Dynamic Calcium Carbonate Scaling in Porous Media under Gas/Liquid Two-Phase Flow Conditions

Summary With the continuous production of gas wells, formation water is produced alongside natural gas, resulting in a gradual increase in its content in the production fluid. Due to the change in reservoir conditions in the production process, the precipitation dissolution balance in the formation water is destroyed. Furthermore, scaling anions and cations in the formation water deposit in the near-well zone generate calcium carbonate (CaCO3) scale, which hinders oil and gas flow in the reservoir. It is therefore necessary to explore the near-well scaling mechanism in the gas well production process, as well as prediction methods, in depth. In this paper, we comprehensively examine the influence of thermodynamic and kinetic theories and flow dynamics on CaCO3 scale formation, establishing a prediction model for this process in porous media to quantitatively predict the pressure, ion concentration, saturation index (SI), porosity, and resulting permeability change trends. Through a dynamic scaling experiment involving CaCO3 in porous media, we explore the influence of temperature, pressure, and gas and liquid flow rates on the formation of CaCO3 scale in porous media, verifying the accuracy of the established model. We find that the error between the model’s predicted value and that calculated in the experiment is under 15%, which could provide a theoretical basis and technical support for solving the scaling problem in the near-well area of gas wells.