Measurement of Sediment Surface Heat Flow and its Application in Deepwater Exploration

A tremendous amount of heat is constantly transported from the earth’s center to the surface by thermal convection and conduction. A portion of the heat conducted through the earth’s crust is used to drive the chemical reactions that transform sedimentary organic matter into petroleum. At any point in the sediment column, the conductive heat flow is the product of the temperature gradient and thermal conductivity. Heat flow (Q), measured in mW/rn2, is determined by multiplying the site thermal conductivity (k), measured in W/m-K, with the geothermal gradient (G), measured in mKJm, and determined from the thermistors. Accurately measuring this heat and understanding its transport mechanisms through the crustal rocks are essential to the science of deepwater petroleum exploration. The thermal history of deepwater sedimentary basins is of great interest to petroleum geologists because the hydrocarbon maturation process is controlled primarily by the temperature the source rock has experienced since its deposition. Researchers mathematically constrain the sedimentary thermal history by building a physical model that simulates the processes whereby the sediments become gradually heated by geothermal heat as they are deposited, buried, and compacted over time. The researcher must have detailed knowledge of the sedimentation history, the thermal properties of the sediments, and the regional geothermal heat flux in order to reconstruct the thermal history of the basin of interest.