Three short radius horizontal wells drilled in the steeply dipping Sub-Hoyt"E" Sands of the Midway Sunset field showed encouraging performance. Thesesuccesses prompted a three dimensional thermal simulation study to evaluateadditional horizontal well potential and to optimize the remaining steam flooddevelopment. During this study, four medium horizontal wells were also drilledwith very encouraging initial performance. All seven wells seem to performwithin simulation and analytical expectations. This study improved theunderstanding of reservoir dynamics leading to a revised operating anddevelopment policy. Key conclusions are to place horizontal wells close to theoil-water contact, drill long horizontal laterals, and heat the oil inproximity to the horizontal wells. These give an optimum recovery, a morestable oil-water contact, and minimize water coning problems. Simulationresults and additional field surveillance led to a revised field developmentplan currently underway in this mature steam flood.


Historically, California's heavy oil fields have been developed with steamsoaking and steam flooding of reservoirs developed with conventional, verticalwellbores. In 1990–1991 three short radius horizontal wells were drilled in theheavy oil E Sands of the Midway Sunset Field to test their potential in maturethermal recovery projects. The successes of these wells, described in detail inthe literature', prompted a simulation study to determine the potential longterm impact of horizontal wells on E Sand reservoir management. Since the startof this study, four medium radius horizontal wells have been successfullydrilled and produced in the E Sands. Based on study recommendations and currentsuccess, horizontal wells should play a key role in the optimization ofremaining E Sand oil recovery as well as similar Midway Sunset reservoirs.

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