Simulation of Sand Arching Mechanics Using an Elasto-Plastic Finite Element Formulation

Abstract

This work is a simulation of sand production mechanics using an elasto-plastic ftnite element formulation. An open vertical well was considered in order to simulate the performance of near-wellbore unconsolidated sand during hydrocarbon production.In the simulation procedure, the assigned values of the initial stress fteld around the wellbore were taken from previous sand arching experiments conducted at the Colorado School of Mines on a similar well conftguration using 20/40 frac sand. The mechanical rock properties used in simulation were also taken from previous experimental work. The model did not require fluid properties such as density and viscosity be determined. The values of cohesion and pressure drop across the open well sandface were varied in the simulation of hydrocarbon production through the considered wellbore.Through multiple simulations, the effect of these variations on the stability of the sand surrounding the wellbore was observed. In this study, stability is considered to be elastic behavior and plastic behavior is assumed to indicate failure.It is concluded that sand production from a well can be modeled using the elasto-plastic ftnite element formulation. The stability of the sand around the wellbore depends on the pressure-drop across the sand face and the cohesion of the sand grains. The model presented can provide information on whether a producing zone will exhibit sand production problems.

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