Abstract: Targeted Horizontal Drilling at the Sooner "D" Sand Unit, DJ Basin, Colorado: A Case History

Mark A. Sippel, Scott Singdahlsen

Reservoir compartmentalization has a detrimental affect on waterflood recovery of oil from the fluvial and delta front facies of the "D" Sand reservoir at the Sooner Unit in Weld county, Colorado. Reservoir characterization studies of the reservoir include 3-D seismic, detailed geological correlation and engineering evaluations. 3-D seismic data clearly collaborate the internal geometry of sediment thickness within the unit area and indicate several lineaments across the depositional grain. Static and transient reservoir pressure data also demonstrate a high degree of compartmentalization.

The purpose of the reservoir characterization studies were to target and select infill drilling locations to optimally improve reservoir sweep by waterflooding. Management decided to attempt horizontal re-completions in existing injection wells to improve sweep, connect reservoir compartments and utilize the existing surface-facility infra-structure. Horizontal re-completions in this reservoir appeared to be a match of technology with the reservoir problem.

A reservoir area with high oil-in-place per acre, but with negligible secondary response, was selected for a horizontal re-completion attempt with an adjacent injection well. Horizontal drilling results indicate that a barrier was penetrated at a horizontal reach of 250 ft. The location of the barrier was consistent with seismic and pressure transient data. Unfortunately, the shale above the reservoir sandstone collapsed despite careful attention to drilling mud properties and hydraulics. The horizontal completion efforts were aborted after several attempts. Current plans are to drill vertical injection wells at infill locations identified as the targets of the horizontal re-completion program.

AAPG Search and Discovery Article #90959©1995 AAPG Rocky Mountain Section Meeting, Reno, Nevada