Patent ID: 7369979
Filing Date: 2008-05-06
Classification: E21B

Abstract:
1. A method for forecasting production for a well, said well having a wellbore and a wellhead, said wellbore penetrating a reservoir comprising a plurality of layers, said well producing fluid from said layers of said reservoir through said wellbore, said fluid from said layers being produced commingled within said wellbore, said method comprising: (g) providing wellbore data describing said wellbore, (h) providing flowing wellhead pressure data representing the flowing wellhead pressure as a function of time for said well, (i) providing a forecast schedule representing a series of times at which a production forecast is desired, (j) providing layer data representing properties of each of said layers of said reservoir, (k) providing a plurality of single-layer predictive reservoir models corresponding to said layers, wherein the improvement comprises (l) providing a tubing pressure gradient model, (m) coupling said plurality of single-layer predictive reservoir models with said tubing pressure gradient model so as account for pressure drop between adjacent layers as well as between said wellhead and said reservoir, (n) computing for each time in said series of times a total well flow rate, a layer flow rate for each of said layers, and a flowing sandface pressure for each of said layers, whereby the computed total well flow rates represent a production forecast of said well at said series of times.