Tubing & Casing Connection

Monday, September 21, 2009 by ShoXee

Tubing and Casing connection.

An oil field tubular connection is provided for joining metallic tubulars at a well site. At least one end of each tubular is provided with a frustoconical external sealing surface for metal-to-metal sealing engagement with a corresponding surface of an adjoining tubular. A plurality of antigalling grooves provided along the external sealing surface each project radially inward thereof and circumferentially encircle the threaded end of the tubular member and seal the groove from fluid communication with the interior of the tubular member. The antigalling grooves are particularly well suited for use with a low angular taper sealing surface of less than approximately 7 degree, and reduce galling between the metal sealing surfaces during makeup of the connection. Each tubular connection may also include an energizing groove spaced axially between the exterior sealing surface and the threads on the tubular member. The energizing groove receives excess thread lubricant, and has a uniform radial depth circumferentially about the tubular member for reducing the cross-sectional thickness of the tubular member, thereby allowing the exterior sealing surface to move radially outward in response to increased tubing pressure and allowing more flexibility for increased interference between the sealing surfaces during makeup of the connection.

Type of tubing connection:-

1) External upset.
2) Non-upset.
3) Flush Joint.

External Upset Tubing.

The external upset area near a tubing joint must achieve the structural integrity required to safely assemble the tubing string. In some cases, the upset area is used in handling the tubing string by providing a seat for the elevators. However, in many cases, special tubing elevators incorporating slips that engage on the external surface of the tubing wall are used to avoid excessive stresses in the tool-joint area.

Non-Upset Tubing

A non-upset tubing section, a tubular coupling, a connection for non-upset tubing sections, and a method for connecting the non-upset tubing section and the tubular coupling are disclosed. Methods for fabricating the non-upset tubing section and the tubular coupling are also disclosed. In one embodiment, the non-upset tubing section has an outer diameter of about 2 3/8 inches and, in another embodiment has an outer diameter of about 2 7/8 inches. The non-upset tubing section also has an externally tapered threaded surface having approximately eight rounded threads per linear inch. The tubular coupling has an outer diameter of about 2 7/8 inches, for use with at least one 2 3/8 inches OD tubing section, or about 3 1/2 inches, for use with at least one 2 7/8 inches OD tubing section. The coupling also has an internally tapered threaded surface having approximately eight rounded threads per linear inch and having a pitch diameter of about 2.258 inches for use with the 2 3/8 inches OD tubing section or about 2.729 inches for use with the 2 7/8 inches OD tubing section; Each pitch diameter is measured at a plane located about 1.250 inches from a plane located at a face of the coupling. To connect the non-upset tubing section with the tubular coupling, a thread compound is applied to either or both the threaded surface of the non-upset tubing section and the threaded surface of the tubular coupling. The non-upset tubing section is then inserted into one end of the coupling, and either the tubing section or the coupling is turned relative to its mating part until the non-upset tubing section and coupling reliably connect and seal.

Flush Joint Tubing

A type of tubing connection in which the internal or external surfaces are the same diameter throughout the tubing joint. Internal flush joints are most common, offering no restriction to fluid flow. Externally flush joints are typically used in more specialized applications, such as washover pipe for fishing operations, to allow adequate outer diameter (OD) clearance.

The TPS-MULTISEAL FLUSH JOINT Tubing and Casing connection is a non upset two step integral joint, suitable for use as liners and moderate depth casing. Characteristics:

-14° metal to metal internal pressure seal.
-30° metal to metal internal external pressure seal and torque shoulder.
-Completely flush OD and ID for maximum annular and running clearances.
-Pin and Box threads machined directly into pipe wall, no coupling required.
-Damaged threads can be simply cut off and remachined.
-Two step non tapered buttress type thread form.
-No thread intererence, so no tendency to thread galling.
-Stable two thread flank stabbing.
-Cannot be cross threaded.
-Fast make up.
-Integral connection halves the number of threaded connections (no mill connection).
-External pressure integrity in excess of pipe body.
-Repeatable sealing capability on multiple make and breaks.

Note: Some of the Flush Joint Tubing sometime is good for External sealing OD and internal sealing ID that the moving seal are can able to run thru without any interference on ID and OD but study with care is needed in the dimension.

-Disadvantage of using Flush joint tubing is it has lower tensile strength as compare to other type of tubing joint.
-Not for Hanging heavy hange weight, if really needed then the Well completion engineer have to be assure on the maximum hanging weight and the tensile strength of tubing joint.
-it normally come with thin wall.