Nagihara, Seiichi1, Kelly Opre Jones2, Michael Jones3, Michael
Smith4, James Brooks5, Bernie Bernard5, Neil
Summer5, Trevor Lewis6
(1) Texas Tech University, Lubbock, TX
(2) Unocal, Sugarland, TX
(3) Scout Petroleum, Houston, TX
(4) Minerals Management Service, New Orleans, LA
(5) TDI-Brooks International, College Station, TX
(6) Sidney Geophysical Consultants, Sidney, BC
ABSTRACT: Heat Flow and Deep Sedimentary Temperatures in the Eastern Gulf of Mexico
The geothermal regime of the eastern Gulf of Mexico has been studied from seafloor heat flow measurements and bottom-hole temperature data in the continental shelf, slope, and abyssal plain. Heat flow through seafloor was measured at roughly 150 locations mainly in the deepwater by TDI-Brooks International. The bottom-hole temperature (BHT) data were obtained from about 150 wells located in the continental shelf and upper slope. The BHT data were corrected for the thermal disturbance associated with drilling. Based on these data sets, models for heat flow through the sedimentary column have been produced. There are systematic variations in the sedimentary thermal regime in the eastern Gulf. We believe that three types of mechanisms are primarily responsible for the variations. The first is the thermal blanketing effect of the sedimentation of the Mississippi submarine fan. An inverse correlation exists between seafloor heat flow and thickness of the Pleistocene sediments. The second is the structural transition between oceanic and continental crusts, which affects primarily sediments deeper than the fan deposits. For example, offshore Alabama, heat flow through the deep sediments is ~30 mW/m2 on the lower slope and increases to ~60 mW/m2 on the shelf. The radiogenic heat production in the transitional crust may be responsible for the heat flow increase up the slope. Third, salt diapirs elevate heat flow through the overlying sediments, because their thermal conductivities are two to four times greater than the surrounding sediments. Constraining these factors is essential in thermal maturation modeling in this region.
AAPG Search and Discovery Article #90026©2004 AAPG Annual Meeting, Dallas, Texas, April 18-21, 2004.