Numerical simulation of solids production in slip-lines type breakout modes using standard and Cosserat continua

Solids production is a serious problem faced by the petroleum industry during production stages. Particles or groups of particles of formation rock are produced together with oil or gas being pumped which has highly damaging effects on pipes and valves. Solids production can be caused by several factors including the stresses developed around the boreholes/perforations, the drawdown, mechanical and hydraulic properties of the formation rock and the type of containment measures adopted. Numerical simulation of solids production presents a considerable challenge as intricacies of breakout processes must be correctly simulated in order to correctly predict rates of solids production. The present paper presents the development of a finite element based program for simulating the process of solids production, considering fluid-mechanical coupling in standard and Cosserat elasto-plastic continua. The present paper presents results, using the developed computer code, for the simulation of one specific observed breakout mode in laboratory experiments, the one associated with the formation of slip lines. Numerical aspects of the simulations are discussed. The paper deals specifically with hydrostatic states of stress and, in particular, the paper analyzes and discusses the influence of the material microstructure (through its characteristic length) in rates and amount of solids produced.