The Tirrawarra Sandstone is the primary producing zone at Tirrawarra field in the Cooper Basin of South Australia, where it contains 146 million barrels (MMbbl) of unrecovered oil. Because previous reservoir models had failed to predict reservoir performance accurately and development drilling had yielded poor results, we undertook this study in order to construct a three-dimensional descriptive model of the Tirrawarra Sandstone reservoir, within which we calculated the volumes and residency of original and remaining oil in place.

This report documents research done on the mature and prolific McAllen Ranch gas field in South Texas, as part of the Secondary Gas Recovery (SGR) project funded by the Gas Research Institute, U.S. Department of Energy, and State of Texas.ABSTRACTA Secondary Gas Recovery project study in South Texas demonstrated that reservoir compartmentalization can result in reserve growth in a mature gas field. McAllen Ranch is an important field in that it typifies South Texas gas fields that produce from the deep, overpressured sandstone reservoirs of the Oligocene Vicksburg Formation.