Sand production in an oil and gas industry is a complex phenomenon causing operational costs to increase drastically, so controlling or managing sand has become very important in reservoir planning and development. During sand production, formation grains or chunks are detached from formation cavities due to mechanical loading processes, then transported to the wellbore by the flowing fluids, either oil, water or gas. This article presents a new model for sand production forecasts, which model couples the fluid flow and geomechanics and includes a sand production relationship. For the mechanical behavior an elastoplastic constitutive model and a sand production relationship is used, meanwhile, the fluid is slightly compressible and monophasic. The sand production relationship states that sand production occurs after high shear plastic strains are accumulated. FEM method is used for the numerical solution of the resulting system. To verify the model’s behavior, results for a hypothetical case are compared with laboratory and previous reported in the literature related with sanding behavior. Among others results, is the relationship between the mechanical loading as a mechanism to promote sanding. Finally, in order to quantify the most important variables in sanding, a sensitivity analysis is performed. This analysis shows the effect of in situ stress state, sanding parameters and cohesion, being, after the sanding parameters, the cohesion as the most important variable for sand produced mass. The presented model has an important potential and its easy applicability positions it as an easy tool for matching and forecasting sand production.
Sand production is found in several reservoirs, commonly in poor or not cemented formations. Among sanding problems are: reduction or cessation of production, damage to the flow equipment either down-hole or in surface. Reason why sand management uses sand risk indicators to work with sanding, but when the risk is high (including economic impacts) then it is required the use of methods for sand control and mitigation.
There exist several ways to infer sand production potential such as dimensionless relationships (Bazanti & Desai, 1988), total compressibility to shear modulus ratio (Khamehchi & Reisi, 2015), neural network applications (Kanj & Abousleiman, 1999) and analytical solutions. Unfortunately, these methods do not predict sand production levels which are required to design properly the development plan for a wellbore or reservoir.
Numerical models are used to determine with higher detail the forecasts of sand production, and this way a numerical sand production model is presented accounting. The objective of the current work is to evaluate the influence of selected properties in sand produced mass. Ideally, sand production is a coupled problem which involves pressure changes, flow velocities, geomechanical behavior and sanding is a results of this variables changing during different operations.