Tianhao Wu, Associate Professor, Institute for Advanced Study of Oriental Polytechnic Technology

Chensong Zhang, Associate Professor

Microscopic mechanism of seepage and fracture process in shale matrix and numerical simulation method

19:30-21:00 November 30 (Wednesday) , Tencent Meeting ID: 124-107-886 Meeting Password: 2022

The production of oil and gas from organic-rich shale formations has changed the worldwide economy and energy outlook. Although extensive research on macroscopic behaviors in shale has been carried out, the mechanisms of fluid flow and mechanical processes at the microscale are not fully understood, which is a key factor for production rate prediction and hydraulic fracturing efficiency improvement. We provide a systematic investigation of multiscale pore structure in organic-rich shale by means of a combination of various advanced imaging techniques, which achieves insight into the major features at each scale and suggests affordable techniques for specific objectives. A comprehensive workflow is proposed based on the characteristics acquired from the multiscale pore structure analysis to simulate the gas transport process. The results of apparent permeability from simulations agree well with the values acquired from experiments. Considering the difficulties in the experiments, molecular dynamics (MD) simulations have been given much attention to gain insights into the mechanisms. Generally, kerogen is the predominant component of organic matter in most shale gas/oil formations. We provide a systematic study on the failure mechanisms of typical minerals from organic-rich shale by molecular dynamics simulations. The results indicate that the Mohr–Coulomb failure criterion and tensile strength criterion can describe the failure envelope of the kerogen matrices very well. The kerogen matrices have lower Young’s modulus, compressive strength, tensile strength, and fracture toughness than typical minerals. It reveals that kerogen is a potentially weak component in shale, and the fractures may initiate and propagate around kerogen aggregates. The effects of different fracturing fluids, including H2O and CO2, are also examined. This work provides a practical method to link the nanoscale and macroscale mechanical properties in organic-rich shales and kerogen, which sets the stage for investigating the complex mechanisms of hydraulic fracturing in the organic-rich shale formation. 

报告人简介：
   吴天昊，东方理工高等研究院助理教授，副研究员，博士生导师。毕业于北京大学，获工学学士、经济学学士、理学博士学位，先后在美国油藏工程研究所、莱斯大学开展博士后研究工作。主要从事非常规能源开发和二氧化碳地质封存等领域的基础与应用基础研究，专注于多孔介质多场耦合过程的微观实验与模拟等研究方向。研究成果曾被行业顶级期刊Nano Energy选为封面文章，被Water Resources Research评为编辑亮点。作为主要科研人员承担或参与国家自然科学基金委国际合作重点项目、联合基金重点项目，以及与美国艾克森美孚石油公司（ExxonMobil）、沙特阿美（Saudi Aramco）、卡塔尔北方石油公司（North Oil Company）等国际大型公司的合作项目；受邀担任美国化学学会（ACS）石油基金项目评审专家；长期担任SPE Journal、Fuel、Energy & Fuels、Journal of Petroleum Science and Engineering、Journal of Natural Gas Science and Engineering等国际知名期刊审稿人。