Abstract: Open Apertures, Fracture Orientations, and Their Correlations to Production in the Mesaverde Group in the San Juan Basin 

Abstract

Late Cenozoic fault trends affiliated with the Rio Grande Rift have been identified as significant conduits for enhanced gas production in the San Juan Basin. Open aperture fractures have been studied at scales ranging from microscopic core analyses to 3-D seismic mapping. Anomalously high producing wells are aligned along these sets of fractures and demonstrate as much as ten times the production rate of matrix wells. The primary orientation of the open aperture fractures is N5-10E with a secondary orientation of N30-40E along reactivated Laramide faults. The integration of geologic studies, engineering data, and seismic interpretation have been critical to developing these conclusions. Reconstructing the tectonic history of the basin was the first and most important step. Field work along the flanks of the basin was followed by petorphysical evaluations of cores from wells in the basin. Several wells were evaluated for their performance and their interfence with surrounding wells. These studies have mutually supported these two orientations for open aperture fractures. In 1995 four well were drilled to test these conclusions. All four were successful beyond expectation.