BACKGROUND

[0001] This disclosure relates generally to connected expandable tubular members in a wellbore. In particular, this disclosure relates to the radial expansion of tubular members that are connected via a threaded connection offering improved efficiency as compared to conventional expandable threaded connections.

[0002] During hydrocarbon exploration, a wellbore typically traverses a number of zones within a subterranean formation. Wellbore casings are then formed in the wellbore by radially expanding and plastically deforming tubular members that are coupled to one another by threaded connections. In certain wellbore environments, existing apparatus and methods for coupling together and radially expanding tubular members may not be suitable.

[0003] For example, a series of expanded tubular members can be subjected to elevated axial loads during installation, under pressure loading, even when subjected to significant temperature (e.g., 300 degF) during certain wellbore operations. The maximum axial load that can be applied to a series of expanded tubular members is, in most instances, limited by the threaded connections between adjacent tubular members. To quantify the performance of an expandable threaded connection, connections are often referred to as having an efficiency, which is defined as the tensile rating of the connection divided by the tensile rating of the base tubular.

[0004] Upsetting has been used on non-expandable tubulars to increase the efficiency of threaded connections. Upsetting is a known forging process that is used to make thicker walls at the end sections of a tubular. The threads of the connection are then machined out of the end sections of the tubular that have thicker walls. The thickness added by upsetting leaves more material after the threads are machined than without upsetting, and the efficiency of the connection is increased.

[0005] When the added wall thickness is obtained by only increasing the outer diameter of the end sections of the tubular, the upset is an External Upset (EU). When the added wall thickness is obtained by only decreasing the inner diameter of the end sections of the tubular, the upset is called an Internal Upset (IU). The added wall thickness can also be obtained by increasing the outer diameter of the end sections of the tubular as well as decreasing the inner diameter of the end sections of the tubular, sometimes requiring two hits (strikes) to form the upset. In these cases, the upset is called an Internal-External Upset (IEU). Sometimes it takes two hits (strikes). Upsetting is thus expensive to operate. Further, once upset, the tubulars are heat treated to a desired grade. Heat treating to treat the tubulars after upsetting is also expensive.

[0006] In addition to cost, upsetting may present several challenges specific to expandable tubulars. One challenge may be that the thicker wall will increase the force required to expand the connection to a level that may be much higher than the force required to expand the base tubular. Another challenge may be that the thicker wall may not expand uniformly, and thus, the expansion may hinder the connection performance, such as its capability to seal. Yet another challenge may be that the thicker wall may interfere with the inner diameter of the casing or hole into which the tubulars are expanded. Interference with the inner diameter of the casing or hole could drive up the expansion force to an undesirable value.

[0007] Thus, there is a continuing need in the art for methods and apparatus for connecting expandable tubular members that provide increased efficiency and ability to handle increased tensile loads in the well.

SUMMARY

[0008] This disclosure describes a method of making an expandable tubular assembly having an expandable threaded connection and/or a wellbore casing.

[0009] The method may comprise the step of forming an upset end of a first tubular member. The upset end of the first tubular member may have a wall thickness that is greater than a wall thickness of a main body of the first tubular member. The method may further comprise heat treating the first tubular member after forming the upset end.

[0010] The method may comprise the step of enlarging an inner diameter of an end section of the first tubular member such that the end section has a second inner diameter that is greater than a first inner diameter of the main body of the first tubular member. For example, the second inner diameter may be at least 103% of the first inner diameter. Enlarging the inner diameter of the end section of the first tubular member may be performed by subtractive manufacturing. [0011] The method may comprise the step of machining a threaded pin end on the end section of the first tubular member. Machining the threaded pin end may be performed by subtractive manufacturing. The subtractive manufacturing may leave a distance between the minor diameter of the threads and the second inner diameter of at least 75% of the wall thickness of the main body of the first tubular member.

[0012] The method may further comprise the step of forming an upset end of a second tubular member. The upset end of the second tubular member may have a wall thickness that is greater than a wall thickness of a main body of the second tubular member. The method may further comprise heat treating the second tubular member after forming the upset end.

[0013] The method may comprise the step of enlarging an inner diameter of an end section of the second tubular member such that the end section has a second inner diameter that is greater than a first inner diameter of the main body of the second tubular member. For example, the second inner diameter may be at least 103% of the first inner diameter. Enlarging the inner diameter of the end section of the second tubular member may be performed by subtractive manufacturing.

[0014] The method may comprise the step of machining a threaded box end in the end section of the second tubular member. Machining the threaded box end may be performed by subtractive manufacturing. The subtractive manufacturing may leave a distance between the major diameter of the threads and an outer diameter of the upset end of the second tubular member of at least 75% of the wall thickness of the main body of the second tubular member.

[0015] The method may comprise forming an expandable assembly having an expandable threaded connection by engaging the threaded box end and the threaded pin end. The expandable connection has an efficiency greater than 90%. The threaded pin end or the threaded box end may include at least two grooves to accommodate sealing members.

[0016] The method may comprise making a casing in a wellbore by disposing the expandable assembly in the wellbore; and moving an expansion cone longitudinally through the first tubular member, the expandable threaded connection, and the second tubular member so as to radially expand the first inner diameter and the second inner diameter to an expanded inner diameter. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] For a more detailed description of the embodiments of the present disclosure, reference will now be made to the accompanying drawings, wherein:

[0018] Figure 1 is a partial cross-sectional view of an expandable tubular member.

[0019] Figure 2 is a partial cross-sectional view of an expandable threaded connection in an unexpanded condition.

[0020] Figure 3 is a partial cross-sectional view of an expandable threaded connection in an expanded condition.

[0021] Figures 4A-4C are partial sectional views of a box end of an expandable tubular illustrating steps of a method of making the box end of the expandable tubular.

[0022] Figure 5 is a partial sectional view of a pin end of an expandable tubular illustrating a final step of a method of making the pin end of the expandable tubular.

DETAILED DESCRIPTION

[0023] It is to be understood that the following disclosure describes several exemplary embodiments for implementing different features, structures, or functions of the invention. Exemplary embodiments of components, arrangements, and configurations are described below to simplify the present disclosure; however, these exemplary embodiments are provided merely as examples and are not intended to limit the scope of the invention. Additionally, the present disclosure may repeat reference numerals and/or letters in the various exemplary embodiments and across the Figures provided herein. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various exemplary embodiments and/or configurations discussed in the various figures. Moreover, the formation of a first feature over or on a second feature in the description that follows may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed interposing the first and second features, such that the first and second features may not be in direct contact. Finally, the exemplary embodiments presented below may be combined in any combination of ways, i.e., any element from one exemplary embodiment may be used in any other exemplary embodiment, without departing from the scope of the disclosure. [0024] Additionally, certain terms are used throughout the following description and claims to refer to particular components. As one skilled in the art will appreciate, various entities may refer to the same component by different names, and as such, the naming convention for the elements described herein is not intended to limit the scope of the invention, unless otherwise specifically defined herein. Further, the naming convention used herein is not intended to distinguish between components that differ in name but not function. Additionally, in the following discussion and in the claims, the terms "including" and "comprising" are used in an open-ended fashion, and thus should be interpreted to mean "including, but not limited to." All numerical values in this disclosure may be approximate values unless otherwise specifically stated. Accordingly, various embodiments of the disclosure may deviate from the numbers, values, and ranges disclosed herein without departing from the intended scope. Furthermore, as it is used in the claims or specification, the term "or" is intended to encompass both exclusive and inclusive cases, i.e., "A or B" is intended to be synonymous with "at least one of A and B," unless otherwise expressly specified herein.

[0025] Referring initially to Figure 1, an expandable tubular 10 comprises a main body 12 having a threaded box end 14 and a threaded pin end 16. The main body 12 has an unexpanded inner diameter 18 and a wall thickness 20. The box end 14 and pin end 16 are disposed on sections of the tubular that are "upset" from the main body 12 and have an unexpanded outer diameter 22 that is greater than the outer diameter of the main body 12. The box end 14 and pin end 16 also have a nominal wall thickness 24 that may be greater than the wall thickness 20 of the main body 12. The box end 14 includes threads 26 formed on its inner surface that are configured to engage with threads 28 formed on the outer surface of the pin end 16. The threads 26, 28 may be any threads suitable for use with expandable tubulars. In certain embodiments, the box end 14 and/or pin end 16 may include grooves to accommodate sealing members (e.g., O-rings) or other features to facilitate sealing engagement of the expandable tubulars 10.

[0026] Figure 2 shows the box end 14 of one expandable tubular 10A engaged with the pin end 16 of another expandable tubular 10B to form an expandable tubular assembly 30. The coupled box end 14 and pin end 16 form an expandable threaded connection within an upset section 32 that has an inner diameter 34 that is larger than the inner diameter 18 of the main bodies 12. Upset section 32 also has an outer diameter 36 that is larger than the outer diameter of the main bodies 12. [0027] In operation, an expansion cone (not shown) having an expansion diameter that is greater than both inner diameter 18 and inner diameter 34 is moved axially through the tubular assembly 30 so as to radially expand the tubular member 10B, the upset section 32, and then tubular member 10A. As shown in Figure 3, once the expansion is complete, the now expanded tubular assembly 30, including the upset section 32, has a substantially uniform inner diameter 40. The thickness of the wall section 42 of the expanded upset section 32 may remain greater than the wall thickness of the main bodies of the tubulars, thus providing added strength in the connection. Because the expansion diameter of the expansion cone is larger than both inner diameter 18 of the main bodies 12 and inner diameter 34 of the upset section 32, both unexpanded inner diameters are expanded to the same expanded inner diameter 40.

[0028] By forming the threaded connections on upset portions of the tubular having wall thicknesses greater than the thickness of tubular' s main body, the disclosed embodiment that provides a threaded connection that has a thicker wall section 42 as compared to conventional expandable flush-joint connections without an unacceptable increase in the expansion forces needed to expand the threaded connection. Therefore, the disclosed embodiments provide greater resistance to tensile loads, and therefore a greater efficiency, as compared to conventional expandable threaded connections.

[0029] Figure 4 A illustrates, in ghost lines, a portion of the tubular member 10A before the step of forming an upset end, and in solid lines, the portion of the tubular member 10A after the step of forming the upset end. The upset end of the tubular member 10A has a wall thickness 38 that is greater than the wall thickness 20 of the main body 12 of the tubular member 10A. As shown, the upset is an Internal -External Upset (TEU). The tubular member 10A is preferably heat treated after forming the upset.

[0030] Figure 4B illustrates the portion of the tubular member 10A shown in Figure 4 A after the step of enlarging an inner diameter of an end section of the tubular member 10A, such that the end section has the second inner diameter 34, which is greater than the first inner diameter 18 of the main body 12. As shown, the enlargement of the inner diameter of the end section has been performed by subtractive manufacturing (e.g., by cutting, milling or grinding). The second inner diameter 34 is preferably at least 103% of the first inner diameter 18. [0031] Figure 4C illustrates the portion of the tubular member 10A shown in Figure 4B after the step of machining a threaded box end 14 in the end section of the tubular member 10A. Only one thread is illustrated for the sake of simplicity, but several threads are usually machined. As shown, the machining of the threaded box end 14 is performed by subtractive manufacturing. The subtractive manufacturing may leave a distance 44 between the major diameter of the threads and an outer diameter of the upset end of the tubular member 10A of at least 75% of the wall thickness 20 of the main body 12. The threaded box end 14 preferably includes at least two grooves to accommodate sealing members (e.g., O-rings). Such example configuration permits that the expandable connection remains sealed after radial expansion.

[0032] The pin end 16 of the tubular member 10B may be made using steps initially similar to the process illustrated in Figures 4A and 4B, that is, an upset end may be formed on the tubular member 10B, such that the upset end has a wall thickness that is greater than the wall thickness of the main body 12 of the tubular member 10B, and the tubular member 10B is preferably heat treated after forming the upset. Further, an inner diameter of an end section of the tubular member 10B is also enlarged, for example by subtractive manufacturing, such that the second inner diameter 34 is preferably at least 103% of the first inner diameter 18.

[0033] Figure 5 illustrates a portion of the tubular member 10B after the step of machining a pin end 16 in the end section of the tubular member 10B. Again, only one thread is illustrated for the sake of simplicity, but several threads are usually machined. As shown, machining the threaded pin end 16 has been performed by subtractive manufacturing. The subtractive manufacturing preferably leaves a distance 46 between the minor diameter of the threads and the second inner diameter of at least 75% of the wall thickness 20 of the main body 12.

[0034] The wall section 42 of the threaded connection (shown in Figure 3) has a thickness that is the sum of the distance 44 (shown in Figure 4C) and the distance 46 (shown in Figure 5). Accordingly, the wall section 42 may have a thickness of at least 150% of the nominal wall thickness 20.

[0035] While the disclosure is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and description. It should be understood, however, that the drawings and detailed description thereto are not intended to limit the disclosure to the particular form disclosed, but on the contrary, the intention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the present disclosure.