Abstract
Generally, horizontally completed oil producers are susceptible to localized gas coning during their life due to the gas/oil contact encroaching the well bore. Even a small difference in permeability and/or relative permeability along the well bore can result in gas coning, which impacts oil production and gas handling issues. Production optimization can be achieved by selectively shutting in areas where gas coning has broken into the wellbore, thus improving drainage efficiency.
A new system has been developed to passively sense gas inflow into the well. Once gas is detected in sufficient levels a valve is activated which shuts off the flow path into the well. The valve is designed to detect fluid density changes, and will activate once a predetermined decrease in production fluid density is reached, indicating gas coning. Incorporated in a sand face screen completion, each screen joint includes a phase-sensitive valve that enables it to work independently of the others. This approach has the benefit of shutting off unwanted gas inflow without the need for costly well intervention. Used in conjunction with zone isolation packers to eliminate annular flow, flow normalization can be achieved across the production interval1 . The design can also be adapted to shut off water flow, as well as gas, in the event of water coning into the wellbore.
This paper will detail the development process of this new passive gas shut-off valve, including laboratory testing performed to qualify the technology. Plans for full-scale two-phase flow testing, conducted in cooperation with a major North Sea operator, will also be discussed.
