Method and apparatus for sealing pipe perforations

摘要

Ball sealers for flowing into casing perforation holes in a wellbore to selectively seal off those perforations receiving a disproportionately large amount of well treatment fluid being injected through the perforations. The ball sealers (22) are comprised of a spherical outer deformable shell (42) defining a central core portion filled with nondeformable particulate matter (46) which is sized small enough to flow with the shape of the deformable outer shell (42) and large enough so that as it consolidates under the force of fluid flow pressure, it will cause the outer shell to bridge over the perforation opening (18) when the force of fluid flowing into the casing (12) pushes the ball sealer (22) against and into the perforation opening (18). The particles (46) are also arranged so that when fluid flow is stopped into the casing and the fluid flow force is no longer applied to the ball seals, the particulate matter (46) will become unconsolidated to relax the bridge and permit the entrapped energy in the deformed outer shell (42) to expel the ball from the perforation opening.