钙质砂岩-沉凝灰岩组合致密油储层孔隙类型及成因:以二连盆地阿南凹陷下白垩统腾一下段为例
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摘要
从微观尺度对二连盆地阿南凹陷下白垩统腾一下段3口取芯井55块致密油储层样品开展孔隙类型及成因进行系统研究。利用AM2井,A43井和H20井3口典型井的岩心(100 m)、薄片(200片)、背散射(60个)、扫描电镜(18块)、荧光显微镜(150片)及PCAS(6块)等方面资料及方法,对目的层进行了岩石类型、沉积特征、孔隙类型、分布及成因等方面的系统研究。研究结果表明,阿南凹陷腾一下段岩性复杂,发育滨浅湖、浅湖、半深湖、火山灰沉积及重力流沉积等多种类型沉积相。钙质砂岩和沉凝灰岩的油气显示最好,是目的层致密油勘探的重点目标。砂岩储层的孔隙主要包括残余粒间孔、粒间扩大孔和溶蚀孔。沉凝灰岩储层的孔隙以溶蚀孔为主,其次为粒间孔和构造微裂缝。沉凝灰岩的平均面孔率为12.05%,要高于砂岩的平均面孔率9.13%。腾一下段致密油储层孔隙的成因包括压实及脱水作用、溶蚀作用、沉凝灰岩的脱玻化作用、构造应力作用。目的层的沉凝灰岩在地质历史时期遭受了强烈的溶蚀作用并表现为重稀土亏损。目的层砂岩和沉凝灰岩中的长英质、碳酸盐及凝灰质组分普遍发生了强烈溶蚀作用,溶蚀作用是目的层致密油储层孔隙成因的主导因素。
55 samples collected from 3 drilling holes in the lower Cretaceous Teng1 section tight oil reservoir are studied by means of thin section observation, backscattering analysis,SEM analysis,fluorescence microscopy observation and PCAS analysis, so as to understand comprehensively the lithology, sedimentary character,pore types,distribution and genesis of the target layer.It shows that the Teng1 tight oil reservoir is composed of complicated lithology with development of shore shallow lake facies,shallow lake facies,semi-deep lake facies,volcanic ash deposition and gravity flow facies.Obvious oil and gas shows occur in calcium sandstone and tuffite,which are the key exploration target.Pores in the sandstone reservoir consist of residual intergranular pores,intergranular expansion pores and dissolution pores.The pores in the tuffite reservoir are mainly composed of dissolution pores with minor intergranular pores and microfractures,and the surface rate of tuffite(12.05%) is higher than that of sandstone(9.13%).The genesis of porosity in the Lower Teng1 section includes compaction,dehydration,dissolution,devitrification of tuffite and tectonic stress.Tuffite in the target layer was subjected strong dissolution with loss of heavy rare earth.In the target layer,strong dissolution commonly occurs in the quartz-feldspathic, carbonate and tuff compositions in the tuffite and sandstone.Therefore,dissolution is the dominant factor in the pore formation in the target tight oil reservoir.
55 samples collected from 3 drilling holes in the lower Cretaceous Teng1 section tight oil reservoir are studied by means of thin section observation, backscattering analysis,SEM analysis,fluorescence microscopy observation and PCAS analysis, so as to understand comprehensively the lithology, sedimentary character,pore types,distribution and genesis of the target layer.It shows that the Teng1 tight oil reservoir is composed of complicated lithology with development of shore shallow lake facies,shallow lake facies,semi-deep lake facies,volcanic ash deposition and gravity flow facies.Obvious oil and gas shows occur in calcium sandstone and tuffite,which are the key exploration target.Pores in the sandstone reservoir consist of residual intergranular pores,intergranular expansion pores and dissolution pores.The pores in the tuffite reservoir are mainly composed of dissolution pores with minor intergranular pores and microfractures,and the surface rate of tuffite(12.05%) is higher than that of sandstone(9.13%).The genesis of porosity in the Lower Teng1 section includes compaction,dehydration,dissolution,devitrification of tuffite and tectonic stress.Tuffite in the target layer was subjected strong dissolution with loss of heavy rare earth.In the target layer,strong dissolution commonly occurs in the quartz-feldspathic, carbonate and tuff compositions in the tuffite and sandstone.Therefore,dissolution is the dominant factor in the pore formation in the target tight oil reservoir.
引文
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[2] 刘江斌,任战利,李文厚,等.鄂尔多斯盆地旬邑地区三叠系延长组长81致密油成藏主控因素[J].矿物岩石,2016,36(4):95-103.
[3] Nicolaas M,Jolanta C,Saulius S.Quartz cementation mechanisms and porosity variation in Baltic Cambrian sandstones[J].Sedimentary Geology,2007,195:135-159.
[4] 赵贤正,金凤鸣,王权,等.陆相断陷盆地洼槽聚油理论及其应用-以渤海湾盆地冀中凹陷和二连盆地为例[J].石油学报,2011,1 (32):18-24.
[5] 李秀英,肖杨,杨全凤,等.二连盆地阿南洼槽岩性油藏及致密油勘探潜力[J].中国石油勘探,2013,18(6):56-61.
[6] 邹才能,陶士振,侯连华,等.非常规油气地质[M].北京:地质出版社,2011,1-310.
[7] 杨华,李士祥,刘显阳.鄂尔多斯盆地致密油、页岩油特征及资源潜力[J].石油学报,2013,34(1):1-11.
[8] Lima R.D,Deros L F.The role of depositional setting and diagenesis on the reservoir quality of Late Devonian sandstones fron the Solonaues Basin,Brazilian Amazonia[J].Marine and Petroleum Geology,2003,19:1 047-1 071.
[9] 尹帅,丁文龙,代鹏,等.利用波速比求取致密砂岩基质矿物剪切模量新方法[J].矿物岩石,2015,35(3):110-114.
[10] 蓝宝锋,蒋立伟,钱挣,等.考虑孔隙和微裂缝的煤层气储层压汞曲线分析模型[J].矿物岩石,2017,37(1):119-119.
[11] Lommatzsch M,Exner U,Gier S,et al.Dilatant shear band formation and diagenesis in calcareous,arkosic sandstones,Vienna Basin(Austria)[J].Marine and Petroleum Geology,2015,62:144-160.
[12] McBride E F.Quartz cement in sandstones:A review[J].Earth-Science Reviews,1989,26:69-112.
[13] Robinson A,Gluyas J.Model-calculations of loss of porosity in sandstones as a result of compaction and quartz cementation[J].Marine and Petroleum Geology,1992,9:319-323.
[14] Yang Y S,Liu K Y,Mayo S,et al.A data- constrained modeling approach to sandstone microstructure characterization[J].Journal of Petroleum Science and Engineering,2013,105:76-83.
[15] 汪建明,陈可睦,宁仁祖.宁芜北段某些次火山岩和蚀变岩中的稀土元素[J].岩石矿物及测试,1985,4(2):97-102.
[16] Zhang J C,James L,William S.Stress,porosity,and failure-dependent compressional and shear velocity ratio and its application to wellbore stability[J].Journal of Petroleum Science and Engineering,2009,69,193-202.
[17] 尹帅,丁文龙,孙雅雄,等.泥页岩单轴抗压破裂特征及UCS影响因素[J].地学前缘,2016,23(2):75-95.
[18] 尹帅,丁文龙,胡秋嘉,等.基于声学数据反演定量评价致密砂岩储层微裂隙应力敏感性新方法[J].岩土力学,2017,38(2):409-417.