US Patent 10053949 Cement retainer and squeeze technique

A cement retainer comprises a plug that may be run into casing on a wire line and set in a conventional manner. A passage through the plug allows cement to be pumped therethrough. A wiper plug follows the cement, wipes the inside of the casing and latches onto the retainer to prevent back flow of cement. In some embodiments, the cement retainer and wiper plug are made of drillable materials allowing a series of squeeze operations to be conducted, one after another without undue delay, and then be drilled up in a single bit run. In some embodiments, the cement retainer and wiper plug are made of metals, drillable or non-drillable, or other long lived materials in order to plug wells in the process of abandoning them.