塔北哈拉哈塘—英买力地区深层油气运移与成藏地球化学特征

采用地质、地球化学分析对哈拉哈塘—英买力地区油气特征、烃源灶部位、油气运移与成藏特征进行了反演研究。结果表明:原油物理与化学特征差异显著但有序分布,原油成熟度差异显著但成因相近。油-油、油-岩成熟度对比显示英买力地区原油与研究区埋深相近的泥灰岩没有可比性,哈拉哈塘地区深部奥陶系原油与埋深6 500~7 500 m的烃源岩成熟度相当,指示烃源灶为相邻凹陷。油气运移与成藏具有:1准差异聚集特征,从斜坡低部位至高部位,油气相态从轻质油—中质油—稠油呈规律性分布;2断层控制油气运移与聚集,油气主要聚集在断层附近,烃类流体性质、储层质量显著受控于断层,高气/油比油气主要出现在断层泄压区;3风化壳显著控制油气聚集与分布,油气主要分布在准层状风化壳上、下的岩溶储层内,具有多期充注成藏特征;4油气成藏模式为异地源-断控运移-准差异聚集-风化壳储油-多期叠加成藏模式。

Geochemical features of deep hydrocarbon migration and accumulation in Halahatang-Yingmaili area of the northern Tarim Basin

Based on geologic and geochemical analysis, an inversion study is conducted on hydrocarbon features, hydrocarbon kitchen location, hydrocarbon migration and accumulation features in Halahatang-Yingmaili area of the northern Tarim Basin. The results indicate that crude oil has significantly different physical and chemical properties, but showing an ordered distribution. Moreover, the crude oil has similar genesis, although there is a significant difference in oil maturity. As shown by maturity correlation of oil-oil and oil-source rock, there is no comparability between crude oil in Yingmaili area and marlstone at the similar burial depth in the study area. The deep Ordovician crude oil in Halahatang area and the source rock at the burial depth of 6 500-7 500 m have an equivalent maturity, indicating adjacent depression is the hydrocarbon kitchen. Hydrocarbon migration and accumulation have following characteristics:(1) Quasi-variance accumulation, from low to high slope, oil and gas is distributed regularly in the form of light oil, medium oil and heavy oil, respectively; (2) Control of faults on hydrocarbon migration and accumulation, hydrocarbon accumulation mainly appears near the faults, and hydrocarbon fluid properties and reservoir quality are directly controlled by faults, hydrocarbons with high gas-oil ratio mainly occur in stress relief area of faults; (3) Significant control of weathering crust on hydrocarbon accumulation and distribution, hydrocarbons are mainly distributed in karst reservoir above and below the quasi-layered weathering crust, characterized by multi-phase filling and accumulation; (4) The mode of hydrocarbon accumulation is identified as allochthonous source-fault controlled hydrocarbon migration-quasi-variance accumulation-weathering crust reservoir-multi-phase superposition.