GB851700A - Method and apparatus for sealing water formations in a well - Google Patents

Abstract

851,700. Stabilizing earth formations. SHELL INTERNATIONALE RESEARCH MAATSCHAPPIJ N.V. July 20, 1959 [July 21, 1958], No. 24840/59. Class 68(1). A water formation traversed by a well borehole is sealed by lowering into the well, at the end of a pipe string, a predetermined volume of a sealing fluid in a container of drillable material, the container being positioned adjacent to the formation to be sealed and then subjected to fluid pressure applied through the pipe string sufficient to force the sealing material from the container into the annular space between the container and the wall of the well and into the said formation. Fig. 1 shows an arrangement for sealing a formation at the bottom of the borehole, the container 10 resting upon the bottom of the well and the weight or part of the weight of the drill string 15 compressing the packer 13. A sliding plug 23, preferably of rubber, is placed above the sealing fluid 22 and separates the pressure-applying fluid in the drill pipe therefrom. The pressure applied to the fluid 22 blows out plugs 20, 21 and the fluid passes into the annular space and the formation. The plug 23 seals the ports 16, 17 and prevents the superposed fluid, e.g., water from following the sealing fluid. The drill string 15 is unscrewed, either above or below the packer according to whether the threads 12 or 14 are left handed, and the sealing fluid is allowed to set around the container 10 which may be drilled away by a full-size bit, or may be allowed to remain if drilling is continued with a smaller bit. A ball is dropped through the string 15 to seat upon a valve plate 18 to prevent water from running out of the string as it is run out of the well. In Fig. 2, the apparatus is designed for sealing a formation above the bottom of the well. The packing means comprise a lower cup member 28 on the container 25, and an upper cup member 40 on a tube 36 connected by a bayonet joint 37, 38 with the container 25 and screwed into the drill string 47. To permit fluid in the well to escape as the string and container 25 are run in, the tube 36 has ports 41, 42 which are closed when the container 25 is adjacent to the formation to be sealed, by dropping a short tube down the drill string and thus striking the valve 43 down to rest upon stops 45. The resilient plug 35 may now be forced down by fluid pressure until it rests upon a grating 34 above the blow-out plug holes 32, 33. The short tube is closed by a dropped ball, the bayonet joint is uncoupled and the drill string and packer parts 36, 40 are withdrawn. The bayonet joint may be above the tube 36 if it is desired to leave this part in the well. Sealing fluids mentioned are resins, synthetic resins, plastics, synthetic plastics such as phenol formaldehyde, polyurethane, epoxy and ureaformaldehyde resins, silica gel, acrylamide gels and various gum solutions.