Geothermal Heat Flow in the Gulf of Mexico
Seiichi Nagihara, Texas Tech University - Geosciences
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Why study geothermal heat flow in the Gulf? Geothermal heat flow is obtained as the geothermal gradient multiplied with the thermal conductivity of the rock in the same depth interval. By studying how heat flow varies geographically, researchers can make inference on the geologic history, the earth's structure, and migration of fluid (water, oil, and gas) through rocks. In the Gulf of Mexico, like in many other oil-producing sedimentary basins, geothermal heat is the energy that drives the chemical reactions of transforming organic matters in sediment into petroleum. The geothermal regime also influences the formation of byproducts such as hydrogen sulfide gas. In addition, knowledge of heat flow helps researchers in studying the tectonic processes that created the Gulf in the Triassic through Jurassic time. |
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Hydrogen Sulfide-bearing Reservoirs Hydrogen sulfide (H2S) gas is extremely toxic and corrosive to most steel. If H2S is encountered during a drilling operation, it is a major hazard. Occurrence of H2S has been observed at a number of fields along the United States coast of the Gulf of Mexico, especially deep gas fields off Alabama. High formation temperatures of deep reservoirs are considered a favorable condition for the chemical reactions that yield H2S. Currently efforts are underway by oil industry to further explore deep gas reservoirs in the northern continental shelf of the Gulf. In assisting such efforts, in collaboration with researchers at the U.S. Minerals Management Service, I am conducting a review of geothermal gradient and deep sedimentary temperature of the continental shelf off Alabama through Texas. Temperature and other data from thousands of existing wells are being assembled into a GIS (geographic information systems)-accessible database. |
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| Map showing the fields where H2S occurrence has been previously reported (red) and the locations of the wells examined so far (black). | ||
| More information on the Geosciences Heat Flow laboratory here. | ||
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Related Publications Nagihara, S., and K. O. Jones, 2005, Geothermal heat flow in the northeast margin of the Gulf of Mexico: Amer. Assoc. Petrol. Geol. Bull., v. 89, p. 821-831. Nagihara, S., and M. A. Smith, 2005, Geothermal gradient and temperature of hydrogen sulfide-bearing reservoirs in the continental shelf off Alabama: Amer. Assoc. Petrol. Geol. Bull. v. 89, p. 1451-1458. Nagihara, S., 2003, Three-dimensional inverse modeling of refractive heat flow anomaly associated with salt diapirism: American Association of Petroleum Geologists Bulletin, v. 87, p. 1207-1222. Nagihara, S., J. M. Brooks, B. B. Bernard, N. Summer, G. Cole, and T. Lewis, 2002, Application of marine heat flow data important in oil, gas exploration: Oil & Gas Journal, v. 100.27, p. 43-49. Nagihara, S., J. G. Sclater, J. D. Phillips, E. W. Behrens, T. Lewis, L. A. Lawver, Y. Nakamura, J. Garcia-Abdeslem, and A. E. Maxwell, 1996, Heat flow in the western abyssal plain of the Gulf of Mexico: Implications for thermal evolution of the old oceanic lithosphere: J. Geophys. Res., v. 101, p. 2895-2913. Nagihara, S., J.G. Sclater, L.M. Beckley, E.W. Behrens, and L.A. Lawver, 1992, High heat flow anomalies over salt structures on the Texas continental slope, Gulf of Mexico: Geophys. Res. Let., v. 19, p. 1687-1690.
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