The San Juan Basin, located in northwestern New Mexico and southwestern Colorado, is one of the most prolific natural gas producing regions, and one of the largest gas basin in the United States in terms of total estimated gas reserves. More coalbed methane has been produced from the San Juan Basin than the rest of the world combined. This paper analyzes the performance of original and infill wells producing from the Fruitland Coal formation and offsetting Chevron's acreage position in key areas of the North San Juan Basin. Subsurface and production data of these wells available in the public domain formed the basis for the project team to recommend an infill drilling program to maximize the value of the company's current acreage position.

The project team developed a comprehensive approach to arrive at a probabilistic production forecast and utilized subsurface data on coal gas content and bulk density available in public domain for San Juan Basin to confirm the remaining gas-in-place and need for additional takeaway points in the reservoir. Decline curve analysis was used to assess the production performance of more than one hundred infill wells drilled since 2007 and to determine the potential impact on the expected ultimate gas recovery of the offset original 160-acre spacing wells. Understanding potential interference risk was critical to justifying the need for downspacing.

The project team recommended drilling additional infill wells based on several criteria: no observation of significant interference with the majority of existing producers, considerable remaining gas-in-place that could not be developed at the current well spacing and a positive correlation between performance of Fruitland Coal wells and the thermal maturity of the San Juan Basin. The project team performed data analysis of four different type producing areas (TPAs) delineated within the basin based upon similar reservoir characteristics and production behavior. The data analysis confirmed the opportunity to drill and reduce spacing for improved recovery in areas where underlying geologic parameters like reservoir connectivity and reduced permeability has led to low recovery.

You can access this article if you purchase or spend a download.