Patent ID: 6484102
Filing Date: 2002-11-19
Classification: G01V

Abstract:
A method for generating a log of a subsurface formation, comprising:obtaining corresponding values of porosity and water saturation for locations in said subsurface formation; establishing a relationship between porosity and irreducible water saturation level for said formation by utilizing the general relationship (&PHgr;b)(S&ohgr;i)=d â€ƒin which &PHgr;=porosity, S&ohgr;i=irreducible water saturation, b is an exponent and is set equal to the slope of a straight line fitted to data points of a plot of said corresponding values of porosity versus said corresponding values of water saturation, said corresponding values of porosity and water saturation each being plotted on a logarithmic scale, and d is a constant and is set equal to the value of water saturation at which an extrapolation of said straight line reaches a porosity value equal to 1 on said plot of said corresponding values of porosity versus said corresponding values of water saturation; and applying said established relationship between porosity and irreducible water saturation to a porosity log of said subsurface formation to generate a log of irreducible water saturation.