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Abstract: Petroleum Geology of the Estancia Basin, New Mexico: An Exploration Frontier

Ronald F. Broadhead

The Estancia basin of central new Mexico is an asymmetric, north-south-trending structural depression that originated during the Pennsylvanian. The present-day basin covers 1600 mi2. The basin is bounded on the east by the late Paleozoic Pedernal uplift, on the west by the Tertiary Manzano and Los Pinos Mountains, on the north by the Espanola basin, and on the south by Chupadera Mesa. The depth to the Precambrian ranges from 9000 ft in the eastern part of the basin to less than 1500 ft in the western part. Basin fill consists primarily of Pennsylvanian and Wolfcampian (Permian) clastics. The Pennsylvanian section contains significant shelf limestones in the western part of the basin.

Forty-three exploratory wells have been drilled in the basin; only 17 have been drilled to Precambrian. Numerous shows of oil and gas have been reported. From the 1930s until the 1960s, CO2 was produced from lower Pennsylvanian sandstones in two small fields on the western flank of the basin.

Dark-gray to black Pennsylvanian shales are probable source rocks. They are mature to marginally mature; TAI values range from less than 2.0 to 3.2. TOC is greater than 0.5% in many of these shales. Kerogen types are mixed amorphous, algal, herbaceous, and woody, indicating that gas, or both gas and oil, may have been generated.

Pennsylvanian sandstones are good reservoirs. They are fine- to coarse-grained subarkosic arenites and quartz arenites. Porosity ranges from 10 to 20% in the more porous, coarser-grained sandstones.

AAPG Search and Discovery Article #90980©1994 AAPG Southwest Section Meeting, Ruidoso, New Mexico, April 24-26, 1994