Application of Bore Hole Images in the Piceance Basin

By

Randy Koepsell

Schlumberger Oilfield Services, Greenwood Village, CO

Stephen P. Cumella

Williams Production RMT Company, Denver, CO

David A. Uhl

EnCana Oil & Gas (USA) Inc, Denver, CO

The fluvial and marine sands in the Mesaverde formation in the Piceance Basin contain significant gas reserves. These sands are very low permeability (microdarcy) reservoirs ranging from fluvial to marine shoreface. Identification of productive sand is complicated by natural fractures, both micro and macro, differing connate water salinity, and varying amounts of dispersed shale. Evaluation of productivity for individual zones is difficult considering most wells have comingled production. The evaluation of these reservoirs using traditional open-hole logs can be difficult. Many productive sands were previously bypassed because they were thought to be wet. Better defining the sedimentological and fracture characteristics of the Mesaverde reservoir sands can significantly impact the economics of completion dollars.

This paper will present examples of borehole image logs that were used for: •Evaluation of natural fractures in both sand and coal.

•Orientation of the present day stress field.

•Determination of sand body orientation, both fluvial and marine, with estimates of the channel width.

•Identification of productive sands with low formation resistivity via seeping gas.

Cumulative production history, sand isopaching, and completion flow back data will be compared to these results.

AAPG Search and Discovery Article #90004©2002 AAPG Rocky Mountain Section, Laramie, Wyoming