渝东南牛蹄塘组页岩成岩作用及其对孔隙的影响

发布时间：2018-11-28 13:35

【摘要】：以渝科1井钻遇的下寒武统牛蹄塘组页岩为研究对象,探讨渝东南地区过成熟页岩中成岩作用对孔隙发育的影响。伊利石结晶度和等效镜质体反射率Ro测定,显示牛蹄塘组页岩处于有机质过成熟的晚成岩阶段。通过场发射扫描电镜和气体吸附实验对页岩孔隙进行了定性和定量表征。页岩孔隙主要由有机质孔隙、粒内孔隙和粒间孔隙组成,以中孔为主,平均直径为4.93nm,总孔体积平均为0.014 3cm~3/g。牛蹄塘组页岩经过强烈的压实作用和胶结作用使得粒间孔隙欠发育。黏土矿物大多已伊利石化,伊利石平均质量分数为86%,伊蒙混层平均质量分数为13%,黏土矿物中的孔隙以伊利石中的粒内孔隙为主。溶解作用使得碳酸盐矿物产生粒内孔隙和粒间孔隙,孔隙直径较大。有机质成熟作用产生了有机质孔隙,随着有机质成熟度的进一步增加,有机质内的有机质孔隙体积和孔隙直径都不断减小。页岩的孔隙因不同成岩作用的共同改造而变化。
[Abstract]:Taking the Lower Cambrian Niutetang formation shale drilled from well Yuke 1 as the research object, the effect of diagenesis on pore development in overmature shale in southeastern Chongqing was discussed. The measurement of Illite crystallinity and equivalent vitrinite reflectance (Ro) indicates that the Niulitang formation shale is in the late diagenetic stage of overmaturation of organic matter. The shale pores were characterized qualitatively and quantitatively by field emission scanning electron microscopy (SEM) and gas adsorption experiments. Shale pores are mainly composed of organic matter pores, intragranular pores and intergranular pores, with an average diameter of 4.93 nm and an average pore volume of 0.014 3 cm ~ (3) g. Through strong compaction and cementation, the intergranular pores of Niutetang formation shale underdevelop. The average mass fraction of Illite is 86 and the average mass fraction of Illite is 13. The pores in clay minerals are dominated by the intragranular pores of Illite. Dissolution results in the formation of intragranular and intergranular pores in carbonate minerals with larger pore diameters. The maturation of organic matter leads to the formation of organic pores, and with the further increase of organic maturation, the pore volume and pore diameter of organic matter decrease continuously. The porosity of shale varies with the joint transformation of different diagenesis.
【作者单位】：中国地质大学地球科学与资源学院;地质过程与矿产资源国家重点实验室;
【基金】：国家自然科学基金项目(41572134) 高等学校博士学科点专项基金优先发展领域项目(20120022130001)
【分类号】：P618.13

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