Geological drilling is also a core drilling. It is the use of a diamond drilling tool that passes the rotating speed and torque to the bottom of the hole and rock through a diamond drill tool. Through continuous and efficient cutting, it reaches the purpose of breaking into the rock. Usually, the submersible drilling is also 20 meters left and right, and some deep holes are drilling even up to several thousand meters. Therefore, the force of the diamond drill tool in the hole is very complicated. If the unsuitable operation causes the torque to be greater than the upper limit of the drill, then the drilling tool will be broken. Once the drilling tool is broken, its fishing operation is both time-consuming and laborious, and there is a great danger of discarding the drill hole, causing great economic loss. So it is necessary to study the reason of the fracture of diamond drill bit.
The main reasons for drilling tool breakage are diamond drill bit itself, operational technology and geological reasons.
First, the drilling tool itself causes the diamond drill bit to break.
There are many manufacturers of diamond drill tools in China, whose production level is uneven and the quality must be different, and the maintenance of drilling tools is also the key to the life of drilling tools. Therefore, the reasons for the broken drill tools are as follows:
(1) drill pipes such as core pipes and drill pipes are not straight, causing their torque to increase greatly in straight drilling holes.
(2) there is a quality problem in the material of drilling tools, especially the uneven rigidity and toughness of the drilling tool as a result of insoluble impurities and uneven components in the material, and the drilling regulation parameters are not suitable, such as excessive pressure and fast drilling speed.
(3) wear is serious or crack and other defects, after use, maintenance is not in place, next time use inspection is not strict, so that the problem drilling tools down to the hole.
(4) the technical condition of the equipment used is not good, such as the poor stability of the rig, the clearance of the gyration bearing, the power shortage of the power machine, the unstable work when the overload is loaded, the uneven water supply and pressure of the reciprocating pump, and the pulsation of the flushing fluid.
Two. Operation technology causes fracture of drill bit.
If the good horse matches the saddle, the good drilling equipment and drilling tools are hard, it is difficult to achieve the ideal drilling efficiency and easy to break the drilling tools. The main reasons for the operation of the drilling tools are as follows:
(1) the strength of rig foundation is not enough and the rigs are not fixed on the foundation.
(2) the structure design of drilling hole is unreasonable, and the diameter of drill pipe and the diameter of core pipe are not well matched with the aperture.
(3) there is no stable joint with coarse diameter drilling tools; using curved drill rod and core tube; using blunt or normal wear bits (diamond fragmentation, lip partial grinding, bit ellipse wear, etc.);
(4) the selection of drilling procedure parameters is not suitable for the properties of rock drilled; blind pressuring and increasing drilling speed;
(5) the drill rod locking joint is not concentric; the drill rod, because of the uneven wear (especially in the curved hole), causes uneven thickness and ellipticity in the process of manufacturing or in the process of use, causing the drill rod to be inhomogeneous and unbalanced in rotation.
(6) the active drill pipe is bent, overlong and eccentric in the vertical shaft.
(7) the borehole is bent;
(8) the use of heavy lifting water diversion joints and water supply pipes;
(9) residual core or other metal objects at the bottom of the hole;
(10) the hole is clean inside; there are seriously over diameter holes in drilling, or there are hanging blocks when drilling, suddenly sticking, drilling and firing.
Three. Geological reasons lead to fracture of drill bits.
The drilling layers of diamond bits are often not single, broken and other complex strata. These external objective conditions have a great influence on the stability of diamond drill tools. It is very easy to break the drilling tools, and it is easy to cause the main formation of this situation.
(1) the rock layer is broken and the fissure is developed.
(2) the soft and hard rock changes frequently.
(3) rock bedding, foliation and sharp angles formed on the borehole axis;
(4) the karst cave and the development of the air.
(5) the granularity of the strata is uneven and heterogeneous.
(6) the hardness and strength of the rock are not uniform.
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