Petroleum geology of the McGregor Range, Otero County, New Mexico

Abstract

The McGregor Bombing and Artillery Range is a U.S. Army training and testing facility in Otero County, New Mexico. It encompasses several tectonic elements including the Otero platform, the Hueco Mountains, the Tularosa Basin, and the Sacramento Mountains. Only nine exploratory wells have been drilled within the Range. The most recent well was drilled in 1954. Oil and gas production has not been established. Gas was discovered during 1997 in the Harvey E. Yates No. 1Y Bennett Ranch well, drilled 10 miles east of the Range. This well marks the first commercially viable gas discovery in an otherwise unproductive frontier region. Petroleum source rocks are Devonian shales, Mississippian shales and limestones, and Pennsylvanian shales and limestones. Source rocks are generally thermally mature in the southern part of the range and are immature to marginally mature in the northern part of the Range. Thermal maturity increases with proximity to Tertiary-age intrusive complexes and also probably increases within Pennsylvanian grabens due to increased burial depth. Reservoir rocks are present within the Ordovician, Silurian, Mississippian, and Pennsylvanian sections. Ordovician and Silurian reservoirs are dolostones with well-developed vugular porosity. The Mississippian section may contain some carbonate reefal reservoirs. Pennsylvanian strata are dominantly basinal deposits and potential reservoirs include carbonate debris flow deposits; shallow water reservoir facies may be present on intrabasinal uplifts. Tertiary igneous sills may also be reservoirs where they have intruded Mississippian or Pennsylvanian source rocks.