The Monell Unit of the Patrick Draw Field, Wyoming: CO2 Flood in an Old Field Using New Technology

Lim, Frank H. ¹, Heather N. Ramsey¹ (1) Anadarko Petroleum Corporation, The Woodlands, TX

Since its discovery in 1959, the Patrick Draw Field, located in Sweetwater County, Wyoming, has undergone primary and secondary (waterflood) recovery with cumulative production of 60 mmbo and 130 bcfg from the Almond UA-5 sandstone formation. Located on the east flank of the Rock Springs Uplift, the field is comprised of two federal units, the northern Arch Unit and the southern Monell Unit. In 2000, Anadarko Petroleum Corporation acquired its interests in the field as part of a merger with Union Pacific Resources. At the time, the Monell Unit was producing only 10 bopd and with 65% of the 110 million barrels of OOIP still unrecovered. Due to several factors including the homogeneous nature of the reservoir (average 20% porosity, 30 md permeability, 30 ft net pay), 43° gravity oil, and 120° F reservoir temperature, the Monell Unit was identified as an excellent candidate for miscible CO₂ EOR. Anadarko initiated a pilot using a single CO₂ injection well that utilized advanced technologies to thoroughly evaluate the pilot flood in a shorter timeframe. This enabled the project to quickly proceed to an 80 well, Phase 1 CO₂ flood expansion (2003- 2004) using repeated 80 acre, 5 spot patterns. Production rates have increased to over 2,000 bopd per day. In 2006, 27 more wells will be drilled in Monell in Phase 2 of expansion and 81 wells are planned for the final Phase 3 expansion by 2008. Peak production is expected in 2010 approaching rates of 10,000 bopd per day.

AAPG Search and Discovery Article #90055©2006 AAPG Rocky Mountain Section Meeting, Billings, Montana