Sanding experiments were carried out on weak sandstones with uniaxial compressive strengths in the range of 2 MPa to 25 MPa. The sandstones were either reservoir rocks or those with appropriate physical and mechanical properties to be good model materials.

The experiments involved simulating a perforation or openhole well, by flowing fluid/gas down a hole in a cylindrical rock sample. No radial flow component was present. The flow velocity could be varied, while the sample was hydrostatically stressed to values up to 70 MPa. Deformation of the hole, and the initiation and subsequent flow of sand are viewed and monitored using a specially designed optical method.

Significant differences in behavior were seen for the different rock types. The weakest rock showed compactant behavior, whereas the stronger rocks showed a more brittle response with the formation of breakouts in sanding tests.

The data will be used in the future in the elastoplastic modeling of the perforation geometry.

Experiments of this type provide a simple route to direct observation of sanding in experimental perforations or openhole wells, and give new insight into the mechanisms of failure and the diversity of these mechanisms with different rock types.

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