A NEW THEORY AND METHODOLOGY FOR MODELING SAND PRODUCTION

This paper is concerned with the issue of sand production and in particular depletion induced sanding. The problem of sand production is costing the industry hundreds of millions of dollars per year. By a reliable prediction of sand production not only the sometimes unnecessary expensive sand control measures that are employed can be avoided, but also under properly designed and controlled conditions, several folds of improvement in oil and gas production can be achieved. In this paper some ideas on the physics of the problem is introduced. These ideas clarify how sanding occurs in general and more specifically under the depletion mechanism. Next, a set of unconventional triaxial tests is proposed that employ as much similar loading patterns to the real case as possible. A material model is presented for simulating the behaviour of the formation against the applied loads particularly in aged reservoirs. Furthermore, a model for numerical simulations of these experiments is presented that resembles the loading pattern on the laboratory samples. The proposed behaviour of the reservoir as a result of the depletion is numerically evaluated and covered. The result of the numerical analyses confirms the proposed model and scenario as explained. It also evaluates the effect of cohesion and friction angle and initial cap- pressure on the depletion at the time of failure. The phenomenon of the pore collapse is modelled by using a Mohr-Coulomb considering strain softening/hardening cap model.