Rotating control device with positive drive gripping device

A rotating control device can include a rotatably mounted seal which sealingly engages a drill string, and a gripping device which grips the drill string and thereby forces the seal to rotate with the drill string. A drilling method can include positioning a drill string in a rotating control device, gripping the drill string with a gripping device of the rotating control device, and rotating the drill string, gripping engagement between the gripping device and the drill string causing a seal of the rotating control device to rotate along with the drill string. A well system can include a drill string, and a rotating control device including a seal which sealingly engages the drill string and a gripping device which grippingly engages the drill string.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit under 35 USC §119 of the filing date of International Application Serial No. PCT/US11/31367 filed 6 Apr. 2011. The entire disclosure of this prior application is incorporated herein by this reference.

BACKGROUND

The present disclosure relates generally to equipment utilized and operations performed in conjunction with drilling a wellbore and, in an embodiment described herein, more particularly provides a rotating control device with a gripping device for positive drive of a seal in the rotating control device.

A rotating control device includes a seal which seals about a drill string therein. Changing the seal is time-consuming and labor-intensive, and can be hazardous in certain situations. Therefore, it will be appreciated that it would be desirable to prevent wear of, or damage to, the seal.

DETAILED DESCRIPTION

Representatively illustrated inFIG. 1is a well system10and associated method which can embody principles of this disclosure. In the well system10, a drill string12extends downwardly through a blowout preventer (BOP) stack14on a wellhead16. A top drive18(including, e.g., a hydraulic or electric motor) is used to rotate the drill string12, to thereby cause rotation of a drill bit (not shown) at a far end of the drill string, and thereby drill into the earth.

A rotating control device (RCD)20seals off an annulus formed radially about the drill string12, so that the well below the wellhead16is isolated from atmosphere. An outlet22allows for circulation of fluid (such as drilling mud, etc.) through the well below the RCD20.

At this point it should be noted that the well system10is described herein as merely one example of a variety of well systems in which the principles of this disclosure can be incorporated. For example, it is not necessary for the drill string12to be rotated with the top drive18, since in other examples the drill string could be rotated with a kelly and rotary table, or with a mud motor, etc. Thus, it will be appreciated that the principles of this disclosure are not limited in any manner to the details of the well system10and associated method depicted in the drawings or described herein.

Referring additionally now toFIG. 2, a prior art rotating control device (RCD)23is representatively illustrated. The RCD23is of the type which includes a seal24for sealingly engaging the drill string12, to thereby seal off an annulus26formed radially between the drill string and an outer body28of the RCD.

Rotating control devices are also known in the art as rotating blowout preventers, rotating heads, rotating control heads, rotating diverters, etc. Rotating control devices seal about drill strings while the drill strings rotate therein.

The seal24is mounted to a generally tubular mandrel30. Bearings32provide for rotation of the mandrel30and seal24relative to the body28.

Although the seal24and mandrel30can rotate with the drill string12, friction between the seal and the drill string is relied on to cause rotation of the seal. Unfortunately, relative rotation between the drill string12and the seal24can cause damage to the seal, thereby shortening its useful life.

In some situations in the past, the mandrel30has been forced to rotate with the drill string12by engaging the mandrel with a bushing (not shown) on a kelly (not shown). However, this system only works if a kelly is used in the drilling operation (a kelly is not used if the top drive18ofFIG. 1is used to rotate the drill string), and this system requires that the seal24usually seals against the polygonal kelly (and not against the cylindrical drill string).

Referring additionally now toFIG. 3, the RCD20is representatively illustrated apart from the remainder of the well system10. The RCD20is similar in many respects to the RCD23, in that it includes the seal24, body28, mandrel30and bearings32.

However, the RCD20further includes a gripping device34attached at an upper end of the mandrel30. The gripping device34is depicted schematically inFIG. 3, but more detailed descriptions of examples of the gripping device are provided below.

The gripping device34grips the drill string12in a unique manner, and thereby forces the mandrel30and seal24to rotate with the drill string. This prevents (or at least mitigates) relative rotation between the drill string12and the seal24. The drill string12can, however, displace longitudinally (e.g., in a direction along a longitudinal axis35of the drill string) through the gripping device34as a wellbore being drilled by the drill string deepens, or as the drill string is tripped into or out of the wellbore.

Referring additionally now toFIG. 4, an enlarged scale cross-sectional view of one configuration of the gripping device34is representatively illustrated. In this view, it may be seen that the gripping device34includes gripping jaws36, which are pivotable about pivots38.

As depicted inFIG. 4, the jaws36are fully radially inwardly disposed, in which position the jaws can readily grippingly engage the drill string12therein. Teeth40are provided on the jaws36for gripping the drill string12, but preferably the teeth are configured so that they do not mar an outer surface of the drill string (which passes through the seal24), and/or the jaws can be made of a material (such as aluminum, etc.) which has a hardness less than that of the drill string.

Supports42inwardly support the jaws36when the supports are received in a reduced lateral dimension section44of the gripping device34. Furthermore, torsion springs46bias the jaws36radially inward into gripping engagement with the drill string12.

The jaws36are also biased upward relative to a body48of the gripping device34by compression springs50. In particular, the springs50bias the pivots38upward, thereby tending to displace the supports42into the reduced lateral dimension section44.

Referring additionally now toFIG. 5, the gripping device34is representatively illustrated with the pivots38and jaws36downwardly displaced relative to theFIG. 4configuration. In this position of the pivots38and jaws36, the supports42are not within the reduced lateral dimension section44, but are instead within an increased lateral dimension section52, and so the jaws36can pivot outward about the pivots38.

The configuration ofFIG. 5results from an enlarged diameter part of the drill string contacting an inclined upper surface54between each respective pivot38and jaw36. For example, a coupling56(such as the one depicted inFIG. 1, but lower on the drill string12) can displace downward as the wellbore is being drilled, or as the drill string is being tripped into the wellbore. The coupling56will contact the inclined surfaces54, causing the pivots38and jaws36to displace downward from theFIG. 4position to theFIG. 5position, and causing the jaws to pivot outward as needed to allow the coupling to pass through the gripping device34.

Note that the jaws36rotate about axes58of the pivots38which are transverse relative to the drill string axis35.

Referring additionally now toFIG. 6, another configuration of the gripping device34is representatively illustrated. In this configuration, the jaws36pivot about the pivots38which have their axes58parallel to the drill string axis35, and inclined surfaces54are provided on upper and lower ends of the jaws.

The jaws36are pivotably mounted on carriers60which are laterally displaceable relative to the body48. Biasing devices, such as springs (not shown), may be used to bias the carriers60and jaws36radially inward relative to the body48.

The inclined surfaces54on the upper and lower ends of the jaws36cause the jaws to be displaced radially outward if an enlarged diameter section of the drill string12contacts the jaws, whether the enlarged diameter section is being displaced upwardly or downwardly through the gripping device34. Note that inclined surfaces54could be provided on upper and lower ends of the jaws36in the configuration ofFIGS. 4 & 5, if desired.

Referring additionally now toFIG. 7, a cross-sectional view of the gripping device34, taken along line7-7ofFIG. 6is representatively illustrated. In this view it may be seen that the jaws36are shaped so that a gripping force exerted by the jaws on the drill string12will increase if there is relative rotation between the drill string and the jaws.

Specifically, if the drill string12rotates in a clockwise (right-hand) direction as indicated by arrows62inFIG. 7, and the jaws36grip the drill string (torsion springs46continually bias the jaws into gripping engagement with the drill string), then relative rotation between the drill string and the jaws will cause the jaws to pivot counter-clockwise about the pivots38, thereby causing the gripping force exerted by the jaws on the drill string to increase. This is due to the jaws36having radiused gripping surfaces64which are eccentric relative to the pivot axes58.

It may now be fully appreciated that the above disclosure provides several advancements to the art of constructing and operating rotating control devices. The rotating control device20mitigates wear of, and damage to, the seal24due to relative rotation between the seal and the drill string12.

The above disclosure describes a rotating control device20which can include a rotatably mounted seal24which sealingly engages a drill string12. A gripping device34grips the drill string12, and thereby forces the seal24to rotate with the drill string12.

The gripping device34may include a gripping jaw36which grips the drill string12. The gripping jaw36may be biased into contact with the drill string12. The jaw36may be displaceable radially relative to the drill string12.

The jaw36may pivot about an axis58which is transverse relative to the drill string12. The jaw36may pivot about an axis58which is parallel to a longitudinal axis35of the drill string12.

Rotation of the drill string12relative to the gripping device34can cause a gripping force exerted by the gripping device34to increase.

Also described above is a drilling method. The method can include positioning a drill string12in a rotating control device20, gripping the drill string12with a gripping device34of the rotating control device20, and rotating the drill string12, gripping engagement between the gripping device34and the drill string12causing a seal24of the rotating control device20to rotate along with the drill string12.

Rotating the drill string12may include increasing a gripping force exerted by the gripping device34when the drill string12rotates relative to the gripping device34.

Gripping the drill string12may include engaging a gripping jaw36of the gripping device34with the drill string12. Engaging the gripping jaw36may include pivoting the gripping jaw36.

The method may also include displacing the gripping jaw36radially outward relative to the drill string12as an increased diameter section of the drill string12displaces through the rotating control device20.

The method may also include attaching the gripping device34to a mandrel30of the rotating control device20, the mandrel30being fixed relative to the seal24.

The above disclosure also describes a well system10, which can include a drill string12, and a rotating control device20including a seal24which sealingly engages the drill string12, and a gripping device34which grippingly engages the drill string12.

The well system10may also include a top drive18which rotates the drill string12.

It is to be understood that the various embodiments of the present disclosure described herein may be utilized in various orientations, such as inclined, inverted, horizontal, vertical, etc., and in various configurations, without departing from the principles of the present disclosure. The embodiments are described merely as examples of useful applications of the principles of the disclosure, which is not limited to any specific details of these embodiments.

In the above description of the representative embodiments of the disclosure, directional terms, such as “above,” “below,” “upper,” “lower,” etc., are used for convenience in referring to the accompanying drawings. In general, “above,” “upper,” “upward” and similar terms refer to a vertical direction upward from the earth's surface, and “below,” “lower,” “downward” and similar terms refer to a vertically downward direction.

Of course, a person skilled in the art would, upon a careful consideration of the above description of representative embodiments of the disclosure, readily appreciate that many modifications, additions, substitutions, deletions, and other changes may be made to the specific embodiments, and such changes are contemplated by the principles of the present disclosure. Accordingly, the foregoing detailed description is to be clearly understood as being given by way of illustration and example only, the spirit and scope of the present invention being limited solely by the appended claims and their equivalents.