陆相与过渡相煤系页岩孔隙结构及分形特征对比——以鄂尔多斯盆地东北缘延安组与太原组为例

发布时间：2018-02-21 03:44

本文关键词： 煤系页岩低温氮气吸附 FHH模型孔隙结构分形维数　出处：《石油学报》2017年09期 　论文类型：期刊论文

【摘要】：基于低温氮气吸附分形几何学研究方法,对鄂尔多斯盆地东北缘陆相延安组及海陆过渡相太原组富有机质煤系页岩进行孔隙结构和分形特征研究,运用分形FHH模型计算了大孔隙(4.34~100nm)和小孔隙(4.34nm)对应的分形维数D_1与D_2,对比讨论了孔隙结构参数与分形维数的关系,以及TOC、矿物含量对两者的影响。研究结果表明:(1)延安组孔径分布在1.8~59nm,呈"双峰型",以墨水瓶状、狭缝状和平行板状孔为主;太原组孔径主要分布在3~4.5nm,呈"单峰型",以墨水瓶状孔为主。(2)煤系页岩具有双重分形特征,D_1与D_2正相关,且D_1D_2,表明大孔隙空间结构更加复杂。延安组两类孔隙空间结构均比较复杂,太原组大孔隙空间结构非常复杂,而小孔隙均质性强。(3)煤系页岩平均孔径越小,微小孔隙越多,比表面积越大,总孔体积越大,分形维数越大,即孔隙结构越复杂,孔表面越不规则;延安组D_1、D_2和太原组D_1均可反映各自孔隙结构特征。(4)太原组孔隙结构参数和分形维数受TOC及矿物成分含量影响较延安组明显。(5)延安组页岩储层优于太原组,更利于煤系页岩气的吸附、赋存、扩散和渗流。
[Abstract]:Based on the fractal geometry study method of nitrogen adsorption at low temperature, the pore structure and fractal characteristics of organic rich coal-bearing shale in the continental Yanan formation and the marine and continental transitional Taiyuan formation in the northeastern margin of Ordos Basin were studied. Using the fractal FHH model, the fractal dimension D _ S-1 and D _ 2 corresponding to the macropore (4.34 ~ 100nm) and the micropore (4.34nm) are calculated. The relationship between the pore structure parameters and the fractal dimension is discussed. The results show that the pore size distribution of the Yan'an formation is 1.859 nm, which is "double peak", with ink bottle, slit and parallel plate-like pores. The pore size of Taiyuan formation is mainly distributed in 3 ~ 4.5nm, which is "single peak" type. The coal shale has double fractal characteristics, such as D _ 1 and D _ 2, which is positively correlated with D _ 2. Moreover, D1D _ 2 shows that the macropore spatial structure is more complex, the two types of pore spatial structure are more complex, the Taiyuan formation is very complicated, while the smaller the average pore size of coal shale is, the more tiny pores are. The larger the specific surface area is, the larger the total pore volume is and the larger the fractal dimension is, that is, the more complex the pore structure is, the more irregular the pore surface is. The pore structure parameters and fractal dimension of Taiyuan formation are obviously affected by TOC and mineral content. The shale reservoir of Yan'an formation is better than Taiyuan formation. More conducive to coal shale gas adsorption, occurrence, diffusion and seepage.
【作者单位】：中国矿业大学地球科学与测绘工程学院;
【基金】：国家自然科学基金项目(No.41572141) 中国地质调查局地质调查项目(DD20160187)资助
【分类号】：P618.13

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