MATHEMATICAL MODELING OF SHALE SWELLING IN WATER BASED MUDS

摘要

A method of servicing a wellbore comprises determining a cation exchange capacity of a sample of a shale, determining a swelling characteristic of the shale using the cation exchange capacity, determining a composition of a wellbore servicing fluid based on the swelling characteristic, and drilling the wellbore using the wellbore servicing fluid. The swelling characteristic of the shale can be determined using the cation exchange capacity of the shale and a salt concentration in an equation comprising a term of the form: Am% salt = f(m,z)*(x) (cation exchange capacity)y where Am% salt is a final swelling volume of the shale in contact with an aqueous fluid having a salt concentration of m%, f(m,z) is a function based on the salt concentration of m% relative to salt concentration of z% in the aqueous fluid in contact with the shale, and x and y are empirical constants.