Numerical Simulation of Low-Permeability Reservoirs with considering the Dynamic Boundary Layer Effect

Chuanzhi Cui,Xiangzhi Cheng,Yinzhu Ye,Yingfei Sui,Zhen Wang,Yu Wang

doi:10.1155/2021/6637727

Abstract

Surface active components, salt component, and polar molecules in the fluid may adsorb on the solid surface and form the boundary layer during low-speed flow in a porous medium, which will influence the flowing law in the porous medium. Previous studies on flowing in low-permeability reservoirs mainly focus on the effects of the threshold pressure gradient. But few of them have considered the time-varying effect of the boundary layer thickness in solving the numerical simulation. The correlation among the boundary layer thickness and pressure gradient was established by regressing the experimental data of boundary thickness versus pressure. On this basis, the mathematical model of oil-water two-phase flow which involves influence of the boundary layer was constructed, and the comparative analysis of the development effect is performed. Results demonstrated that the boundary layer thickness is sensitive to the throat radius and pressure gradient, and the boundary layer thickness decreases dynamically with the increase of pressure gradient. The displacement velocity and accumulative oil production with boundary layer effect decrease when comparing with that without the boundary layer effect. Meanwhile, the boundary layer accelerates the breakthrough of water. With the reduction of production pressure difference, the difference between accumulative oil production with and without the boundary layer effect increases, which indicate that the dynamic effect of the boundary layer is intensified.

Highlights

Due to the interface interaction between solid and liquid, there is a fluid layer on the surface of the porous media which fluid properties change with the flow and the fluid in it is called the boundary layer fluid
The formation of the boundary layer on the solid phase surface is related with the interaction force between the solid surface and molecules
Since the boundary layer fluid is the closest to the solid phase surface, the interaction between rock molecular and fluid molecules reaches the maximum and the fluid molecules are in an ordered arrangement, showing the characteristics of solids [3] (Figure 1)

Summary

Introduction

Due to the interface interaction between solid and liquid, there is a fluid layer on the surface of the porous media which fluid properties change with the flow and the fluid in it is called the boundary layer fluid. The formation of the boundary layer on the solid phase surface is related with the interaction force between the solid surface and molecules. Particle dynamics is used to simulate and characterize the influence of the boundary layer on flowing. It can be known from Equation (1) that the effective radius is sffiffiffiffiffiffiffiffiffiffiffi rE = 4 8πμΔLpQ: ð2Þ. By combining the study experiment on the microscale flow in this paper, the influencing factors of the boundary layer were analyzed and the quantitative characterization method of dynamic changes of the boundary layer was established. Contrast analyses of the development effects with considering the boundary layer were carried out

Characterization Methods of Dynamic Features of the Boundary Layer Thickness

Model Solving and Result Analysis

15 MPa 20 MPa

Conclusions