Method and Apparatus for Catching and Retrieving Objects in a Well

Abstract

A magnet assembly can be attached to, or placed in the vicinity of, a conventional bell nipple to generate a magnetic field within the central bore of the bell nipple. The magnetic field catches falling metal objects and prevents such objects from passing beyond the bell nipple and entering the subterranean portions of a wellbore. An optional diverter assembly slows the velocity of falling metal objects before reaching the magnet assembly, while also wiping the outer surface of pipe or other items lowered into a wellbore.

Description

CROSS REFERENCES TO RELATED APPLICATION

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.

STATEMENTS AS TO THE RIGHTS TO THE INVENTION MADE UNDER FEDERALLY SPONSORED RESEARCH AND DEVELOPMENT

NONE

BACKGROUND OF THE INVENTION

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.

SUMMARY OF THE PRESENT INVENTION

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.

BRIEF DESCRIPTION OF THE DRAWINGS

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.

FIG. 1 depicts a side perspective view of a magnet sleeve assembly of the present invention in a closed position.

FIG. 2 depicts a side perspective view of a magnet sleeve assembly of the present invention of the present invention in an open position.

FIG. 3 depicts a side sectional view of a conventional bell nipple assembly and related equipment installed on a drilling rig.

FIG. 4 depicts a side sectional view of a bell nipple assembly equipped with a magnet sleeve assembly of the present invention.

FIG. 5 depicts a side sectional view of a bell nipple assembly equipped with a magnet sleeve assembly and diverter assembly of the present invention.

FIG. 6 depicts a side sectional view of a bell nipple assembly equipped with an alternative embodiment magnet sleeve assembly and diverter assembly of the present invention.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION

Referring to the drawings, FIG. 1 depicts a side perspective view of a magnet sleeve assembly 10 of the present invention in a closed position. Generally, said magnet sleeve assembly 10 of the present invention is installed in close proximity to the upper opening of a wellbore (such as, for example, near a bell nipple assembly). Said magnet sleeve assembly 10 generates a magnetic field that is beneficially directed toward the wellbore to catch falling metal objects and prevent such objects from entering the subterranean portions of said wellbore.

Still referring to FIG. 1, magnet sleeve assembly 10 comprises first semi-cylindrical member 11 and second semi-cylindrical member 12 joined by at least one hinge assembly comprising hinge body members 13 and hinge pin 14. When said first and second semi-cylindrical members are joined together as depicted in FIG. 1, magnet sleeve assembly 10 has a substantially cylindrical shape. In the preferred embodiment depicted in FIG. 1, magnet sleeve assembly 10 further comprises opposing connection plate members 15 and 16. Fasteners such as threaded bolts 17 can be disposed through aligned holes in said opposing connection members 15 and 16 to secure first semi-cylindrical member 11 and second semi-cylindrical member 12 together. Optional handles 19 can be provided on the sides of magnet sleeve assembly 10.

Still referring to FIG. 1, magnets 20 are disposed on first and second members 11 and 12. In the preferred embodiment of the present invention, said magnets 20 comprise are typically rare earth or ceramic magnets exhibiting desired magnetic characteristics (that is, creates their own persistent magnetic field).

FIG. 2 depicts a side perspective view of magnet sleeve assembly 10 of the present invention in a substantially open position. As noted above, magnet sleeve assembly 10 comprises first semi-cylindrical member 11 and second semi-cylindrical member 12 moveably joined by hinges having hinge body members 13 and hinge pins 14. Opposing connection members 15 and 16 have aligned holes 18 for receiving bolts 17 which, in turn, are used to secure first semi-cylindrical member 11 and second semi-cylindrical member 12 together. As depicted in FIG. 2, optional handles/lifting eyes 19 are provided on the sides of magnet sleeve assembly 10.

FIG. 3 depicts a side sectional view of a conventional bell nipple assembly 120 and related equipment installed on a drilling rig. Bell nipple assembly 120 comprises a length of pipe 123 having a central through-bore 124, as well as a side outlet port 121 and outlet line 122. As depicted in FIG. 3, bell nipple assembly 120 is connected at its upper end to rotary assembly 130, and at its lower end to blow-out preventer (“BOP”) assembly 110. Rotary assembly 130 is mounted at rig floor 140 having upper surface 141, and defining an upper opening 131. BOP assembly 110 is connected to wellhead 100 which is mounted to the upper portion of a wellbore (not shown in FIG. 3) extending into the earth's crust. BOP assembly 110 generally comprises ram assembly 111 and annular preventer assembly 112.

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.

FIG. 4 depicts a side sectional view of the same basic well components as depicted in FIG. 3, except that magnet sleeve assembly 10 is installed on central body member 123 of bell nipple assembly 120. Additionally, optional gate valve assembly 30 is installed between bell nipple assembly 120 and BOP assembly 110. In the preferred embodiment, magnet sleeve assembly 10 of the present invention can be sized based on the dimensions of bell nipple assembly 120.

Although magnet sleeve assembly 10 is depicted in FIG. 4 as being secured in a fixed or stationary position, it is to be observed that magnet sleeve assembly 10 of the present invention can be mounted at or near bell nipple assembly 120 using an assembly that selectively moves the magnets of said magnet sleeve assembly 10 away from said bell nipple assembly when desired. For example, it may be beneficial to selectively move said magnets away from bell nipple assembly 120 to prevent magnetic interference with logging tools or other equipment that may be sensitive to magnetic fields, or when circulating large concentrations of metallic debris in a rig mud system (such as, for example, when milling up stuck metal objects in a well). Such assembly for repositioning said magnets can be manually operated, or remotely actuated using pneumatic or hydraulic power.

Still referring to FIG. 4, gate assembly 30 can be closed to extend substantially across central through-bore 124 of bell nipple assembly 120. Said gate assembly 30 permits a secondary means for quickly closing access to the upper surface of the well bore when pipe is out of the well. Although said gate assembly 30 can be manually operated, in the preferred embodiment it is remotely actuated using pneumatic or hydraulic power.

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 FIG. 4, magnet sleeve assembly 10 of the present invention, and more particularly magnets 20 thereof, create magnetic field 21. In the preferred embodiment, said magnetic field is generally focused or directed toward central through-bore 124 of bell nipple assembly 120. As a result, metal objects dropped into the upper opening 131 of a well, such as chain segments 150, are caught in said magnetic field 21; accordingly, such metal objects do not pass bell nipple assembly 120, and do not enter the subterranean portions of a well bore. Such objects (such as, for example, chain segments 150) can be easily retrieved from bell nipple assembly 120.

FIG. 5 depicts a side sectional view of a bell nipple assembly 120 equipped with magnet sleeve assembly 10, as well as optional diverter assembly 40 and optional gate assembly 30 of the present invention. In the preferred embodiment, diverter assembly 40 is mounted above 10 magnet assembly, and has a plurality of substantially flexible fingers 41 that extend into central through-bore 124 of bell nipple assembly 120. Said fingers 41 act as an impediment to slow the velocity of a falling objects passing through central through-bore 124 of bell nipple assembly 120. Although said diverter assembly 40 may only “break” the fall of an object, even a momentary reduction of velocity can greatly improve the ability of magnet assembly 10 to catch larger and/or heavier objects.

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. FIG. 6 depicts a side sectional view of a bell nipple assembly equipped with an alternative embodiment magnet sleeve assembly and diverter assembly of the present invention.

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, FIG. 5 depicts magnet assembly 10, diverter assembly 40 and gate assembly 30 mounted above side outlet port 121 of bell nipple assembly 120. Because any liquid in central through-bore 124 of bell nipple assembly 120 drains through said side outlet port 121, the liquid level within said through-bore 124 does not extend above said outlet port 121. Accordingly, magnetic field 21 generated by the magnet assembly 10 extends into a “dry” portion of bell nipple assembly 120 (that is, the portion of central through-bore 124 of bell nipple assembly 120 that does not contain drilling mud or other liquid).

Conversely, as depicted in FIG. 6, magnet sleeve assembly 10 can be installed proximate to bell nipple assembly 120, and positioned below said outlet port 121 of bell nipple assembly 120. In such an installation, magnetic field 21 generated by magnet assembly 10 extends into a “wet” portion of bell nipple assembly 120 (that is, a portion of bell nipple central through-bore 124 that contains drilling mud or other liquid).

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.

Claims

1. A magnet assembly comprising at least one magnet proximate to a bell nipple assembly having an upper end, a lower end and a central bore, wherein said at least one magnet generates a magnetic field directed toward said central bore.

2. The magnet assembly of claim 1, further comprising a gate assembly disposed below said at least one magnet.

3. The magnet assembly of claim 1 further comprising a diverter assembly disposed above said at least one magnet, wherein said diverter assembly comprises at least one flexible member extending into said central bore of said bell nipple assembly.

4. The magnet assembly of claim 1, wherein said at least one magnet comprises a rare earth material.

5. The magnet assembly of claim 1, wherein said at least one magnet comprises a ceramic material.

6. The magnet assembly of claim 1, further comprising:

a. a first body member having at least one magnet attached thereto;

b. a second body member having at least one magnet attached thereto, said second body member hingeably attached to said first body member.

7. The magnet assembly of claim 6, further comprising an automated assembly for opening and closing said first and second body members.

8. A method for catching objects falling in a well comprising the step of placing at least one magnet proximate to a bell nipple assembly having a central bore, wherein said at least one magnet generates a magnetic field directed at said central bore of said bell nipple assembly.

9. The method of claim 8, further comprising a gate valve assembly disposed below said at least one magnet.

10. The method of claim 8, further comprising a diverter assembly disposed above said at least one magnet.

11. The method of claim 10, wherein said diverter assembly comprises at least one flexible member extending into said central bore of said bell nipple assembly.

12. A method for catching objects falling in a bore extending between a rig floor of a rig and a wellhead of a well, comprising the step of generating a magnetic field directed at said bore.

13. The method of claim 12, wherein said magnetic field is generated by at least one magnet disposed between said rig floor and said wellhead.

14. The method of claim 13, further comprising a gate valve assembly disposed below said at least one magnet.

15. The method of claim 13, further comprising a diverter assembly disposed above said at least one magnet.

16. The method of claim 15, wherein said diverter assembly comprises at least one flexible member extending into said bore.