Numerical Simulation Study On The Sweep Control Mechanism Of Gas Flooding In Tight Oil Reservoirs

Tight oil reservoirs are widely distributed and have a large proportion of reserves.At present,there are many gas injection and development in such reservoirs,the permeability and porosity of the matrix are low,and the oil and gas flow channels are mainly fractures.Reservoir fractures are developed across scales,and the reservoir is highly heterogeneous,prone to gas channeling,low in recovery,and huge in development potential.However,gas injection is greatly affected by reservoir heterogeneity and viscous fingering,and gas channeling is easy to form in the presence of fractures and high-permeability channels.When applied to thicker reservoirs,the effect of gravity differentiation is more obvious.Therefore,it is necessary to improve gas channeling with sweeping control technology,clearly understand the law of gas channeling in reservoirs,the mechanism of action of gas channeling sweeping and control technology,and determine the corresponding technical policy boundaries,which has guiding significance for improving reservoir recovery.This paper firstly studies the gas channeling law of gas flooding in tight oil reservoirs through numerical simulation of the reservoir.According to the actual data,three models of vertical well gas flooding,single well gas injection huff and puff,and double well gas flooding are established,and their gas channeling channels are respectively established.Characterized and analyzed its influencing factors.In the vertical well gas flooding model,the permeability of the high-permeability zone is more obvious than the atmospheric channeling.In the single-well gas injection huff and puff model,the larger the fracture length gap,the more obvious gas channeling at the long fractures.In the dual-well gas flooding model,the fracture length and the presence of connected fractures have the greatest impact on gas channeling.After that,the gas channeling and control systems were screened,and foam and CO₂-responsive gel were selected respectively,and their performance evaluation experiments were carried out,and their reservoir applicability was evaluated according to the fractured core injection experiment.Then the foam and CO₂ responsive gel are simulated to clarify the mechanism of gas channeling and control technology.The gas channeling and control technology can make the distribution of air intake in each fracture of a single well more uniform,and the air intake in short fractures on the plane can be more uniform.Increase the oil significantly,which helps to reduce the gas channeling caused by fracture communication in the process of double-well gas flooding.At the same time,the gas channeling and control technology can improve the problem of preferential migration of injected gas to the upper part of the reservoir,so that the reservoir can be produced more uniformly in the vertical direction.Finally,parameter optimization and system optimization were carried out on the Jimsar reservoir model.The CO2-responsive gel has better stimulation effect on single-well gas injection huff and puff,and the recovery factor increased by 3.3%.The effect is even better,with a 2.5%increase in recovery.