Characterization of the Grayburg Reservoir of the Mobil University unit 15/16 in Dune Field, Crane County, Texas

Access full-text files



Journal Title

Journal ISSN

Volume Title



A project was initiated by the Bureau of Economic Geology in 1981 to investigate the distribution and nature of oil production in Texas. Approximately 500 reservoirs having a cumulative production of more than 10 million barrels of oil each were included in this study; these reservoirs have produced more than 71 percent of the total Texas production. These larger reservoirs were grouped into 47 plays based on the original depositional setting of the rocks and source and on reservoir and trap characteristics. Twenty-seven of these plays located in the Paleozoic basins of North and West Texas account for 73 percent of the total in-place oil in the state. Most of the Paleozoic production is from dolomite reservoirs. Results of this initial reservoir characterization project by the Bureau are summarized in the "Atlas of Major Texas Oil Reservoirs" (Galloway et al., 1983). Reservoirs producing from the San Andres/Grayburg Formations were selected for study because of their high cumulative production and low recovery efficiencies (30 percent average). For example, in Texas, 51 percent (80 billion barrels) of the original oil in place and 43 percent (46 billion barrels) of the cumulative production are from the Permian Basin (Figs. 1 and 2). Within the Permian Basin, 83 percent (16.6 billion barrels) of the cumulative production is from carbonates (Fig. 3), and 46 percent (7.7 billion barrels) of this is from San Andres/Grayburg reservoirs (Fig. 4). Therefore, San Andres/Grayburg reservoirs are major contributors to Texas oil production (17 percent of the total cumulative production of Texas) (Fig. 5). Better geological definition of reservoirs incorporated into engineering models and studies should lead to more efficient development of secondary and tertiary recovery methods.


LCSH Subject Headings