Print this pageOptimization of the Countess UU Pool- An Integrated Geological Interpretation of a Glauconitic Compound Incised Valley System
ROBERTSON, CHRISTINE A., LISA GRIFFITH, LEE HUNT, and BRIAN A. ZAITLIN
The Countess-Alderson trend is a 56 mile stretch of a Lower Cretaceous (Glauconitic Formation) incised valley system that extends over 300 miles from Northern Montana into central Alberta, Canada. The 122 pools in the trend have produced over 100 Mmbbls of oil and 300 BCF of gas since the 1950s. Recent optimization of many pools using a multi-disciplinary approach has led to a better understanding of the nature of this incised valley system.
The Countess UU Pool, (Township 18, Range 16 W4M) discovered in 1989, was placed on waterflood in 1991. It has produced 1.8 Mmbbls of oil and water cut is currently in excess of 80%. While recovery factors along the trend average 45%-60%, evaluation of the UU pool indicated an expected recovery factor of less than 40%. A study was undertaken to better understand the geological controls on the pool as a first step to optimization of the waterflood.
The pool lies at the junction of two distinct incised valleys backfilled by multiple estuarine channel fills. Central basin and overbank deposits as well as younger lithic channels provide the seal and sculpt the top of the reservoir. Relief on the reservoir bottom is attributed to salt solution and differential compaction.
It was only through the integration of seismic, production and geological data that a reasonable geological interpretation of the pool was possible. The study resulted in 2 potential delineation wells, 1 exploratory well, and 2 workovers. Recovery is expected to increase by 10%-15%, resulting in an additional 1 Mmbbls of recoverable oil.