Patent ID: 7913757
Filing Date: 2011-03-29
Classification: C04B,C09K

Abstract:
1. A method of cementing a wellbore in a subterranean formation comprising: (i) evaluating the subterranean formation to which a cement composition is to be introduced; (ii) preparing a base cement composition comprising water and a cement, the base cement composition being formulated so as to impart a baseline set of physical properties determined by evaluation of the subterranean formation in step (i); (iii) determining and, if necessary, adjusting a ratio of the compressive strength to tensile strength (CTR) of the base cement composition to produce a firstly optimized cement composition, wherein adjusting the CTR comprises adding plastic fibers, carbon fibers, glass fibers, or combinations thereof to the base cement composition in an amount effective to provide the firstly optimized cement composition having a CTR in a first optimizing range of from about 5 to about 9; (iv) determining and, if necessary, adjusting an elastic modulus (EM) of the firstly optimized cement composition to produce a secondly optimized cement composition, wherein adjusting the EM comprises adding an elastomer, a rubber, or combinations thereof in an amount effective to provide the secondly optimized cement composition having an EM in a second optimizing range of from about 30% to about 70% of the EM of the base cement composition; (v) determining and, if necessary, adjusting Poisson's ratio (PR) of the secondly optimized cement composition to produce a thirdly optimized cement composition, wherein adjusting the PR comprises adding gas, resilient graphite, flexible compressible beads, a resilient material, or combinations thereof in an amount effective to provide the thirdly optimized cement composition having a PR in a third optimizing range of equal to or less than 0.18; (vi) placing the firstly, secondly, or thirdly optimized cement composition in the wellbore; and (vii) allowing the composition to set.