LOOFF, KARL M., Geologic Consultant, Lovelady, TX; and KURT M. LOOFF, Sofregaz US Inc., Houston, TX

Abstract: Possible Geologic Influence on Salt Falls Associated with the Storage Caverns at Bryan Mound, Brazoria County, Texas

A frequency distribution map of the number of salt falls associated with the various storage caverns at the Bryan Mound facility exhibits a pattern which suggests a geologic influence. To investigate this possibility, the upper 2500 ft of the undifferentiated Plio-Pleistocene strata which encloses the salt dome were studied for evidence of possible differential salt movement. Correlation of well logs in the area provided the basis for dividing the strata into seven mappable units. Each unit was isopached and in conjunction with a map of the salt stock evaluated for evidence of differential salt (spine) movement. The possible boundary zones between areas of differential movements were projected into the salt. In instances where similar trends were observed across the dome, a projection of the boundary zone was made through the salt stock.

A composite of all the boundary zone projections was made and overlaid on the salt map. This map suggests that the salt stock is composed of two separate spine complexes separated by a complex boundary zone area. When this map is compared to the frequency distribution map, caverns with the large number of salt falls commonly are closely associated with the projected boundary zones particularly the zone separating the main spine complexes. Likewise those caverns which have experienced few or no salt falls tend to be located within the spine complexes. The isopachs of the two intervals which overlie the salt stock provide evidence for the more recent development of a younger spine. 

AAPG Search and Discovery Article #90924©1999 GCAGS Annual Meeting Lafayette, Louisiana