DRILL TOOL STRING ASSEMBLY

DRILL TOOL STRING ASSEMBLY

The tool string consists of one or more sections of drill pipe, a stabilizer (drill collar) and a bit. In assembling the tool string, the stabilizer is the first item installed, then comes a section of drill pipe and finally the bit.

To install the stabilizer proceed as follows:

1. Place the stabilizer to be installed in a position so as to be accessible to the auxiliary inch line. Clean and lubricate the threads and shoulders on each end of the stabilizer. Install a lifting bell on the pin (upper) end of the stabilizer and lift it onto the drilling deck with the auxiliary winch line. Securely block the stabilizer horizontally on blocking sufficient enough to place the stabilizer 8-10 inches above the drill deck. Remove the auxiliary winch line.

2. Remove the guide bushing from the hole in the drill deck. Place the guide bushing on the upper end of the stabilizer with the tapered end of the bushing toward the lower (box) end of the stabilizer. Reattach the auxiliary winch line to the lifting bell.

3. Install the stabilizer and drill bushing in the hole in the drill deck. Make sure the drill bushing is seated properly. Lower the stabilizer until the slots in the stabilizer are aligned with the tool wrenches. Extend the tool wrenches to hold the stabilizer in place.

4. Remove the auxiliary winch line from the stabilizer and secure it out of the way. Remove the lifting bell from the stabilizer and store it.

NOTE: The use of stabilizers that have been modified or that do not allow this procedure to be used should be avoided. The use of nonstandard stabilizers will make assembly and disassembly of the tool string difficult and dangerous.

Stabilizer Installation

Controls for Drill Pipe Installation

To install a single section of drill pipe proceed as follows:

1. Lower the rotary/pulldown unit until the pipe coupling on the unit can be reached from the drill deck. Set the hoist brake and depress the drill/propel control OFF pushbutton. Clean the inside threads on the coupling to remove any dirt or old lubricant. Apply a coat of drill thread compound to the threads and shoulder of the coupling.

INSTALLING DRILL PIPE

NOTE: Use only drill pipe thread compound on the pipe threads. Drill pipe thread compound contains material that will prevent the threads from seizing and galling under the severe pressure encountered on the pipe threads.

2. Depress the drill/propel control ON pushbutton and release the hoist brake. Raise the rotary/ pulldown unit to a position on the mast so as to clear the pipe rack as it comes into place. Set the hoist brake.

3. Verify that the main compressor/hydraulic pump motor is running, the hoist/pulldown speed selector switch is in PIPE RACK/JOINTS position, the operating mode selector switch is in DRILL position, and on the operator’s display terminal that the head is clear of pipe rack. Place the pipe rack selector switch in #1 position. The pipe rack joystick will now control only the #l pipe rack.

4. Lift and move the joystick rearward (OVER HOLE position) to move the pipe rack over the hole. Once the rack is over the hole return the joystick to the NEUTRAL position.

5. Release the hoist brake and lower the rotary/pulldown unit until it is approximately 1 foot above the upper end of the drill pipe. Reset the hoist brake.

6. Turn the rotary rheostat clockwise until the rotary drive unit coupling begins to turn at approximately 5 RPM as shown on operator’s display terminal operator’s display screen. Release the hoist brake and carefully lower the rotary drive unit until the coupling contacts the drill pipe. Allow the rotary/pulldown unit to lower under gravity while the coupling is threading onto the pipe.

7. When the drill pipe begins to turn with the rotary coupling, stop the rotary motion and check the joint between the coupling and the pipe. The shoulders on the pipe and coupling must be together. If there is clearance between the shoulders, it will be necessary to tighten the joint some more before the pipe is removed from the rack. If the shoulders of the pipe and coupling are contacting, the joint is made up.

CAUTION: The threads on the drill pipe are tapered to make assembly and disassembly of the pipe easier. The threads are designed to disengage after only a few revolutions of the pipe. Failure to have the pipe shoulders contacting may result in the pipe joint uncoupling and the pipe falling from the rotary/pulldown unit.

There is no provision made for holding the pipe stationary in the rack while the joint is tightened. If the joint does not tighten using the above procedure it may be necessary to apply a small amount of hoist power to the rotary/pulldown unit to lift it slightly to remove the pressure from the drill threads.

CAUTION: Do not lift the drill pipe. Lift the rotary/pulldown unit only enough to relieve the pressure on the threads. Lifting the unit enough to lift the pipe will not only put pressure on the other side of the threads, but may also allow the pipe rack upper gate to open. Should the joint uncouple at this point, the drill pipe may fall out of the rack, causing death, serious injury or serious machine damage.

If the pipe joint does not make up by relieving the weight of the drive unit from the threads it will be necessary to inspect and/or repair the threads on the rotary coupling and the drill pipe. Inspect the threads for rough surfaces and burrs and apply a liberal coat of thread compound to them. The threads should have a smooth finish and no burrs or dirt that will hinder joint make-up. The joint shoulders should also be clean and smooth and should have compound applied.

After cleaning and repairing the threads, try making the joint again. If the joint cannot be made, either the drill pipe or the coupling is defective. Replace the pipe or coupling as necessary.

8. Once the joint is made up between the coupling and the pipe, the pipe is now ready to be lifted out of the pipe rack pocket. Lift the pipe approximately a foot above the top of the pocket to allow the pipe rack to swing out of the way. Set the hoist brake.

9. Once the pipe has been lifted clear of the pipe rack, swing the pipe rack to the STORED position by lifting and pushing the joystick forward to the STORED position.

NOTE: Verify that the upper gate on the pipe rack is open before retracting the pipe rack. Retracting the pipe rack with the gate closed will cause damage to the pipe rack.

10. Once the pipe rack has been stored the pipe should be cleaned out using the bailing air. Remove all personnel from the area and turn on the bailing air for a moment. After cleaning the pipe, clean and lubricate the threads and shoulder on the lower end of the pipe and the upper end of the stabilizer.

CAUTION: Before working around the tool string set the hoist brake. Depress the drill/propel control OFF pushbutton.

Stabilizer Installation

11. Release the hoist brake and lower the rotary/pulldown unit until the drill pipe is approximately 1 foot above the upper end of the stabilizer. Reset the hoist brake.

12. Turn the rotary rheostat clockwise until the drill pipe begins to turn at approximately 5 RPM as shown on operator’s display terminal operator’s display screen. Release the hoist brake and carefully lower the rotary drive unit until the drill pipe contacts the stabilizer. Allow the rotary drive unit to continue to lower under gravity while the drill pipe is threading onto the stabilizer.

13. When the stabilizer begins to turn with the drill pipe, check the joint between the stabilizer and the pipe. The shoulders on the pipe and stabilizer must be together. If there is clearance between the shoulders, it will be necessary to tighten the joint some more before the stabilizer is released. If the shoulders of the pipe and stabilizer are contacting, the joint is made up.

Installation of the drill bit is the last step in preparing the tool string.

To install the bit, proceed as follows:

1. Hoist the completed drill pipe/stabilizer assembly 2 to 3 ft (0.6 to 0.9 m) off the drill deck. Place the bit basket (furnished with machine) into the hole left by the guide bushing in the drill deck. Remove all personnel from the drilling deck and the immediate area. Turn on the main air stream to blow any contaminants from the drill pipe and stabilizer.

Bit Installation

2. Place the bit into the bit basket. Coat the threads and shoulders of the bit and stabilizer with drill pipe thread compound.

3. Turn the rotary rheostat clockwise until the tool string begins to turn at approximately 5 RPM as shown on operator’s display terminal operator’s display screen. Release the hoist brake and slowly lower the rotary/pulldown unit and tool string onto the bit. Lower the drive unit in small increments until the threads catch and the stabilizer starts to thread itself onto the bit. As soon as the threads start to catch, set the hoist brake and let the stabilizer screw itself onto the bit.

4. When the joint is tight the rotary unit will slow down and the rotary load meter will show an increased load. At this point return the rotary rheostat to the neutral position.

5. After making the bit to stabilizer joint, hoist the rotary drive unit to allow the bit basket to be removed. Remove the bit basket and store it in a safe place.

6. Lower the completed tool string so that the guide bushing is seated in the hole in the drill deck. Set the hoist brake and depress the drill/propel control OFF pushbutton. The tool string is now complete for single pass drilling or for the first pass of multiple pass drilling.