Development of simulations based correlations to predict the cement volume fraction in annular geometries after fluid displacements during primary cementing

Primary cementing involves the Newtonian and non-Newtonian fluid displacements. In this process cement replaces mud in the casing-formation annulus. The spacer fluids are used as a buffer between mud and cement and help in displacing mud as well. Once set cement acts as a barrier for zonal isolation. In an ideal cement job 100% of annular volume is occupied by cement. In this study a computational fluid dynamics (CFD) model is used for a 50 ft virtual well model section. It is initially filled with mud and subsequently swept by one annular volume of spacer followed by one annular volume of cement. The performance of mud displacement process under varying conditions of spacer density, viscosity and displacement rates is studied. Temporal variation of the mud volume fraction in different axial sections is used to monitor the efficiency of displacement process and behavior of fluids involved. Based on these simulation results, a correlation is developed to predict the final cement volume fraction in the annulus for the given operating conditions. The results of this study will help in better understanding the complex flow physics involved in the combination of Non-Newtonian and Newtonian fluid displacements.