Patent Application
20130333897
1. Field of the Disclosure
Embodiments disclosed herein relate generally to subsea drilling More particularly, embodiments disclosed herein relate to a diverter cover assembly and methods of using the diverter cover assembly.
2. Background Art
Wellbores are drilled deep into the earth's crust to recover oil and gas deposits trapped in the formations therein. Typically, these wellbores are drilled using a drill bit rotated on an end of 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 through the rock formations. Furthermore, in addition to cooling and lubricating the drill bit, drilling mud also performs the secondary function of removing the drill cuttings from the bottom of the wellbore and applying a hydrostatic column of pressure to the drilled wellbore.
Referring to
Oftentimes, tools and equipment are accidentally dropped down an annulus (not shown) or the central bore 52 of the diverter 50 while performing maintenance, which requires running retrieval equipment or tools downhole and retrieving these items before continuing operation. Previously, to cover the central bore 52 of the diverter 50, a cover of some type, such as a wooden board, was pulled across the central bore 52 when performing maintenance to prevent tools from falling downhole. However, any type of drillpipe running through the diverter 50 rendered this method ineffective.
Accordingly, there exists a need for a diverter cover assembly that prevents costly and time consuming retrieval of dropped tools from a wellbore and that is capable of closing on variable diameter pipe as well as open holes.
In one aspect, embodiments disclosed herein relate to a diverter cover assembly including a first arrangement of sliding plates positioned above a central bore of a diverter and movable in substantially opposite directions to open and close over the central bore.
In other aspects, embodiments disclosed herein relate to a method of using a diverter cover assembly including providing a diverter cover assembly having a first arrangement of sliding plates positioned above a central bore of a diverter and movable in substantially opposite directions and moving the first arrangement of sliding plates and closing the central bore of the diverter.
Other aspects and advantages of the invention will be apparent from the following description and the appended claims.
The following description is directed to various exemplary embodiments of the disclosure. The embodiments disclosed herein should not be interpreted, or otherwise used, as limiting the scope of the disclosure, including the claims. In addition, those having ordinary skill in the art will appreciate that the following description has broad application, and the discussion of any embodiment is meant only to be exemplary of that embodiment, and not intended to suggest that the scope of the disclosure, including the claims, is limited to that embodiment.
In one aspect, embodiments disclosed herein relate to a wellbore cover assembly that prevents tools and/or other equipment from being dropped into a wellbore. Particularly, certain embodiments of the present disclosure may relate to a diverter cover assembly that is coupled or attached on top of a diverter assembly and prevents dropping tools and equipment down an annulus or bore of the diverter during maintenance. The diverter cover assembly may be closed around variable pipe diameters, or may be closed over an open hole absent any pipe running through the diverter.
Referring now to
Similarly, the inside sliding plate 124 is operable with hydraulic cylinders 132, and extendable pistons (not shown) of the hydraulic cylinders 132 are connected to the inside sliding plate 124 by pins (not shown) or other similar linkages. The outside sliding plate 122 and inside sliding plate 124 may be positioned at slightly different heights above the diverter 50 so that in a closed position the sliding plates may slightly overlap to completely close over the central bore 52 of the diverter. Either the outside sliding plate 122 may pass over the inside sliding plate 124, or vice versa. In certain embodiments, there may be a vertical clearance between the outside sliding plate 122 and the inside sliding plate 124 (as the outside sliding plate 122 passes over or under the inside sliding plate 124). Example vertical clearances include clearances of about one quarter inch, one-half inch, and one inch. In other embodiments, the vertical clearance may be greater than one inch.
A separate hydraulic system (not shown) may provide hydraulic pressure to operate the hydraulic cylinders. In certain embodiments, the hydraulic cylinders may be operated at around 3,000 psi. This may be beneficial because of the hydraulic supply provided on a drilling rig, which may typically have a hydraulic system pressure of around 3,000 psi. In other embodiments, the hydraulic cylinders may be operated within a range of about 1,500 and 5,000 psi.
The outside sliding plate 122 and inside sliding plate 124 are movable back and forth over the central bore 52 of the diverter 50 (in opposite directions) by extending and retracting pistons of the hydraulic cylinders 130 and 132, respectively. In certain embodiments, the hydraulic cylinders 130 and 132 may be 1½ inch bore size hydraulic cylinders; however, those skilled in the art will appreciate other hydraulic cylinders sizes that may be used, both larger and smaller In alternate embodiments, one of ordinary skill in the art will understand that pneumatic cylinders or electric motors may also be used to move the sliding plates. In some embodiments, a controller or control system (e.g., a computer or other electronic device) may interface with components used to move the sliding plates (e.g., hydraulic, electric, pneumatic cylinders), such that an operator may provide inputs to effect movement of the sliding plates.
The outside sliding plate 122 is a crescent-shaped plate having a substantially circular inner diameter 123. It will be understood that the outside sliding plate 122 may be formed in other shapes or configurations as well. Similarly, the inside sliding plate 124 may be a crescent-shaped plate or otherwise. The inside sliding plate 124 has a substantially circular inner diameter 125, which when brought together with the circular inner diameter 123 of outside sliding plate 122, forms a substantially circular diameter that may be closed around variable diameters of drillstring. The sliding plates 122 and 124 may generally be relatively thin metal plates which are cut to shape using a saw or torch, or other known cutting methods. Other rigid materials may also be used for the sliding plates 122 and 124. For example, in certain embodiments, the plates 122 and 124 may have a thickness of between about 1 and 5 inches. Alternatively, the sliding plates 122 and 124 may be thicker plates depending on the amount of strength desired to resist or support equipment that may be accidentally dropped thereon.
Referring briefly to
Now referring to
In certain embodiments, as shown in
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Further, as shown in
Methods of using a diverter cover assembly 100 as described above are as follows, and in reference to
The sliding plates may be moved and closed around any diameter of drillpipe extending through the diverter. For example, in certain embodiments, the diverter cover assembly 100 may include sensors (not shown) that indicate when the sliding plates make contact with the drillpipe, which automatically stops further closing of the sliding plates. In other embodiments, an operator may manually adjust the sliding plates until they contact the drillpipe. In still further embodiments, the sliding plates may be closed proximate the drillpipe while not in contact, such that only a small gap (e.g., ½ inch) exists between the closed sliding plates and the drillpipe to prevent any tools or other objects from falling into the wellbore. In other embodiments, the diverter cover assembly 100 and related control circuitry may be configured to detect obstructions between the sliding plates and the drillpipe (e.g., the hand of an operator) and open the sliding plates to prevent damage or injury.
Advantageously, embodiments of the present disclosure provide a diverter cover assembly that is capable of closing a diverter in any situation to perform maintenance without the worry of objects falling down the wellbore through an open diverter and disrupting activity. It may also prevent damage to the top of the diverter and inside the diverter. The diverter cover assembly may be easily retrofitted on existing diverters or installed on new diverters. In addition, the diverter cover assembly may be operated using hydraulic pressure already available on the drilling rig.
While the present disclosure has been described with respect to a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that other embodiments may be devised which do not depart from the scope of the disclosure as described herein. Accordingly, the scope of the disclosure should be limited only by the attached claims.
