摘要
川东南盆缘复杂构造区龙马溪组页岩总有机碳(total organic carbon,TOC)含量高、热演化成熟度高,但构造条件复杂,其微观孔隙结构特征及分形特征相关研究较少且与四川盆内页岩存在差异,亟需进一步深入研究。为更好地表征页岩孔隙结构非均质性及其对页岩气富集的影响,综合运用核磁共振、高压压汞及扫描电镜等技术,定量表征复杂构造区页岩微观孔隙结构特征。基于分形理论,利用高压压汞、核磁共振方法获得不同尺度孔隙的分形维数,并探讨分形维数与孔喉结构参数、TOC含量、矿物组分含量的关系及其地质意义。结果表明:川东南盆缘复杂构造区页岩主要发育有机孔、粒间孔和微裂缝。孔隙结构具有多重分形特征,不同尺度孔喉分形维数存在差异,大孔喉复杂程度高于小孔喉,孔隙总分形维数为2.4702~2.8191,均值为2.6256,反映复杂构造区页岩发育更为复杂的孔隙结构,为页岩气提供大量吸附点位,对页岩气聚集具有积极作用。TOC含量和石英含量等因素的共同影响,造成研究区页岩的强非均质性和复杂的孔隙结构特征。与四川盆内页岩相比,研究区页岩孔径分布较广、分形维数偏低。综合分析页岩孔隙结构及分形特征可为昭通示范区、整个川渝盆缘山地页岩有利储集层段优选提供重要参考。
The total organic carbon(TOC)content and thermal evolution maturity of the Longmaxi Formation shale in the complex tectonic area of the southeastern Sichuan Basin are high,but the tectonic conditions are complex.There are few studies on the microscopic pore structure characteristics and fractal characteristics of the Longmaxi Formation shale,which are different from the shale in the Sichuan Basin and need to be further studied.In order to better characterize the heterogeneity of shale pore structure and its influence on shale gas enrichment,nuclear magnetic resonance,high-pressure mercury injection and scanning electron microscopy were used to quantitatively characterize the microscopic pore structure characteristics of shale in complex structural areas.Based on the fractal theory,the fractal dimensions of pores with different scales were obtained by high pressure mercury intrusion and nuclear magnetic resonance.The relationship between fractal dimension and pore throat structure parameters,TOC content and mineral composition content and its geological significance were discussed.The results show that organic pores,intergranular pores and micro-fractures are mainly developed in the shale of complex structural area in southeastern Sichuan Basin.The pore structure has multifractal characteristics,and the fractal dimensions of pore throats at different scales are different.The complexity of large pore throats is higher than that of small pore throats.The total fractal dimension of pores is 2.4702~2.8191,with an average of 2.6256.It reflects that the shale in the complex structural areas develops more complex pore structure,provides a large number of adsorption points for shale gas,and has a positive effect on shale gas accumulation.The combined effects of TOC content and quartz content result in strong heterogeneity and complex pore structure characteristics of shale in the study area.Compared with the shale in the Sichuan Basin,the shale in the study area has wide pore size distribution and low fractal dimension.Comprehensive analysis of shale pore structure and fractal characteristics can provide an important reference for the optimization of favorable shale reservoir sections in Zhaotong demonstration area and the whole Sichuan-Chongqing basin margin.
作者
柴兵强
赵峰
计玉冰
王维康
陈雷
程青松
闫旭
CHAI Bing-qiang;ZHAO Feng;JI Yu-bing;WANG Wei-kang;CHEN Lei;CHENG Qing-song;YAN Xu(Natural Gas Geology Key Laboratory of Sichuan Province,Southwest Petroleum University,Chengdu 610500,China;School of Geosciences and Technology,Southwest Petroleum University,Chengdu 610500,China;PetroChina Zhejiang Oilfield Company,Hangzhou 310023,China)
出处
《科学技术与工程》
北大核心
2023年第12期4973-4983,共11页
Science Technology and Engineering
基金
中国石油-西南石油大学创新联合体科技合作项目(2020CX020000)。
关键词
孔隙结构
分形特征
页岩
龙马溪组
川东南
pore structure
fractal characteristics
shale
Longmaxi Formation
southeast Sichuan
