Predicting accurate inflow pressure and flow profile of horizontal laterals is one of the biggest impediments in achieving their optimum performance. Reservoir simulators are capable of simulating flow in the reservoir up to the fluid entry points in the well reasonably well. Wellbore simulators can simulate flow from the fluid entry points up to the surface delivery system. The integrated system can be simulated numerical reservoir simulators adequately assuming a single point fluid entry to the well. However, accurate foot by foot prediction of pressure and flow profile at the reservoir/well interface of long horizontal wells is a challenge. Some simulators attempt to simulate this detailed inflow profile using some simplified approach. A few semi-analytical modeling approach is also available in the literature. They use average parameter values in their calculation. These simplifying assumptions result in less than accurate inflow profile prediction to the extent that they are inadequate for some design optimization studies.

In this paper we describe coupling of a 3-D numerical reservoir simulator with a wellbore simulator in a simple manner which is capable of predicting a detailed inflow profile along long horizontal wells. Flow and pressure along the laterals are iterated between the simulators at each point of interface until they converge. This convergence is repeated at desired time intervals ultimately resulting in a fully converged integrated reservoir-wellbore simulation with the detailed and accurate inflow profile. The algorithm was initially tested manually and later automated. Results of the work is presented along with an application (designing Inflow Control Devices) aimed at achieving uniform flow profile along horizontal laterals. This is a powerful capability which will enable us optimize horizontal completions to the extent which was not possible before.

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