Numerical analysis of sand/solids production in boreholes considering fluid-mechanical coupling in a Cosserat continuum

Sand/solids production is a serious problem faced by the petroleum industry during production stages. Particles/groups of particles of the formation rock are produced together with pumped oil or gas causing highly damaging effects on pipes and valves. This phenomena can be caused by several factors including the stresses developed around the boreholes/perforations and fluid flow, which break and erode the rock, respectively. Numerical simulation of sand/solids production presents a considerable challenge as intricacies of failure processes must be correctly simulated. This paper presents a finite element based procedure for simulating the process of sand/solids production, considering fluid-mechanical coupling in an elasto-plastic Cosserat continuum. It is believed that the enhanced deformation modes included into Cosserat continua may contribute for proper modeling of the deformational behavior and failure modes of the cemented/non-cemented granular materials involved. Bogdanova-Bontcheva and Lippmann's constitutive model was implemented in order to model the granular materials involved. Finally, the work presents the analysis of sand/solids production in a hypothetical borehole. For comparison purposes, different characteristic lengths of the material are adopted and analysis is also performed using standard continua.