Wells – Above ground apparatus – With assembly or disassembly means
Reexamination Certificate
1999-07-30
2001-08-21
Neuder, William (Department: 3672)
Wells
Above ground apparatus
With assembly or disassembly means
C166S085400, C166S077520, C166S077530, C175S085000
Reexamination Certificate
active
06276450
ABSTRACT:
BACKGROUND OF THE INVENTION
The drilling of oil wells has traditionally been dangerous and labor intensive, due in part to the potential for blowouts. A “blowout”, which is an uncontrolled eruption of gas and oil from a well, is caused by a massive influx of formation fluid into the well bore at extremely high pressure. In many cases, blowouts occur at pressures sufficiently high to damage rig equipment and injure rig personnel. Blowout preventers (BOP's) are valves placed on top of a well to prevent blowouts. U.S. Pat. No. 4,535,852 to Boyadjieff and Krasnov describes the use of a blowout preventer valve in a top drive drilling system and is incorporated by reference in its entirety into the present disclosure.
Top drive drilling systems (TDS's) rotate the upper end of a drill string directly by a drive system suspended from a traveling block, rather than using a traditional rotary table and kelly. U.S. Pat. No. 4,449,596 to Boyadjieff describes a TDS and is incorporated by reference in its entirety into the present disclosure. Two IBOP's (Inside Blowout Preventers) and a saver sub are typically threadedly connected to the drive shaft of a TDS. For example, often an upper IBOP can be threaded to the drive shaft, a lower IBOP can be threaded to the upper IBOP, and a saver sub can be threaded to the lower IBOP. The drill string is then threaded onto the saver sub. Thus, rotational motion is transferred from the drive shaft of the TDS, down through the upper IBOP, the lower IBOP and the saver sub, to the drill string.
The threaded connections between the drive shaft of a TDS, an upper IBOP, a lower IBOP, a saver sub and a drill string, must be torqued to a high level in order to survive the forces encountered in a conventional drilling operation, with the higher components being torqued significantly tighter than the lower components. Thus, these components are typically too tight to rely on the torque provided by a conventional TDS to break the connections. To provide the required high torques, U.S. Pat. No. 4,449,596 describes a special torque wrench, or “pipe handler”, that provides additional force for making and breaking these tight connections. Such torque wrenches work well for “breaking out”, or loosening, and “making up”, or tightening, the connections between the upper IBOP, the lower IBOP, the saver sub and the drill string, but have not been able to be used for breaking out the upper IBOP. The problem is that the torque wrench has no way of reaching the main shaft of the TDS in order to keep it from rotating while applying torque to the upper IBOP.
In order to prevent blowouts, IBOP's are tested frequently to make sure they hold pressure. On average, a problem is found with an IBOP every two to three months, leading to its replacement. Traditionally, upper IBOP's have been removed manually using modified tong hangers which can weigh as much as 600 pounds. The hangers are taken off and the tongs are picked up with tugger lines. During this process, several strong people are required to hold the tongs level so they can bite into the upper IBOP and the main drive shaft of the TDS. Extreme lateral forces are exerted on the tongs, potentially causing them to break and injure the workers using them. This manual procedure takes an average of eight to ten hours of dangerous, difficult and frustrating labor. Clearly, it would greatly improve safety and efficiency if an automated method for replacing the upper IBOP could be provided.
SUMMARY OF THE INVENTION
An apparatus and method for the rapid replacement of upper blowout preventers of the present invention allows for safe and rapid replacement of the upper IBOP. The present invention provides modifications to existing TDS and pipe handler/torque wrench systems (for example, the torque wrench described in U.S. Pat. No. 4,449,596) by providing a hydraulic pressure booster to increase the operating pressure of the pipe handler/torque wrench, an air amplifier to increase the air pressure to the TDS main shaft brake in order to immobilize the shaft temporarily, a drive ring, and a rotary table back-up structure (RTBS) for providing a torque back-up for removing the upper IBOP.
In the method of the present invention, the saver sub and lower IBOP are first broken out, or loosened, with the pipe handler/torque wrench and removed. The upper IBOP is then broken out by placing the RTBS over the rotary table with the rotary table and the TDS main shaft locked. The modified TDS and pipe handler/torque wrench are then used together with the RTBS and drive ring in order to rapidly and safely replace the upper IBOP.
To realize the advantages outlined above, one embodiment of the apparatus for rapid replacement of upper blowout preventers includes: a torque back-up structure engageable in a stationary relationship relative to the drill floor; a drive shaft brake adapted to substantially prevent rotation of the drive shaft; a torque wrench adapted to simultaneously grip the torque back-up structure and the drill string component; the torque wrench operable to apply torque to the drill string component relative to the backup structure to thereby turn the drill string component relative to the drive shaft; the torque back-up structure is secured to a rotary table of the drill floor; the drive shaft brake includes an air amplifier for increasing the pressure of a source of air pressure for substantially locking the drive shaft against the rotational force required to turn the drill string component relative to the drive shaft; the torque wrench is attached to a hydraulic pressure booster providing hydraulic pressure to the torque wrench to turn the drill string component; the drill string component is an upper IBOP; a drive ring engages the drill string component and the torque back-up structure in order to prevent relative rotational motion.
To realize the advantages outlined above, one embodiment of the method for rapid replacement of upper blowout preventers includes: positioning a torque back-up structure so as to stabilize the drill string component; locking a drive shaft using a drive shaft brake in order to prevent rotary motion of the drive shaft; utilizing a torque wrench to simultaneously grip the torque back-up structure and the drill string component; utilizing the torque wrench to apply torque to the drill string component and to turn the drill string component relative to the drive shaft; securing the torque back-up structure to a rotary table of a drilling rig; providing amplified air pressure produced by an air amplifier in order to substantially lock the drive shaft against the rotational force required to turn the drill string component relative to the locked drive shaft; providing hydraulic pressure to the torque wrench in order to turn the drill string component, wherein the hydraulic pressure is produced by a hydraulic pressure booster; the drill string component is an upper IBOP.
Other features and advantages of the present invention will be apparent from the following detailed description when read in conjunction with the accompanying drawings.
REFERENCES:
patent: 4449596 (1984-05-01), Boyadjieff
patent: 4535852 (1985-08-01), Boyadjieff et al.
patent: 4813493 (1989-03-01), Shaw et al.
patent: 5388651 (1995-02-01), Berry
patent: 5921329 (1999-07-01), Armstrong
Christie Parker & Hale LLP
Neuder William
Varco International, Inc.
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