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[0001]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[0002]NONEBACKGROUND OF THE INVENTION[0003]1. Field of the Invention[0004]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 b...

AI Technical Summary

Benefits of technology

The present invention is an apparatus that helps catch falling metallic objects in a wellbore to save rig time and enhance overall safety. It includes a magnet assembly that can be positioned away from sensitive equipment to prevent magnetic interference. A diverter assembly is also included to slow the velocity of falling objects and clean the outer surface of pipe or equipment passing through a bell nipple. Finally, a full-closing gate assembly can be opened or closed when pipe is not in the well to stop falling objects and save time and expense.

Problems solved by technology

Unfortunately, not all objects that a bell nipple guides into a wellbore are beneficial.

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.

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.

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.

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.

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.

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.

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