Autonomous Inflow Control Devices (AICDs) are a relatively new technology with the potential to improve the production performance of horizontal wells. The devices control the inflow of reservoir fluid to equalise influx along the length of a horizontal well, and adjust the level of constraint depending on the fluid flowing such that water production is hindered and oil production is promoted. In order to assess the effectiveness of autonomous ICDs compared to passive ICDs, which apply a constant level of restriction, numerical simulations and sensitivity studies were conducted.

A detailed model of the lower completion of a theoretical horizontal well was constructed using an Integrated Production Modelling (IPM) simulator. ICDs were represented using an Inline Programmable Element and equations to calculate the pressure drop of a range of different passive and autonomous ICDs were input. Simulations run on this model allowed the pressure drop across each ICD to be analysed, and the liquid rates at the heel and toe of the well to be compared, to assess how effective the ICDs are in promoting a balanced influx from the reservoir along the entire horizontal length of the well. Oil viscosity, heterogeneous permeability, and oil-water-contact levels were then varied to evaluate the behaviour of the ICDs in different scenarios.

Analysis of the simulation results suggests that none of the tested ICDs are the best performers in every scenario. The Rate Controlled Production (RCP) Valve AICD is the most effective device in heavy oil wells and in wells with uneven oil-water-contacts. The EquiFlow AICD is the optimum performing devicein a reservoir with heterogeneous permeability, and the nozzle ICD is the most effective device in light oil wells. Comparative study of the behaviour of passive vs autonomous ICDs indicates that there is a difference in performance between these two types of ICDs. In some cases autonomous ICDs can provide significant benefits, where as in others the passive ICDs are just as effective.

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