Comprehensive Transient Modeling of Sand Production in Horizontal Wellbores

The design of the most appropriate completion technique for a horizontal wellbore is still a formidable task. The choices are whether to opt for an openhole or a cased completion and, whether to gravel pack or there will be no need for sand production control under prospective operational conditions. This paper introduces a predictive tool that forecasts not only the initiation of sanding, but also its rate and severity in real time. All possible failure mechanisms including shear, tensile and volumetric have been included in the proposed model. Experimental data on large block tests are used to support the validity of the proposed numerical model. A series of well-documented experiments on a large size horizontal wellbore was numerically simulated utilizing a finite difference package. The model covers the interaction between fluid flow and mechanical deformation of the medium, capturing all possible mechanisms of failure. Providing the means of encompassing the sequential nature of sanding and the direct modeling of progressive character of the cavity, the suggested model is the first to be reported using a fully coupled transient simulation approach. The removal process of the qualified elements is simulated in the model, and the criteria that are used for this process are in accordance with the physics of sand production. This numerical tool can be used to address the main factors related to sand production problem that include the conditions under which sanding takes place and how extensive if indeed it occurs. The model shows excellent agreements with experimental results in terms of borehole deformation and sanding rates. The model predicted initiation of shear failure from the sides of the borehole and its propagation to the top and sides of the sample. Likewise, it became evident that removal of the failed material during production may trigger more sanding through development of shear failure to the formerly intact material that may continue to fail accordingly. More importantly, the agreement between the numerical and experimental well face deformation as well as sanding rate and volume suggests that an accurate prediction of sanding can be made by using the proposed numerical modeling. Therefore, a sound decision in completion selection and sand control strategy can be suggested. Avoiding unnecessary gravel packing, and other sand controlling 'and prevention techniques can be achieved by utilizing the proposed model, which in turn reduces the cost of well completion dramatically. In addition, the production decline due to gravel void throat block by fine movement can be prevented. A wide use of the proposed model is expected immediately in the oil industry.