Handling: hand and hoist-line implements – Grapple – Well type
Reexamination Certificate
2000-07-18
2001-06-12
Cherry, Johnny D. (Department: 3652)
Handling: hand and hoist-line implements
Grapple
Well type
C294S086330, C294S086340
Reexamination Certificate
active
06244642
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to bridge plugs and retrieving tools therefor and in particular to retrievable bridge plugs which may be placed in pressurized oil and gas well bores to temporarily seal a portion of the well bore, and which require equalization before retrieval.
BACKGROUND OF THE INVENTION
Bridge plugs are tools which are typically lowered into a cased oil or gas well. When set in position inside the casing, a bridge plug provides a seal to isolate pressure between two zones in the well. Retrievable bridge plugs are often used during workover operations when a temporary separation of zones is required.
Typical bridge plugs are shown in U.S. Pat. No. 4,436,150 issued to Barker on Mar. 13, 1984; U.S. Pat. No. 4,898,239 issued to Rosenthal on Feb. 6, 1990; and U.S. Pat. No. 5,727,632 issued to Richards on Mar. 17, 1998. Retrievable bridge plugs typically have anchor elements and sealing elements. The anchor elements are used to grip the inside surface of the well casing, thereby preventing the bridge plug from moving up or down within the casing, once set. The sealing elements engage the inside surface of the well casing to provide the requisite seal between the plug and the casing. Typically, the bridge plug is set in position by radially extending the anchor elements and the sealing elements to engage the well casing. To retrieve the bridge plug from the well casing, a retrieving tool is lowered down the casing to engage a retrieving latch, which, through a retrieving mechanism, retracts the anchor elements and the sealing elements, allowing the bridge plug to be pulled out of the well bore.
During workover operations, a pressure differential across the plug often develops. It is desirable to equalize this pressure differential before the anchor and sealing elements are disengaged. Equalization prevents the loss of control over the bridge plug, wherein the tool may be blown up or down a well casing in response to the pressure differential. As exemplified by the prior art bridge plugs listed above, such equalization is typically effected through the opening of a bypass passage through the interior of the plug, prior to disengagement of the anchor and sealing elements.
However, a problem is often encountered with the effect of debris on the operation of the plug. Such debris may have an adverse effect on the operation of the plug. If sufficient debris remains on top of the plug, it may block the proper functioning of the mechanism used to open the bypass passage, making it very difficult, if not impossible for the pressure to equalize across the plug. Further, if a significant amount of debris accumulates on top of the bridge plug, it may be difficult, or impossible to engage the retrieving latch to retract the anchor and sealing elements. Finally, debris accumulation inside the bridge plug may adversely affect the relative movement of various parts within the bridge plug.
With prior art retrievable bridge plugs, even with the bypass passage sealed, fluid in the well is allowed to enter the interior of the plug. Further, no structure protects the uphole opening of the bypass passage, and debris is allowed to accumulate adjacent this opening. Moreover, no means are provided by the bridge plug to protect, or clear the retrieving latch used to disengage the anchor and sealing elements.
With known retrieving tools, once the retrieving tool has latched onto the bridge plug, accidental unlatching of the bridge plug may occur due to jarring motions, or forces imparted on the bridge plug or retrieving tool when the bypass passage is opened. Also, while the bridge plug is being lifted out of the well bore, jarring, or friction against the well casing may cause the anchor elements to move to their extended positions, locking the bridge plug in place within the casing, necessitating emergency recovery procedures. Once the retrieving tool and bridge plug have been removed from the well bore, it is difficult to separate the two, additional machinery often being required.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a retrievable bridge plug and retrieving tool therefor which reduces the effect of debris on the proper operation of the plug.
According to a broad aspect, the present invention provides a bridge plug for use in a well bore having a well wall, the bridge plug comprising: (a) an elongated body having an internal bypass passage; (b) anchors mounted on said elongated body, said anchors being extendible from a retracted position, in which they are held out of contact with the well wall, to an extended position in which they engage the well wall; (c) a seal mounted on said elongated body, said seal being extendible from a retracted position, in which it is held out of contact with the well wall, to an extended position in which it engages the well wall and forms an annular seal between the elongated body and the well wall; (d) a setting mechanism operable to set and lock said anchors and seal in their extended positions; (e) a release mechanism operable to disengage said anchors and seal from the well wall; (f) said internal bypass passage having a top and a bottom opening, said top opening located uphole from said seal, said bottom opening located downhole from said seal; (g) a top bypass closure adjacent said top opening of the internal bypass passage, and a bottom bypass closure adjacent said bottom opening of the internal bypass passage, each of said top and bottom bypass closures being mounted on said elongated body for movement between a first position in which the internal bypass passage is open, and a second position in which the internal bypass passage is sealed, and the top and bottom openings of the internal bypass passage are closed, substantially preventing debris from entering the internal bypass passage; and (h) a bypass sealing mechanism operable to move said top and bottom bypass closures between said first and second positions.
According to another aspect, the present invention provides a bridge plug for use in a well bore having a well wall, the bridge plug comprising: (a) an elongated body having an internal bypass passage; (b) anchors mounted on said elongated body, said anchors being extendible from a retracted position, in which they are held out of contact with the well wall, to an extended position in which they engage the well wall; (c) a seal mounted on said elongated body, said seal being extendible from a retracted position, in which it is held out of contact with the well wall, to an extended position in which it engages the well wall and forms an annular seal between the elongated body and the well wall; (d) a setting mechanism operable to set and lock said anchors and seal in their extended positions; (e) a release mechanism operable to disengage said anchors and seal from the well wall, said release mechanism being operable by a retrieving tool acting upon retrieving tool engaging elements mounted on the elongated body; (f) said internal bypass passage having a top and a bottom opening, said top opening located uphole from said seal, said bottom opening located downhole from said seal; (g) a directing shroud located over the top opening of the internal bypass passage; (h) a bypass sealing mechanism operable to selectively open and seal said internal bypass passage, whereby the directing shroud substantially protects the top opening of the internal bypass passage from debris and, when the internal bypass passage is open, directs part of any fluid flowing uphole through the internal bypass passage over the retrieving tool engaging elements.
According to a further aspect, the present invention provides a retrieving tool having top and bottom ends, for retrieving downhole tools from a well bore, such downhole tools having a top end and a plurality of transversely extending retrieving lugs, the retrieving tool comprising: (a) a tubing attachment interface for detachably attaching the retrieving tool to tubing; (b) a retrieving lug guide having a bottom end, said retrieving lug guide comprising
Serafin Vitold
Shkurti Piro
Tate Barry
Cherry Johnny D.
Polar Completions Engineering Inc.
Tarolli, Sundheim, Covell Tummino & Szabo L.L.P.
LandOfFree
Retrievable bridge plug and retrieving tool does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Retrievable bridge plug and retrieving tool, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Retrievable bridge plug and retrieving tool will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2445597