电磁辐射下海陆相页岩孔隙结构演化差异研究

Investigation of differences in pore structure evolution between marine and continental shale under electromagnetic radiation

电磁辐射是一种绿色页岩油气储层改造技术,相比常规热传导加热,电磁辐射加热页岩的孔隙结构更为复杂。参考前人在不同辐射时间和功率条件下页岩孔隙演化的研究,将海相页岩和陆相页岩在电磁辐射下的孔隙结构进行对比分析。选取龙马溪组海相页岩与鄂尔多斯盆地陆相页岩,借助自主研制的电磁辐射装置、氮气吸附、高压压汞、场发射扫描电镜等表征手段和Image J软件,研究了电磁辐射下海陆相页岩孔隙结构演化规律及差异。结果表明:相同的辐射时间,陆相页岩终温较海相页岩高;高TOC质量分数的海相页岩以有机孔增加为主,而高黏土含量的陆相页岩以裂缝开度增加为主;电磁辐射下,页岩有机质热解、黏土矿物脱水收缩以及热应力差等的共同作用,导致页岩孔隙和裂隙增加,显著提高了储层的渗流能力。

Electromagnetic radiation is a green technology that can reform shale oil and gas reservoir.Compared with conventional heat conduction heating,the pore structure of shale heated by electromagnetic radiation is more complex.Referring to previous studies on shale pore evolution under different radiation time and power conditions,this paper compares and analyzes the pore structure of marine shale and continental shale under electromagnetic radiation.Taking marine shale of Longmaxi Formation and continental shale of Ordos Basin as examples,with the help of self-developed electromagnetic radiation device,nitrogen adsorption,high-pressure mercury injection,field emission scanning electron microscope and other characterization means and Image J software,the evolution rules and differences of pore structure of marine and continental shale under electromagnetic radiation are studied.The results show that the final temperature of continental shale is higher than that of marine shale at the same radiation time.The marine shale with high TOC content is dominated by the increase of organic pores,while the continental shale with high clay content is dominated by increase of fracture opening.Under the electromagnetic radiation,the combined effects of pyrolysis of organic matter,dehydration and shrinkage of clay minerals and thermal stress difference of shale lead to the increase of pores and fractures,which significantly improve the seepage capacity of shale.