蛋白石硅质页岩成岩过程中的孔隙结构变化特征

发布时间：2018-11-01 17:44

【摘要】：为研究硅质页岩成岩演化过程中的孔隙结构变化,选取松辽盆地嫩江组低演化蛋白石硅质页岩和渝东南高演化五峰—龙马溪组样品,在X射线衍射分析基础上,采用氮气等温吸附技术,开展了成岩作用过程中蛋白石硅质页岩的孔隙结构变化特征研究。结果显示较低演化的蛋白石硅质页岩比表面积和孔容均远高于较高演化的蛋白石硅质页岩,低演化页岩2 nm以上孔隙主要集中在2~3 nm区间,其次分布在20~30 nm区间,2 nm以下孔隙主要集中在0.6~0.8 nm区间,总孔容主要由10~30 nm区间孔隙贡献;高演化页岩2 nm以上孔隙主要集中在2~3 nm区间,2 nm以下孔隙主要集中在0.6~1 nm区间,总孔容主要由2~30 nm区间孔隙贡献。将五峰—龙马溪组硅质页岩与其相比,发现纳米孔隙在成岩过程中大幅丧失,孔容缩小至原始的1/3~1/10。五峰—龙马溪组硅质页岩中2~30 nm区间的孔隙对孔容的贡献最大,30~200 nm范围内孔隙有微小贡献,2 nm以下的孔隙在成岩演化过程中几乎消失殆尽,显示出成岩作用对不同孔径孔隙的改造程度存在差异性。
[Abstract]:In order to study the pore structure changes in the diagenetic evolution of siliceous shale, the samples of low evolution opal siliceous shale of Nenjiang formation and Wufeng Longmaxi formation with high evolution in southeastern Chongqing were selected and analyzed by X-ray diffraction. The pore structure characteristics of opal siliceous shale during diagenesis were studied by nitrogen isothermal adsorption technique. The results show that the specific surface area and pore volume of the low-evolution opal siliceous shale are much higher than those of the high-evolutional opal siliceous shale. The pores above 2 nm of the low-evolution shale are mainly concentrated in the range of 2 ~ 3 nm, and then distributed in the range of 20 ~ 30 nm. (2) the porosity below nm is mainly in the 0.6 ~ 0. 8 nm interval, and the total pore volume is mainly contributed by the porosity in the 10 ~ 30 nm interval; The pores above 2 nm of highly evolved shale are mainly concentrated in the 2 ~ 3 nm interval, the pores below 2 nm are mainly concentrated in the 0.6 ~ (-1) nm interval, and the total pore volume is mainly contributed by the pore size in the 2 ~ (30) nm interval. Compared with the siliceous shale of the Wufeng-Longmaxi formation, it is found that the nanometer pores are lost in the diagenetic process, and the pore volume is reduced to 1 / 3 / 1 / 10 of the original. The pore in the siliceous shale of Wufeng Longmaxi formation has the largest contribution to the pore volume in the range of 20 ~ 30 nm, and the pore under 2 nm is almost disappeared during the diagenetic evolution, and the pore has a small contribution in the range of 30 ~ 200 nm. It shows that the degree of diagenesis on different pore pores is different.
【作者单位】：中国石化油气成藏重点实验室;中国石化石油勘探开发研究院无锡石油地质研究所;
【基金】：国家自然科学基金(U1562106) 国家油气重大专项(2016ZX05036002) 中国石化科技部项目(P15097)资助
【分类号】：P618.13

【相似文献】