Pore Scale Characteristic Study Of Shale Oil Based On Digital Cores

Since the exploration and development of conventional oil and gas resources has reached a plateau after decades of exploitation,more and more people are paying attention to unconventional resources.For a long time,the verified energy supply in China was not able to satisfy the domestic demand,and import oil is still accounting for a big figure.As a result,it is urgent to find and exploit more unconventional oil and gas resources,whilw shale oil being one of the most potential one.Considering the complicated structure in shale oil reservoir,the flowing condition is differed from the conventional ones,so related researches are necessary.With the great development of computer technology,digital rock arises and pushes the development of simulation researches.Because of its own characteristic,Lattice Boltzmann Method has been widely used in micro-scale flow simulation.In this paper,a method is introduced which can construct 3-D digital rock based on SEM-MAP picture of shale core.The method can also help to study the characteristics of pore and throat as well as flowing,which can find out the flowing pattern of shale oil.Firstly,pictures in diverse resolutions are taken from the SEM-MAP picture of shale core,which is then binaried with watershed segmentation algorithm.The 3-D digital cores in multiple scales are constructed next from the pictures by Markov Chain Monte Carlo method.With the help of pore network model,the pore and throat characteristics of digital cores in multi scales are analyzed and coupled.Secondly,A flowing model which takes slip boundary conditions in consideration is constructed with Lattice Boltmann Method.To make the model more realistic,it is altered according to the Knudsen number.The altered model is used to calculate the absolute permeabilities of digital rocks in diverse scales,and the overall absolute permeability of the digital rock is then calculated based on the distributions of pore and throat radiuses.Thirdly,a binary color model based on Lattice Boltmann Method is constructed to study the two-phase flow in 3-D digital cores.By altering the parameters,the influences of density ratio,viscosity ratio of the fluids and other factors can be discussed.