A. Nouri - Dalhousie University, Halifax, Canada
H. Belhaj - Dalhousie University, Halifax, Canada
H. Vaziri - BP-AMOCO, Houston, Texas, USA

Sand production is a major problem that operating oil companies have been facing for many years. There have been numerous modeling attempts to simulate sand failure and production mechanisms. However, none of the shear and tensile failure models has considered volumetric failure mode. Even though volumetric failure mechanism has been well investigated in studying the phenomenon of land subsidence, but its role in sand production of oil and gas wells has been ignored. In this paper, the likelihood of contribution of this mechanism in sand production is addressed.In the numerical study, a finite difference model, which captures the fluid/solid interaction, was used. The model was validated with experiments, conducted under uniaxial strain conditions on the samples to study volumetric failure mechanism, while traditional triaxial tests were performed on the same type of samples to learn about shear characteristic of the material. The mechanical parameters achieved through these tests were fed in the numerical model that covers all tensile, shear and volumetric failure mechanisms. By using numerical and experimental tools it was obvious that volumetric failure mode, i.e. pore collapse, has a significant contribution to sanding. Even though shear and tensile failure may take place in the well face only, pore collapse can be triggered in a zone very close to the cavity hole. Subsequent to production of shear or tensile failed material from the open face, pore collapse induced disintegrated material may be exposed to cavity face, and potentially massive sanding may occur

Sand Production, Volumetric Failure, Pore Collapse