A molecular dynamics investigation into the polymer tackifiers in supercritical CO2 fracturing fluids under wellbore conditions

SC-CO₂ fracturing technology is a feasible method for green extraction of unconventional oil and gas reservoirs. However, due to a series of problems such as sand transportation during SC-CO₂ fracturing, CO₂ thickening has become the focus of current research. Polymer thickeners have been widely used in oilfields. Due to the macroscopic nature and limitations of laboratory experiments, we have not been able to elucidate the microscopic mechanism of polymer thickening CO₂ and the viscosity change of the CO₂ fracturing fluid system downhole after polymer addition. In this study, we used all-atom modeling and molecular simulation of the COMPASSII force field. We selected nine polymers to study their microscopic properties and the factors affecting their effects. Finally, we simulated the viscosity change of the CO₂ system after the addition of polymer tackifiers in the wellbore under the CO₂ fracturing construction conditions by combining the data from one well in the oilfield.