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High Sediment Temperatures along the Corsair Growth Fault System in the Texas Continental Shelf

Nagihara, Seiichi 1
1 Department of Geosciences, Texas Tech University, Lubbock, TX.

A recently compiled database of bottom-hole temperatures (BHTs) reported from the wells in the Texas continental shelf reveals a trend of elevated sediment temperatures along the Corsair growth fault system. The BHTs have been corrected for the thermal effect of drill fluid circulation by the Horner plot technique. There are several major growth fault systems in the coastal plain and continental shelf of Texas and Louisiana. Previous researchers have identified high-sediment-temperature trends along the Wilcox and Frio systems on the coastal plain. But, not every growth fault system shows a similar trend of hot sediments. Within the continental shelf area of the present study, at least 3 growth fault systems have been previously identified, but only the Corsair system shows a clear linear trend of high temperatures. At several locations along the fault system, sediment temperature at 4-km depth is 30° to 40° F higher than that of the surrounding areas. A portion of the Wanda growth fault system on the outer shelf also shows some high temperatures, but it is not possible to determine whether or not they form a linear trend, mainly because of limited data coverage. With regard to the cause of the high sediment temperatures, previous researchers suggested for the Wilcox and Frio systems that hot pore fluids escaping from deep, over-pressured sediments migrate upward through some of the faults and elevate sediment temperatures in the vicinity. A similar mechanism is possible for the Corsair system. Previous reservoir fluid analyses performed for a gas field along the Corsair system suggested that deep-cutting faults there act as the conduits for upward migration of fluids expelled from deep Mesozoic sediments. A limited coverage of seismic profiles in the study area also indicates that the localities of hot sediments tend to coincide with deep-cutting faults. In addition, if there are large salt masses in the detachment zones, their high thermal conductivity may contribute to the occurrence of the high sediment temperatures.

 

AAPG Search and Discovery Article #90090©2009 AAPG Annual Convention and Exhibition, Denver, Colorado, June 7-10, 2009