鄂尔多斯盆地延长组砂质纹层发育特征与油气成藏
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摘要
鄂尔多斯(盆)地中南部地区,三叠系延长组页岩内部存在大量的砂质纹层,该类纹层的发育与油气成藏的关系还不明确。为了深入揭示砂质纹层的地质特征、探索砂质纹层的发育对油气成藏的有利作用,综合利用岩心观察、镜下识别及有机地化分析技术,对砂质纹层的岩性特征、物性特征、裂缝发育及油气赋存开展了综合性研究。结果表明,砂质纹层的岩性涵盖粉砂岩、泥质粉砂岩、粉砂质泥页岩;纹层主要呈薄纹层、薄条带及薄夹层的形式出现。砂质纹层的存在,改变了岩性的接触方式。砂质纹层越发育,岩性交互程度越强,往往越有利于排烃。砂质纹层的存在,有利于孔隙的发育,间接改善了储层物性。砂质纹层的存在,改变了岩石的力学性质,使得裂缝展布规律得以改变。砂质纹层的存在,为液态油、溶解气和游离气提供了更多的赋存空间。鄂尔多斯盆地中南部地区,富含砂质纹层的页岩是现今的油气勘探开发目标;深湖相厚层页岩尽管油气潜力巨大,但现有的工程技术尚不能进行有效开发,是未来的勘探开发目标。
There are a lot of sandy laminations in the Triassic Yanchang Formation shale in the central and southern Ordos Basin,but their influence on hydrocarbon accumulation is not clear. In order to reveal the geological characteristics of sandy lamination and explore its favorable effect on hydrocarbon accumulation,we have studied its lithologic and porosity-permeability characteristics,fracture development as well as oil and gas accumulation,through integration of methods such as core observation,microscopic identification,and organic geochemical analysis. The result shows that,the lithology of sandy lamination is mostly siltstone,argillaceous siltstone,and silty shale; the lamination mainly appears in the form of thin lamina,thin band,and thin interbed. And the existing sandy laminations have changed the way of lithological contact: denser development of the sandy lamination promotes more intense alternation of rock lithology,which is usually more favorable for hydrocarbon expulsion from source rocks. Besides,the sandy lamination favors pore size growth,so improving the physical property of the reservoir in turn. It changes the mechanical property of rocks,resulting in the change of distribution patterns of fractures. It also provides larger reservoir space for liquid hydrocarbon,dissolved gas,and free gas. Shale with highly developed sandy lamination in the Ordos Basin is the main target for present exploration and development,whereas thick deep-lacustrine shale,which is abundant in hydrocarbon,but due to limitations of present developing techniques,may only be producible in the future.
There are a lot of sandy laminations in the Triassic Yanchang Formation shale in the central and southern Ordos Basin,but their influence on hydrocarbon accumulation is not clear. In order to reveal the geological characteristics of sandy lamination and explore its favorable effect on hydrocarbon accumulation,we have studied its lithologic and porosity-permeability characteristics,fracture development as well as oil and gas accumulation,through integration of methods such as core observation,microscopic identification,and organic geochemical analysis. The result shows that,the lithology of sandy lamination is mostly siltstone,argillaceous siltstone,and silty shale; the lamination mainly appears in the form of thin lamina,thin band,and thin interbed. And the existing sandy laminations have changed the way of lithological contact: denser development of the sandy lamination promotes more intense alternation of rock lithology,which is usually more favorable for hydrocarbon expulsion from source rocks. Besides,the sandy lamination favors pore size growth,so improving the physical property of the reservoir in turn. It changes the mechanical property of rocks,resulting in the change of distribution patterns of fractures. It also provides larger reservoir space for liquid hydrocarbon,dissolved gas,and free gas. Shale with highly developed sandy lamination in the Ordos Basin is the main target for present exploration and development,whereas thick deep-lacustrine shale,which is abundant in hydrocarbon,but due to limitations of present developing techniques,may only be producible in the future.
引文
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[14]王轩,高岗,李佳烨,等.碳酸盐岩缝合线与基质的排烃效应——以川东地区石炭系和奥陶系碳酸盐岩为例[J].石油与天然气地质,2017,38(3):534-542.Wang Xuan,Gao Gang,Li Jiaye,et al.Hydrocarbon expulsion of stylolite and matrix in carbonate rocks:A case study from the Ordovician and Carboniferous carbonate rocks in Eastern Sichuan Basin[J].Oil&Gas Geology,2017,38(3):534-542.
[15]陈中红,查明.济阳坳陷古近系烃源岩结构及排烃的非均一性[J].石油勘探与开发,2003,30(6):45-48.Chen Zhonghong,Zha Ming.The structure of source rocks and characteristics of hydrocarbon expulsion-An example from Paleogene system in Jiyang Depression[J].Petroleum Exploration and Development.2003,30(6):45-48.
[16]王香增,范柏江,张丽霞,等.陆相页岩气的储集空间特征及赋存过程——以鄂尔多斯盆地陕北斜坡构造带延长探区延长组长7段为例[J].石油与天然气地质,2015,36(4):651-659.Wang Xiangzeng,Fan Bojiang,Zhang Lixia,et al.Reservoir space characteristics and charging process of Lacustrine shale gas-a case study of the Chang 7 member in Yanchang Block in Shanbei slope of Erdos Basin[J].Oil&Gas Geology,2015,36(4):651-659.
[17]王香增,张丽霞,李宗田,等.鄂尔多斯盆地延长组陆相页岩孔隙类型划分方案及其油气地质意义[J].石油与天然气地质,2016,37(1):1-7.Wang Xiangzeng,Zhang Lixia,Li Zongtian,et al.Pore type classification scheme for continental Yanchang shale in Ordos Basin and its geological significance[J].Oil&Gas Geology,2016,37(1):1-7.
[18]Loucks R G,Reed R M,Ruppel S C,et al.Morphology,genesis,and distribution of nanometer-scale pores in siliceous mudstones of the Mississippian Barnett shale[J].Journal of Sedimentary Research,2009,79(12):848-861.
[19]李士祥,邓秀芹,庞锦莲,等.鄂尔多斯盆地中生界油气成藏与构造运动的关系[J].沉积学报,2010,28(4):798-807.Li Shixiang,Deng Xiuqin,Pang Jinlian,et al.Relationship between petroleum accumulation of Mesozoic and tectonic movement in Ordos Basin[J].Acta Sedimentologica Sinica,2010,28(4):798-807.
[20]蒲泊伶,蒋有录,王毅,等.四川盆地下志留统龙马溪组页岩气成藏条件及有利地区分析[J].石油学报,2010,31(2):225-230.Pu Boling,Jiang Youlu,Wang Yi,et al.Reservoir-forming conditions and favorable exploration zones of shale gas in Lower Silurian Longmaxi Formation of Sichuan Basin[J].Acta Petrolei Sinica,2010,31(2):225-230.
[2]Slatt R M,Brien N R.Pore types in the Barnett and Woodford gas shales:Contribution to understanding gas storage and migration pathways in fine-grained rocks[J].AAPG Bulletin,2011,95(12):2017-2030.
[3]王冠民,钟建华,马在平.湖泊纹层状沉积物的同生期变化研究述评[J].世界地质,2003,22(3):231-236.Wang Guanmin,Zhong Jianhua,Ma Zaiping.Syngenetic changes in lacustrine lamellar sediments[J].Global Geology,2003,22(3):231-236.
[4]Sutton S J,Ethridge F G,Almon W R,et al.Textural and sequencestratigraphic controls on sealing capacity of Lower and Upper Cretaceous shales,Denver basin,Colorado[J].AAPG Bulletin,2004,88(8):1185-1206.
[5]Lash G G,Engelder T.An analysis of horizontal microcracking during catagenesis:Example from the Catskill delta complex[J].AAPG Bulletin,2005,89(11):1433-1449.
[6]Rokosh D,Pawlowicz J,Anderson S,et al.Shale fabric,mineralogy and effective porosity of the Upper Colorado Group[C].Alberta:CSPG CSEG CWLS Convention,2009:572-576.
[7]Broadhead R F,Kepferle R C,Potter P E.Stratigraphic and sedimentologic controls of gas in shale-example from upper Devonian of northern Ohio[J].AAPG Bulletin,1982,66(1):10-27.
[8]程明,罗晓容,雷裕红,等.鄂尔多斯盆地张家滩页岩粉砂质夹层/纹层分布、分形特征和估算方法研究[J].天然气地球科学,2015,26(5):845-852.Cheng Ming,Luo Xiaorong,Lei Yuhong,et al.The distribution,fractal characteristic and thickness estimation of silty laminae and beds in the Zhangjiatan shale,Ordos Basin[J].Natural Gas Geoscience,2015,26(5):845-852.
[9]杨潇,姜呈馥,孙兵华,等.砂质纹层的发育特征及对页岩储层物性的影响——以鄂尔多斯盆地南部中生界延长组为例[J].延安大学学报:自然科学版,2015,34(2):18-23.Yang Xiao,Jiang Chengfu,Sun Binghua,et al.Development characteristics of sandy laminae and their effects on physical properties of shale reservoirs:a case study of the Mesozoic Yanchang Formation in the southern Ordos Basin[J].Journal of Yan An University(Natural Science Edition),2015,34(2):18-23.
[10]袁选俊,林森虎,刘群,等.湖盆细粒沉积特征与富有机质页岩分布模式——以鄂尔多斯盆地延长组长7油层组为例[J].石油勘探与开发,2015,42(1):34-42.Yuan Xuanjun,Lin Senhu,Liu Qun,et al.Lacustrine fine-grained sedimentary features and organic-rich shale distribution pattern:A case study of Chang 7 Member of Triassic Yanchang Formation in Ordos Basin,NW China[J].Petroleum Exploration and Development,2015,42(1):34-42.
[11]Er Chuang,Li Yangyang,Zhao Jingzhou,et al.Characteristics of lacustrine organic-rich shale:A case study of the Chang7 Member,Triassic Yanchang Formation,Ordos Basin,China[J].Natural Gas Geoscience,2016,1(2):173-185.
[12]Wang X Z,Zhang L X,Jiang C F,et al.Hydrocarbon storage space within lacustrine gas shale of the Triassic Yanchang Formation,Ordos Basin,China[J].Interpretation,2015,3(2):15-23.
[13]刘国恒,黄志龙,姜振学,等.鄂尔多斯盆地延长组湖相页岩纹层发育特征及储集意义[J].天然气地球科学,2015,26(3):408-417.Liu Guoheng,Huang Zhilong,Jiang Zhenxue,et al.The characteristic and reservoir significance of lamina in shale from yanchang formation of Ordos Basin[J].Natural Gas Geoscience,2015,26(3):408-417.
[14]王轩,高岗,李佳烨,等.碳酸盐岩缝合线与基质的排烃效应——以川东地区石炭系和奥陶系碳酸盐岩为例[J].石油与天然气地质,2017,38(3):534-542.Wang Xuan,Gao Gang,Li Jiaye,et al.Hydrocarbon expulsion of stylolite and matrix in carbonate rocks:A case study from the Ordovician and Carboniferous carbonate rocks in Eastern Sichuan Basin[J].Oil&Gas Geology,2017,38(3):534-542.
[15]陈中红,查明.济阳坳陷古近系烃源岩结构及排烃的非均一性[J].石油勘探与开发,2003,30(6):45-48.Chen Zhonghong,Zha Ming.The structure of source rocks and characteristics of hydrocarbon expulsion-An example from Paleogene system in Jiyang Depression[J].Petroleum Exploration and Development.2003,30(6):45-48.
[16]王香增,范柏江,张丽霞,等.陆相页岩气的储集空间特征及赋存过程——以鄂尔多斯盆地陕北斜坡构造带延长探区延长组长7段为例[J].石油与天然气地质,2015,36(4):651-659.Wang Xiangzeng,Fan Bojiang,Zhang Lixia,et al.Reservoir space characteristics and charging process of Lacustrine shale gas-a case study of the Chang 7 member in Yanchang Block in Shanbei slope of Erdos Basin[J].Oil&Gas Geology,2015,36(4):651-659.
[17]王香增,张丽霞,李宗田,等.鄂尔多斯盆地延长组陆相页岩孔隙类型划分方案及其油气地质意义[J].石油与天然气地质,2016,37(1):1-7.Wang Xiangzeng,Zhang Lixia,Li Zongtian,et al.Pore type classification scheme for continental Yanchang shale in Ordos Basin and its geological significance[J].Oil&Gas Geology,2016,37(1):1-7.
[18]Loucks R G,Reed R M,Ruppel S C,et al.Morphology,genesis,and distribution of nanometer-scale pores in siliceous mudstones of the Mississippian Barnett shale[J].Journal of Sedimentary Research,2009,79(12):848-861.
[19]李士祥,邓秀芹,庞锦莲,等.鄂尔多斯盆地中生界油气成藏与构造运动的关系[J].沉积学报,2010,28(4):798-807.Li Shixiang,Deng Xiuqin,Pang Jinlian,et al.Relationship between petroleum accumulation of Mesozoic and tectonic movement in Ordos Basin[J].Acta Sedimentologica Sinica,2010,28(4):798-807.
[20]蒲泊伶,蒋有录,王毅,等.四川盆地下志留统龙马溪组页岩气成藏条件及有利地区分析[J].石油学报,2010,31(2):225-230.Pu Boling,Jiang Youlu,Wang Yi,et al.Reservoir-forming conditions and favorable exploration zones of shale gas in Lower Silurian Longmaxi Formation of Sichuan Basin[J].Acta Petrolei Sinica,2010,31(2):225-230.