Sequence Stratigraphy and Hydrocarbon Exploration: Updip Wilcox Trend in South Texas

W. M. Smith, J. A. Breyer

Five unconformity-bounded depositional sequences occur in the subsurface lower and middle Wilcox in south Texas. All of the sequences are oil and gas productive in the updip Wilcox trend. Forty-four class D and E oil and gas fields, with a combined cumulative production of over 40 million bbl of oil and 12,000 million ft³ of gas, produce from the lower and middle Wilcox in a 4,000-mi² area in the northern part of the Rio Grande embayment. Much of the established production is from sands associated with the basal unconformity of each sequence. Twenty-four of the 38 fields producing from Sequence B produce from the basal sand in the sequence. Most of the fields occur in areas of relatively low sand percent. The low-sand areas occur in different places n different sequences because the locus of sand accumulation shifted during the deposition of the Wilcox Group. The potentially productive low-sand areas are not apparent on a sand percent map for the composite lower and middle Wilcox. The techniques we used to delineate potential productive areas in the updip Wilcox trend in south Texas can be applied throughout much of the Gulf Coast basin and in other petroleum provinces with terrigenous clastic depositional systems as well.

AAPG Search and Discovery Article #91030©1988 AAPG Annual Convention, Houston, Texas, 20-23 March 1988.