• 责任者：Ma Xinhai (Exploration and Development Research Institute ; Daqing Oilfield Company Ltd. ; Daqing 163712 ; China)
• 刊名：Petroleum Geology & Oilfield Development in Daqing
• 出版年：2013
• 卷期：32(1)
• 关键词：热演化 ; thermal evolution ; 成藏期 ; pool-forming period ; 蒙古 ; Mongolia
• 页码：p.59-64
• 图表：illus., 3 tables, 20 refs.
• 分类号：1003
• issnNo：ISSN1000-3754
• isbnNo：CN23-1286/TQ

South Tumtsag Sag is a very important sag for oil ＆ gas exploration in Tumtsag Basin. For quite a long time, the systematc researches on the geothermal evolution history and stage-time of petroleum reservoir formation have not been engaged. Therefore many methods are adopted to statistically analyze almost hundred of tested geo- thermal data and 330 Ro data of the organic matters. The studies show that the geothems rise linearly with the in- crease of the depth--the typical characteristics of transmitting-type geothermal field; the geothermal gradients in each sedimentary formation of Early Cretaceous system ranged from 4.48~ C/hm to 5.37~ C/hm, which are greater than the present. From Early Cretaceous period to now, the field in South Tumtsag Sag has experienced the process of temperature reduction. At the meantime, the stimulations of the histories of the individual wellg geothermal evo- lution and hydrocarbon generation ＆ expulsion are conducted. The achievements prove that the geothermal evolution degree was finished in the stage of Late Yimin Formation ; the primary petroleum source rock in South Tumtsag Sag began to expel hydrocarbon at the stage of Yimin Formation （the end of Early Cretaceous period ） , but the amount was small ; while the large amount of hydrocarbon was expelled at the stage of Qingyuangang Formation （ 95～70 Ma, Late Cretaceous period） , which was almost 85% of total expelled hydrocarbon. Combined with the structures and sedimentation-evolution analyses, the latter is calculated and determined as the key reservoir-forming stage for the hydrocarbon expulsion-migration and being entrapped, which is the main petroleum reservoir-forming stage-time in South Tumtsag Sag.