FIELD-SCALE SIMULATION OF HORIZONTAL WELLS

A technique for the efficient modelling of horizontal wells in reservoir simulation is presented. This technique treats the horizontal well as a second "porosity" as in the dual-porosity approach for naturally fractured reservoirs. The well "permeability" and "relative permeabilities" are adjusted to yield the pressure drop and phase slip predicted from multiphase flow correlations. Because the wellbore flow equations are cast into the same form as the reservoir flow equations, efficient techniques that have been developed for reservoir simulation can readily be applied. Examples illustrating the application of this method are given for the prediction of the performance of a horizontal well in a reservoir where water and gas coning are important. A validation of the model is provided by comparing oil rates and cumulative oil produced with results obtained from a line source-sink representation of the wellbore and comparing pressure drop and slip with results from a two-phase flow correlation for a case where the wellbore pressure drop is relatively small.