This paper presents an analytical model for predicting the sanding tendency of a gas well. The onset of sand production in a cased well may result from the failure of the perforation tunnel to withstand both the in-situ stress and the flow/production induced stresses. The failure conditions of a cylindrical perforation tunnel subject to single phase gas flow in a friable sandstone formation, have been studied using elastoplastic stress analysis. The failure criterion employed in this paper is the critical equivalent plastic strain, which is the maximum plastic strain that can be sustained without failure and consequent sand production.

The effects of various production conditions have been evaluated by considering the pore pressure distribution associated with the production of gas. The results demonstrate that the flow of gas in the perforation tunnel tends to increase the instability, however compared to standard Darcy flow conditions, the inclusion of the non-Darcy flow effect due to high production rate, will significantly increase the instability. The effect on stability of the tunnel geometry, rock deformation and strength have been studied to assist in the evaluation of the influence of perforation geometry, in terms of shot density and phasing, on sand instability. The results show that an optimum perforation geometry requires a compromise between the productivity ratio and cavity stability.

The results obtained by running the model against a North Sea gas reservoir demonstrate that the model is a useful tool for designing sand free production completions or alternatively assessing the sensitivity of the sanding tendency to operational parameters.

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