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ISBY, JOHN S., DANIEL B. ROBERTSON, RACHAEL H. MAYS, SIMON ANDERSON, ANDREW HILL, and DING HSU, no affiliation given

ABSTRACT: A Multi-Disciplinary Approach to Horizontal Well Planning in the Prudhoe Bay Field, Alaska

A recently drilled horizontal well in the Prudhoe Bay Field, the F-47, was a success due to multi-disciplinary planning. An integrated team effort that incorporated geology, geophysics, petrophysics, reservoir engineering, production engineering and drilling engineering evaluated the target area, planned and drilled the well.

This well targeted a thin wedge of oil at the base of the Ivishak Formation, the main Prudhoe Bay reservoir. The objective section is within the deltaic portion of the reservoir and is characterized by a low KV/KH reservoir; fine-grained sandstone through siltstone with numerous shale layers of varying continuity interspersed. The objective section is bound on top by a relatively continuous shale layer that serves as a barrier to gas coning from the overlying gas-oil contact within the fluvial portion of the reservoir. The lower boundary is a layer of heavy oil/tar below which lies the aquifer.

The drilling strategy involved placing the well toward the base of the reservoir, to maximize standoff from the overlying gas and facilitate maximum drainage of the light oil column. The well was deliberately drilled across two faults. The wellbore penetrated the heavy oil/tar layer to define the base of the reservoir section, inverted and flattened out to maximize standoff, and then climbed structure as it crossed the two faults - from hanging wall to foot wall in both cases, to penetrate the best quality reservoir.

The completion involved a fully cemented and perforated liner in the horizontal section. Initial flow rate after cleanup was 4300 bbl of oil/day at low gas/oil ratio and water cut.

AAPG Search and Discovery Article #90988©1993 AAPG/SVG International Congress and Exhibition, Caracas, Venezuela, March 14-17, 1993.