells with gas lift equipment and provide for rigless conversion from jet pump lift to gas lift. Safety and environmental concerns as well as state regulations necessitate installation of a fail-closed subsurface safety valve to stop uncontrolled flow from a well. Installation of a jet pump across a standard production sliding sleeve circulation device had the advantage of:minimizing additional downhole equipment for jet pumping,making rigless conversion to gas lift simple (close the sliding sleeve and install gas lift valves in the side pocket mandrels), andleaving no flow restrictions in the tubulars following the conversion to gas lift. The use of a subsurface safety valve set below the jet pump and actuated by jet pump power fluid had been demonstrated on Marathon's Dolly Varden platform in the same field. P. 375^ |
