Patent Document ID: 20160208585
Application ID: 15061530
Patent Flag: 0

Claim One:
1. A computer implemented method of forming a model of determined well production rate of component fluids from a well in a subsurface reservoir and of determined layer completion rates of perforated well intervals in the well, from measured total well production, with a coupled well reservoir model during reservoir simulation of well production at a time step during life of the subsurface reservoir, the coupled well reservoir model being organized into a reservoir grid subdivided into a plurality of reservoir cells at the perforated well intervals, the perforated well intervals in the reservoir being located at a plurality of formation layers, the formation layers having unknown well potentials, transmissibilities and fluid completion rates for component fluids at the time step, and the formation layers comprising vertical fluid flow layers having vertical fluid flow therefrom and flow barrier layers with no vertical fluid flow therefrom, the formation layers further having a permeability, transmissibility, thickness and a layer potential, the coupled well reservoir model further having a plurality of well cells at locations of the well in formation layers of the reservoir, the computer implemented method determining layer completion rates for the component fluids from the formation layers of the well and well production rates of the component fluids from the well, the computer implemented method comprising the steps of: (a) forming a full computation matrix reservoir model of reservoir data of cells of the model, including the reservoir data for the reservoir cells at the perforated well intervals, the reservoir data including the permeability, thickness and a potential for the formation layers; (b) forming a reduced well model system matrix by assembling as single vertical flow layers in the matrix the data of the vertical fluid flow layers of vertical fluid flow layers having vertical fluid flow therebetween and being located between flow barrier layers in the reservoir model; (c) determining a bottomhole pressure for the well; (d) forming a coupled reservoir well model comprising the full computation matrix reservoir model and the reduced well model system matrix, treating the well as a bottomhole, pressure specified well having the determined bottomhole pressure, the coupled reservoir well model being in the form of a matrix: 
 [ T ci ][Φ i ]=[{tilde over (b)} i ] wherein T ci is a matrix of the transmissibilities of the adjacent reservoir cells to the well cells at the perforated well intervals; Φ i is a vector of unknown reservoir potentials for the adjacent reservoir cells; and {tilde over (b)} 1 is a vector of the well net inflow data for the well from the adjacent reservoir cells; (e) solving the coupled reservoir well model for the fluid flows in the reservoir cells of the formation layers and the transmissibilities and potentials of the reservoir cells at the time step for each of the formation layers; (f) solving the coupled reservoir well model for the productivity indexes of the well cells at the perforated well intervals of the reservoir at the time step; (g) determining layer completion rates for the component fluids of the vertical fluid flow layers and the flow barrier layers of the well based on the determined productivity indexes of the reservoir and well cells at the perforated well intervals of the reservoir at the time step; (h) determining total well production rate for the well from the determined layer completion rates for the component fluids of the vertical fluid flow layers and the flow barrier layers of the well at the time step; and (i) forming a record of the determined layer completion rates for the component fluids of the vertical fluid flow layers and the flow barrier layers of the well and the determined total well production rate for the well at the time step.