1,436 exploratory and 3,668 development wells in South Texas Railroad Commission districts 1, 2, and 4. For the adjacent offshore, completions totaled 46 exploratory and 19 development wells. Of 63 onshore Miocene exploratory tests, 40 (63%) were successful, but only 2 opened new fields. The Oligocene Frio and Vicksburg trends received 474 and 119 onshore exploratory tests. Exploratory drilling for Eocene objectives totaled 455 wells. Biggest reserves additions were contributed by gas reservoirs found along the deep Wilcox flexure trend. A total of 272 wells sought Cretaceous objectives.--Modified journal abstract.