Patent Document ID: 9164191
Application ID: 13023728
Patent Flag: 1

Claim One:
1. A computer implemented method of forming a model of determined well completion rates of component fluids of a subsurface reservoir from measured total well production by reservoir simulation of well production, at a time step during life of the subsurface reservoir, from a vertical well in the subsurface reservoir with a coupled well reservoir simulator model, the reservoir simulator model having formation layers having unknown formation pressures and completion rates at the time step, the formation layers comprising vertical fluid flow layers having vertical fluid flow therefrom and flow barrier layers with no vertical fluid flow therefrom, the coupled well reservoir simulator model being organized into a plurality of cells including a plurality of well cells at locations of the vertical well in formation layers of the reservoir, and a plurality of reservoir cells adjacent the well and having unknown formation pressures and completion rates at the time step, the method comprising the computer implemented steps of: forming a reduced system model consisting of: interval well cells between flow barrier layers of the reservoir assembled by combining vertically disposed well cells of the vertical flow formation layers having vertical fluid communication therebetween and being located between flow barrier layers in the coupled reservoir model; and reservoir cells adjacent the interval well cells; solving the reduced system model for a bottom hole pressure of the well; solving by reservoir simulation the coupled well reservoir model of the well cells and reservoir cells for layer completion rates of component fluids of the well cells of each of the formation layers of the coupled well reservoir model at the time step, treating the well as having the determined bottom hole pressure of the well; determining a simulator total well production rate for the well from the layer completion rates of the component fluids of the formation layers of the coupled reservoir model of the well at the time step; comparing the simulator total well production rate for the well with the measured total well production at the time step to determine if simulator convergence is achieved; and, if so, forming a record of the layer completion rates of the component fluids for the layers at the well cells and of the determined total well production rate for the well at the time step; and if the results of the step of comparing indicate convergence is not achieved, iterating to the step of solving by reservoir simulation the coupled well reservoir model, determining a simulator total well production rate for the well from the well completion rates of the component fluids, and comparing.