鄂尔多斯盆地延长组深水岩相发育特征及其石油地质意义
摘要: 鄂尔多斯盆地湖盆中部地区三叠系延长组长7油层组广泛发育深水沉积。沉积物的粒度、沉积结构与构造、有机地球化学等特征研究表明,深水沉积岩可划分为四种岩相类型,分别为油页岩岩相、暗色泥岩岩相、砂质泥岩与泥质砂岩岩相和砂岩岩相。其中,油页岩岩相有机碳含量高,有机质类型好,测井曲线具有高阻、高伽马、低电位和时差跳跃频繁等特征;暗色泥岩岩相具有富含有机质、中低阻、中高伽马、高密度和高时差等特征;砂质泥岩与泥质砂岩岩相具有中电阻、低伽马、高密度、时差跳跃频繁等特征,泥质含量 20~70%;砂岩岩相表现出低的电阻、时差和伽马、泥质含量小于20%的特征,并刻画了各种深水岩相的剖面发育特征。深水斜坡带和湖底平原区的岩相组合存在较大的差异。深水岩相对非常规油气资源意义重大,其中油页岩岩相和暗色泥岩岩相为盆地中生界主力烃源岩,深水砂岩岩相是盆地大规模致密油的重要储集体,砂质泥岩与泥质砂岩岩相、暗色泥岩岩相富含丰富的页岩油资源,也具有潜在经济价值。
Features of Deepwater Lithofacies, Yanchang Formation in Ordos Basin and Its Petroleum Significance
Abstract: Deep-water deposit of Ch7 member, in Trssic Yanchang Formation, is widely distributed in the center of Ordos basin. Study on particle size, sedimentary textures and structures and organic geochemistry shows that sedimentary rock in deep water can be summed up as four types, i.e. oil-shale lithofacies, dark-mudstone lithofacies, siltstone-mudstone lithofacies and sandstone lithofacies. The oil-shale lithofacies is characterized by high organic carbon content and good type of organic matter, with higher value of resistivity and natural gamma, clear negative anomalies of SP curves, and the curves of acoustic interval transit times varies sharply; dark-mudstone lithofacies characterized by being rich with organic carbon, mid-low value of resistivity, midhigh value of natural gamma and high value of density and acoustic interval transit times; siltstone-mudstone lithofacies by mid value of resistivity, low natural gamma, high density and sharply varied curves of acoustic interval transit time, with mud content ranges about 20~70%;and sandstone lithofacies by low value of resistivity and acoustic interval transit time, and natural gamma, with mud content lower than 20%. The shape of different lithofacies are defined and configuration difference of lithofacies at deepwater slope and lake bottom plain is illustrated in detail. It is pointed out that deep-water rock has great significance for unconventional oil and gas resources. For example oil shale lithofacies and dark-mudstone lithofacies, as the main source rock of Mesozoic, contribute greatly for the formation of large scale reserviors in Ordos basin; the deepwater sandstone lithofacies provides extensive spaces for large-scale tight oil; and deepwater siltstone-mudstone and oil shale lithofacies is the important accommodation for shale oil and has the potential of economic value.
鄂尔多斯盆地延长组深水岩相发育特征及其石油地质意义[J]. 沉积学报, 2013, 31(05): 928-938.
引用本文: |
鄂尔多斯盆地延长组深水岩相发育特征及其石油地质意义[J]. 沉积学报, 2013, 31(05): 928-938.
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Features of Deepwater Lithofacies, Yanchang Formation in Ordos Basin and Its Petroleum Significance[J]. Acta Sedimentologica Sinica, 2013, 31(05): 928-938.
Citation: |
Features of Deepwater Lithofacies, Yanchang Formation in Ordos Basin and Its Petroleum Significance[J]. Acta Sedimentologica Sinica, 2013, 31(05): 928-938.
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