Importance

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Abstract

Perforation tunnels and other voids or spaces in earth formations in communication with wells are sealed more effectively by injecting and pre-packing resin-coated particulates (sand) into such tunnels or voids and allowing the sand to consolidate to form a substantially rigid, permeable mass. A lead slurry of relatively fine grained cement is then injected to fill the interstices formed in the permeable material occupying the tunnels or voids. A larger or more coarse grain cement is then injected to form a substantially impermeable, rigid filter cake at the interface of the wellbore and the permeable mass to prevent loss of cement slurry out of the tunnels or voids before the cement is set. Vertical and deviated or generally horizontal wellbores having perforation tunnels or voids which suffer unwanted cement drainage prior to setting of conventional oil well cements are more effectively sealed by the sequential injection of the permeable material followed by injection of settable cement slurries.

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First Claim