海陆过渡相页岩孔隙结构表征及页岩气渗流规律模拟
Pore structure characterization of marine-continental transitional shale and seepage law simulation of shale gas
刘印华 1杨英 2马文涛 1李江涛 2吴建军 1魏建光 2蔺景德 1袁洋1
作者信息
- 1. 中国石油煤层气有限责任公司工程技术研究院,陕西西安 710082;中联煤层气国家工程研究中心有限责任公司,北京 100095
- 2. 东北石油大学,黑龙江大庆 163318
- 折叠
摘要
鄂尔多斯盆地大宁-吉县区块海陆过渡相页岩储层非均质性强,碳质页岩和纯页岩的孔隙结构特征及页岩气渗流规律具有明显的差异,然而目前针对不同岩性孔隙结构下的页岩气渗流规律研究较为缺乏.文中以这2种岩性页岩为研究对象,基于CT扫描、扫描电镜物理实验技术,测定了二者的基质孔隙和层理缝特征参数,对比了二者的孔隙结构差异,构建了考虑吸附效应和滑脱效应的格子玻尔兹曼数值模拟方法,分析了二者孔隙结构对页岩气渗流规律的影响.研究结果表明:1)碳质页岩裂缝呈空间网状结构,纯页岩裂缝为平行层理方向裂缝.与纯页岩相比,碳质页岩孔隙尺度较大,但孔隙数量较少,孔隙度更低.2)页岩孔隙中存在明显的滑脱效应.滑脱效应提高了气相流动速度,页岩气从孔隙壁面解吸减缓了孔隙压力降低速率,延长了生产时间.建议在开发纯页岩层段时,适当降低生产压差,增强小孔隙中的滑脱效应;在开发碳质页岩层段时,适当增加生产压差,通过解吸作用提高页岩气产量.
Abstract
The marine-continental transitional shale reservoir in Daning-Jixian Block of Ordos Basin has strong heterogeneity,and the pore structure characteristics and the shale gas seepage laws of carbonaceous shale and pure shale have obvious differences.However,at present,the study on seepage laws of shale gas in pore structures of different lithologies is relatively lacking.Taking these two kinds of lithologic shale as the research objects and based on CT scanning and scanning electron microscopy physical experiment technology,the characteristic parameters of matrix pores and bedded fractures of these two lithologies are measured,the pore structure differences of these two lithologies are compared,a Lattice Boltzmann numerical stimulation method considering adsorption effects and slippage effects is constructed,and the influence of pore structures of these two lithologies on seepage laws of shale gas is analyzed.The results show that:(1)Fractures of carbonaceous shale show a spatial network structure,while fractures of pure shale are in parallel bedding direction.Compared with pure shale,carbonaceous shale has larger pore size,but fewer pores and lower porosity.(2)There are obvious slippage effects in shale pores.The slippage effects increase the flow velocity of gas,and the desorption of shale gas from pore walls alleviates the reduction of pore pressure and extends the production time.During the exploitation of pure shale layers,it is suggested that the production pressure difference should be reduced properly,and the slippage effects in small pores could be improved.During the exploitation of carbonaceous shale layers,the production pressure difference should be increased properly,and the shale gas yield could be improved by desorption.
关键词
海陆过渡相/页岩/孔隙结构/格子玻尔兹曼/渗流规律Key words
marine-continental transitional facies/shale/pore structure/Lattice Boltzmann/seepage law引用本文复制引用
基金项目
中国石油前瞻性基础性技术攻关项目(2021DJ2006)
出版年
2024
NETL
NSTL
万方数据