Shorelines bordering the bays of Texas are generally not as dynamic as those along the Gulf of Mexico. Nevertheless, the predominantly erosional movement of these bay shorelines translates to large losses of wetlands, arable uplands, and recreational and residential property. The shorelines occur along steep clay bluffs, along salt- and brackish water marshes, along sand and shell beaches, at the base of moderate slopes composed mainly of sand, and in newly formed areas filled by dredged material.

Discovery of volcanic glass detritus in fluvial deposits of the middle Frio Formation (Seeligson and Stratton fields) of South Texas has resulted in a new classification of reservoir types (type I and type II) within this formation. Type I reservoirs consist of sandstones that do not contain volcanic glass and have an average permeability of 36 md (geometric mean).

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.