GEOTHERMAL HISTORY RECONSTRUCTION OF ZHANHUA SAG, JIYANG DEPRESSION

Based on available well temperatures and vitrinite reflectance (R^o) data, geothermal history of zhanhua sag,Jiyang Depression was reconstructed with synthesizing lithosphere-scale and basin-scale multi-linear model offered in this paper. The study result indicates: (1) the heat flow evolution curve shows a general tendency of decreasing slowly interrupted by two picking up periods that shapes‘a saddle’from the Paleocene to the Present. The calculated heat flow is about 83.6 mW/m² in the early Paleocene corresponding to active rift region, however, the present heat flow gets down to 63mW/m² as the global average value. (2) the main oil bearing layers experienced long term slowly heating process, subsequently, it is still at the ‘oil generation window', and has a wide range depth for oil existence. So, the geothermal evolution background is favorable to oil generation. The conclusion can also be further proofed by the rifting model of Bohaiwan Basin, and is useful to oil exploration in this area.