Conflicting Resource Development in Southeast New Mexico: a Regional Look at Morrow Formation Gas

Patrick Walsh
New Mexico Bureau of Geology and Mineral Resources
New Mexico Institute of Mining and Technology, Socorro, NM

Several factors have led to reservoir underdevelopment in the Morrow Formation in southeast New Mexico, including conflicting interests with potash development companies, government regulations protecting potash resources, lack of completions within successful wells, and lack of exploration. Over the past 70 years, the Secretary of the Interior has set aside 777 square miles of southeastern New Mexico, referred to as the Secretary of the Interior’s Potash Area (SPA), to preserve potash resources. Oil and gas drilling are severely limited within the SPA, and leases are managed by the Bureau of Land Management. The Morrow Formation reservoirs have significant undiscovered reserves in the SPA. Morrow Formation production-well density is roughly half that of the surrounding area, which may also be underdeveloped. Operators have drilled a few directional wells to target Morrow Formation reservoirs while avoiding potash resources near the boundaries of the protected area, and they used horizontal wells to develop the shallower Brushy Canyon Formation in one area. Older abandoned wells within the SPA may be used in the future for drilling islands, but this practice has not yet begun. The purpose of this paper is to provide structural and stratigraphic maps of Morrow Formation reservoir horizons, to present areas with future potential, and to suggest future development scenarios. The paper also provides a regional Morrow Formation depositional picture and correlates this regional description to field scale interpretations.
     The Morrow Formation is typically divided into two intervals, the Morrow clastic and the overlying Morrow lime. The fluvial-deltaic to shallow marine Morrow clastic interval currently provides more than 40% of the natural gas production within the SPA. Depth to Morrow clastic production ranges from ~11,000 to ~14,000 feet in the SPA. This study divides the Morrow clastic interval into three informal subunits based on log character and uses flooding surfaces marked by correlatable bounding shales. The resulting net sand maps for these subunits indicate an overall transgression from deltaic to distributary mouth bar or reworked delta within the interval, leading up to deposition of overlying carbonates and marine shales. Trends of producing wells along depositional axes that are interpreted in this report indicate potential areas for future exploration and development. Future drilling will target depositionally complex reservoirs. The author recommends directional and horizontal drilling, aided by 3D seismic imaging, to explore and develop SPA resources.

AAPG Search and Discover Article #90065©2007 AAPG Southwest Section Meeting, Wichita Falls, Texas