Facies Characterization of Carbonates by Use of Well Logs, Sligo Formation (Lower Cretaceous), South Texas

$2.00

W, H. Michael Basham,
Texas Petroleum Research Committee,
Myron H. Dorfman,
University of Texas

SPWLA TWENTY-FOURTH ANNUAL LOGGING SYMPOSIUM, JUNE 27-30, 1983

1983

Abstract

A study was undertaken to determine if the various facies repre- sented in the carbonate- Sligo formation (Lower Cretaceous) could be defined by well log analysis in a six county area along the platform margin of this formation in south Texas. Complete suites of well logs penetrating the Sligo from some 36 wells were used within an area where excellent geologic data based upon examination of over 900′ of core from 50 wells had defined the facies and environments of deposition. The carbonate system consists of a complex series of vertically sequenced supratidal oolite-shoals, grading to packstones, both of which contained porosity and permeability. These, in turn, grade into non-permeable mud-supported wackestones and mudstones in low energy environments, both downdip in the lower shelf environments and updip in the intertidal regions.