Abstract: Methods and apparatus for creating a downhole buoyant casing chamber. The buoyant casing chamber may be created after the casing has been at least partially run into the wellbore. Some embodiments also allow circulation of fluid as the casing is being run after the creation of the buoyant chamber. A method of the invention comprises running a length of casing into the well to a first step, forming a buoyant chamber in the casing, filling the chamber with buoyant fluid, either a gas or a light liquid, and running the casing to a second depth greater than the first depth. The apparatus used comprises a length of casing, a floating device disposed in a lower end of the casing and forming a lower boundary of a buoyant chamber, a packer for sealingly engaging the casing in an upper end of the buoyant chamber, and a volume of buoyant fluid to fill the chamber.

Abstract: Methods and apparatus for creating a downhole buoyant casing chamber. The buoyant casing chamber may be created after the casing has been at least partially run into the wellbore. Some embodiments also allow circulation of fluid as the casing is being run after the creation of the buoyant chamber. A method of the invention comprises running a length of casing into the well to a first step, forming a buoyant chamber in the casing, filling the chamber with buoyant fluid, either a gas or a light liquid, and running the casing to a second depth greater than the first depth. The apparatus used comprises a length of casing, a floating device disposed in a lower end of the casing and forming a lower boundary of a buoyant chamber, a packer for sealingly engaging the casing in an upper end of the buoyant chamber, and a volume of buoyant fluid to fill the chamber.

Abstract: Methods and apparatus for creating a downhole buoyant casing chamber. The buoyant casing chamber may be created after the casing has been at least partially run into the wellbore. Some embodiments also allow circulation of fluid as the casing is being run after the creation of the buoyant chamber. A method of the invention comprises running a length of casing into the well to a first step, forming a buoyant chamber in the casing, filling the chamber with buoyant fluid, either a gas or a light liquid, and running the casing to a second depth greater than the first depth. The apparatus used comprises a length of casing, a floating device disposed in a lower end of the casing and forming a lower boundary of a buoyant chamber, a packer for sealingly engaging the casing in an upper end of the buoyant chamber, and a volume of buoyant fluid to fill the chamber.

Abstract: Methods and apparatus for creating a downhole buoyant casing chamber. The buoyant casing chamber may be created after the casing has been at least partially run into the wellbore. Some embodiments also allow circulation of fluid as the casing is being run after the creation of the buoyant chamber. A method of the invention comprises running a length of casing into the well to a first step, forming a buoyant chamber in the casing, filling the chamber with buoyant fluid, either a gas or a light liquid, and running the casing to a second depth greater than the first depth. The apparatus used comprises a length of casing, a floating device disposed in a lower end of the casing and forming a lower boundary of a buoyant chamber, a packer for sealingly engaging the casing in an upper end of the buoyant chamber, and a volume of buoyant fluid to fill the chamber.

Abstract: Methods and apparatus for creating a downhole buoyant casing chamber. The buoyant casing chamber may be created after the casing has been at least partially run into the wellbore. Some embodiments also allow circulation of fluid as the casing is being run after the creation of the buoyant chamber. A method of the invention comprises running a length of casing into the well to a first step, forming a buoyant chamber in the casing, filling the chamber with buoyant fluid, either a gas or a light liquid, and running the casing to a second depth greater than the first depth. The apparatus used comprises a length of casing, a floating device disposed in a lower end of the casing and forming a lower boundary of a buoyant chamber, a packer for sealingly engaging the casing in an upper end of the buoyant chamber, and a volume of buoyant fluid to fill the chamber.

Abstract: Methods and apparatus for creating a downhole buoyant casing chamber. The buoyant casing chamber may be created after the casing has been at least partially run into the wellbore. Some embodiments also allow circulation of fluid as the casing is being run after the creation of the buoyant chamber. A method of the invention comprises running a length of casing into the well to a first step, forming a buoyant chamber in the casing, filling the chamber with buoyant fluid, either a gas or a light liquid, and running the casing to a second depth greater than the first depth. The apparatus used comprises a length of casing, a floating device disposed in a lower end of the casing and forming a lower boundary of a buoyant chamber, a packer for sealingly engaging the casing in an upper end of the buoyant chamber, and a volume of buoyant fluid to fill the chamber.

Abstract: The present invention relates to reverse-cementing apparatus. The reverse-cementing apparatus is a float apparatus connected in a pipe string to be cemented into a wellbore. The float apparatus includes an outer housing connected to the casing string. A check valve for preventing flow from the wellbore into the pipe string is disposed in the housing. The check valve is releasably disposed in the housing so that it can be removed from the housing once the pipe string is in place. A flow path for fluid from the wellbore into the pipe string is therefore provided. Cement displaced into the annulus will cause fluid in the wellbore to enter the pipe string through the housing so that the pipe string can be cemented in place utilizing a reverse-cementing method.

Abstract: The present invention provides an improved subsurface release cementing plug apparatus for use in a string of pipe during the cementing of the pipe in a well bore. The apparatus includes a hollow cementing plug seat member adapted to be connected in the string of pipe near the bottom thereof and a cementing plug assembly releasably connectable to a circulation tool or casing running tool in the top of the string of pipe. The cementing plug assembly includes a top cementing plug having an external annular seating surface formed thereon for sealingly engaging a top internal annular seating surface of the cementing plug seat member, and a bottom cementing plug releasably connected to the top cementing plug having an external annular seating surface formed thereon for engaging a bottom internal annular seating surface of the cementing plug seat member.

Abstract: An improved well cementing plug assembly adapted to be connected to a string of drill pipe or a circulation tool for use in a pipe during the cementing of the pipe in a well bore is provided. The top and bottom plugs are selectively releasable by activating balls dropped into the plug assembly. Different sizes of plugs can be used utilizing the same inner tubes and other assembly parts, and the top plug slides on its inner tube when a pressure differential is exerted on it thereby insuring a seal between the top and bottom plugs when the plugs are landed on a float shoe or the like.

Abstract: Floating apparatus for well casing including a check valve disposed in a sleeve, wherein the sleeve is receivable within an outer case. In the case of a float collar, the outer case comprises coupled upper and lower casing string sections; while in the case of a float shoe, the outer case is individually coupled to a lower casing string section. The valve includes a valve housing, wherein a first cement body portion attaches the valve housing to the sleeve. When the embodiment of the invention is constructed as a float collar, the sleeve includes an annular flange that is outwardly extended therefrom and is received between ends of coupled upper and lower casing string sections for holding the sleeve and affixed valve within the outer case. A seal is provided between the flange and upper casing string section.

Abstract: Improved well casing fill apparatus and methods for filling a casing string with well bore fluid while running the string into a well bore and then cementing the casing in the well bore are provided. A well casing fill apparatus of this invention is basically comprised of a tubular housing having a well bore fluid fill port extending through a wall thereof and a closing sleeve slidably disposed in the tubular housing between an upper open position whereby the fill port is uncovered to a lower closed position whereby the closing sleeve covers the fill port. The closing sleeve includes a cementing plug landing seat thereon for receiving a cementing plug and slidably moving the closing sleeve to the closed position.

Abstract: A floating apparatus for use in a casing string. The apparatus includes an outer sleeve having a check valve centrally positioned therein. A body portion, which may be comprised of high compressive strength cement, is affixed to the check valve and the housing. The body portion has an upper end and a lower end. An upper seal is disposed above the upper end of the body and sealingly engages the housing and the outer sleeve. A lower seal is disposed in the sleeve below the lower end of the body portion, and sealingly engages the valve housing and the outer sleeve, so that fluid flowing through the outer sleeve cannot communicate with the body portion.

Abstract: A metal-to-metal annular seal for use in downhole tools which may include annular elastomeric backup seals. In each embodiment, a sealing member has a pair of annular frusto-conical lips adapted for sealing engagement with a cylindrical sealing surface on a member of a downhole tool. The sealing member may be a separate component or an integral part of another member of the downhole tool. A seal energizing member may be used.