The Study On The Thermal History Restore And The Oil Or Gas Generate On Songliao Basin Sanzhao Depression

As the most important depression of hydrocarbon generation, the time when the hydrocarbon generation in Sanzhao depression is very important to the oil exploration of Songliao Basin. Thermal history is restored by vitrinite reflectance, apatite fission-track, fluid inclusions and other indicators, with ancient heat flow method and ancient geothermal gradient method in this paper. After the thermal history restored, the thermal history in every sub-tectonic units is similar. The formation's had reached the highest temperature in history in every sub-tectonic units. The Qn1 of Sanzhao Depression, the source rock layer had been impacted by the higher heat flow that reached the higher temperature in the late Cretaceous. It is the higher average temperature of about 100℃, and this temperature have a great influence on evolution of organic matter for the oil-generating. So the Qn1 source rock in every tectonic units have entered into the main oil-generating stage. According to vitrinite reflectance's fitting results, it can be seen that the organic matter's evolution of Qn1 source rock have reached a mature stage(Ro>0.7%). Some layer in other area have reached high mature stage(Ro>1.3%). N2 source rock in some tectonic units have entered into the hydrocarbon generation stage. The high-temperature phase is corresponding to the oil-generating stage of source rock. It reveals that temperature have the significant impact on the oil or gas generating. The time when oil and gas generated in source rock in the late Cretaceous, while the present oil and gas structures in basin has been basically formation at that time. So as an important hydrocarbon generation in Songliao Basin, the lots of oil and gas generation in Sanzhao depression in that time played an important role in the large-scale oil and gas accumulation in Songliao basin.