Patent ID: 9121263
Filing Date: 2015-09-01
Classification: E21B

Abstract:
1. A method for predicting cleanup of a wellbore fluid sample, the method comprising: (a) drawing the fluid sample into a downhole tool via a probe assembly; (b) measuring optical densities of the fluid sample at a plurality of different times while drawing the fluid sample in (a); (c) selecting a plurality of the optical densities measured in (b); (d) processing a fluid transport model to compute theoretical optical densities as a function of a pumpout volume of the fluid sample; and (e) causing a processor to adjust one or more inversion parameters in the fluid transport model to obtain a fit between the optical densities selected in (c) and the theoretical optical densities computed in (d), wherein the inversion parameters include (i) a depth of mud filtrate invasion, (ii) a viscosity ratio between a formation fluid and an oil based mud filtrate, (iii) a formation thickness, (iv) an optical density of the formation fluid, and (v) an optical density of the oil based mud filtrate.