Patent ID: 7555390

Claim:
A method of producing a log of a characteristic of a formation surrounding a borehole, comprising: a) moving a resistivity logging tool through the borehole a plurality of times to obtain each time resistivity measurements at a plurality of radial depths of investigation for a plurality of borehole distances; b) utilizing said resistivity measurements, generating starting estimates of residual oil saturation S or and connate water saturation S wc for each of said plurality of borehole distances; c) utilizing said starting estimates and said resistivity measurements, conducting an initial global multidimensional search for starting values of residual water saturation S wr and filtrate loss quantities Q i for each of said plurality of borehole distances; d) utilizing said starting values of residual water saturation, finding starting values for maximum residual oil saturation S orm at each of said plurality of borehole distances; e) using said starting values of connate water saturation S wc , said starting values of residual water saturation S wr , said starting values of maximum residual oil saturation S orm said starting values of filtrate loss quantities Q i , i=1, . . . N for each of said plurality of borehole distances, and a first flow model relating S wr , S wc , S orm and Q i to resistivity, generating first resistivity estimates at different radial depths into the formation, (i) comparing said resistivity estimates generated by said first flow model to said resistivity measurements, and (ii) based on said comparing, iteratively modifying at least one of said starting values, generating updated resistivity estimates at said different radial depths into the formation utilizing said modified starting values, and comparing resulting updated estimates to the actual measurements to make determinations of at least one formation parameter; and f) displaying an indication of a value of said at least one formation parameter as a log over borehole distance.