Common Accidents Of Drill Bit Damage, And Its Analysis, Very Valuable

December 28, 2021by Drilling-tools0
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1、Hammer head fracture

Hammer head fracture location mostly occurs in the hammer head spline upper reducer. Common causes of hammer head fracture are.

(1) poor quality of the hammer head body itself, stress concentration, fatigue resistance, shear strength is low.

(2) excessive drilling pressure leads to bending and vibration of the drilling tool, or uneven hardness of the ground leads to unstable work of the hammer head, the hammer head is subjected to continuous high frequency changes in torque, and the hammer head breaks due to fatigue damage under the action of multiple alternating impact forces and alternating shear stress.

2, prevention and treatment measures

(1) the use of good quality manufacturers, in order to reduce the quality of the hammer head and the occurrence of accidents in the hole. Hammer head quality strict inspection, strictly prevent damage to the hammer head into the well.

(2) Adjust drilling parameters in advance when entering loose, dissolved fracture zones, broken zones and soft and hard uneven formations.

(3) When the stratigraphic situation is unknown, drill with small drilling pressure first, and then slowly increase the pressure to make the drilling even and smooth, and avoid drilling with large drilling pressure and high speed.

(4) When drilling soft rock formations, lower the drilling pressure to prevent the carbide teeth from eating into the rock too deeply, which will lead to an instant increase in torque on the hammer head.

(5) Use a diving hammer with an anti-release sleeve as much as possible to prevent the hammer head from falling into the well when it breaks.

(6) If the hammer head breaks into the bottom of the well, it should be salvaged in time.

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3、Hammer tooth breakage

Most of the hammer teeth are damaged due to abnormal breakage, especially the teeth located at the outermost edge of the hammer head are most likely to break.

Hammer tooth breakage

The main reasons for abnormal chipping of hammer head teeth are roughly divided into 3 aspects: stratigraphy, drilling technical parameters and operation methods.

Technical measures

(1) Adjust the technical parameters of drilling in advance.

(2) Test drilling with small drilling pressure.

(3) Small drilling pressure and low speed.

(4) Evenly feed pressure.

(5) Select suitable hammer head.

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4、Hole hammer blockage

The blockage of falling objects is due to the unclean drilling tools and ground pipeline, the attachment of the inner wall, especially the rust and tiny debris on the inner wall of the new drill pipe, which fall off under the action of compressed air to the upper end of the submerged hammer to block the air duct, resulting in poor air supply or no wind.

Solution measures

(1) Clean up the ground air pipeline, especially the gate valve and the elbow of the pipeline where it is difficult to clean as much as possible.

(2) Thoroughly clean the inner wall of drilling tools in the hole before drilling, so that the inner wall of drilling tools can be cleaned into the well.

Causes and solutions for blockage of submersible hammer by rock powder sucking backwards

Clogging of the submersible hammer by reverse suction generally occurs when there are more residual chips in the well, especially in the condition of “thick paste”, due to improper operation, insertion of “thick paste” when drilling, when the submersible hammer backstop valve is not sealed well, the pressure difference between inside and outside the circulation channel is large, and the rock powder at the bottom of the well is sucked from the submersible hammer with The rock powder at the bottom of the well is sucked backwards from the perforating hammer fit gap.

T45 102mm Bench drilling bits (2)

Measures to solve the blockage of the submersible hammer by rock powder sucking backwards

(1) Check the backstop valve of the hammer carefully before drilling and replace the damaged parts.

(2) Check carefully whether the clearance and sealing performance of the piston and inner (outer) cylinder, piston and air distribution valve are intact, and replace damaged parts.

(3) Strictly enforce the operating procedures to avoid blockage of the rock powder due to improper operation.

(4) Use a reasonable combination of drilling tools, and add a floating valve joint at 150-200m of drilling tools to overcome the backward suction of rock powder caused by the pressure difference in the circulation channel.

(5) When the air supply is not smooth, immediately move the drilling tool up and down drastically, and immediately after it is ineffective

(6) When the air supply is not smooth, move the drilling tool up and down drastically immediately.

5、Deep hole hammer jamming

Falling objects are also caused by unclean drilling tools and ground pipeline, large particle size adhering to the inner wall (mud block, rock chips, etc.), and other large particle size debris falling into the drill pipe to the upper end of the submersible hammer stuck in the backstop valve part, so that the backstop valve can not be quickly reset.

T45 64mm button bit (7)

Measures to solve the problem of mud block stuck in the submersible hammer

(1) Carefully check and clean the drilling tools to ensure that there is no debris on the inner wall of the drilling tools.

(2) Regularly check the sealing and spring reset performance of the backstop valve of the submersible hammer, and replace the wearing parts in time.

(3) Check all parts of the submersible hammer carefully.

(4) Use special oil injector to ensure normal lubrication of the hammer.

(5) Each time before adding the drill pipe, the slag must be fully drained.

(6) Strictly clean and mark the drilling rods used for cementing, and try not to use such rods, but use strict cleaning and inspection measures to ensure smooth construction.

The rock chip backward suction blocking the submersible hammer is due to the pressure imbalance inside and outside the drilling tool, and the rock chip not completely drained from the bottom of the well enters the submersible hammer under the action of the pressure difference between inside and outside, jamming the piston and the spline of the hammer head or blocking the exhaust channel.

Measures to solve hammer spline jamming

(1) Check the backstop valve of the submersible hammer carefully before drilling and replace damaged parts.

(2) Check carefully whether the clearance and sealing performance of the piston and inner (outer) cylinder, piston and air distribution valve are intact, and replace damaged parts.

(3) Strictly implement the operation procedures to prevent the blockage of rock chips by backward suction due to improper operation.

(4) Adopt a reasonable combination of drilling tools, and also borrow the method of adding a floating valve joint at 150-200m of the drilling tools to solve the problem of backward suction of rock chips.

(5) Drain the chips diligently to reduce the residual chips at the bottom of the well.

38mm taper button bit (8)

Mud ring wrapping

Mud ring wrapping is the formation of mud ring and wrapping the drilling tool by the rock powder (chips) adhering to the drilling tool surface or well wall. After the mud ring is formed, the annular space becomes small and the rock chips cannot be removed smoothly and continue to gather at the mud ring to form a mud package, which can completely block the borehole in serious cases and cause sticky buried drilling accidents.

Analysis of causes

Stratigraphic factors: micro gushing water and wet stratum, micro gushing water in the stratum forms liquid film on the well wall and makes the rock powder wet, the liquid film on the well wall and the rock powder bond with each other to form rock chip group, and the rock chip group cannot be completely brought out of the wellbore by air when it adheres and gathers at the well wall and hammer head to form mud ring, and the phenomenon of mud group adhering and gathering to form mud ring is especially serious.

Solution measures

(1) Change the drilling process. Drill with wet strata, a small amount of water seepage, and use atomized drilling (water injection and dilution) for layers such as chert and dolomite.

(2) Diligent chip removal. Every 0.5~1m drilling, lift the drilling tool off the bottom of the well for debris removal.

(3) Increase the air compressor. Increase the air supply, improve the upward return air speed, and enhance the effect of sand removal.

(4) Reasonable configuration of drilling tools. Select reasonable drill collar and drill pipe.

(5) Short-distance drilling to scratch the well wall. Prevent mud ring formation and thickening of the well wall.

33mm R25 button bit (2)

6、Card, buried drill

Stratigraphic factors: geological formations, dissolution, fractures and faults generated by joints lead to loose rock, weak cementation, and gushing water leads to partial water absorption and swelling of rock, disintegration, well wall falling blocks, collapse and buried submerged hammer. Technology: High-frequency shock in drilling destroys the overall structure of the rock, high-speed airflow (stripping) destroys the structure of the rock wall, and the circulating medium does not balance the wall protection function and water immersion reduces the structural force of the mud shale, resulting in the falling of the block card hammer head and collapse of the buried submersible hammer.

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Technical measures

(1) Observe diligently.

(2) Move drilling tools diligently.

(3) Stop drilling in time to deal with it.

(4) Tug and unblock.

(5) Inject foam to relieve the obstruction by strong chip removal.

(6) Short start drilling to explore the well wall.

(7) Foam drilling.

(8) Change the process of wall protection drilling.

(9) Mud injection to protect the wall.

(10) Milling and uncapping.

Contact: Bruce Lee

Email:bruce@kingkongdrillsltd.com

Whatsapp/Phone:+8617638571343

www.kingkongdrillsltd.com

www.chinadrillingtools.cn

www.kingkongdrillslimited.com


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