High temperature flexible cementing compositions and methods for using the same

Abstract

Natural fiber-containing cement compositions for cementing wellbores in high stress and high temperature environments. The cement compositions may contain natural mineral fiber materials such as wollastonite in an amount of greater than about 10% and in an amount selected to be effective to achieve ratios of flexural strength to compressive strength of cured cement that are greater than about 0.35 at downhole temperatures of greater than about 180° F.

1 - 19 . (canceled)  
     
     
         20 . A fiber-containing cement composition, comprising a hydraulic cement base and a natural mineral fiber; wherein said natural mineral fiber is present in an amount greater than about 10% by weight of cement; wherein said natural mineral fiber is also present in said fiber-containing cement composition in an amount selected to be effective so as to result in a cement slurry and a cured cement composition formed from said cement slurry having a ratio of flexural strength to compressive strength that is greater than or equal to about 0.35 when said cement slurry is exposed to a temperature of greater than about 180° F.; and wherein said natural mineral fiber comprises at least one calcium silicate natural mineral fiber.  
     
     
         21 . The fiber-containing cement composition of  claim 20 , wherein said calcium silicate natural mineral fiber comprises at least one of wollastonite, pyrophillite, algamatolite, or a mixture thereof.  
     
     
         22 . The fiber-containing cement composition of  claim 20 , wherein said calcium silicate natural mineral fiber comprises wollastonite.  
     
     
         23 . The fiber-containing cement composition of  claim 22 , wherein said hydraulic cement base comprises Portland Cement.