Novel ferrofluids for use in cementing wells

Abstract

Novel cementitious and non-cementitious ferrofluids are disclosed which have properties making them suitable for use in cementing wells. The cementitious fluids comprise: (a) a hydraulic cement, (b) finely divided magnetic particles, (c) a bonding agent or a surfactant, and (d) a liquid medium. The binding agent or surfactant is present in the compositions in an amount sufficient to render the compositions stable in a magnetic field. When used in cementing wells, the cementitious ferrofluids are implaced in the annulus separating a casing from the formation in a wellbore by conventional techniques and the slurry is subsequently subjected to an activating magnetic field that causes movement of the magnetic particles in the slurry. The non-cementitious ferrofluids comprise: (a) finely divided magnetic particles, (b) stabilizing agent, and (c) a liquid medium. The movement of the magnetic particles results in a "scrubbing" action against the surface of the casing and the formation and a mixing of the slurry which helps displace any residual drilling mud. The net result is better bonding of the cement.

Dependencies are inferred from the claim text.