A significant proportion of the future oil production is expected to be driven by water injectors and in reservoirs that are sand prone. Achieving sweep efficiency and sand control in such formations is challenging. In many cases the ideal sand control is no sand control (e.g., a C&P completion) requiring rigorous sanding assessment. Sand production in injectors often go unnoticed until it is too late (sand covering the pay) making it difficult to ascertain the specific set of conditions resulting in sanding and the severity of the individual sanding episodes. Based on physics and mechanisms governing sanding, general factors can be postulated on the causes of sanding but not in a quantitative form. To provide a deeper insight into this matter, a numerical study has been undertaken to model sanding in injectors with due account of several inter-coupled factors including injection pressure, crossflow, waterhammer pressure pulses, degradation of the formation matrix resulting from repeated shut-downs and others.

This paper describes the concepts used for sand production modelling and shows application of the model to a field problem involving a C&P completion in a sand prone reservoir. The results show the mode and magnitude of sanding are influenced by the rock properties, injection operations and the equipment type and installation. The cases analyzed indicate a correspondence between the rate of shut-in and the onset of sanding. In cases involving unconsolidated sands, the waterhammer effects have a pronounced impact on sanding. Sand control can be omitted in even very weak rocks provided the injection pressure is optimized, frequency of hard shut-downs is controlled and hardware is positioned in such a manner to reduce the waterhammer pressure pulse magnitude. The proposed modeling can be used in determining the sand sump capacity required over the projected life of the well.

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