Patent Application
20150247387
This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the presently described embodiments. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present embodiments. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.
In order to meet consumer and industrial demand for natural resources, companies often invest significant amounts of time and money in finding and extracting oil, natural gas, and other subterranean resources from the earth. Particularly, once a desired subterranean resource such as oil or natural gas is discovered, drilling and production systems are often employed to access and extract the resource. These systems may be located onshore or offshore depending on the location of a desired resource. Further, such systems generally include a wellhead assembly mounted on a well through which the resource is accessed or extracted. These wellhead assemblies may include a wide variety of components, such as various casings, valves, pumps, fluid conduits, and the like, that control drilling or extraction operations.
As will be appreciated, wells are often lined with casing that generally serves to stabilize the well and to isolate fluids within the wellbore from certain formations penetrated by the well (e.g., to prevent contamination of freshwater reservoirs). Such casing is frequently cemented into place within the well. During a cement job, cement can be pumped down a casing string in a well, out the bottom of the casing string, and then up the annular space surrounding the casing string. The cement is then allowed to set in the annular space.
Certain aspects of some embodiments disclosed herein are set forth below. It should be understood that these aspects are presented merely to provide the reader with a brief summary of certain forms the invention might take and that these aspects are not intended to limit the scope of the invention. Indeed, the invention may encompass a variety of aspects that may not be set forth below.
Embodiments of the present disclosure generally relate to the installation of casing hangers in wellhead assemblies. In some instances, such as during cementing of the casing strings within the wells, top drives or other rotating machines are used to drive rotation of casing hangers and attached casing strings. In a cementing context, such rotation may reduce undesirable voids in the cement. But this rotation can also cause tightening of a threaded connection between the casing hanger and a device (e.g., a landing joint or a running tool) that transmits torque from the rotating machine to the casing hanger, and this tightening can hamper disconnection of the torque-transmitting device from the casing hanger. In at least some embodiments, however, a casing hanger has anti-rotation features, such as keys, that can be used to prevent rotation of the casing hanger to facilitate disconnection of the landing joint or other torque-transmitting device.
Various refinements of the features noted above may exist in relation to various aspects of the present embodiments. Further features may also be incorporated in these various aspects as well. These refinements and additional features may exist individually or in any combination. For instance, various features discussed below in relation to one or more of the illustrated embodiments may be incorporated into any of the above-described aspects of the present disclosure alone or in any combination. Again, the brief summary presented above is intended only to familiarize the reader with certain aspects and contexts of some embodiments without limitation to the claimed subject matter.
These and other features, aspects, and advantages of certain embodiments will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:
Specific embodiments of the present disclosure are described below. In an effort to provide a concise description of these embodiments, all features of an actual implementation may not be described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure.
When introducing elements of various embodiments, the articles “a,” “an,” “the,” and “said” are intended to mean that there are one or more of the elements. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. Moreover, any use of “top,” “bottom,” “above,” “below,” other directional terms, and variations of these terms is made for convenience, but does not require any particular orientation of the components.
Turning now to the present figures, a system 10 is illustrated in
The hangers 22 can be positioned on landing shoulders 24 within the tubing and casing heads. These landing shoulders 24 can be integral parts of the tubing and casing heads or can be provided by other components, such as packoffs, other sealing assemblies, or landing rings disposed in the tubing and casing heads. Each of the hangers 22 can be connected to a tubing string 26 or a casing string 28 to suspend such strings within the well 14. The well 14 can include a single casing string 28 or include multiple casing strings 28 of different diameters. Casing strings 28 are often cemented in place within the well. During a cement job, cement is typically pumped down the casing string. A plug is then pumped down the casing string with a displacement fluid (e.g., drilling mud) to cause the cement to flow out of the bottom of the casing string and up the annular space around the casing string.
Rotating the casing string during cementing can increase uniformity of the cement about the casing string and reduce the size or frequency of undesirable cavities or fissures in the cement. Further, rotating the casing string can also facilitate running of the casing string into the well through the wellhead. The casing strings can be rotated via casing hangers attached to the casing strings. Any suitable devices or machines may be used to rotate the casing hangers (and their attached casing strings) and to run the casing stings into wells. For example, a top drive can be used to run a casing string into a well and to rotate the casing string.
One example of a wellhead assembly 30 that facilitates rotating of a casing string is depicted in
Additional aspects of the wellhead assembly 30 are illustrated in the exploded view of
The casing hanger 32 can be rotated to cause an attached casing string, such as casing string 80 (
Although the threaded connection can transmit torque from the landing joint 38 to the casing hanger 32 to rotate the casing string, rotating the casing hanger 32 in this manner can also tighten the threaded connection. In some instances, this tightened connection could hinder disengagement of the landing joint 38 from the casing hanger 32 following installation. That is, when the rotational direction of the landing joint 38 is reversed, the casing hanger 32 could rotate with the landing joint 38 rather than unthreading from it. Accordingly, casing hangers 32 can include anti-rotation features that cooperate with complementary features of other wellhead components to inhibit rotation of the casing hangers 32 while disconnecting landing joints 38.
In some embodiments, these anti-rotation features include keys on the casing hanger 32. For instance, as depicted in
Certain other features are also depicted in
While one example of a casing hanger 32 with anti-rotation features is illustrated in
An example of the casing hanger 32 being run into a wellhead assembly is generally depicted in
The casing hanger 32 is attached to a casing string 80 via a threaded interface 84 and can be run into the wellhead assembly through the blowout preventer stack 76. In at least some embodiments, the casing hanger 32 includes an upper end with a threaded surface 86 that enables the casing hanger 32 to receive a threaded end 88 of the landing joint 38. This, in turn, allows the casing hanger 32 to be inserted into the wellhead without a separate running tool connecting the landing joint 38 to the casing hanger 32.
The casing hanger 32 and attached casing string 80 can be rotated as the casing hanger 32 is run into the wellhead. For example, during cementing of the casing string 80 within the well (e.g., by pumping cement through the bottom of the string 80 and up the surrounding annulus), the casing hanger 32 can be positioned within the wellhead assembly over the landing shoulder 66 and rotated through the blowout preventer stack 76 by the landing joint 38, as generally indicated by arrow 92 in
Whether rotated above or within the wellhead assembly, this rotation can tighten the threaded connection between the casing hanger 32 and the landing joint 38. In some instances, simply reversing the direction of rotation may not be sufficient to disconnect these two components. That is, friction at the tightened threaded connection between the landing joint 38 and the casing hanger 32 can cause the casing hanger 32 to also rotate in the reversed direction with the landing joint 38 rather than unthreading the connection. But in accordance with the present techniques, mating anti-rotation features (e.g., keys 52 and slots 68) are used to limit rotation of the casing hanger 32 with respect to the landing shoulder 66 to facilitate disconnection of the landing joint 38 (or some other installation device, such as a device having a running tool connected to the landing joint 38) from the casing hanger 32.
For example, the casing hanger 32 can be lowered into the keyed engagement with the landing shoulder 66, as generally depicted in
Engagement of the casing hanger 32 with the landing shoulder 66, as generally shown in
Additionally, although certain embodiments are described above as having mating engagement of the casing hanger 32 and the landing shoulder 66 of the packoff 48, other embodiments may take different forms. The casing hanger 32 could be landed on some other component besides the packoff 48, for example. Mating engagement of the casing hanger 32 with a landing shoulder of this other component (e.g., a casing head or another component disposed in the bore of a wellhead) could prevent rotation of the casing hanger 32 as an installation tool (e.g., a running tool connected to the landing joint 38 or the landing joint 38 alone) is unthreaded from the casing hanger 32.
While the aspects of the present disclosure may be susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and have been described in detail herein. But it should be understood that the invention is not intended to be limited to the particular forms disclosed. Rather, the invention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the following appended claims.
