Method and apparatus for placing buoyant ball sealers

Abstract

A method and apparatus are described for diverting fluid when treating a subterranean formation penetrated by a well provided with casing having a plurality of perforations. Ball sealers having a density less than fluid in the casing are lowered down the casing between upper perforations and lower perforations. A screen means is positioned above the ball sealers to prevent upward migration of the balls to a level adjacent the upper perforations. A preferred screen means comprises a cage which is open at its lower end and has openings in its upper end which prevent passage of ball sealers therethrough and permits fluid flow down the casing and through the cage. The cage with the ball sealers therein is lowered down the casing by a conventional wireline. Once the cage and ball sealers are between the upper and lower perforations, a treating fluid more dense than the ball sealers is injected into the well to cause fluid flow. The treating fluid is caused to flow through the screen means to carry the ball sealers down the casing to plug the lower perforations while leaving the upper perforations open to fluid flow.

Dependencies are inferred from the claim text.