Study Of Flow Characteristics Of Liquid-solid Two Phases In Micro-channel

Petroleum occurs naturally in sedimentary rocks that contain abundant clay minerals,sandstone particles, fine particles of rock and quartz crystals. The existence of solid fine particles can influence oil velocity and free path, and finally change porosity of micro-channel of rock cracks due to fine particles deposition, thus affect the migration of crude oil in underground petroleum reservoirs. Concerning this issue, the research methods so far are mostly from the angle of macroscopic, rarely from the perspective of micro-scale analysis.And the work of numerical simulation is much rarer. Therefore, it is necessary to carry out simulation and analyzing on the migration of fine particles in the micro-pore structure of the oil reservoir layers.Flow behavior of liquid-solid two-phases is simulated by means of DEM-CFD in a micro-channel of rock cracks. In the mathematical model, the continuous mode is established to simulate the fluid flow, the collisions of particles were modeled by discrete element model,and considering the effect of inter-phase coupling. For the physical model, the two-dimensional straight micro-channel numerical model and rough micro-channel numerical model were established respectively for mechanics simulation. In this paper, we have investigated effect of micro-channel porosity, liquid viscosity, liquid velocity and particle diameter on liquid-solid two-phase flow in the micro-channel, and obtained the regulation of the instantaneous distribution of fine particle, particle trajectory, residence time, the instantaneous axial velocity of particle, the axial velocity of liquid, mean granular temperature and the contact force within the micro-channel.Simulated results show that with the decrease of porosity of micro-channel, the movement of representative particle is intense. With an increase of porosity of micro-channel,the mean value(MV) and standard deviation(SD) of contact force of sand grains are decreased, at the same time, the axial velocity of liquid phase fluctuations decrease, and tends to be stable. The residence time and the normal contact force of particles increases with an increase of liquid viscosity and mean granular temperature of the particles is a downward trend overall. The instantaneous axial velocity of particles, the mean granular temperature and the contact force are increased with an increase of liquid velocity, while the residence time of sand grains reduces with an increase of liquid velocity. When the fine particle size increases,the instantaneous axial velocity of particles is decreased leading to the extension of residence time.