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a device in a borehole for covering and sealing separate zones in oil, gas, and water wells and holes drilled for purposes of geological exploration. It was first proposed in the late 19th century.
Bottom-hole, straddle, and isolating packers are the principal types. The bottom-hole packer, with a bed shutoff valve, is installed in the bottom of a well, above the filter section. Used in wells that will be in operation for long periods, such packers are used during bottom-hole repairs to prevent accidental blowouts that are caused by high reservoir pressure or Christmas tree twist-off. Straddle packers are used for isolating borehole cavities connected with different producing formations. They permit the removal of the liquid or gas separately from each formation level through a single well bore, and they also permit selective injection of a liquid or gas into different beds through the same well. Isolating packers, which seal the annular space and make it possible to direct the entire flow of extracted fluid (gas or water) through a central tubing string, are used when the formation fluid has a highly abrasive or strongly corrosive effect on the production string.
G. V. MOLCHANOV