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    海拉尔盆地呼和湖凹陷热演化史与油气关系

    Relations between the thermal history and petroleum generation in the Huh Lake depression, Hailar basin

    • 摘要: 提要:呼和湖凹陷现今地温梯度为3.54℃/100 m,属于中温型地温场。根据镜质体反射率、包裹体测温和磷灰石裂变径迹法恢复了呼和湖凹陷古地温演化史,研究表明呼和湖凹陷早白垩世古地温梯度可达3.7~6.5℃/100 m,古地温梯度高于现今地温梯度,古地温高于今地温。古地温恢复及热史模拟表明最高古地温是在早白垩世晚期达到的,下白垩统烃源岩热演化程度主要受古地温场控制。热演化史与油气关系研究表明呼和湖凹陷油气生成期主要有两期,分别是早白垩世晚期及古近纪以来,且以早白垩世晚期为主要成藏期,古近纪以来由于目的层温度降低生烃强度减弱。

       

      Abstract: Abstract:The present geothermal gradient of the Huh Lake depression is 3.54℃/100 m, so it is a middle-temperature geothermal field. The paleogeothermal gradient reconstructed by the vitrinite reflectance, microthermometric measurements of fluid inclusions and fission-track path method was 3.7-6.5℃ /100 m, which is higher than the present geothermal gradient, and the ancient subsurface temperatures are higher than the present subsurface temperatures. The reconstruction of the paleogeothermal gradient and modeling of the thermal history indicate that the maximum paleogeothermal values were reached in the Late Cretaceous and that the paleogeothermal field controlled the maturity of Lower Cretaceous hydrocarbon source rocks. Study of the relation between the thermal history and hydrocarbon shows that the formation of hydrocarbon in the Huh Lake depression mainly progressed through two stages: the late Early Cretaceous stage and stage since the Paleogene, with the late Early Cretaceous being the main stage of hydrocarbon accumulation. The intensity of hydrocarbon generation has become weak since the Paleogene with decreasing temperatures in the target strata.

       

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