Patent Application
20130020096
NONE
1. Field of the Invention
The present invention pertains to a method and apparatus for preventing unwanted objects from entering subterranean portions of a wellbore. More particularly, the present invention pertains to the use of magnetic field(s) to catch falling objects within a wellbore. More particularly still, the present invention pertains to an apparatus for generating magnetic field(s) between a rig floor of a drilling or completion rig and a wellhead, such as in or near a bell nipple assembly, in order to prevent unwanted objects from falling into a wellbore below said wellhead.
2. Brief Description of the Prior Art
A bell nipple is a large diameter length of pipe utilized on most drilling and completion rigs. In most cases, a bell nipple is installed at or near the top of a rig's blowout preventers and extends to the well opening at the rig floor; the bell nipple typically serves as a “funnel” to guide drilling tools into and out of the upper opening of a well. Most conventional bell nipples also serve as conduits for drilling muds and/or other fluids present within a well. As such, most conventional bell nipples are typically configured with a side outlet to permit fluid to flow from a well to a rig's surface fluid treating equipment such as shale shakers and mud tanks.
Unfortunately, not all objects that a bell nipple guides into a wellbore are beneficial. Objects can sometimes accidentally fall into a wellbore from the rig floor. In other instances, objects can be purposely thrown or dropped into a well as an intentional act of sabotage. If such objects are not stopped before entering the subterranean portion of the wellbore, the objects can prevent downhole equipment from functioning properly and can often impede the drilling and completion process.
Relatively large objects can generally be retrieved from a wellbore using specially designed “fishing tools.” Such fishing tools are lowered into a wellbore and connect to a dropped object within the wellbore. Thereafter, the fishing tools and the connected object can both be safely retrieved from the wellbore. In many instances, the retrieval process for such large objects can be relatively simple because the size of the objects enables such objects to be grasped and lifted out of the wellbore.
By contrast, relatively small objects dropped in a wellbore and particularly metal objects—can often cause the most disruption to downhole equipment and related operations. For example, during completion operations, small pieces of metal present in a wellbore can prevent packers and other completion tools from sealing against a casing wall. During open hole drilling operations, such small metal objects can destroy very expensive downhole equipment such as Polycrystalline Diamond Compact (PDC) bits.
Such small objects can also be very difficult to retrieve from a wellbore, as they are often too small to be grasped using conventional fishing tools. This is especially true for small metal objects, and particularly small metal objects that have an irregular shape or small pieces that can be broken up during the retrieval process. Unfortunately, many drilling rigs typically have many small metal objects (such as, for example, wrenches, chain, bolts, tong dies and nuts) at or near the rig floor. Such objects, which are in relatively close proximity to the upper opening of a well, are at risk of falling into a wellbore.
As noted above, such relatively small metal objects can cause significant disruptions to downhole operations. Further, fishing operations for small metal objects can be very time consuming and, as a result, very costly. Accordingly, the best way to prevent such disruptions and to avoid long and expensive fishing operations for such small objects is to keep such objects from entering a wellbore in the first place.
Rig operating procedures frequently dictate that when no pipe is present in a wellbore that the blind rams in the blow out preventer (“BOP”) assembly be closed in order to block access to the wellbore and keep any unwanted falling objects from entering the wellbore from above the BOP assembly. If an object is dropped into the well at the rig floor, with the blind rams closed, the object will not fall all the way into the subterranean portion of a wellbore; however, this solution is less than optimal, because object must still be retrieved from the top of the rams before operations can resume. Such retrieval process typically requires draining the BOP assembly to locate the object, opening the bonnet in the BOP assembly, finding and retrieving the object, and closing and retesting the BOP assembly to the required test pressures. This retrieval process—while frequently quicker and less expensive than fishing the item from the bottom of the well—is nonetheless expensive and time consuming and costly.
Thus, there is a need for an apparatus and method for catching dropped objects, and particularly metallic objects, before such objects enter the subterranean portion of a well. Such apparatus and method should prevent dropped objects from falling further into a wellbore, and should hold such objects for ultimate retrieval and removal from a wellbore. Such apparatus can be disposed at virtually any location(s) between a rig floor of a drilling or completion rig, and a wellhead assembly of a well. In many cases, said apparatus can be situated at or in proximity with a bell nipple assembly.
The present invention comprises an apparatus for generating a magnetic field that can be attached to, or placed in the vicinity of, or made an integral part of a conventional bell nipple. The magnetic field is used to catch falling metal objects from passing beyond the bell nipple and entering the subterranean portions of a wellbore.
In the preferred embodiment, the apparatus of the present invention comprises the following primary components, or combinations thereof, that cooperatively work together to catch falling metallic objects in a wellbore, thereby saving rig time and enhancing overall safety:
Magnet Assembly:
A magnet assembly of the present invention comprises at least one magnet and is disposed on, around, or as an integral part of the bell nipple. The magnet(s) of the magnet assembly of the present invention can be sized based on the internal diameter of a bell nipple, as well as the ability to catch certain representative objects that have been dropped into or fished out of wellbores in the past.
In the preferred embodiment, the magnet assembly of the present invention can be mounted at or near the bell nipple using a movable assembly, such that said magnets can be selectively moved or positioned away from the bell nipple to prevent magnetic interference with logging tools or other equipment that may be sensitive to magnetic fields.
Divert (Finger) Assembly:
A diverter assembly can be mounted above the magnet assembly, and can act as a barrier to slow the velocity of a falling object passing through a bell nipple. Although said diverter assembly may only “break” the fall of an object, even a momentary reduction of velocity can greatly improve the ability of the magnet assembly to catch larger and/or heavier objects.
As a secondary function (in addition to slowing the velocity of falling objects), the diverter assembly of the present invention also acts as a wiper to clean the outer surface of pipe or other equipment passing through the bell nipple. Frequently, multiple different pipe sizes are used in the same drill string, which is a practice known as a tapered drill string. Several diverter assemblies of the present invention can be stacked to match each of the different pipe sizes that are being used in a tapered string. Use of such multiple diverter assemblies eliminates the need to work over an open wellbore to change out conventional pipe wipers, thereby resulting in time savings and a decrease in the chance that objects will be inadvertently dropped into a wellbore.
Gate Assembly:
A full closing gate that can extend across the central bore of the bell nipple (that is, the path into the well) is beneficially positioned under a magnet apparatus. The gate serves as a secondary closure of the well bore when the rig has pipe out of the hole.
The full-closing gate assembly of the present invention, which can be selectively operated by a driller or other automated system, can be closed when pipe is not in the well in order to stop falling objects. Said gate assembly of the present invention saves time and expense associated with actuating the BOP assembly and, further, eliminates the need for such unnecessary actuation.
Dimensions set forth herein and in the attached drawings are illustrative only and are not intended to be, and should not be construed as, limiting in any way.
The foregoing summary, as well as the following detailed description of the preferred embodiments, is better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, the drawings show certain preferred embodiments. It is understood, however, that the invention is not limited to the specific methods and devices disclosed. Further, dimensions, materials and part names are provided for illustration purposes only and not limitation.
Referring to the drawings,
Still referring to
Still referring to
Bell nipple assembly 120 acts as a “funnel” to guide drilling tools into and out of the upper opening of a wellbore. Unfortunately, not all objects that a bell nipple guides into a wellbore are beneficial, such as chain segment 150 that is depicted falling in central through-bore 124 of bell nipple assembly 120. If falling objects such as chain segment 150 are not stopped before entering the subterranean portion of a wellbore, such objects can prevent downhole equipment from functioning properly and can often negatively impede the drilling process as detailed herein.
Although magnet sleeve assembly 10 is depicted in
Still referring to
Said gate assembly 30 of the present invention can be actuated when pipe is not in the well as an additional means to prevent falling objects from entering subterranean portions of a wellbore, especially when metal objects have fallen into said wellbore (and must be retrieved), or when the present invention must be removed or checked. Said gate assembly 30 of the present invention saves time and expense associated with actuating the BOP assembly 110 just to “catch” falling objects and, further, eliminates the need for such unnecessary actuation which creates undesirable wear and tear on said BOP assembly 110. The primary function of BOP assembly 110 is to hold back fluid pressure from below, often in an emergency or unexpected situation. Because such unnecessary actuation of said BOP assembly 110 can negatively affect subsequent functionality and reliability of said BOP assembly 110, the inclusion of gate assembly 30 (particularly in conjunction with the other components of the present invention) provides a significant added element of safety to rig operations.
As depicted in
As a secondary function (in addition to slowing the velocity of falling objects), diverter assembly 40 of the present invention also acts as a wiper to clean the external surfaces of pipe or other equipment passing through bell nipple assembly 120. Frequently, multiple different sizes of pipe are used in the same drill string, which is a practice known as a tapered drill string. If desired, multiple diverter assemblies 40 of the present invention can be stacked to match each of the different pipe sizes that are being used in a tapered string. Use of such multiple diverter assemblies eliminates the need to work over an open wellbore to change out conventional pipe wipers, thereby resulting in time savings and a decrease in the chance that objects will be inadvertently dropped into a wellbore.
Said magnet assembly can be beneficially positioned proximate to a bell nipple, and situated above or below the side outlet of said bell nipple. For example,
Conversely, as depicted in
In the event that an object has fallen or been dropped into a well, any pipe or other equipment can first be retrieved from said well. Thereafter, for installations equipped with gate assembly 30, said gate assembly 30 can be shifted to a closed position. Thereafter, bell nipple 120 can be removed, or the internal surfaces of said bell nipple assembly 120 can otherwise be accessed, in order to retrieve the dropped or fallen object. With gate assembly 30 in a closed position, any object that may fall out of magnetic field 21 will be stopped at said gate assembly 30 (thereby permitting fast and easy retrieval), and will not fall into BOP assembly 110 or subterranean portions of a well situated therebelow. As noted above, said gate assembly 30 saves time and expense by eliminating the need for actuating BOP assembly 110 simply to block entry into subterranean portions of a wellbore.
It is to be observed that the magnet assembly of the present invention can be disposed at virtually any position along the distance that exists between: (1) a rig floor of a drilling or completion rig; and (2) a wellhead of a well being serviced by said drilling or completion rig. For example, it is possible that said magnet assembly of the present invention and related method could be incorporated directly within a BOP assembly or wellhead assembly. However, without limiting the scope of the present invention in any manner, the simplest and most effective manner of implementing the present invention will frequently involve positioning the magnet assembly of the present invention proximate to a bell nipple assembly as described herein.
The above-described invention has a number of particular features that should preferably be employed in combination, although each is useful separately without departure from the scope of the invention. While the preferred embodiment of the present invention is shown and described herein, it will be understood that the invention may be embodied otherwise than herein specifically illustrated or described, and that certain changes in form and arrangement of parts and the specific manner of practicing the invention may be made within the underlying idea or principles of the invention.
PRIORITY OF U.S. PROVISIONAL PATENT APPLICATION SER. NO. 61/510,229, FILED Jul. 21, 2011, AND U.S. PROVISIONAL PATENT APPLICATION SER. NO. 61/610,757, FILED Mar. 14, 2012, BOTH INCORPORATED HEREIN BY REFERENCE, IS HEREBY CLAIMED.
| Number | Date | Country | |
|---|---|---|---|
| 61510229 | Jul 2011 | US | |
| 61610757 | Mar 2012 | US |
