--> Abstract: Henry Field: An Independent's Approach to an Enhanced Oil Recovery Project, by J. C. Mullarkey and L. C. Gerard; #90987 (1993).

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MULLARKEY, J. C., and L. C. GERARD, Washington Energy Resources, Englewood, CO

ABSTRACT: Henry Field: An Independent's Approach to an Enhanced Oil Recovery Project

Henry field in Uinta County, Wyoming, produces from multiple Cretaceous sandstones. The enhanced recovery target reservoir, the Middle Dakota 4A Sand, is a retrograde gas-condensate reservoir at a depth of 13,500'. The field was discovered in 1980 and a pilot injection program was initiated in 1985, reinjecting produced gas from the Upper Dakota 2A Sand.

Initial material balance calculations utilizing isopachs, cross sections, production and pressure data indicated a profitable enhanced oil recovery project. A geologic subcommittee was formed and compiled a databook with logs, completion information, and core data for 22 wells. Structure and isopach maps were prepared and input into an eight-component reservoir simulation model.

The Dakota structure map shows 80' of closure and over 100' of hydrocarbon column. Examination of data from Dakota cores in 13 wells allowed an interpretation of the 4A Sand as a braided stream system, flowing north. The reservoir sand has an aggradational stacking geometry with good continuity along the channel axis but is laterally discontinuous. Hydrocarbons were emplaced in the late Cretaceous and subsequent to emplacement, porosity destructive diagenesis continued in the water leg of this reservoir, creating an effective bottom seal. The Moxa Arch then rotated into its present day southern plunge resulting in a tilted hydrocarbon water contact.

Reservoir modeling proceeded with geologic input and resulted in a predicted increase in liquid hydrocarbon recovery of 45% (an additional 6.2 million barrels of condensate, 7.3 billion cubic feet of gas and 2.5 million barrels of natural gas liquids), if a fully developed, natural gas pressure maintenance program was implemented. The project was approved by the working interest owners, and the reservoir is expected to respond to injection within 24 months of the initial meeting.

This project demonstrates that potential enhanced oil recovery projects can be identified and implemented by independent oil companies and that geologically, braided stream deposits can be viable targets for secondary recovery. Coordination and extensive information sharing between technical disciplines and regulatory agencies can greatly speed project start-up, thereby increasing the project's present worth.

AAPG Search and Discovery Article #90987©1993 AAPG Annual Convention, New Orleans, Louisiana, April 25-28, 1993.