Preparation And Plugging Performance Of Fly Ash Reinforced Amphiphilic Polymer Composite Gel

The amphiphilic polymer gel has plenty of advantages,such as high gel strength,high shear resistance ability,and high aging stability,and has been developed and gradually applied in oilfields.However,under the high mineralization and high calcium-magnesium reservoir conditions,the amphiphilic polymer gel performs poor gelling time and gel strength,and is easy to be dehydrated and broken.In this paper,the fly ash reinforced amphiphilic polymer composite gel will be prepared and studied so as to be applied in high mineralization and high calcium-magnesium reservoirs for profile control.The salt-thickening amphiphilic polymer was designed and synthesized in the laboratory,and its molecular structure was characterized by means of infrared spectroscopy and hydrogen nuclear magnetic spectroscopy.With the synthetic amphiphilic polymer as the main agent,the amphiphilic polymer gel was constructed,and the type and concentration of the main agent and crosslinking agent were selected by analyzing the gel strength and pressure resistance ability,and then the optimal construction conditions of amphiphilic polymer gel were obtained.Through analyzing the gel strength and viscoelastic properties,the concentration of added fly ash was selected and the optimal construction conditions of fly ash reinforced amphiphilic polymer composite gel were obtained.Through measurement of gel strength,pressure resistance ability and viscoelastic properties,the influence behaviors of reservoir environment factors,such as presence of crude oil,shear condition,and high-temperature aging condition,on performance of fly ash reinforced amphiphilic polymer composite gel were explored.Through measuring microscopic morphology and electrification property,the reinforcing mechanism of composite gel is analyzed.Through physical simulation experiments,the plugging performance of the composite gel in the heterogeneous reservoir model and fractured reservoir model were explored.The results show that the optimal construction conditions of fly ash reinforced amphiphilic polymer composite gel are 0.10%fly ash,4000 mg·L^-1 PADC and 0.25%organic chromium.Under high temperature（80℃）and high mineralization(80113.18 mg·L^-1)reservoir condition,the gel strength of composite gel can reach H grade,the gelling time is 3 days,the pressure resistance value can reach 0.068 MPa,and viscoelasticity of amphiphilic polymer composite gel is greatly improved compared with amphiphilic polymer gel.The fly ash reinforced composite gel exhibits stronger shear resistance ability and higher aging stability,and can maintain excellent performance under the presence of crude oil.In the composite gel system,fly ash particles can make the gel network denser and support the gel framework by being embedded in gel network through the synergistic effect of adsorption and electrostatic interaction.Within the experimental range,the larger the permeability ratio of heterogeneous reservoir,the better the profile control effects of composite gel.The smaller the fracture width of fractured reservoir,the better the plugging effects of the gel.Compared with amphiphilic polymer gel,composite gel performs better plugging effects in both two types of simulated reservoirs.