Pipe joints or couplings – Particular interface – Annular socket
Reexamination Certificate
2002-05-22
2004-03-30
Nicholson, Eric K. (Department: 3679)
Pipe joints or couplings
Particular interface
Annular socket
C285S333000, C285S390000, C285S382000, C285S334000
Reexamination Certificate
active
06712401
ABSTRACT:
The invention relates to a threaded tubular connection that can undergo plastic deformation by diametrical expansion and to the connection obtained after such expansion.
Threaded tubular connections are known that are formed between two great-length pipes or between a great-length pipe and a coupling and used in particular to produce casing strings or tubing strings for hydrocarbon wells or the like, such as those for geothermal wells.
Traditionally, wells are drilled with tools of different diameters, the top of the well being drilled using a large diameter tool, of the order of 500 mm, for example, while the well bottom is drilled at a smaller diameter, of the order of 150 mm. The wells are then cased using a plurality of concentric strings all suspended from the surface, pipes with the larger diameter extending from the surface to a depth of a few hundred meters and the smaller diameter pipes extending from the surface to the bottom of the well. The space between the casing pipes and the ground is generally cemented.
When the well is completely drilled and cased, a tubing string is lowered inside the smaller diameter casing string to allow hydrocarbons to rise to the surface.
Thus, fitting a well requires the use of a large number of pipes of different dimensions that are as thin as possible so as not to require too large a casing pipe diameter near the surface.
Taking into account the required mechanical characteristics, casing pipes and production pipes are generally produced from heat treated steel and are connected together by threaded connections, the thickness of the threaded connections being generally larger than that of the regular portion of the pipes and necessitating gaps in the diameters between the concentric strings.
API specification 5 CT from the American Petroleum Institute defines threaded tubular connections between great-length pipes (integral joint tubing, extreme line casing) and threaded and coupled connections comprising two threaded connections for connecting two great-length pipes using a coupling.
A number of patents have improved such connections and threaded connections: For example French patent FR 1 489 013, European patent EP 0 488 912 and U.S. Pat. No. 4,494,777 have aimed to produce threaded tubular connections known as “premium” connections with a particularly good seal thanks to metal—metal sealing surfaces and abutments between the male and female elements.
Very recently, new ways of using tubular strings in hydrocarbon wells have been considered, consisting of expanding the diameter of the pipes in the string by 10% to 20% using a mandrel forced through the inside of the column: see patents or patent applications: WO 93/25799, WO 98/00626, WO 99/06670, WO 99/35368, WO 00/61915, GB 2 344 606 and GB 2 348 657.
Such expansion can, for example, allow a casing string to be placed without having to cement the space between the external peripheral surface of the pipes and the surface of the hole drilled in the ground or lowering a string with a low bulk with respect to the hole.
Such expansion can also enable to plug holes in a casing or tubing pipe perforated by corrosion or by friction of the drilling strings, or to lower pipes with a low bulk which will be expanded to the desired diameter once in position.
However, the expansion technique can above all allow wells to be drilled that have a uniform diameter over their entire length and casing can be carried out using a string with a constant diameter, the pipes being introduced in the unexpanded state then expanded in situ to the diameter of the well.
It is then possible to substantially reduce the number of pipes required to fit a well by doing away with the largest diameter and thickest pipes, and thus reducing the cost of the well. It can even be thought of drilling a well directly with the casing string, which would then act as the drilling string.
However, prior art threaded tubular connections such as those described in U.S. Pat No. 4,494,777 do not allow such uses.
With such connections, after expansion:
an absence of a seal is observed which in particular prevents expansion from being carried out by hydraulically forcing the mandrel along the column;
sprue is observed from the male end towards the interior of the connection, which considerably and unacceptably reduces the operational internal diameter of the string by producing an internal projection into the space defined by the operational internal diameter;
possibly, the lip may be observed to break by exceeding the deformation capacity of certain particularly highly stressed zones due to variations in thickness along the male and female elements with respect to the thickness of the pipe body.
For this reason, the documents cited above dealing with expansion techniques only describe welded connections (coils of pipes previously butt-welded, deployed from the surface) or friction connections (“slips”) as embodiments of the connections between the pipes, while threaded connections are known for their performance combining mechanical strength, a seal under all service conditions and the possibility of making a series of consecutive makeup-breakout trips.
It should be noted that U.S. Pat. No. 5,924,745 and WO 98/42947 describe threaded connections for connecting pipes known as “EST” pipes (expansible slotted tubing) provided with longitudinal slots allowing the pipes at the bottom of the hydrocarbon production wells to be expanded diametrically by passing an expansion mandrel through those pipes. Such threaded connections are not aimed at providing a seal, given that the pipes are provided with slots traversing the wall of the pipes and allowing a fluid that is outside the pipe (hydrocarbon from the field) to enter the pipe and rise to the surface therein.
We have thus sought to develop a threaded tubular connection that can resist the expansion operation in the well and which is tight to liquids and if possible to gases after said expansion operation.
We have also sought a simple, cheaply produced threaded tubular connection.
We have also sought a threaded connection with good metallurgical characteristics under operational conditions and thus, after expansion, with a sufficient yield strength in that condition, and free of brittleness and with good sulphide stress cracking characteristics.
In accordance with the present invention, the threaded tubular connection for expansion comprises a male threaded element with an external male threading at the end of a first pipe and a female threaded element with an internal female threading at the end of a second pipe.
Beyond the male threading and moving towards the free end of the element, the male threaded element comprises a male, non threaded lip with an external peripheral surface and terminates in a male end surface that is annular in shape and with a partially transverse orientation.
The female threaded element comprises a female threading that mates with the male threading and a non-threaded female housing for the male lip. This housing comprises an internal peripheral surface and a female shoulder surface that is annular in shape and with a partially transverse orientation connected to the internal peripheral surface of the second pipe.
The male threading is made up into the female threading to a position in which the surface of the male end is engaged against the surface of the female shoulder.
In accordance with a general characteristic of the invention rendering the threaded tubular connection capable of being sealed and of having a maximum internal cross section for passage after having undergone diametrical expansion in the plastic deformation region, the male end and female shoulder surfaces have complementary shapes producing, before expansion, embedding of the male end surface in that of the female shoulder.
Further, the external peripheral surface of the male lip is disposed with a small clearance from the internal peripheral surface of the female housing.
Embedding of the male end surface in that of the female shoulder means a bending moment on the free end of the male li
Coulon Jean-Luc
Noel Thierry
Roussie Gabriel
Varenne Emmanuel
Nicholson Eric K.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Vallourec Mannesmann Oil & Gas France
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