Molecular Dynamics Simulation of Calcium Sulfate Nucleation in Homogeneous and Heterogeneous Crystallization Conditions: An Application in Water Flooding

During water flooding of the oil reservoir, deposition of calcium sulfate on the pore surface causes formation damage and affects oil recovery efficiency. Thus, a clear understanding of this scale’s early crystallization stage is crucial to optimize and control the precipitation process. For the first time in this study, molecular dynamics simulation has been utilized to study the formation pathway of calcium sulfate in homogeneous and heterogeneous systems to address precipitation and deposition processes and the temperature influence on this phenomenon. We found four distinct steps in crystal evolution regardless of the temperature effect in both precipitation and deposition systems that confirmed the prenucleation theory. The results indicated that the induction time was strongly affected by temperature and solid surface presence at a specified supersaturation level. The influence of the solid surface is pronounced at higher temperature conditions in comparison to the bulk phase. The nucleation time varied between 2 and 12 ns at the high supersaturating level, depending on the temperature and crystal formation condition.