基于热模拟实验的富有机质泥页岩孔隙演化研究进展

Research Advance on Pore Evolution of Organic-rich Shale Based on Thermal Simulation Experiment

富有机质泥页岩是非常规油气领域重要的研究对象,揭示其孔隙演化特征对于研究页岩油气赋存机理具有重要意义,并为页岩油气资源评价以及勘探开发提供参数。热模拟实验结合扫描电镜,气体吸附和高压压汞等实验技术手段可应用于泥页岩孔隙演化的研究。相比于开放体系和封闭体系,半封闭半开放实验体系的设计是更接近地下真实地质过程,其更适用于孔隙演化的研究。富有机质泥页岩孔隙演化是有机质和矿物在高温高压及流体等多因素长时间共同作用的结果,基于热模拟实验条件下总结归纳了富有机质泥页岩孔隙演化特征(有机孔和无机孔两个方面)、孔隙演化主要控制因素(有机质生烃作用,矿物转化和压实作用)以及孔隙演化模型。尽管热模拟实验实现了对同一泥页岩样品全孔隙演化阶段的研究,但孔隙演化的研究还不够系统,问题在于:泥页岩样品在热模拟实验高温高压条件下易碎裂,导致样品制备上的困难;热模拟实验温压条件很难模拟地下真实成岩和生烃的过程;热模拟实验成本较高导致其不能大量开展,因此得到的样品和孔隙相关参数的数据也不够充足。如何系统地研究富有机质泥页岩孔隙演化也正是未来需要关注和研究的重点。

Organic-rich shale is an important research object in the field of unconventional oil and gas.Revealing the pore evolution characteristics of organic-rich shale is of great significance for figuring out the mechanism of shale oil and gas accumulation,which can also provide parameters for shale oil and gas resources evaluation and exploration and development.Combined with scanning electron microscopy,gas adsorption and high pressure mercury injection techniques,thermal simulation experiment can be applied to the study of pore evolution of organic-rich shale.Compared with open system and closed system,the design of the semi-closed and semi-open experimental system proves to be closer to the underground real geological process,which is more suitable for the study of pore evolution.The pore evolution of organic-rich shale is the result of long-term interaction of organic matter and minerals under the conditions of high temperature,high pressure and fluids.Based on the premise of thermal simulation experiments,several factors such as pore evolution characteristics(organic pores and inorganic pores),the controlling factors of pore evolution(organic hydrocarbon generation,mineral transformation and compaction)and pore evolution model were summarized firstly.Although the thermal simulation experiment realized the study of the whole pore evolution stage of the same shale sample,yet the study of pore evolution was a little far away from a systematical research.The problem was that the shale sample was easily broken under the high temperature and high pressure conditions of the thermal simulation experiment,resulting difficulties in sample preparation.Then,it was difficult to simulate the process of underground diagenesis and hydrocarbon generation in the thermal simulation experiment.Due to the high cost of thermal simulation experiment,it could not be carried out in large quantities,and the data of sample and pore related parameters gained were not enough.How to systematically study the pore evolution of organic-rich shale should be the focus of further attention and research future.