Study On Simulation Method Of Gas-water Two-phase Flow In Shale Digital Core

Hydration which produces a great influence on shale gas flow will be happened during gas shales development process when fracturing and treatment fluids interact with shale.Few dynamic and quantitative researches on mechanism of gas-water two-phase flow in shale have been done so far.As a result,people are not quite clear about the basic movement law of gas-water two-phase flow in shale.This paper makes quantitative study on water absorption characteristics of shale samples and changes caused by water absorption based on shale hydration experiments.Water absorption capacity and linear expansion rate of samples are measured and their influence factors are analyzed.Based on the scanning electron microscope(SEM)and CT scanning experiments,obvious matrix pore dilatancy and micro cracks producing in shale samples interacted with water are observed.Calculation results indicate that surface porosity and average pore diameter are significantly increased.Results of shale gas permeability measurement experiment demonstrate that gas permeability of samples after hydration increased significantly.This paper reconstructs shale digital core based on actual shale core sample images and the effects of shale hydration.Mathematical model of seepage is established by lattice Boltzmann method and the process of gas-water two-phase flow is simulated.The distribution of shale gas and water in matrix pore and fracture is definite by numerical simulation.This paper has important significance in providing basis theory of guiding efficient exploitation of gas shale.