Patent Grant
9038729
The present disclosure generally relates to apparatus and methods for sealing in offshore wellbores. More particularly, the present disclosure relates to apparatus and methods to seal against a drill pipe in subsea wellbores offshore during drilling operations.
Wellbores are drilled deep into the earth's crust to recover oil and gas deposits trapped in the formations below. Typically, these wellbores are drilled by an apparatus that rotates a drill bit at the end of a long string of threaded pipes known as a drillstring. Because of the energy and friction involved in drilling a wellbore in the earth's formation, drilling fluids, commonly referred to as drilling mud, are used to lubricate and cool the drill bit as it cuts the rock formations below. Furthermore, in addition to cooling and lubricating the drill bit, drilling mud also performs the secondary and tertiary functions of removing the drill cuttings from the bottom of the wellbore and applying a hydrostatic column of pressure to the drilled wellbore.
As wellbores are drilled several thousand feet below the surface, the hydrostatic column of drilling mud serves to help prevent blowout of the wellbore as well. Often, hydrocarbons and other fluids trapped in subterranean formations exist under significant pressures. Absent any flow control schemes, fluids from such ruptured formations may blow out of the wellbore like a geyser and spew hydrocarbons and other undesirable fluids (e.g., H2S gas) into the atmosphere. As such, several thousand feet of hydraulic “head” from the column of drilling mud helps prevent the wellbore from blowing out under normal conditions.
However, under certain circumstances, the drill bit will encounter pockets of pressurized formations and will cause the wellbore to “kick” or experience a rapid increase in pressure. Because formation kicks are unpredictable and would otherwise result in disaster, flow control devices known as blowout preventers (“BOPs”), are mandatory on most wells drilled today. One type of BOP is an annular blowout preventer. Annular BOPs are configured to seal the annular space between the drillstring and the inside of the wellbore. Annular BOPs typically include a large flexible rubber packing unit of a substantially toroidal shape that is configured to seal around a variety of drillstring sizes when activated by a piston. Furthermore, when no drillstring is present, annular BOPs may even be capable of sealing an open bore. While annular BOPs are configured to allow a drillstring to be removed (i.e., tripped out) or inserted (i.e., tripped in) therethrough while actuated, they are not configured to be actuated during drilling operations (i.e., while the drillstring is rotating). Because of their configuration, rotating the drillstring through an activated annular blowout preventer would rapidly wear out the packing element.
As such, rotating control devices are frequently used in oilfield drilling operations where elevated annular pressures are present. A typical rotating control device (RCD) includes a packing element and a bearing package, whereby the bearing package allows the packing element to rotate along with the drillstring. Therefore, in using a RCD, there is no relative rotational movement between the packing element and the drillstring, only the bearing package exhibits relative rotational movement.
In one aspect, embodiments disclosed herein relate to an adapter assembly including a sealing element. Embodiments further include a drive bushing and an adapter flange disposed between the sealing element and the drive bushing.
In another aspect, embodiments disclosed herein relate to a method of assembling a rotational control device including coupling mechanically an adapter flange to a sealing element. Embodiments further include coupling mechanically the adapter flange to a drive bushing and installing the adapter flange, sealing element, and drive bushing in the rotational control device.
In another aspect, embodiments disclosed herein relate to an adapter assembly comprising a first sealing element; a second sealing element. Embodiments also include an adapter flange disposed between the first sealing element and the second sealing element.
This summary is provided to introduce a selection of concepts that are further described below in the detailed description. This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used as an aid in limiting the scope of the claimed subject matter.
In one aspect, embodiments disclosed herein relate generally to apparatuses and methods for sealing in offshore wellbores. Specifically, the present disclosure relates to apparatus and methods to seal against a drill pipe in subsea wellbores offshore during drilling operations.
Typical RCD sealing elements have metal inserts bonded to an elasotmer portion and are fastened to the RCD bearing assemblies with threaded-bolts. The component of the bearing assembly that is fastened to the sealing elements, called a “drive-bushing,” typically has threaded holes drilled into it and a set of screws are then used to securely bolt sealing elements inserted from the bottom-up. The sealing elements that are used in such assemblies are referred to as “bolt-on” assemblies and require cut-aways or grooves to enable the bolting process as well as to accommodate the bolt-heads, which are conventionally larger than the threaded portion of the bolts. The location of the bolt is typically fixed and is the same for all sizes of sealing-elements.
Because conventional sealing-elements are bolted from the bottom-up and the location of the bolts is fixed, the insert's allowable diameter is limited. In such a case when a sufficiently large tool-joint of a size that approaches the insert diameter is stripped through the sealing element, significant shear stress on the elastomer may result in material damage, referred to in the art as “chunking,” which is detrimental to the life of the sealing element. Additionally, the cut-away or grooves on the sealing elements that are required for such bottom-up bolting causes some areas of the sealing elements to be effectively thinner in cross-section, thereby causing them to be weaker and more susceptible to failure. Furthermore, bottom-up bolting may result in losing bolts downhole when they are not properly secured, thereby causing damage to drilling tools.
Referring to
From top to bottom, riser assembly 106 includes a diverter assembly 108 (shown including a standpipe and a bell nipple), a slip joint 110, a rotating control device 112, an annular blowout preventer 114, a riser hanger and swivel assembly 116, and a string of riser pipe 118 extending to subsea wellhead (not shown). While one configuration of riser assembly 106 is shown and described in
Because offshore drilling platform 100 is a semi-submersible platform, it is expected to have significant relative axial movement (i.e., heave) between its structure (e.g., rig floor 102 and/or lower bay 104) and the sea floor. Therefore, a heave compensation mechanism must be employed so that tension may be maintained in riser assembly 106 without breaking or overstressing sections of riser pipe 118. As such, slip joint 110 having a lower section 122, an upper section 124, and a seal housing 126, may be constructed to allow 30′, 40′, or more stroke (i.e., relative displacement) to compensate for wave action experienced by drilling platform 100. Furthermore, a hydraulic member 120 is shown connected between lower bay 104 and hanger and swivel assembly 116 to provide upward tensile force to string of riser pipe 118 as well as to limit a maximum stroke of slip joint 110. To counteract translational movement (in addition to heave) of drilling platform 100, an arrangement of mooring lines (not shown) may be used to retain drilling platform 100 in a substantially constant longitudinal and latitudinal area.
Looking to
Referring to
Referring to
Referring to
By connecting sealing element 325 to drive bushing 330 through adapter flange 320, the insert diameter of the rotary control device may be effectively increased, thereby preventing premature sealing element's 325 failure when large diameter tool joints are used. Additionally, because the sealing element 325 and drive bushing 330 are attached through vertical orientation of an adapter, there is no need for cutaways or grooves present on typical sealing elements, as described above, thereby allowing for uniform rubber thickness along the circumference of sealing element 325. Additionally, the vertical orientation of sealing element 325, adapter flange 320, and drive bushing 330 hold screws 335 in place, thereby decreasing the risk of losing screws 335 downhole.
Sealing element 325 may be formed from various elastomeric materials such as various rubbers. Examples of rubbers that may be used include nitrile butadiene, hydrogenated nitrile butadiene, natural, nitrile, and polyurethane rubbers. Those of ordinary skill in the art will appreciate that the specific type of rubber may vary depending on the operational requirements of the drilling operation.
Referring to
After attachment of adapter flange 420 to the sealing element, a plurality of screws may be disposed in a second plurality of mechanical attachment apertures 445, thereby allowing adapter flange 420 to be secured to a drive bushing (not shown). In this embodiment, the second plurality of mechanical attachment apertures 445 include an open slot 450, thereby allowing screws to be inserted through open slot 450 such that a screw may be secured against a bearing surface 455. In alternative embodiments, second plurality of mechanical attachment apertures 445 may not include an open slot, and instead, second plurality of mechanical attachment apertures 445 may include a bearing surface against which a screw is inserted, thereby allowing adapter flange 420 to be coupled to the drive bushing.
Referring to
The locking groove 465 may include various geometric features to effectively hold screws 470 in place. For example, in one embodiment, locking groove 465 may include a lip into which a portion of the screw 470 is rotated into during engagement. The lip may then effectively hold screw 470 in place. In an alternate embodiment, locking groove 465 may include a raised portion into which screw 470 may be press fit. In still an alternate embodiment, locking groove 465 may include a progressive wedge having a larger diameter at a top location 475 progressing axially downward to a relatively smaller diameter at a bottom location 480.
Referring to
Referring to
In an alternate embodiment, an adapter flange may be coupled to a drive bushing through apertures, and adapter flange subsequently coupled to a sealing element through engagement of screws upwardly extending from the sealing element. The sealing element may then be “locked” in place by rotation of the sealing element relative to the adapter flange, such as through an open slot on the adapter flange. The screws may then be tightened, thereby securing the adapter flange to the sealing element.
Referring to
In the embodiment illustrated in
Advantageously, embodiments of the present disclosure may provide apparatuses and methods for attaching drive bushings and sealing elements of RCDs through use of an adapter flange. The adapter flange may advantageously allow for the vertical coupling of drive bushing and sealing elements without the requirement to decrease the volume of elastomer in the sealing element. Because elastomer volume may be maintained, the strength of the seal may be increased, thereby decreasing the likelihood of premature failure. Also advantageously, embodiments of the present disclosure may provide locking grooves at the mechanical attachment locations, thereby preventing mechanical fasteners from being lost downhole, which in conventional assemblies could result in damage to drilling tools.
Although only a few example embodiments have been described in detail above, those skilled in the art will readily appreciate that many modifications are possible in the example embodiments without materially departing from this invention. Accordingly, all such modifications are intended to be included within the scope of this disclosure as defined in the following claims. In the claims, means-plus-function clauses are intended to cover the structures described herein as performing the recited function and not only structural equivalents, but also equivalent structures. Thus, although a nail and a screw may not be structural equivalents in that a nail employs a cylindrical surface to secure wooden parts together, whereas a screw employs a helical surface, in the environment of fastening wooden parts, a nail and a screw may be equivalent structures. It is the express intention of the applicant not to invoke 35 U.S.C. §112, paragraph 6 for any limitations of any of the claims herein, except for those in which the claim expressly uses the words ‘means for’ together with an associated function.
This applications claims the benefit of a related U.S. Provisional Application Ser. No. 61/387,302 filed Sep. 28, 2010, entitled “Adapter Flange for Rotary Control Device,” to Leduc et al., the disclosure of which is incorporated by reference herein in its entirety.
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| Number | Date | Country | |
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| Number | Date | Country | |
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| 61387302 | Sep 2010 | US |
