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ABSTRACT: Eileen West End Development, Prudhoe Bay Field, Alaska

Alison Cooke

The western periphery of Prudhoe Bay field is made of small faulted structures referred to as the Eileen West End area. Development plans for Eileen West End consist of drilling approximately 90 production wells on 80-ac spacing, two nonconventional (> 85°) gas injectors, and one to two conventional gas injectors from two gravel pads (W and Z pads). The confirmation sequence of 20 wells was prioritized to provide information about the structure, fluid contacts, reservoir rock quality, and shale extent in the areas of the nonconventional gas injectors and to maximize broad initial offtake.

Drilling began with two rigs in February 1988, and production started up from Eileen West End in June 1988. In October 1989, 46 wells produced 50,000 BOPD. Peak capacity of 60,000 BOPD is expected by May 1990. Gas cap gas injection was initiated in the West End along with production. Two nonconventional gas injectors currently inject 90 MMCFD. A final injection rate for the West End is targeted at 130 MMCFD. Initiating injection concurrently with production will forestall additional pressure depletion from offtake in the Main field of Prudhoe Bay.

Integration of geologic reservoir description and engineering data is crucial to optimize reservoir development. Current efforts include mud logging, sidewall core sampling, formation pressure testing, and fluid contact monitoring with open-hole and cased-hole logs. These data are interpreted to identify areas of gas or water influx and gas breakthrough, to define the extent of permeability barriers, to evaluate pressure support requirements, and to effectively plan the remaining conventional and nonconventional producers.

AAPG Search and Discovery Article #91003©1990 AAPG Annual Convention, San Francisco, California, June 3-6, 1990