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 in an equation comprising a term of the form:
Az % salt=x(cation exchange capacity)y
where Az % salt is a final swelling volume of the shale in the presence of an aqueous fluid having a salt concentration of z %, and x and y are empirical constants, determining a composition of a wellbore servicing fluid based on the determined 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 defining the relation Az % salt=x (cation exchange capacity)y.

主权项

1. A method of servicing a wellbore comprising:
determining a cation exchange capacity of a sample of a shale; determining a swelling characteristic of the shale using the cation exchange capacity in an equation comprising a term of the form:
Az % salt=x(cation exchange capacity)y where Az % salt is a final swelling volume of the shale in the presence of an aqueous fluid having a salt concentration of z %, and x and y are empirical constants, wherein x and y are determined base on an analysis of at least one measured final swelling volume value and at least one measured CEC value of at least one shale sample, wherein the at least one measured final swelling volume value of the at least one shale sample is determined in the presence of a sample fluid having the salt concentration of z %; determining a composition of a wellbore servicing fluid based on the determined swelling characteristic; and drilling the wellbore using the wellbore servicing fluid.