Numerical simulation and experimental study on the whole process of gravel packing in horizontal wells

Abstract

The gravel packing completion method for horizontal wells has the benefits of long-term high production, wellbore stability, and sand production prevention. The numerical model is critical for gravel packing scheme design and construction guidance in horizontal wells. A lot of work has been done on the numerical model of gravel packing in horizontal wells, but there are still challenges, such as being unable to simulate the entire process, assuming density and viscosity remain constant during horizontal migration, and not integrating formation properties and actual string structures. Therefore, based on the detailed analysis of the whole process of gravel packing flow in horizontal wells, a numerical model, which includes the model of the ground pipes and vertical well sections and an improved three-dimensional numerical model of horizontal sections has been established in this paper. The impact of gravel packing on the horizontal well is then investigated. The accuracy of the pressure calculation model is then evaluated through friction experiments of different types of fluids utilizing a horizontal circular pipe flow device, in which the average error between the measured pressure drop and the calculated pressure drop of the flow friction experiments of water is 1.30%. while as slurry with a proppant concentration of 20% flows, the average error is 6.50%. Many sets of gravel packing experiments are carried out using a full-scale horizontal well gravel packing experimental apparatus to validate the improved three-dimensional numerical model. Finally, numerous well schemes are designed and constructed. After comparing the design parameters and treatment parameters of seven wells, the maximum total time error is 5.78%, the maximum pressure error in the alpha-wave stage (the forward packing stage of gravel from heel to toe in the horizontal wellbore) is 7.3%, and the maximum pressure error in the beta-wave stage (the reverse packing stage of gravel from toe to heel in the horizontal wellbore) is 9.9%, which shows excellent field applicability of the improved model.