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Study On Petroleum Accumulation Process In Baiyinchagan Depression

Posted on:2009-03-09Degree:MasterType:Thesis
Country:ChinaCandidate:F HeFull Text:PDF
GTID:2120360242484328Subject:Oil and Natural Gas Engineering
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Baiyinchagan Depression Locates in Chuanjing sub-basin of Erlian Basin, is a residual growth of Mesozoic half-graben fault depression overlaying Hercynian Fold. In recent years, a series of achievements and understandings in oil and gas exploration have been achieved in Baiyinchagan Depression, and Zhongyuan Oilfield has established an oil and gas production base in this area, which is another one following the production base in the Dongpu Depression area. Behind exploration breakthroughs, there is an inevitable challenge to face, i.e. how to organically integrate theory with practice in oil and gas exploration and guide exploration practice by using exploration theory. By using new theories and approaches in petroleum geology, the paper aims to determine petroleum accumulation pattern in the Baiyinchagan Depression by analyzing the petroleum accumulation condition, associating petroleum accumulation process with hydrocarbon generation, migration, trap formation, and hydrocarbon accumulation, and finding out the relations between hydrocarbon generation & migration and trap formation & development (with focus on the dynamic process of hydrocarbon migrating from source rock into trap),and the next exploration target is estimated.The study indicates that Baiyinchagan Depression is mainly composed of four sets of source rock including No.2 Member of Aershan Formation, Tengger Formation, No.1 Member of Duhongmu Formation, and No.2 & No.3 of Duhongmu Formation. The source rock in the No.1 Member of the Duhongmu Formation has a high abundance of organic substances yet with low maturity, and so contributes less to hydrocarbon generation. Both Tengger Formation and No.2 Member of Aershan Formation have high abundance of organic substances with high maturity, and so contribute a lot to hydrocarbon generation.The reservoirs have favorable physical properties in Duhongmu Formation, which become worse as the depth increases of formation. The cap rocks provides good confining conditions, and an earlier formation means better capping. Faults, unconformities, and high-permeability strata form the conduction system through which oil and gas can migrate. Structural traps, stratigraphic traps, and lithologic traps are developed.According to the depression's hydrocarbon generation & expulsion history, late depositional stage of No.1 Member of Duhongmu Formation, depositional stage of No.3 Member of Duhongmu Formation, and depositional stage of Saihantala Formation are main depositional stages which are respectively corresponding to the three sets of source rock: No.2 Member of Aershan Formation, Tengger Formation, and No.1 Member of Duhongmu Formation. Oil and gas migration starts from the hydrocarbon-generating depression towards its north and south slopes. Comparative analysis of oil sources shows that the crude originates mainly from source rocks in No.2 Member of Aershan Formation and Tengger Formation.Structures, sedimentary reservoirs, and source rock control petroleum accumulation process. Different structural belts and different structural modes in a structural belt have their respective petroleum accumulation pattern.The study indicates that Baiyinchagan Depression has considerable exploration potential with good conditions for oil and gas accumulation. By integration of theory with practice, there will be certainly new discoveries.
Keywords/Search Tags:petroleum accumulation condition, petroleum accumulation process, petroleum accumulation pattern, Baiyinchagan Depression, Erlian Basin
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