Unlocking Viscous Oil of the Schrader Bluff and Ugnu Formations at Milne Point Unit, North Slope, Alaska

L. Micaela Smith, Pat Archey, Josef Chmielowski, Scott Digert, Matt Green, Kyle Johnson, William Mathews, Walter Quay, Sean Petersen, Jim Seccombe, Brad Simpson, Dennis Urban, Larry Vendl, Chris West, and Doug Wilson
BP Exploration Alaska, Anchorage, AK

The Milne Point Unit (MPU) on the North Slope of Alaska has begun to unlock the 26 billion barrels OOIP of viscous oil from the Ugnu and Schrader Bluff formations. The Schrader Bluff Formation (SBF) contains 2 billion barrels OIP and is comprised of unconsolidated, stacked, shoreface marine sandstones, informally termed the “O” and “N”-sands. SBF viscosities currently being produced range from 20 – 200 cP. The overlying Ugnu Formation consists of unconsolidated, fluvial to deltaic sands that contain the majority of the OOIP. The oil in the Ugnu Formation is more viscous, ranging from 200 to over 2,000 cP.

Focused development efforts in the Schrader Bluff over the past three years have been successful, yielding over 20 mbopd of current viscous production, approximately 40% of the total production at the MPU. Incorporation of the subsurface reservoir description, characterization, and modeling with a fully integrated team for well planning, design, and operations has contributed to this success. Economic success of production from the SBF is due to a step-change in well design from conventional deviated, vertical wells that produce on the order of a few hundred bopd to geo-steered, horizontal multi-lateral wells that produce upwards of 2000 bopd. Due to greater reservoir and fluid complexity than in the SBF, an additional step-change will be needed in fluid characterization, well design and completions, and recovery mechanism as commercial production is sought from the highly-viscous Ugnu Formation.

AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005