海陆过渡相煤系页岩孔隙分形特征及影响因素——以沁水盆地北部太原组为例  

Fractal Characteristics and Interfering Factors of Microscopic Pores in Marine-Continental Transitional Coal Shale:A case study of the Taiyuan Formation in the northern Qinshui Basin

作　　者：聂万才 张廷山[1] 王铭伟 吴玟 谭秀成[1] NIE WanCai;ZHANG TingShan;WANG MingWei;WU Wen;TAN XiuCheng(School of Geoscience and Technology,Southwest Petroleum University,Chengdu 610500,China;Natural Gas Evaluation Project Department of Changqing Oilfield Company,Xi'an 710018,China;School of Oil&Gas Engineering,Southwest Petroleum University,Chengdu 610500,China;Development Department,PetroChina Southwest Oil&Gasfield Company,Chengdu 610051,China)

机构地区：[1]西南石油大学地球科学与技术学院,成都610500 [2]长庆油田分公司天然气评价项目部,西安710018 [3]西南石油大学石油与天然气工程学院,成都610500 [4]中石油西南油气田分公司开发事业部,成都610051

出　　处：《沉积学报》2024年第3期1047-1057,共11页Acta Sedimentologica Sinica

基　　金：国家自然科学基金项目(41772150)。

摘　　要：【目的】为分析沁水盆地北部太原组海陆过渡相煤系页岩孔隙分形特征及影响因素。【方法】通过对阳泉区块太原组样品进行总有机碳(TOC)含量、成熟度测试及X射线衍射、低温氮气吸附实验,基于(Frenkel Halsey Hill,FHH)理论模型计算样品孔隙分形维数,分析矿物含量、有机地化特征及孔隙结构参数对孔隙分形维数的影响。【结果】太原组煤系页岩TOC含量介于0.57%~6.40%,平均为3.18%;有机质镜质体反射率(R_(o))介于1.96%~3.24%,平均为2.49%;煤系页岩微观孔隙具有双重分形特点,其中表面分形维数(D_(1))介于2.507 9~2.663 9,结构分形维数(D_(2))介于2.527 1~2.809 4;有机质含量及成熟度与D_(1)、D_(2)均呈正相关关系,孔隙结构参数与D_(1)、D_(2)具有良好的正相关性,但与D_(2)相关系数高于D_(1),指示微孔对孔隙结构参数的影响更强;分选、磨圆度高的陆源碎屑石英多具规则孔隙形态,造成石英含量与D_(1)、D_(2)呈负相关关系;碳酸盐岩矿物及长石主要提供宏孔,其含量与页岩D_(1)及D_(2)均呈负相关关系;黏土矿物在长期压实作用下孔径减小,微孔数量增加,孔隙形态复杂,其含量与分形维数D_(1)及D_(2)呈正相关关系。【结论】海陆过渡相煤系页岩微观孔隙具有双重分形特点,有机质含量、成熟度、孔隙结构参数和黏土矿物含量增大可导致其微观孔隙分形维数变大,陆源碎屑石英、长石和碳酸盐矿物含量增多可导致其微观孔隙分形维数变小。[Objective]To analyze the pore fractal characteristics and interference factors from the coal measure shale of the Taiyuan Formation in the northern Qinshui Basin.[Methods]Total organic carbon(TOC)content,maturity,X-ray diffraction,and low-temperature nitrogen adsorption experiments were conducted on samples of the Taiyuan Formation in the Yangquan block.The fractal dimension of a sample pore was calculated based on the(Frenkel Halsey Hill,FHH)theoretical model,which analyzes the influence of mineral content,organic geochemical characteristics,and pore structure parameters on the pore fractal dimension.[Results]The results show that the TOC content of coal measure shale in the Taiyuan Formation is between 0.57%and 6.40%,and the average is 3.18%;the vitrinite reflectance of organic matter(R_(o))is between 1.96%and 3.24%,and the average is 2.49%.The coal-measure shale micropores have double fractal characteristics,of which fractal(D_(1))is between 2.5079 and 2.6639,dimension(D_(2))is between 2.5271 and 2.8094,and the organic matter content and maturity are positively correlated with D_(1) and D_(2).The pore structure parameters have a positive correlation with D_(1) and D_(2),but the correlation coefficient with D_(2) is higher than that of D_(1),indicating that micropores have stronger influence on pore structure parameters.The input of terrigenous clastic quartz with high sorting and roundness leads to regular pore morphology,resulting in a negative correlation between quartz content and D_(1) and D_(2).Carbonate minerals and feldspar primarily provide macropores,and their contents are related to shale.Both D_(1) and D_(2) are negatively correlated,and the pore size of the clay minerals decreases under long-term compaction,whereas the number of micropores increases,and the pore shape is complex,which is positively correlated with fractal dimensions D_(1) and D_(2).[Conclusions]The micropores of the coal measure shale in marine continental transitional facies have dual fractal characteristics.The increase of organ

关 键 词：煤系页岩 孔隙结构 分形特征 海陆过渡相 太原组 沁水盆地 

分 类 号：P618.13[天文地球—矿床学]