Patent ID: 6766255
Filing Date: 2004-07-20
Classification: G01V

Abstract:
A method of determining subsidence in a reservoir, said subsidence resulting from a continual withdrawal of hydrocarbon deposits and other fluids from said reservoir, comprising the steps of:(a) estimating rock displacement parameters u, v, and w representing rock movement in the x, y, and z directions; (b) determining &egr;x,y,z (â€˜x,y,z elongation strainsâ€™) and &ggr;xy,yz,zx (â€˜shear strainsâ€™) from the rock displacement parameters u, v, and w; (c) determining &sgr;x,y,z (â€˜elastic normal rock stress in x,y,z directionsâ€™) and &tgr;xy,yz,xz (â€˜elastic shear stressâ€™) from the &egr;x,y,z and &ggr;xy,yz,zx; (d) solving a set of rock momentum balance differential equations from the &sgr;x,y,z and the &tgr;xy,yz,xz and determining if any residuals exist, the rock displacement parameters u, v, and w representing accurate rock displacement parameters for said reservoir when the residuals are substantially equal to zero; and (e) determining said subsidence in said reservoir from said accurate rock displacement parameters determined from step (d), by solving a final set of failure criterion equations, which comprise the residuals and any derivatives, to determine a set of rock plastic displacements, said rock plastic displacements forming a part of said rock displacement parameters u, v, and w.