Hui'anbu - Majiatan Upper Paleozoic Petroleum System

Huianbu-Majiatan Area ,located on the west edge of Ordos Basin, covers two tectonic units: West Edge Fault Belt and Tianhuan Depression, of which the Upper Paleozoic has not been invested adequate exploration. Based on the former research achievements , it is turned out that Upper Paleozoic of Huianbu-Majiatan Area has preferable exploration potential .Meanwhile studying the petroleum system of upper Paleozoic in Huianbu-Majiatan Area will make for systematically investigating petroliferous geologic condition and directing the future exploration decisions, which is expected to find new energy sources.Using modern testing techniques, combining the regional data with well data synthesizing outcrop and indoor work , beginning with the tectonic evolution and the sedimentation evolution ,the static elements and geologic process are studied directed by the petroleum system theory and concerned with principles of holism, development and integration. The research work is concentrated on the following aspects, (1)studying the hydrocarbon source rock condition in studied area ; (2)studying the reservior in studied area and its reserving capability; (3) studying the forming process and the type of trap and sealing capability of the cap; (4) Based on the studying results of burial history ,thermal history and hydrocarbon generation history, the critical moment is ascertained; (5)the petroleum system of upper Paleozoic in the studied area is compartmentalized and assessed. The research conclusions are as follows.1.Shanxi Formation and Taiyuan Formation source rock bear characteristics of high organic material content, contrarily, Shihezi Formation can not be identified as effective hydrocarbon source rock. Ⅲ-type organic material is in the highest flight and bears high maturity degree.2.The reservior is mainly constituted by Shanxi Formation and Lower Shihezi Formation.The reserving capability of the north stratum is better than that of the south.3.The structural trap and stratigraphic trap constitute the main type in the studied area. The structural trap formed in Yanshan Movement of the late Jurassic epoch and Himalayan Movement of early Tertiary epoch. The stratigraphic trap formed in late Paleozoic era. Meanwhile fluid trap ,which mainly formed in Yanshan Movement and Himalayan Movement, is not dominant. 4. Upper Shihezi Formation and Shanxi Formation are favorable regional cap. Andpartial cap ,which consists of Taiyuan ,Shanxi and Shihezi Formation,the sealing capability is favorable and have two sealing mechanisms: hydrocarbon concentration sealing mechanism and physical capability sealing mechanism.5.Synthesizing the analysis of hydrocarbon generation history ,the late Cretaceous epoch is ascertained as the critical moment .And the elements of petroleum system have a favorable collocating sequence.6.Based on the results hereinbefore, two petroleum systems are confirmed. And Tianshui-Shigouyi Taiyuan Formation (?) Petroleum System is considered excellent and Shigouyi-Lingwu Shanxi Formation (?) Petroleum System takes second place.