Development of the Endicott Field (Kekiktuk Formation), North Slope, Alaska

Abstract

Endicott field, located 2 mi offshore in the Arctic Ocean, produces approximately 100 MBPD from Mississippian Kekiktuk Formation fluvial sands. The field is the first Arctic offshore development. Currently, 65 wells have been drilled from two man-made gravel drilling and production islands. Production started in 1987, and 77 MMBO have been produced to date. Original volumes in place are estimated at 1 billion STB, 365 bcf of gas-cap gas, and 750 bcf of solution gas. The Kekiktuk Formation, deposited by a southerly flowing fluvial system in response to the Ellesmerian Orogeny, rests unconformably on Franklinian (Devonian) basement. The field is a combined structural/stratigraphic trap and is delineated by three major normal faults. Within the field, the Endicott Group sediments are truncated by the regional Lower Cretaceous unconformity (LCU). A reservoir seal is provided by the overlying conformable Itkilyariak Formation carbonates and Cretaceous shales above the LCU. Due to complex reservoir geometry, a subzone approach to reservoir development, surveillance, and management has been implemented. Structural dip combined with continuous interbedded shales and sealing intrareservoir faults divide the reservoir into six separate hydrologic subzones. Additionally, structural dip creates narrow oil corridors in each reservoir subzone. All development wells are within approximately 1,500more » ft of the updip gas cap and downdip aquifer. The high priority placed on incorporating reservoir description with surveillance data has resulted in optimal field management and minimized development risk.« less