The Mesaverde Formation of the San Juan Basin, New Mexico and Colorado –

A 50 Year Old Gas Field with Significant Remaining Productivity

By

Brent W. Hale, Scott Roth, and Laura Daniel

Williams Production Company, Tulsa, OK

The Mesaverde Formation, producing primarily from the Blanco Field in New Mexico and the Ignacio Blanco Field in Colorado, has produced over 10 Tcf of gas from over 6600 wells in an area covering over 2500 square miles. Performance monitoring is critical to manage down-spacing the reservoir from 160 acre spacing to 80 acre spacing. An analysis of the production decline trends show that in many areas of the reservoir, down spacing of the field from 320 acre to 160 acre units in during the 1970’s and 1980’s yielded significant incremental reserves. The historical relationship between parent wells and infill wells shows that in most cases, the infill wells have reduced rates and reserves when compared to the parent wells. However, the infill wells do not appear to significantly impact the decline trends of the parent wells because of their incremental reserves. In some areas, infill wells have resulted in modest rate increases in offset wells. Preliminary results from over 1000 wells drilled since the 80 acre spacing was approved indicate that a similar trend will be expected as more of the reservoir is drilled on 80 acre spacing. Some infill well pressure tests show higher than expected reservoir pressures in what was believed to be highly depleted parts of the reservoir. These observed pressures are related to the low permeability and fracturing of the reservoir. They show that there is significant future production potential for this aging gas field.

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