| Hydraulic fracturing,as a technology that uses pressurized fluids to break underground rocks,plays an important role in the development of unconventional oil and gas resources.In order to optimize hydraulic fracturing design or achieve hydraulic fracturing monitoring,researchers have conducted laboratory-scale fracturing simulations.However,to date,there have been few studies on the electrical characteristics of hydraulic fracturing rocks,especially the anisotropic characteristics of complex resistivity and the anisotropic characteristics of permeability.To address this issue,cylindrical and square rock cores were collected and subjected to fracturing experiments,measuring the permeability and complex resistivity of the rock samples before and after fracturing and inverting their dielectric parameters.The pore-permeability and resistivity anisotropy characteristics were analyzed,and based on different models,the pore structure and fracture development characteristics of the rocks were analyzed,and the relationship between pore-permeability parameters and electrical parameters was discussed.This study investigates the effects of hydraulic fracturing on rock samples.The experimental results demonstrate a sharp drop in injection pressure when the rock fractures,resembling a cliff-like pattern.Post-fracturing analysis reveals several significant findings.(1)After fracturing,the complex resistivity of the reservoir rock sample decreases,the porosity and permeability increase,and the polarizability of the columnar core increases,while the polarizability of the square core does not change obviously;(2)The porosity and permeability of the columnar core tend to exhibit anisotropic behavior after fracturing,while resistivity becomes isotropic.As the pressure increases,the porosity of the columnar core becomes anisotropic,while permeability and resistivity tend to be isotropic.Conversely,the permeability and resistivity of the square core display anisotropic tendencies.(3)The pre-fracturing state of the H core adheres to the Archie formula,with the porosity and resistivity exhibiting a power relation with the imaginary part of permeability and resistivity,respectively.However,after fracturing,cracks parallel to the current direction are formed,obscuring the relationship between core permeability and the imaginary part of resistivity.The above research results are of great benefit for us to understand the electrical properties,porosity and permeability of hydraulic fracturing rocks and the characteristics of fluid flow in pores,optimize hydraulic fracturing design and improve oil and gas production. |
