Bottomhole assembly and methods of use

Details Bottomhole assembly and methods of use Bottomhole assembly and methods of use

2001-05-07

2003-05-13

Will, Thomas B. (Department: 3671)

Boring or penetrating the earth

With below-ground tool drive prime mover

Electric

C175S073000, C166S066400

Reexamination Certificate

active

06561289

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to a bottomhole assembly (BHA) for use in well operations, with particular application to use in drilling with a downhole drilling motor and coiled tubing, and the invention relates to related methods of use of a BHA
BACKGROUND OF THE INVENTION
The B J Nowsco directional drilling-using-coiled-tubing (D U C T) is an on-bottom orientation and steering system for the tool string. The orient-while-drilling system provides joystick drilling. The heart of the system, that which enables orient-while-drilling, or on-bottom orientation/steering, or joystick drilling, is a downhole electric-over-hydraulic power pack. This B J Nowsco power pack when combined with a rotating tool can generate torque greater than the reactive torque of the drilling motor. This torque should be greater than at least 700 foot pounds and preferably greater than 1,000 foot pounds. The downhole electric-over-hydraulic power pack can also be advantageously used to power other downhole tools, other than a rotating tool or an orienting tool, such as a circulating valve, or other valves. Also for example, the power pack could power an emergency release tool. The power pack could power a form of orienting tool that varied the offset of an offset joint, such as bent sub angle. (Rams or cams, as well as bents subs, can form species of offset joints, as that term is used herein.)
The power pack is preferably powered by an electric line that runs through coiled tubing. Running an electric line through coil instead of hydraulic lines has several advantages, one being space. Reversible DC motors are preferably selected for the electric motors. Given space constraints, preferably three DC motors would be run in sequence. In a preferred embodiment a hydraulic pump is placed both above and below three DC motors. A clutch is provided for each pump, so that when the motors are run in one direction one of the two hydraulic pumps generates hydraulic pressure in its line while the clutch slips the other pump. When the electric motors are run in the opposite direction, the other clutch slips and the first clutch engages so that the other hydraulic motor generates pressure in its line. The availability of two hydraulic lines facilitates powering double acting pistons. Check valves can be used to lock double acting pistons in place. High pressure relief valves can be used to differentially run second and third systems off the same hydraulic line as the first system. For instance, a first level of pressure could be used to move a piston relating to a rotating orienting member. If the piston were moved to one of its end positions and pressure subsequently built up, a relief valve could open that would allow the hydraulic fluid to then operate a circulation valve, for instance, or a second double acting piston system. A third relief valve could be placed on the same hydraulic line such that after the second piston had been moved to its stop position, pressure further builds up to open a third valve and to permit the hydraulic line to adjust the degree offset of an offset tool, for example, by running a third piston system.
A further aspect of the invention derives from the high level of torque generated by the downhole electric-over-hydraulic power pack when combined with a rotary orienting tool. An orienting tool including a rotating member may preferably be utilized to rotate a bent sub or any other species of offset sub. The high pressure utilized to generate a sufficiently high torque on the rotating member to rotate while drilling has led to the development of a “balanced pressure” rotating member. Balancing the pressure on the rotating member avoids placing excessive force on thrust bearings supporting the rotating member. “Balanced pressure” is used to refer to a design wherein a helical surface receiving the pressure or force from the piston in one longitudinal direction is part of the member that also experiences a counter balancing force in the longitudinal direction due to the hydraulic fluid in the piston chamber. One way to attempt to express this “balanced pressure” design is to state that the piston chamber is located in the unit that contains the helical gears that mate with the helical gears on the piston.
A further feature of the high powered orient-while-drilling system comprises the use of helical gears. The piston imparting rotational movement to a rotating member to orient an offset joint (such as a bent sub) preferably uses helical gears mating with similar gears on the rotating member, in lieu of a lug or key in helical slot system. Helical gears transmit rotational movement to the rotating member. Helical gears can be viewed as a key in helical slot system, and vice versa, wherein the contact surface area between the key and slot has been substantially extended.
A further inventive aspect of the orient-while-drilling system comprises the arrangement of the tool modules in the bottomhole assembly. The orient-while-drilling system places the steering tool and instrument module, including non-magnetic collars if used, above the power pack and orienting system. The orienting tools are placed proximate to or next to the motor and bit or next to a bent sub followed by a motor and bit. Locating the orienting tool near the motor and bent sub has mechanical advantages in terms of rotating an offset joint, or bent sub, against frictional and drag forces.
In the B J Nowsco system although preferably the steering tool is located uphole from the orienting tool, it is yet connected to a rotating member of the orienting tool such that the steering tool rotates with the rotating member. By such means the steering tool tracks the rotation or orientation of an offset joint or bent sub. A quick release tool is preferably connected between a coiled tubing grapple connect and the steering tool and instrument module assembly. An orienting tool assembly may include the DC motors and hydraulic pumps, a circulating valve if operated off the hydraulic pumps, and the orienting tool or tools. A bent housing or other offset joint may be located immediately below the orienting tool or in or associated with the motor and bent housing. A current belief in the industry is that it is necessary to locate the steering tool as close as possible to the bit. It is the experience of the present inventors that greater advantage is achieved by locating the orienting tool adjacent the motor and bit.
An electric line preferably feeds the DC motors of the power pack. The electric line could also power a release tool. Preferably lines also exist to provide for the real-time communication of data from the steering tool, although other communication means are known and can be used. Real-time surface monitoring of downhole data permits joystick drilling. A feedback control loop can govern the rotating and orienting while drilling.
The orient-while-drilling system is capable of rotating in either direction to any degree, limited only by the piston stroke (in a preferred embodiment up to 400°) while drilling, at any time. In practice, corrections would probably be made only when the deviation appeared larger than the noise in the steering data. With the orient-while-drilling system the operator is free to manage the weight on bit in order to suit other needs. The weight on bit need not be managed in order to fine tune the orientation of the offset joint or bent sub.
The availability of a downhole electric-over-hydraulic power pack capable of generating high pressure makes available a hydraulic system capable of adjusting the degree of offset of an offset joint, or in terms of a bent sub, the bend angle. The hydraulic system of the power pack could also be utilized to operate a centralizer, including a centralizer with an adjustable diameter which could function as an anchor.
To review uses for the bottomhole assembly incorporating the downhole electric-over-hydraulic power pack, the hydraulic power can be used to set any valve or combination of valves, not just a single function circulation valve. The hydraulic pow

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