巨厚煤储层孔隙结构的垂向非均质性特征——以青海聚乎更矿区为例  

Vertical heterogeneity characteristics of pore structure for huge thick coal reservoirs:a case study of Juhugeng mining area in Qinghai province

作　　者：王安民[1] 曹代勇[1] 聂敬 秦荣芳[1] Wang Anmin;Cao Daiyong;Nie Jing;Qin Rongfang(College of Geosciences&-Surveying Engineering,China University of Minting and Technology,Beijing 100083,China;No.1 Middle School of Heze Shandong Shandong Heze 274000,China)

机构地区：[1]中国矿业大学(北京)地球科学与测绘工程学院,北京100083 [2]山东省菏泽第一中学,山东菏泽274000

出　　处：《石油学报》2020年第6期691-701,共11页Acta Petrolei Sinica

基　　金：国家自然科学基金项目(No.41902170,No.41572141)资助。

摘　　要：中国北方含煤盆地广泛发育侏罗系巨厚煤储层。以青海聚乎更矿区为研究区,利用扫描电镜、压汞、低温液氮等实验方法,探讨了中侏罗统巨厚煤储层孔隙结构的垂向非均质性特征。研究结果表明,发育在丝质体和半丝质体中的孔隙较多,结构相对较好,丝质体和半丝质体含量越高,样品的孔隙结构复杂程度越低;基质镜质体和均质镜质体中则较少见孔隙发育,其含量越高、样品的孔隙结构非均质性越强。依据镜惰比与凝胶化指数将研究区巨厚煤储层划分出3个水退旋回(旋回Ⅰ、旋回Ⅱ和旋回Ⅲ),大孔和小孔的分形维数随水退表现出减小的趋势,大孔孔容、中孔孔容和孔隙度随水退表现出增大的趋势,其本质是水退致使丝质体和半丝质体含量增大,从而使得孔容增大、孔隙结构复杂程度降低。比较3个旋回的孔隙结构可以发现:旋回Ⅰ较旋回Ⅱ和旋回Ⅲ的孔隙连通性差,整体上孔隙度的分布为旋回Ⅰ>旋回Ⅱ>旋回Ⅲ;大孔孔隙结构的复杂程度表现为旋回Ⅲ>旋回Ⅰ>旋回Ⅱ,中孔孔隙结构复杂程度则表现为旋回Ⅰ>旋回Ⅱ>旋回Ⅲ,而各旋回小孔的孔隙结构相差不大。对巨厚煤储层进行旋回性划分,再比较各旋回孔隙结构的差异性,是一种行之有效的巨厚煤储层物性研究方法,可以为巨厚煤储层评价及勘探开发提供一定理论支撑。The Jurassic huge thick coal reservoirs are widely developed in coal-bearing basins in northern China. Taking the Juhugeng mining area in Qinghai as the study area, using SEM, mercury injection, low-temperature liquid nitrogen and other experimental methods, this paper explores the vertical heterogeneity characteristics of pore structure of the Middle Jurassic huge thick coal reservoirs. The results show that there are more pores with good structure developed in fusinite and semifusinite. The higher the content of fusinite and semifusinite, the less complex the pore structure of the sample. Pores are less developed in heterocollinite and homocollinite. The higher the content of heterocollinite and homocollinite, the stronger the heterogeneity of pore structure of the sample. Based on the vitrinite/intertinite ratio and gelation index, the huge thick coal reservoirs in the study area are classified into three regression cycles, i.e., Cycle Ⅰ, Cycle Ⅱ and Cycle Ⅲ. The fractal dimension of the macro and small pores shows a decrease with regression, and the pore volume of macropores and mesopores and the porosity of mesopores increase with regression. The fact is that the regression leads to an increase in the content of fusinite and semifusinite, so that the pore volume increases and pore structure is less complex. The comparison of pore structures of the three cycles indicates that Cycle Ⅰ has poorer pore connectivity than Cycle Ⅱ and Cycle Ⅲ. Overall, the porosity distribution is shown as Cycle Ⅰ> Cycle Ⅱ> Cycle Ⅲ;the complexity of the macropore structure is shown as Cycle Ⅲ> Cycle Ⅰ> Cycle Ⅱ, the complexity of the mesopore pore structure is shown as Cycle Ⅰ> Cycle Ⅱ> Cycle Ⅲ, and there is no much difference in the pore structure of small pores in each cycle. It is an effective method to study the physical properties of huge thick coal reservoirs by dividing the cyclicity and comparing the differences in pore structure of each cycle, which can provide certain theoretical support for t

关 键 词：巨厚煤储层 孔隙结构 非均质性 旋回 聚乎更矿区 

分 类 号：TE122.2[石油与天然气工程—油气勘探]