The Raton Basin, with an estimated 10 TCF coal-bed methane (CBM) resource base, is one of the premier, on-going plays in North America and is currently producing 200+ MMCFG/D from over 1500 wells. In 1999, El Paso Production began development on its 648,000 mineral acres in Vermejo Park Ranch, New Mexico and Colorado, Southern Raton basin. In the process, El Paso has amassed a robust geotechnical database including 47,000 feet of continuous core, 310 Platform Express/ ECS/ELAN log suites and hydrochemistry data on 400+ producing wells. In addition, El Paso is in the third and final year of a collaborative DOE-funded field, geological, engineering and laboratory study with Sandia National Laboratories, Albuquerque, NM, focusing on the fracture-related “plumbing” system.

Geotechnical insights into this complex CBM play, employing an integrated, data-driven approach, suggest that the basin has undergone a polytectonic history. The maximum horizontal compressive stress during Laramide deformation, created by overthrust indentation into the basin from the west, was generally east–west as recorded by the majority of surface and subsurface natural fracture strikes. Present-day horizontal compressive stress measured by stress-anisotropy logs trends north–south, suggesting a relationship to Rio Grande extension and affecting the design of reservoir stimulations and the placement of wells. Local anomalous structural domains occur within this overall pattern creating structural enhancement of production with reservoirs containing discreet gas content, water chemistry, bottom hole pressure gradients and production profiles. Regional and local gas saturation variation also occurs in both lateral and vertical dimensions with geostatistical studies showing greater similarity in production characteristics in the east–west direction than in the north–south direction. Coked coals, igneous sills and gas-charged, tight sands may also serve as reservoirs, contributing to total non-CBM gas-in-place considerations.

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