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川南地区古生界海相页岩是我国页岩气勘探的主要目标层系之一。利用镜质体反射率古温标恢复了川南地区5口典型钻井的热史,在此基础上模拟了下寒武统筇竹寺组页岩的热演化过程。结果表明,川南地区在古生代热流值较低,二叠纪热流开始增大,川西南地区热流峰值约为110mW/m2,川东南地区为70~90mW/m2,此后热流值快速降低,最终保持在55~65mW/m2并持续至今。川南不同地区的筇竹寺组页岩由于热史和埋藏史的不同,使得烃源岩热演化过程存在差异。川东南地区筇竹寺组页岩在志留纪开始成熟,二叠纪快速演化并达到过成熟阶段。川西南地区筇竹寺组在石炭纪开始成熟,二叠纪在高热流作用下迅速成熟,RO值达到2.5%,其中乐山—龙女寺古隆起地区的筇竹寺组在加里东期和二叠纪埋深相对较浅,烃源岩在古生代处于未成熟阶段,中—晚二叠世开始成熟,三叠纪末期进入高成熟阶段,侏罗纪—白垩纪在深埋增温作用下进入过成熟阶段。
Paleozoic marine shale in southern Sichuan is one of the main target strata of shale gas exploration in China. The thermal history of five typical wells in southern Sichuan was recovered by using the ancient temperature scale with vitrinite reflectance. On the basis of this, the thermal evolution of shale in Qiongzhusi Formation of the Lower Cambrian was simulated. The results show that the Paleozoic heat flow in the southern part of Sichuan Province was lower and the Permian heat flow started to increase. The peak value of heat flow in southwestern Sichuan was about 110mW / m2 and that in southeastern Sichuan was 70-90mW / m2. After that, the heat flux decreased rapidly and remained at 55 ~ 65mW / m2 and continues till now. Due to the difference of thermal history and burial history, the Qiongzhusi Formation shale in different areas of South Sichuan made the thermal evolution process of source rocks different. The Qiongzhusi Formation shale in southeastern Sichuan started to mature in Silurian, and rapidly developed and reached the mature stage in the Permian. The Qiongzhusi Formation in southwestern Sichuan Province began to mature in the Carboniferous. Permian rapidly matured under the action of high heat flux, with an RO value of 2.5%. Among them, Qiongzhusi Formation in the Leshan-Longnian Temple paleo- The Cretaceous is relatively shallow in depth. Source rocks were immature in the Paleozoic, matured in the middle-late Permian, and entered the high maturity stage in the Late Triassic. The Jurassic-Cretaceous was under deep-warming Mature stage.