Browsing by Author "Dorfman, M.H."
Now showing 1 - 2 of 2
- Results Per Page
- Sort Options
Item Geothermal Resources Frio Formation, Middle Texas Gulf Coast(University of Texas at Austin Bureau of Economic Geology, 1975) Bebout, D.G.; Agagu, O.K.; Dorfman, M.H.At depths generally greater than 7,000 feet, the sands and shales of the Frio Formation are overpressured and undercompacted. The insulating effect of these overpressured and undercompacted sediments results in the accumulation of subsurface heat and, thus, high-temperature water. The local variations of depth to top of geopressure are related to the distribution of sand and shale lithologies and to the location of growth faults. For more information concerning origin of geopressure or high temperatures, see Jones (1970) and Dorfman and Kehle (1974). Bruce (1973) discusses the nature of growth faults in detail. The resource in geopressured zone consists of high-temperature water with relatively low salinity and with dissolved methane gas. The objectives of this study were to determine regional sand distribution of the Frio Formation, identify depositional environments, and delineate the geopressured zone and its relationship to sand/shale distribution, growth faults, and fluid temperatures in the Middle Texas Gulf Coast. This study is essentially an extension of that completed earlier for South Texas (Bebout, Dorfman, and Agagu, 1975); all correlation and mapping units are the same as those represented in the South Texas report.Item Geothermal Resources Frio Formation, Upper Texas Coast(1976) Bebout, D.G.; Loucks, R.G.; Bosch, S.C.; Dorfman, M.H.;The objective of this study is to identify major sand trends, which, along with subsurface temperatures and pressures, aid in evaluating the potential of producing geothermal energy from the Frio Formation, Upper Texas Gulf Coast. During the Tertiary, huge quantities of terrigenous sediments were deposited as gulfward-thickening sedimentary wedges along the Texas Gulf Coast. The sand and shale making up these wedges were transported across a broad fluvial plain and deposited in deltaic complexes or were reworked by marine processes into strandplains and barrier islands. Growth faults developed contemporaneously at the site of maximum deposition as a result of rapid loading of large quantities of deltaic and strandplain sands onto previously deposited prodelta and shelf muds. These growth faults allowed the accumulation of extremely thick sections of sand and also caused the isolation of many of these sand bodies from porous updip sands; pressured reservoirs developed after further loading and copaction (Bruce, 1973; Jones, 1975). This study is investigating geopressured geothermal reservoirs in this setting. Limited data obtained from deep wells drilled for oil and gas indicate that many of these large sand reservoirs are filled with water which has high temperature, is relatively low in total dissolved solids, and is saturated with methane gas. To be suitable for electric power generation, the reservoir shouls have a volume greater than 3 cubic miles (which is equivalent to 300 feet of sand distributed areally over more than 50 square miles), permeability greater than 20 millidarcies, and subsurface temperatures higher than 300 degrees F. This report reviews the results of the Bureau of Economic Geology regional study of the Frio Formation in the Upper Texas Gulf Coast. It is a continuation of two similar studies of the Frio in the Lower and Middle Texas Gulf Coast (Bebout, Dorfman, and Agagu, 1975; Bebout, Agagu, and Dorfman, 1975). The objective of these reports is to outline areas (fairways) which appear the most prospective for producing geothermal energy and which therefore deserve further, more detailed study.