This cross section set traverses four Cenozoic depositional sub-provinces: the Rio Grande Embayment, San Marcos Arch, Houston Embayment, and Sabine Arch. For each of these areas, the authors used closely spaced well logs to outline stratigraphic surfaces, para-sequences, and marker beds to delineate regional sequence boundaries, internal stratal architectures, erosional truncation surfaces, and depositional facies associations. Also included are depth ranges of reservoirs in fields adjacent to each line of section.

Formation evaluation in heterogeneous carbonate reservoirs is complicated by the presence of multiple pore types. Acoustic properties, Archie cementation exponents, and permeability transforms differ according to pore type. This study evaluates the various models for estimating vuggy porosity and the Archie cementation exponent from wireline logs, illustrates the difficulty of log interpretation applied to complex pore types, and presents generalized models developed to resolve some discrepancies within various models.

This report summarizes geologic, engineering, and production information on 24 low-permeability, gas-bearing sandstone reservoirs in 13 basins in the United States. The information compiled in this report comes from publicly available sources: Gas Research Institute and Department of Energy project reports, applications by gas producers to state regulatory agencies for tight formation designation, and published literature.