How to Prevent the Drilling Tool from Falling into the Borehole

The drill tool is broken or falling off, the drill bit sleeve is broken, the drill pipe square head is broken, the core is broken, will cause the drill tool to fall out of the borehole.

9.5.2 Analysis of Causes

(1) Safety pin: The use of electric welding rod as drill pin insurance, and no gasket separated, drilling conditions are easy to damage the welding rod safety pin, especially in the ordinary square pin, the pin shaft falls off, the drill bit falls into the hole.

(2) Mixing of square head: the two specifications of Bao E and ordinary square are mixed, and the up-pressure and down-pressure are mixed, resulting in the shear of drill pipe pin under axial pressure; The drill pipe pin shaft is worn fine for a long time, the pin hole is worn for a long time and the hole is enlarged, which increases the probability of the drill pipe pin being cut.

(3) square set square head broken; After long-term use, cracks may occur in the square sleeve of drill bit or the square head of drill pipe. If the cracks are not checked and repaired in time, the cracks spread, resulting in the square sleeve or square head being broken and the drill bit falling out of the manhole.

(4) offset hole; Offset hole produces drill pipe stress, resulting in weak points appear cracks, resulting in square head or core fracture.

(5) Brutal operation; Engine, power head speed is too high, violent vibration, impact or silly drill, single bucket drill, especially after the core all extended, lost the third bar constraints, such as axial pressure output is too large, the core may appear bending arc, continue to pressure may cause the core break.

Preventive Measures for Falling Tools

(1) Boe square: The Boe square head is designed with a double drill pipe pin. Compared with the ordinary square single pin shaft, it can double the insurance in terms of broken pin shaft and falling pin shaft. But at present many customers use Bao 'e side or install a pin... In addition, the Bao 'e side is longer, has good directional and upload pressure mode, which is conducive to bit positioning and effective suppression of off-hole.

(2) Drill pipe pin insurance: The drill pipe pin is equipped with a screw nut device, which limits the movement range of the drill pipe pin. The safety pin is not directly forced, which prevents the damage of the safety pin and eliminates the accident that the drill pipe pin exits and leads to the loss of the bit.

(3) Strengthen the joint: increase the wall thickness of the core joint, increase the strength and height of the reinforcement, the square head joint with a built-in strengthening shaft, or directly use a lengthening solid core joint, strengthen the joint.

(4) Operation control: pay attention to axial pressure output, power head speed and single-bucket penetration depth. Control penetration speed in complex strata can protect components and slow down deviation holes.

(5) Prevention of offset hole: offset hole can produce drilling stress, damage square head and core joint, so to prevent offset hole is equal to prevent the bit off…… Drilling tool selection, drilling tool optimization, optimization of tooth distribution, guide tooth function, operation control, adjustment of the gun, etc., can effectively inhibit the deviation hole or slow down the stress of the drill pipe.

(6) Inspection: square head broken or core broken, the first crack, crack spread fracture, usually such a process. Therefore, check the drill pipe or drill tool regularly, find the problem in time to repair or replace, will kill the hidden trouble in the cradle.