The Maximum Burial Depth in Hydrocarbon Source Rocks on Kongquehe Slope in the Tarim Basin

The strata of the Kongquehe slope in the Tarim basin have suffered from long-term denudation, causing the determination of maximum ancient buried depth in mainly hydrocarbon source rocks to be very difficult. The denudation restricts the conduct of research into the hydrocarbon generation history of the source rocks. Through the use of drilling, seismic, logging, and geochemical data, calculation of the amount of denudation of the main unconformable surface, consideration of the present residual thicknesses of major hydrocarbon source rocks and other data, the authors determine maximum ancient buried depth in four major hydrocarbon source rocks and determines the time required to reach the maximum ancient buried depth. The authors have ascertained four main results through comprehensive analysis. (a) A majority of the Jurassic hydrocarbon source rock passed the hydrocarbon-generating threshold during the Neogene period and are now in the early-mature to mature stage. (b) Carboniferous hydrocarbon source rock is only distributed in the Caohu depression, having crossed the hydrocarbon-generating threshold in the Cretaceous period, and is now in the mature to late-mature stage. (c) Most of the middle-upper Ordovician hydrocarbon source rock crossed the hydrocarbon-generating threshold in the late Ordovician period and is now in the late-mature to over-mature stage. There are two blocks in the east research area that appear to contain the maximum ancient buried depth which may have experienced secondary hydrocarbon generation in the late Silurian. (d) Cambrian-Lower Ordovician hydrocarbon source rock is in the late-mature to over-mature stage and may have experienced secondary hydrocarbon generation in the Cenozoic period in most of Kongquehe area.