Electrochemical Characteristics And Seepage Law Of Acid Fracturing Fracture Network In Rock

Tight sandstone gas is widely distributed in China,but its development has been limited by the problems of single production mode and low production efficiency.Sandstone acid fracturing technology can effectively improve the distribution of fracture network in sandstone reservoir and enhance the seepage capacity of fracture network in reservoir.It is an important method to improve tight gas production and increase production.Therefore,using sandstone acid fracturing technology to study the relationship between fracture network characteristics and seepage in sandstone and improve production efficiency is of great significance to the natural gas industry.In this paper,a rock fracturing method based on acid fracturing technology is proposed.Based on the theory of rock acid corrosion and electrochemical impedance spectroscopy,the corresponding laboratory tests are designed,and the feasibility and effect of acid fracturing method are discussed by numerical simulation.Firstly,the sandstone sample is selected as the test material,and the fracture of the rock sample is realized through the coupling effect of chemical solution and pressure,so that different fracture networks appear in the rock sample.Secondly,through the independently designed electrochemical detection device,the rock sample is connected with the electrochemical workstation to measure the corresponding electrochemical data.Finally,the mechanical properties of sandstone corroded by acid compression are tested through indoor uniaxial compression test,and the relevant models are established by using numerical simulation software,and specific parameters are set to simulate the uniaxial compression process,so as to verify whether the test results are consistent with the simulation effect.The results show that:(1)with the extension of acid pressure corrosion time,the mass loss rate of sandstone corroded by chemical solution with high acid-base concentration increases and the p H value of chemical solution decreases,indicating that part of sandstone falls due to corrosion and reacts with chemical solution in the corrosion process.(2)It is detected by electrochemical means and equivalent circuit fitting method that the solution resistance of sandstone decreases gradually and the electric double layer capacitance increases gradually during the corrosion process,reflecting the influence of chemical solution pressure coupling on the microstructure of sandstone.(3)Through the comparison between the uniaxial compression test results of indoor corroded sandstone and the numerical simulation results,the results are in good agreement.It is expressed as follows: the stress-strain curve is displayed in four stages,and the stress-strain curve obtained from the test is roughly similar to the stress-strain curve obtained from the numerical simulation with the change of chemical solution and corrosion time.It can be explained that the numerical simulation method verifies the corrosion effect of chemical solution on rock,which is a very effective means and provides a deeper research for practical engineering.The results of this research have more important practical engineering significance and reference value for the study of sandstone fracturing methods and the improvement of tight gas extraction efficiency.