Evaluation Of Hydrocarbon Generating Potential From Source Rock Of Chang9Member, Yanchang Formation, Ordos Basin

Ordos Basin is the second largest basin in China. Although the oil and gas explorationeffect of the Ordos Basin Chang9is far from that of Chang7, the discovery of Chang9Member high-quality hydrocarbon source rocks and the good hydrocarbon show and the gainof commercial oil flow in Chang8,9,10Reservoir in recent years, which indicate Chang9Member may be a set of important potential hydrocarbon source rocks. Aiming at thisproblem, this paper adopts a combination of geochemistry, petroleum geology theory as aguide, qualitative evaluation of hydrocarbon generation potential of hydrocarbon from sourcerock of Chang9and qualitative calculation of the hydrocarbon generation and expulsion bymeans of comprehensive study of the geochemistry, geology, drilling, well logging and mudlogging data. Clearly the accumulation contribution of the Chang9hydrocarbon source rocksfor the services of an objective understanding of the relevant objectives of the explorationpotential of the service.Therefore the hydrocarbon generation potential of hydrocarbon from source rock ofChang9Member was researched qualitatively and quantitatively in this paper. The resultindicated that the quality source rock of Chang9Member, Yanchang Formation, Ordos Basinis mainly distributed in Zhidan and Yingwang areas. Calculated from the Ordos Basin, oilgeneration and expulsion are25.22×108t and8.69×108t. Hydrocarbon resources from sourcerock of Chang9Member in Ordos Basin are (2.09~4.17)×108t and (0.06~0.12)×1011m3. Themain period of the generation and expulsion of Ordos basin Chang9source rocks is theCretaceous (145~65Ma). Zhidan and Gaoqiao-Taibai are the major oil generation andexpulsion regions and Guozhuangzi also has a certain intensity of hydrocarbon generation andexpulsion.Yingwang has a certain degree of hydrocarbon generation intensity, but it has notremendous expulsion. Therefore the expulsion efficiency of hydrocarbon from source rock ofChang9Member was researched qualitatively and quantitatively in this paper. The result ofqualitatively and quantitatively hydrocarbon from source rock of Chang9Member indicatedthat the expulsion efficiency of hydrocarbon from source rock of Chang9Member inYingwang area is obviously lower than those of other areas (e.g.Zhidan area). It is only44%,and the average value of those of other areas is82%. The low expulsion efficiency ofhydrocarbon should be an important reason that no breakthrough has been made in theexploration of oil from source rock of Chang9Member in Yingwang area. Comprehensiveutilization of GC, GC-MS and carbon isotope data of oil-source correlation, the results showthat Erdos Chang9source rocks are a set of potential hydrocarbon source rock. Therefore,hydrocarbon resources from source rock of Chang9Member should be considered when oiland gas exploration is conducted in Zhidan area.