| The main target of the Upper Triassic Xujiahe Formation in the middle of the western Sichuan depression Hexingchang-Gaomiaozi,which has dense~super tight clastic reservoir,the complexity of deep geological conditions , strong heterogeneity and cracks,formation water distribution difficult to grasp, exploration difficult. Therefore, it is necessary to Xujiahe Formation fluid causes and characteristics of natural gas do a more detailed study in Hexingchang. This paper analysis nature gas and formation water geochemical characteristics, combined with geological background of the study area, a comprehensive study describes the causes and sources of gas, formation water origin; Further combining the characteristics of Fluid explicit Gas and water distribution rule and distribution dominative factor;Finally, through the anatomy of typical gas reservoir, we analyzed the dynamic process of natural gas accumulation of Xujiahe in the study area, and summed up the gas accumulation model.This paper firstly analyzes the hydrocarbon source rocks of organic carbon, organic sulfur, chloroform bitumen "A", chloroform bitumen race components, kerogen maceral, aliphaltic gas chromatography, aliphaltic gas carbon isotope, vitrinite reflectance, carbon, hydrogen and oxygen elements, sand body division, petrophysical property and cap rock and other relevant documents , explicits hydrocarbon source geochemical characteristics sand body development characteristic, petrophysical characteristics, cap rock the basic characteristics and exhibition cloth and soure-reservior-roof features, etc of the Upper Triassic Xujiahe Formation, we known the xujiahe source rock large thickness, distribution range, high organic matter abundance and high maturity, a single type (mainlyâ…˘main type) features.Based on the analysis of characteristics of natural gas geochemical characteristics ,cleard gas the basic characteristic and genetic types. Gas source comparison indicated that the Jurassic gas of HeXingChang mainly came from the member 5 of Xujiahe formation hydrocarbon source rocks, and the middle Jurassic source rock was its powerful supplement. the member upper 4 gas of XuJiahe formation came from the member lower 4 formation hydrocarbon source rocks contribution. the member lower 4 gas of XuJiahe formation came from the member 3 formation hydrocarbon source rocks. The gas of the member 2 of XuJiahe formation of GaoMiaoZi area was mainly provided by gas source of both XiaoTangZi-Saddle group and the member 2 of XuJiahe formation. The gas of the member 2 of XuJiahe formation of XinChang mainly came from the member 2 of XuJiahe formation and XiaoTangZi-Saddle group hydrocarbon source rocks.Through the research area from stratigraphically formation water constants components, trace components of system analysis, confirmed formation water base geochemical characteristics, divided formation water type.Integrating existing drilling mud logging, well logging, testing, production and so on many kinds of information, defined each single well of the vertical distribution characteristics of XuJiahe formation, combination with geological research achievements,summarized the single well water development features. From formation water hydrogen and oxygen isotopes, ion combination characteristic and trace elements in such aspects as, basic ascertained the formation water causes and sources of xujiahe, xujiahe formation water is mainly for the high concentration of formation water, different layer segment of formation water properties have different water-rock action process.According to the current situation, combined with a gas aquatic tectonic evolution, fracture, crack etc research results, analysis current tectonic and gas water distribution relationship; Using petrophysical material research reservoir heterogeneity of gas water distribution influence; Comprehensive analysis the various geological factors to influence of formation distribution size, summarizes the main gas water distribution control factors.The master control of natural gas and water concentration of member 2 of Xujiahe formation was: reservoir heterogeneity,large faults,sandstone super densification former ancient tectonic high position and favorable microfacies superposition and mining systematic irrationality. The master control of natural gas and water concentration of member4 of Xujiahe formation was:reservoir,Lateral sealing ability,the member upper 4 gas of XuJiahe In the hydrocarbon-generating peak structure and sand disposition relation,crack and the member lower 4 gas of XuJiahe enrichment degree close relationship rock types.Established gas and water distribution pattern and gas rich integrated reservoiring pattern of the member 2 gas of XuJiahe formation, the member upper and lower 4 gas of XuJiahe formation. |
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