The Research Of New Methods For Pore Structure Characterization Of Shale Oil And Gas Reservoirs

In the exploration and development of shale oil and gas,the research on pore structure characteristics of shale oil and gas reservoir has far-reaching significance.In this paper,taking the shale gas reservoir samples of Zhongwufeng-Longmaxi Formation in Changning Weiyuan shale gas demonstration area of Sichuan Basin and the shale oil reservoir samples of Lucaogou Formation in Jimsar national continental shale oil demonstration area of Petro China Xinjiang as the research objects,experimental support is provided t o implement shale oil and gas development parameters,study shale oil occurrence and production rules and further improve shale oil and gas production.In this paper,gas adsorption method and high pressure mercury injection method in fluid invasion method,atomic force microscope(AFM)in image analysis method,computer tomography(CT)method and small angle neutron scattering method(SANS)in non-interference method are mainly used to study and analyze the pore structure and connectivity of shale oil and gas reservoir samples.Finally,it can promote the development of new methods.In the study of shale gas reservoir,126 shale samples from Wufeng and Longmaxi formations(Long1₁¹?long1₁⁴ and long1₂ sub members)are taken as the main research objects in this paper.The samples are classified according to the horizon and the are used in related experiments.The fractal dimensions of Wufeng Longmaxi formation are obtained by calculation.The fractal dimensions of Wufeng,Long1₁¹ and Long1₁² are larger and the fractal dimensions of Long1₂ is smallest.Fractal dimension is positively correlated with TOC,negatively correlated with average pore radius,weakly positively correlated with micropore volume,and positively correlated with specific surface area of shale samples under the condition of similar pore volume.Compared with mudstone and sandstone,the fractal dimension of shale is the largest.During the experiment,the hysteresis loops and AFM images were combined to redefine the hysteresis loops and observe the pore morphology.Combined with hysteresis loop and fractal dimension,the pore complexity of each sublayer sample was determined.Finally,with the help of nano CT scanning technology,it is concluded that Long1₁¹ and Wufeng Formation are the target layers of staged fracturing horizontal well development in the reservoir area,while Long1₁³can be used as the target layers of productivity replacement or three-dimensional development.In the study of shale oil reservoir,first,it is clear that the samples of Jimusaer shale oil reservoir are different from those of shale gas reservoir,and they are mainly dolomite,sandstone and mudstone.Combined with low-temperature nitrogen adsorption experiment and nano CT scanning,the pore morphology and connectivity of three kinds of lithologic samples were analyzed by AFM,and the surface morphology of the samples was directly examined and compared with the shale samples in shale gas reservoir.The scattering length density of the sample was obtained through small angle neutron scattering technique.The one-dimensional data curve and two-dimensional data image were obtained and analyzed.The porosity and pore size distribution of sans were obtained.On this basis,a new small angle neutron scattering high pressure mercury injection full-scale pore size distribution measurement method is established to ensure that the same shale oil core sample can be analyzed at the same temperature.Finally,compared with the full-scale pore size distribution test method based on three fluid invasion methods for shale gas reservoir samples,the advantages of the new method are clarified.