Oil-Water Phase Permeability Simulation Of Low Permeability Sandstone Based On Digital Core Technology

Nowadays,oil and gas resources are increasingly exhausted,but the reserves of low permeability reservoirs are quite abundant in the world.It is undoubtedly a kind of oil and gas resources to be developed.However,low permeability reservoir rocks are characterized by complex pore structure,low porosity,low permeability,high water saturation and poor storage physical properties,which restrict the development and exploitation of low permeability reservoirs.At present,conventional laboratory experiments can only describe the seepage characteristics and laws of low permeability reservoirs at macro level,but can not describe the seepage mechanism of rocks at micro level.Therefore,how to make breakthroughs in conventional experimental methods has become an important issue.In this paper,a set of methods for simulating oil-water phase infiltration at different temperatures by using digital core technology has been established independently.At the same time,the feasibility of using digital core simulation to replace conventional experiments has been demonstrated by combining conventional laboratory experiments.In addition,in order to ensure that the microXCT-400 instrument in the State Key Laboratory of our university can meet the accuracy requirements of sample low permeability sandstone,this paper innovatively combines MCMC and CT scanning methods to establish digital cores.Based on the digital cores established by MCMCMC method under different resolutions,it provides the accuracy basis for the accuracy of CT scanning method to establish digital cores.Firstly,the MCMCMC method is used to establish the digital core and pore network models of sample cores at four different resolutions.The simulation results are compared with the porosity and permeability measured by the experimental method,and the resolution that can accurately characterize the pore structure of the low permeability sandstone is selected,which lays the foundation for the subsequent use of X-CT scanning method to establish the digital core.Then,the digital core is established again by X-CT scanning method(this process requires the use of visualization software Pergeos to denoise,binary,connectivity testing,pore segmentation and other operations on the X-CT scanning image).By comparing the porosity and permeability of the core under MCMCMC,X-CT scanning and real experimental conditions,it is found that the model obtained by X-CT scanning is closer to the experimental results.Finally,the digital core model established by CT scanning method is simplified and repaired,and oil-water phase seepage simulation at different temperatures is carried out with seepage simulation software.By comparing the simulation and experimental results,it is found that the phase permeability curves of the two methods are well fitted and the shape and position are basically the same,which verifies the feasibility of the digital core method.