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Gun Mill for Breaching a Closed Ball in a Subterranean Valve

IP.com Disclosure Number: IPCOM000241270D
Publication Date: 2015-Apr-10

Publishing Venue

The IP.com Prior Art Database

Abstract

A tool that is a combination of a Perforating Gun and Taper Mill is proposed for breaching a closed Ball in a Barrier Valve. The tool is shouldered on the Ball and Slips are engaged in the tubing above the Valve to hold it in place. Shaped Charges, attached to a Retracting Piston with opposed atmospheric chambers, are detonated to breach the Ball. Pressure from detonation causes axial movement of the Retracting Piston. The movement exposes the lower atmospheric chamber to a combination of hydrostatic and detonation pressure, causing it to move upward a considerable distance until it shoulders. The exposed atmospheric chamber acts like a vacuum to clean the debris field created by the detonation. A baffle device catches the swept debris. A shock absorber is provided to prevent the momentum of the Retracting Piston from damaging the Taper Mill. The shock absorber and Shaped Charge mounting components are designed to be fragmented during the detonation. The Slips can then be retracted, allowing the tool to be repositioned and the Taper Mill to finish boring the breached sections of the Ball. Or, if only the upper section has been penetrated, the Taper Mill can be used to penetrate the lower section of the Ball. The combination of functions in one tool could possible save a trip when trying to breach a closed Ball. Barrier Valves are used in subterranean wells to provide a barrier to the formation primarily during the completion phase. At some later date (varying from days to months) the Valve is reopened, typically by remote hydraulic means, so that the well can be put on production. Since the Valves are bi-directional, providing protection against fluid loss as well as protection against formation fluids entering the wellbore, it is typical for a Ball to be the primarily sealing means (as opposed to a Flapper or Sleeve). Should the Valve fail to re-open at the desired time, a secondary method of opening the Valve is typically provided. That method may consist of an additional, independent internal piston and linkage that forces the Ball to an open position. An auxiliary tool may have to be run in the well to actuate that Piston and linkage. Should that secondary method fail, it often becomes necessary to mill out the Ball in order to access the formation. As a general rule, milling is undesirable because of the time required; the difficulty of milling some of the corrosion resistant alloys of which the Balls are typically constructed; and, the uncertainty of the process (maintaining proper weight on the mill, unpredictable or uneven wear on the mill, foreign bodies between the cutting surfaces of the mill and the Ball, etc.). A tool that is a combination of a Perforating Gun and Taper Mill is proposed for breaching the closed Ball in a Barrier Valve (lower end shown in FIG. 1). The tool is shouldered on the Ball and Slips are engaged in the tubing above the Valve to hold it in place. (Note: The upper end of the tool is not shown but is envisioned to be a packer-like device with annular seal, Rocker and/or Piston Slips, and a bypass port.) A Shaped Charge is attached to a Retracting Piston having opposed, balanced atmospheric chambers. The Shaped Charge could be a specially designed Linear Shaped Charge such as the one proposed in OLID 9974 (See FIG. 2). It is enveloped in a Cover, possibly made by metal spinning or casting, so that it can withstand hydrostatic pressure. One means of attaching the Cover to the Shaped Charge is shown in FIG's. 3 and 4. In this concept, Cover Pins are slipped through slots in the Cover and screws are used to draw the Cover into contact with the lower face of the Casement. O-Rings between the Cover and Casement seal the two components preventing moisture from damaging the explosive during storage and preventing well fluids from contacting the explosive components during run-in. Support surfaces in the Casement between the Liner "chutes" (shown in FIG. 2) will provide ample support to the thin Cover as it is exposed to hydrostatic pressure, thus preventing damage to the Liner. A special assembly tool would be required so that a thread would "draw" the Shaped Charge onto the Retracting Piston so that no tamping or wrenching of the Shaped Charge is allowed. The Shaped Charge is then secured to the Retracting Piston with a split Charge Retainer held in a groove by a threaded connection with the Shroud (See FIG's. 3, 5, & 6). The Shroud length is designed to provide the optimum standoff between the Shaped Charge and the Ball. The Retracting Piston has a disjointed through bore allowing circulation through the ID of the tool and back through the annular area between the OD of the tool and the ID of the Valve. This allows sand or debris to be flushed from the top of the Ball as the tool is brought into place. Shear screws attach the Retracting Piston to the Taper Mill. The Shaped Charge is detonated by applying surface pressure to the tubing. Internal to the Retracting Piston are explosive train components similar to those found in the 'RD' Firing Head. A Rupture Disc separating an atmospheric chamber from well hydrostatic is burst when applied surface pressure causes a threshold differential pressure to be reached at the Disc. Pressure surge causes a Hammer to strike an Initiator igniting a time delay fuse. The time delay allows for the applied pressure to be removed or adjusted as desired. Once the fuse is spent, a Booster is detonated and Primacord transfers the explosive wave to the Shaped Charge. The Shaped Charge is detonated and will breach at least the upper section of the Ball. Pressure from detonation causes axial, upward movement of the Retracting Piston shearing the Pins coupling it to the Mill. Additional movement (Travel Dim. 'A') exposes the lower atmospheric chamber in the Retracting Piston to a combination of hydrostatic and detonation pressure, causing it to continue upward at a higher speed. The tool can be designed so that the Retracting Piston moves a considerable distance until it shoulders. A Shock Absorber, possibly made from metal foam acts to prevent the momentum of the Retracting Piston or Shaped Charge mounting components from damaging the lower end of the Taper Mill. The Shaped Charge mounting components (shown in honeycomb crosshatch) are made by additive manufacturing (3-d printing) to have a truss-like structure so that they fragment during the detonation. During the Retracting Piston motion, the exposed lower atmospheric chamber acts like a vacuum to clean the debris field of detonation products and Ball fragments. A baffle device (Spring Baffle) with inward facing "tentacles" catches the swept debris. The Slips can then be retracted, allowing the tool to be repositioned for milling. External threads on the tool are Hydril Wedge threads or equivalent to provide a high torque rating. The tool can then be rotated to allow the Taper Mill to finish boring the breached sections of the Ball. Or, if only the upper section has been penetrated, the Taper Mill can be used to fully open the upper section and penetrate the lower section of the Ball. In previous engineering tests, the inserts on a Taper Mill displayed considerable wear after cutting through the upper section of a corrosion-resistant alloy Ball. In this tool design, the intent is for the Taper Mill to still be relatively unused with at least the upper section of the Ball already removed. So, the combination of functions in one tool could possible save a trip when trying to breach a closed Ball. The Piston is fully retracted inside the Taper Mill so that the Taper Mill itself can act as a suitable drift to verify the Valve is fully open. (Though not shown, a simple locking device could prevent the Retracting Piston from returning to its original position.) The tool could also be configured with Sequential Jet Shaped Charges as shown in FIG's. 7-9. Each of these charges are designed to form sequential plasma jets that may better serve to breach both top and bottom sections of the Ball. FIG. 8 shows the explosive loading for a quantity of four of these Shaped Charges. (The short leg of explosive shown in Section 'C-C' connects the explosive in line with the Booster to the diamond pattern feeding the back of the Shaped Charges.)

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Gun Mill for Breaching a Closed Ball in a Subterranean Valve

A tool that is a combination of a Perforating Gun and Taper Mill is proposed for breaching a closed Ball in a Barrier Valve.  The tool is shouldered on the Ball and Slips are engaged in the tubing above the Valve to hold it in place.  Shaped Charges, attached to a Retracting Piston with opposed atmospheric chambers, are detonated to breach the Ball.  Pressure from detonation causes axial movement of the Retracting Piston.  The movement exposes the lower atmospheric chamber to a combination of hydrostatic and detonation pressure, causing it to move upward a considerable distance until it shoulders.  The exposed atmospheric chamber acts like a vacuum to clean the debris field created by the detonation.  A baffle device catches the swept debris.  A shock absorber is provided to prevent the momentum of the Retracting Piston from damaging the Taper Mill.  The shock absorber and Shaped Charge mounting components are designed to be fragmented during the detonation.  The Slips can then be retracted, allowing the tool to be repositioned and the Taper Mill to finish boring the breached sections of the Ball.  Or, if only the upper section has been penetrated, the Taper Mill can be used to penetrate the lower section of the Ball.  The combination of functions in one tool could possible save a trip when trying to breach a closed Ball.

Barrier Valves are used in subterranean wells to provide a barrier to the formation primarily during the completion phase.  At some later date (varying from days to months) the Valve is reopened, typically by remote hydraulic means, so that the well can be put on production.  Since the Valves are bi-directional, providing protection against fluid loss as well as protection against formation fluids entering the wellbore, it is typical for a Ball to be the primarily sealing means (as opposed to a Flapper or Sleeve).  Should the Valve fail to re-open at the desired time, a secondary method of opening the Valve is typically provided.  That method may consist of an additional, independent internal piston and linkage that forces the Ball to an open position.  An auxiliary tool may have to be run in the well to actuate that Piston and linkage.  Should that secondary method fail, it often becomes necessary to mill out the Ball in order to access the formation.  As a general rule, milling is undesirable because of the time required; the difficulty of milling some of the corrosion resistant alloys of which the Balls are typically constructed; and, the uncertainty of the process (maintaining proper weight on the mill, unpredictable or uneven wear on the mill, foreign bodies between the cutting surfaces of the mill and the Ball, etc.).  A tool that is a combination of a Perforating Gun and Taper Mill is proposed for breaching the closed Ball in a Barrier Valve (lower end shown in FIG.  1).  The tool is shouldered on the Ball and Slips are engaged in the tu...