Micro Seepage Simulation Of Tight Sandstone Based On The Digital Core

The complex pore structure of tight sandstone reservoir rocks is a low-permeability tight reservoir with high water saturation and low reservoir quality.During the development of reservoirs,problems of gas-water co-production and low recovery ratio are common.Through the study of the mechanism of microscopic seepage in tight reservoirs,using the digital rock physics technology to study the permeability of tight sandstones and provide technical support for improving oil and gas reservoir recovery ratio.When measuring the permeability of tight sandstone in the laboratory,due to the complex pore structure,the measurement process is c?mbersome,the measurement accuracy and stability are poor,and the success rate is low.In order to address these issues,this paper explores the use of digital petrophysical methods to simulate laboratory displacement experiments to measure rock permeability.By collecting existing research data in the study area,this paper found that the distribution of pore throat in tight sandstones is the main factor affecting rock permeability.At the same time,the microscopic pores and throats of tight sandstones are quite different.It is difficult to obtain tight sandstones pore characteristics directly by using a single method.Therefore,a variety of experimental techniques,including high-pressure mercury injection,nuclear magnetic resonance(NMR),scanning electron microscopy(SEM),and micro-CT,were used to understand and characterize the microscopic pore structure of tight sandstones from multiple scales.The pore throat radius size,distribution,and connectivity information were obtained to help the selection of the seepage simulation platform.Comparing the application effects of different experimental methods,the scanning electron microscope image was selected as the percolation simulation platform.The foundation of the microscopic seepage simulation of rock is obtaining the microstructure of the rocks accurately.The image that directly reflects the microscopic structure of the rock pores can be obtained by scanning electron microscopy(SEM).With the image processing algorithm,the microscopic pore structure can be extracted.The binary image divides the entire rock into two parts: the skeleton and the pores.The computational fluid dynamics method is used to simulate the microscopic flow of the rock.The meshing process of the pore part adopts a structured grid construction method.The regular rectangular mesh is in pixels.The point is the basic unit,which reduces the calculation error and has the advantages of quickness and convenience.Computational fluid dynamics(CFD)has powerful computational capabilities and fluid property analysis capabilities,enabling visualization of the simulation process and accurate detection of parameters.The simulation results were analyzed to extract the absolute permeability of rock and the relative permeability of each phase fluid.The influence of pore structure on the seepage characteristics of rock was analyzed.The study of rock microscopic flow simulation is of great significance for understanding the flow law of fluids in tight sandstone reservoirs and for interpreting macroscopic reservoir phenomena.At the same time,in reservoir evaluation,rock physics experiments are needed to determine reservoir seepage properties and log interpretation results are verified.For tight sandstones,it is difficult to experimentally study seepage properties.Digital rock physics is an effective alternative.