FIELD OF INVENTION

The present invention relates to a tubular gripping die that optimizes both torque and axial load holding capability. The invention makes possible combined loading into a single tool and die arrangement. The invention also relates to methods of manufacture of said dies.

BACKGROUND OF THE INVENTION

Conventional dies used to grip tubulars for handling applications present the die tooth pattern in a manner which optimizes the axial load needed to restrain the tubular from axial movement. By contrast the tooth pattern presented in a torqueing application present the die teeth in a pattern that is optimized to restrain rotational movement.

There are two primary means to optimize the die's performance; either increased penetration depth of the dies or increased surface contact between the dies and the tubular. Increased penetration depth is not favored as deformation on the tubular body caused by the penetration of the die teeth decreases the usefulness of the tubular.

As seen in Figures 3a and 3b, conventional torqueing dies are typically produced with the die tips flat across, that is, the front face of the die is flat and parallel to the typically flat back of the die. This shape is inexpensive to produce. In use, it is common for the central teeth on the die to contact the tubular while teeth closer to the outer edges of the torqueing die to not make contact with the curved surface of the tubular.

As seen in Figures 2a, 2b and 2c, handling tool dies are generally constructed in a manner which produces a radial die tip pattern, in which the front face of the die is concavely curved to at least somewhat match the tubular outside diameter (OD) and in turn increase the die tip-to-tubular contact area. This is done to maximize contact surface and reduce the bite penetration into the tubular while still being able to grip very heavy tubular string weight which can be greater than 1000 tons. The curved front face also increased the points of contact around the tubular, thereby applying more even radial loads, reducing hoop stresses and reducing the chances of deformation to the tubular. Dies that are used in conventional handling tools apply a specific radial load into the dies which allow for pre-loading the teeth of the die into the tubular for initial bite. Torqueing systems generate a much greater radial load per area of die-tubular contact and the load is often driven higher as torque is applied.

Tubular string is made up by connecting tubular joints; a tubular string can similarly be taken apart by breaking out the tubular joints. These are typically defined as handling applications. In both cases, one joint is rotated to either thread it into the existing tubular string in make up, or to thread the joint out of the tubular string for break out.

At the initial stages of make up or the late stages of break out, the tubular string comprises very few tubular joints and carries very little string weight. As a result, any rotation of a joint for make up into or break out of the string tends to translate into the string itself and causes the string to rotate as well. In this case, the handling dies are not designed to handle torque. The situation requires the use of a back up tong to hold the tubular string in place so that a tubular joint can be rotated either into or off of the tubular strings.

While torqueing dies are used for particular applications that are very different than handling applications, there is still a need to grip tubulars against torqueing and rotation for at least a portion of handling operations.

SUMMARY

A tubular gripping die is presented, the die comprising one or more axial load teeth and one or more torqueing teeth.

A method of manufacturing a tubular gripping die is also presented. The method comprising the steps of: a) forming one or more axial load teeth extending from a base of the die; b) forming one or more torqueing teeth extending from the base of the die; and c) defining a gripping front face of the die, at least a portion of the gripping front face having a concave curvature to align with an outside diameter of the tubular to be gripped

The portion of the gripping front face formed with the curvature comprises any one of said axial load teeth, said torqueing teeth or both. A method of making up a tubular string from a plurality of tubular joints is also presented. The method comprising the steps of:

a) gripping a tubular string comprising one or more joints of tubular at an uphole end of the tubular string with a handling tool, said handling tool comprising one or more dies, each die comprising one or more axial load teeth and one or more torqueing teeth arranged thereon, b) threading a subsequent tubular joint into the uphole end of the tubular string; c) preventing rotation of the tubular string by the gripping action of the one or more torqueing teeth; d) simultaneously supporting weight of the tubular string by the gripping action of the one or more axial load teeth;

The step of preventing rotation of the tubular string is performed in the absence of the use of a backup tong to grip the tubular string.

A tubular handing tool comprising one of more tubular gripping dies, each die comprising one or more axial load teeth and one or more torqueing teeth arranged thereon.

It is to be understood that other aspects of the present invention will become readily apparent to those skilled in the art from the following detailed description, wherein various embodiments of the invention are shown and described by way of illustration. As will be realized, the invention is capable for other and different embodiments and its several details are capable of modification in various other respects, all without departing from the spirit and scope of the present invention. Accordingly the drawings and detailed description are to be regarded as illustrative in nature and not as restrictive.

BRIEF DESCRIPTION OF THE DRAWINGS

A further, detailed, description of the invention, briefly described above, will follow by reference to the following drawings of specific embodiments of the invention. The drawings depict only typical embodiments of the invention and are therefore not to be considered limiting of its scope. In the drawings:

Figures la to lb are end elevation and top plan views respectively of one embodiment of the tubular gripping die of the present invention; Figures 2a to 2c are end elevation, top plan and side elevation views of one example of a prior art axial load die;

Figures 3a to 3b are end elevation, top plan and side elevation views of one example of a prior art torqueing die; Figure 4 is a side perspective view of one example of a tubular gripping die of the present invention;

Figure 5 is a top plan view of the tubular gripping die of Figure 4;

Figure 6A is a side elevation cross sectional view taken along line A-A of Figure 5;

Figure 6B is an end elevation cross sectional view taken along line B-B of Figure 5;

Figure 6C is an end elevation cross sectional view taken along line C-C of Figure 5; Figure 6D is a side elevation view of the tubular gripping die of Figure 5;

Figure 7 is a top perspective view of one example of a tubing handling tool fitted with one example of the tubular gripping dies of the present invention; and

Figure 8 is a side elevation view of a tubular that has been marked by tubular gripping dies of the present invention. The drawing is not necessarily to scale and in some instances proportions may have been exaggerated in order more clearly to depict certain features.

DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS

The description that follows and the embodiments described therein are provided by way of illustration of an example, or examples, of particular embodiments of the principles of various aspects of the present invention. These examples are provided for the purposes of explanation, and not of limitation, of those principles and of the invention in its various aspects.

The present invention seeks to provide a solution to the problem of gripping against tubular torqueing and rotation in handling applications by providing a die that is optimized for both axial load carrying and high torque applications when used with equal radial load applied to the die. In a preferred embodiment, the die presents horizontal teeth for handling the weight of the tubular string and also presents at least a portion of the die with vertical teeth to grip for torqueing applications. For the purposes of the present invention, the term 'horizontal' is understood to mean a direction parallel to a circumference of the tubular being handled; the term 'vertical' is understood to mean a direction parallel to an axis of the tubular being handled. The ratio between horizontal and vertical teeth and the location and arrangement of vertical and horizontal teeth can be optimized for a static radial load applied so that both torque and axial loading conditions can be achieved.

Unlike an arrangement of alternating rows of torqueing dies and axial load dies in a handling tool, the present system only requires one die type be kept on site, and not onsite supplies of both types of dies. The present dies require no specific arrangement of dies within a handling tool, and are not limited to a 50/50 ratio of torqueing dies to axial load dies. The inventors have further found that the present dies can manage greater radial loads than conventional handling tools with a 50-50 ratio of alternating dedicated dies. Furthermore, as discussed in further detail below, the flat teeth tips of conventional torque dies lead to less control in penetration depth. Additionally, conventional dedicate torqueing dies and axial load dies have varying thicknesses that result in one of the two types dies touching and gripping the tubular while the other die type may not. The two different dies are produced in different machines at different times. Even if the two types of dies were designed to the same thickness there would be variation in thickness within the allowed tolerance. By forming a die with both types of teeth arranged on the same die, this difference in thickness and contact is eliminated.

Use of the present tubular gripping dies can eliminate the need for a back up tong in initial make up or later break out operations.

With reference to the figures and particularly Figures la, lb, 4, 5, 6A-6D and 7, the present die 100 is uniquely manufactured with a series of axial load teeth 4 and a series of torqueing teeth 6. The teeth 4, 6 define a gripping front face 2 that is preferably concave to correspond to the outside diameter of a tubular to be handled. Any one of or both the axial teeth 2 and torqueing teeth 4 can be arranged to define the concave front face 2. In a most preferred embodiment, both axial load teeth 4 and torqueing teeth 6 are arranged to define the concave curvature of the front face 2. In one preferred embodiment, as seen in Figure 6B, the concavity of the front face 2 is achieved in the section of the torqueing teeth 6 by means of machining the torque teeth 6 such that one or more torque teeth 6 near an outer edge 8 of the die extend further than one or more torque teeth 6 near a central portion 10 of the die 100. However, it would be understood by a person of skill that a number of other methods of manufacturing the die 100 with a concave front face 2 with respect to the torque teeth 6 are possible. For example, it is possible that a base 12 from which the teeth 4, 6 extend can itself have a concave curved orientation from which all torqueing teeth 6 extend equally. Such curvature in the base 12 can be seen, for example in figure 6C in relation to the axial load teeth 4.

Similarly, while figure 6C shows the axial load teeth 4 extending equally from a curved base 12, it is also possible for the base 12 to be flat in the section of the axial teeth 4 and for axial teeth 4 in rows near the outer edge 8 of the dielOO to extend further than one or more rows of axial load teeth 4 in a central portion 10 of the die. It would be well understood that both torqueing teeth 6 and axial load teeth 4 are formed integrally from the die body, and hence the base 12 is merely a point of reference indicating where the teeth 4, 6 extend from and does not suggest that the teeth 4, 6 are in any way a separate piece or material from the die body.

By providing a curved gripping front face 2 to both torqueing teeth 6 and axial load teeth 4 of the die 100, contact surface and in turn gripping force overall is increased without the need for increasing the bite of the teeth.

Furthermore, by increasing surface contact of the dies 100 into the tubular to be gripped, the dies of the present invention can provide the initial bite and steady and equal radial loading needed for axial load handling while also providing the high gripping force needed for steadily increasing torqueing loads. While the figures illustrate a configuration in which the axial load teeth 4 are composed of three rows of teeth and the torqueing teeth 6 are composed of four teeth, it would be well understood that any number of rows of teeth 4, 6 and any number of teeth 4, 6 may be arranged without departing from the scope of the invention. Since the dies 100 of the present invention are formed with both axial load teeth 4 and torqueing teeth 6 they can grip a tubular string against rotation and torqueing forces during make up and break out. The present dies can reduce or eliminate the need for a backup tong, which in turn reduces the number of pieces of equipment needed on the rig floor as well as reducing set up times and reducing safety hazards caused by extra equipment on the rig floor.

The present dies have been seen to handle up to 50,000 ft-lb of torque without the need for a backup tong. Figure 7 illustrates an example of a tubular handling tool with the dies of the present invention installed therein. Figure 8 shows a tubular marked from being gripped by dies of the present invention.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to those embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein, but is to be accorded the full scope consistent with the claims, wherein reference to an element in the singular, such as by use of the article "a" or "an" is not intended to mean "one and only one" unless specifically so stated, but rather "one or more". All structural and functional equivalents to the elements of the various embodiments described throughout the disclosure that are known or later come to be known to those of ordinary skill in the art are intended to be encompassed by the elements of the claims. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims. No claim element is to be construed under the provisions of 35 USC 112, sixth paragraph, unless the element is expressly recited using the phrase "means for" or "step for".