Thermal Maturity Model of the Arabian Plate

Abstract

Abstract A regional thermal maturity model of Arabian Plate petroleum source rocks was constructed using ExxonMobil's Stellar™ basin-modeling software. The model integrates new plate-wide structural maps at 19 unconformities spanning the Phanerozoic era with estimates of missing section amounts at ten major unconformities and is calibrated to regional temperature and maturity data. Timing of generation and hydrocarbon yields are constrained by kinetic analyses of samples from multiple source rock intervals. Results of the kinetics are integrated with maps of source rock distribution to arrive at the volume and extent of oil and gas generation. Finally, hydrocarbon migration from mature source rock kitchens is evaluated using depth structure-contour maps, and the results are calibrated against known hydrocarbon occurrences and geochemical correlations. The model results highlight several important regional observations regarding timing of hydrocarbon generation and migration, distribution of hydrocarbons and integrity of regional seals. Sensitivity analyses indicate the amount of missing section affects the timing of hydrocarbon generation for selected Arabian Plate source rocks. This may be important to understand the timing of migration relative to trap formation. Some traps appear to have been filled with oil soon after they were formed. However, geochemical correlation and characterization of oils from the region suggest lateral migration of at least 150 km from some areas of mature source rock. Additionally, regional seals such as the Hith appear to limit the extent of vertical hydrocarbon migration for most hydrocarbon systems. However breaches in many regional seals, caused either by erosion, faulting or fracturing, or solution-collapse allow oil and gas to migrate vertically to younger reservoirs.