珠江口盆地晚中生代以来热演化史研究——以Ro和(U-Th)/He为据

The Mesozoic strata of the Pearl River Mouth Basin become one of the new areas for oil and gas exploration for the South China Sea (SCS). So far, there is rare research on the thermal history of the basin at the stage of the Late Mesozoic, which limits the prospective evaluation and exploration of Mesozoic oil and gas resources of marine strata in SCS. Meanwhile, the geothermal history of the basin since the Late Mesozoic research is limited to the Cenozoic. Few results of the Cenozoic thermal history studies on the northern margin of the South China Sea were reported and those results are lack of systematicness and coherence due to the simplification of previous geothermometers. In this project, we chose the Pearl River Mouth Basin as the study area which has a large set of Mesozoic strata defined by the drilling core.The combination of independent inversion and joint inversion based on two geothermometer methods (vitrinite reflectance Ro, and zircon & apatite (U-Th)/He ages) will be performed on single wells at different blocks in the basin and applied to outline the similarities and differences of structure evolutioin between different blocks. The expected results not only can provide thermal history for the Mesozoic hydrocarbon generation history and oil gas potential at the Pearl River Mouth Basin, but also provide geothermal evidences for the basin dynamics study since the late Mesozoic on northern margin of the South China Sea.

珠江口盆地中生界地层已成为南海海域油气勘探的新领域之一。然而，过去对于盆地晚中生代以来的热历史研究仅局限于新生代，十分欠缺对于晚中生代阶段盆地热演化史的认识，目前对于这方面的研究工作几乎处于空白。同时，由于以往古温标资料的单一性，利用古温标手段研究南海北缘新生代热史的成果并不多见也缺乏系统性和连贯性，这大大限制了南海中生界海相地层油气资源的远景评价与勘探工作。本项目拟选择已钻遇大套中生界地层的珠江口盆地作为研究区域，意在以盆地内不同区块的单井为研究对象，采用两种不同的古温标手段（即镜质体反射率Ro、锆石和磷灰石(U-Th)/He年龄）独立反演及联合反演相结合的方式，揭示出不同区块的构造发育异同点和晚中生代以来的热演化历史。此结果不仅可为珠江口盆地中生界生烃史及油气潜力的研究提供热史依据，还可为南海北缘晚中生代以来的盆地动力学研究提供可靠地地热学证据。