Reconstruction of Basal Heat Flow, Surface Temperature, Source Rock Maturity, and Hydrocarbon Generation in Salt-Dominated Dutch Basins
Hanneke M. Verweij, Mônica Souto Carneiro Echternach, Nora Witmans, Rader Abdul Fattah, 2012. "Reconstruction of Basal Heat Flow, Surface Temperature, Source Rock Maturity, and Hydrocarbon Generation in Salt-Dominated Dutch Basins", Basin Modeling: New Horizons in Research and Applications, Kenneth E. Peters, David J. Curry, Marek Kacewicz
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Arapidly growing demand for improved understanding of the Dutch subsurface exists because of the need for alternative energy supplies, such as geothermal energy, as well as for finding and producing more oil and gas in this mature area for petroleum exploration. We use basin modeling to integrate the wealth of new data and information that are increasingly available on the Dutch subsurface. In addition, we develop different approaches to improve the basin modeling results.
Here, we present novel approaches to reconstruct the surface and bottom thermal boundary conditions for basin modeling. The first approach involves assessment of Tertiary sediment-water interface temperatures from information on local and global climate changes that was recently discovered using geobiological and geochemical techniques. The second approach involves multiple one-dimensional probabilistic tectonic heat-flow modeling to calculate the basal heat-flow history and construct paleo–heat-flow maps.
This chapter presents modeling results for the Terschelling Basin and southern part of the Dutch Central Graben that demonstrate the effect of incorporating the tectonic heat-flow boundary condition and detailed knowledge of Tertiary climate changes on source rock maturity and hydrocarbon generation. The simulation results show a marked difference in generated hydrocarbon volumes and a shift in the timing of Tertiary generation compared with simulations using a default surface temperature boundary condition based on paleolatitudes of the research area.
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Temperature-time–based first-order kinetic models are currently used to predict hydrocarbon generation and maturation in basin modeling. Physical chemical theory, however, indicates that water pressure should exert significant control on the extent of these hydrocarbon generation and maturation reactions. We previously heated type II Kimmeridge Clay source rock in the range of 310 to 350°C at a water pressure of 500 bar to show that pressure retarded hydrocarbon generation. This study extended a previous study on hydrocarbon generation from the Kimmeridge Clay that investigated the effects of temperature in the range of 350 to 420°C at water pressures as much as 500 bar and for periods of 6, 12, and 24 hr. Although hydrocarbon generation reactions at temperatures of 420°C are controlled mostly by the high temperature, pressure is found to have a significant effect on the phase and the amounts of hydrocarbons generated.
In addition to hydrocarbon yields, this study also includes the effect of temperature, time, and pressure on maturation. Water pressure of 390 bar or higher retards the vitrinite reflectance by an average of ca. 0.3% Ro compared with the values obtained under low pressure hydrous conditions across the temperature range investigated. Temperature, pressure, and time all control the vitrinite reflectance. Therefore, models to predict hydrocarbon generation and maturation in geological basins must include pressure in the kinetic models used to predict the extent of these reactions.