EXPANSION AGAINST CEMENT FOR ZONAL ISOLATION
A method for improving zonal isolation between formations along a borehole, comprises a) providing a pipe in the borehole, wherein at least a portion of the pipe lies between the formations, b) providing a body of cement in the annulus between the borehole wall and said pipe portion, c) allowing the body of cement to cure until it has reached at least 70 Bearden units consistency, and d) expanding said pipe portion so as to decrease the cross-sectional area of the annulus between the borehole wall and said pipe portion.
1 . Method for improving zonal isolation between formations along a borehole, comprising:
a) providing a pipe in the borehole, wherein at least a portion of the pipe lies between the formations;
b) providing a body of cement in the annulus between the borehole wall and said pipe portion;
c) allowing the body of cement to cure until it has reached at least 70 Bearden units consistency; and
d) expanding said pipe portion so as to decrease the cross-sectional area of the annulus between the borehole wall and said pipe portion.
2 . The method of claim 1 wherein step d) eliminates fluid channels in the cement body.
3 . The method of claim 1 wherein step d) increases the density of the cement body.
4 . The method of claim 1 , further including the step of providing a second cement body in the annulus, wherein the second cement body has a longer cure time than the first cement portion.
5 . The method of claim 4 wherein the second cement body is not cured when step d) is carried out.
6 . The method of claim 4 wherein at least one cement body contains polymers.
7 . The method of claim 6 wherein at least one cement body contains ringing gels.
8 . The method of claim 4 wherein step c) does not cause the second cement body to fracture.
9 . The method of claim 1 , further including the step of providing an exit path for water expelled from the cement during expansion.