Borehole accidents are common in the construction of water well drilling rig
There are five kinds of common hole accidents in the construction of water well drilling rig:
(1) the hard alloy falls off or collapses into the hole, and the diamond and the matrix are damaged and fall off.
(2) the burning of bits.
(3) pipe fracture, mainly refers to drill pipe or core pipe.
(4) the drill string falls off.
(5) stuck drilling tool.
The causes and solutions of the above accidents are recommended as follows:
(1) hard alloy or diamond or matrix damages and falls off the hole bottom
This kind of accident is more likely to occur in hydraulic impact rotation than in ordinary rotary drill.Sometimes due to improper operation, especially in the fracture and broken rock, the revolution and weight on bit must be reduced at the beginning of the return drilling. At this time, the method of controlling footage is generally adopted to resume normal drilling after drilling.In addition, the quality of the bit should be checked before drilling, and the diamond bit that is not solidly welded or damaged should not be run into the hole.
Methods of handling after the accident: all kinds of fishing tools can be used to remove it.Among them, the better are magnetic fishing, fishing clock, flat bottom slag fishing and sink slag fishing, etc.
(2) the burning of bits
The root cause is the drill bit cooling and the hole bottom circulation fluid is not normal.Due to the small liquid channel of some hydraulic impactors during impact rotary drilling, once the debris such as grass root and cotton yarn enters, it is easy to block the liquid channel.Its performance is mainly pump pressure rise, footage speed down.Sometimes the surface is not easy to be detected due to the serious leakage of the drill pipe joint. At this time, the performance is that the hammer stops working (high pressure rubber pipe has no vibration feeling) and the drilling speed decreases.The principle of treatment is mainly to start drilling, and eliminate the above abnormal conditions, and then thoroughly punch hole or try to clean the bottom of the hole sediment after the replacement of the drill bit to start drilling again.
(3) core tube shedding
Due to the constant impact of the impactor, the burden of the core pipe is increased, and the buckle of the thread is broken.In the absence of the appropriate buckle design form, the important preventive measures can only be frequent inspection, resolutely eliminate the buckle unqualified and out-of-tolerance core tube.
(4) The drill is falling off
Mainly refers to the large diameter drilling tool falling off from the hydraulic impactor to the drill bit. The reason for this is that the impactor is "empty drill" before it reaches the bottom of the hole. This causes the connecting thread to buckle or be damaged. The most difficult to handle is the hydraulic impactor. The precautionary measure is mainly to prevent the impactor from being “emptied”. The general impactor linkage joints have the function of preventing "empty strike". Before drilling, it is necessary to figure out the structure and check whether the linkage joint is in good working condition, and avoid the use of impact rotary drill for long-distance reaming operation. The best way to remove the impactor is to use a suitable joint to join the connector on the impactor and remove it as a whole. The method of snapping back and forth is only used when it is unavoidable.The most difficult thing to deal with is the impact hammer. Once the impact hammer is removed, the parts that are common are easily salvaged in the usual way. The YS series springless double-acting hydraulic impactor is equipped with a right-handed fishing thread on the upper end of the quenched impact hammer. As long as the corresponding impact size is selected, the corresponding common male cone and the upper end of the impact hammer are used for the fishing thread. It can be removed smoothly afterwards; the remaining parts can be removed with a female cone or with a male cone. Other core tubes and drills are treated the same as rotary drills.
(5) stuck drill accident
The stuck drilling accident of the water well drilling rig is mainly due to the unsmoothing of the punching liquid road, the excessive accumulation of rock powder, the falling of the hole wall and the burning of the bits. Generally, do not use the method of back-drilling, avoiding the difficulty of unloading the impactor into several sections and increasing the difficulty of handling. It is necessary to use the method of topping, hitting and pulling. If the impactor is still working when the card is drilled, the pump volume should be opened as much as possible to force the impactor to impact without turning. Try to slow down and top or pull at intervals of 10-20 minutes. Repeated several times, the general water well drilling rig stuck accident can be eliminated.
