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Yikuang Technology analyzes the reasons for the damage of the down-the-hole drill bit for you.
Release time:
2021-03-17
Author:
Source:
Air DTH hammer drilling is mainly based on high-frequency impact crushing, which can often reach more than 10 times the drilling speed of regular drilling mode, but it is easy to produce various accidents due to the influence of factors such as operation process and complex formation. Common accidents of air down-the-hole hammer drilling mainly include hammer head fracture, alloy tooth collapse, blockage, blocking, mud ring wrapping, stuck drilling, etc. The systematic technical measures formed for the following typical accidents are highly operable and have popularization value. 1. Hammer head fracture occurs at the upper end of the hammer head spline. The common causes of hammer head fracture are:(1) poor quality of the hammer head itself, stress set
Air DTH hammer drilling is mainly based on high-frequency impact crushing, which can often reach more than 10 times the drilling speed of regular drilling mode, but it is easy to produce various accidents due to the influence of factors such as operation process and complex formation. Common accidents of air down-the-hole hammer drilling mainly include hammer head fracture, alloy tooth collapse, blockage, blocking, mud ring wrapping, stuck drilling, etc. The systematic technical measures formed for the following typical accidents are highly operable and have popularization value.
1. Hammer head fracture
The fracture position of the hammer head mostly occurs at the upper end of the hammer head spline. Common causes of hammerhead fracture are:
(1) The hammer body itself is of poor quality, stress concentration, fatigue resistance and low shear strength.
(2) Excessive drilling pressure leads to large bending and vibration of drilling tools, or uneven formation hardness leads to unstable operation of the hammer head. The hammer head suffers from 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 stresses.
2. Prevention and treatment measures
(1) Select a good quality manufacturer to reduce the hole accidents due to the quality of the hammer head. Strictly inspect the quality of hammerheads to prevent damaged hammerheads from entering the well.
(2) The drilling parameters shall be adjusted in advance when entering the loose and corrosion fissure zone, fracture zone and uneven soft and hard stratum.
(3) When the formation is unknown, drill with small bit pressure first, and then slowly pressurize to make the drilling uniform and stable, and avoid drilling with large bit pressure and high speed.
(4) When drilling soft rock formation, the WOB should be reduced to prevent the carbide teeth from eating too deep into the rock formation, resulting in an instantaneous increase in the torque of the hammer head.
(5) The down-the-hole hammer with anti-stripping sleeve shall be selected as much as possible to prevent the hammer head from falling into the well when it breaks.
(6) If the hammer head breaks and falls into the bottom of the well, it should be salvaged in time.
3. The hammer tooth is broken
Air DTH hammer in the normal drilling process of the hammer tooth wear is small, most of the hammer tooth damage is due to abnormal collapse, especially in the outermost edge of the hammer tooth is the most vulnerable to collapse.
Hammer tooth break
The main causes of abnormal collapse of hammerhead column teeth are roughly divided into three aspects: formation, drilling technical parameters and operation methods.
Technical measures
(1) Adjust drilling technical parameters in advance.
(2) Test drilling with small bit pressure.
(3) small bit pressure, low speed.
(4) uniform pressure.
(5) select the appropriate hammer.
4. The hole hammer is blocked
The blockage of falling objects is due to unclean drilling tools and ground pipelines into the well, attachments on the inner wall, especially rust and tiny sundries on the inner wall of the new drill pipe, which fall off to the upper end of the down-the-hole hammer under the action of compressed air to block the air duct, resulting in poor air supply or no wind.
Solution measures
(1) Clean the ground air pipeline, especially the gate valve and pipeline elbow where it is difficult to clean, disassemble and clean as much as possible.
(2) Thoroughly clean the inner wall of the drilling tool in the hole before tripping in to ensure that the inner wall of the drilling tool is clean and enters the well.
Rock powder back suction blocking DTH hammer causes and solutions
Blocking the down-the-hole hammer due to reverse suction generally occurs when there are more residual cuttings in the well, especially when it is in "thick paste" condition. Due to improper operation and insertion of "thick paste" during drilling, when the check valve of the down-the-hole hammer is not well sealed and the pressure difference between the inside and outside of the circulation channel is large, rock powder at the bottom of the well is sucked back from the matching gap of the down-hole hammer.
Solution Measures of Rock Powder Backward Suction Blocking DTH Hammer
(1) Carefully check the check valve of the down-the-hole hammer before drilling and replace the damaged parts.
(2) carefully check the piston and the inner (outer) cylinder, piston and valve clearance and sealing performance is intact, replace the damaged parts.
(3) Strictly implement the operation procedures to avoid the clogging of rock powder due to improper operation.
(4) A reasonable drilling tool combination can be adopted, and a floating valve joint can be added at 150~200m of the drilling tool to overcome the back suction of rock powder generated under the action of the pressure difference of the circulation channel.
(5) When the air supply is not smooth, immediately move the drilling tool up and down by a large margin, and immediately after it is invalid
Check the trip.
5. DTH hammer blocking
The drop jam is also caused by unclean drilling tools and ground pipelines, large particle size attachments (mud blocks, rock cuttings, etc.) on the inner wall, and other large particle size sundries falling into the drill pipe to the upper end of the down-the-hole hammer and stuck in the check valve, so that the check valve cannot be reset quickly.
Solution Measures for DTH Hammer Clay
(1) Carefully check and clean the drilling tools in the well to ensure that the inner wall of the drilling tools is free of sundries.
(2) Regularly check the sealing performance and spring return performance of the check valve of the down-the-hole hammer, and replace the vulnerable parts in time.
(3) carefully check the parts of the down-the-hole hammer.
(4) the use of special oil injector to ensure the normal lubrication of the down-the-hole hammer.
(5) The slag must be fully discharged before adding the drill pipe each time.
(6) Drill pipes used for cement cementing shall be strictly cleaned and marked, and such drill pipes shall not be used as much as possible. Strict cleaning and inspection measures shall be taken to ensure smooth construction.
Rock cuttings inverted suction jam DTH hammer is an imbalance between the internal and external pressure of the drilling tool. Under the action of the internal and external pressure difference, rock cuttings that have not been completely discharged from the bottom of the well enter the DTH hammer, which will jam the piston and hammer spline or block the exhaust passage.
Measures to Solve Hammer Spline Jam
(1) Carefully check the check valve of the down-the-hole hammer before drilling and replace the damaged parts.
(2) carefully check the piston and the inner (outer) cylinder, piston and valve clearance and sealing performance is intact, replace the damaged parts.
(3) Strictly implement the operation regulations to prevent rock debris from being blocked due to improper operation.
(4) Adopt reasonable combination of drilling tools, and also borrow the method of adding floating valve joint at 150~200m of drilling tools to solve the problem of rock debris backsuction.
(5) Dispatling cuttings frequently to reduce residual cuttings at the bottom of the well.
Mud ring wrap
Mud ring wrapping means that the rock powder (cuttings) adheres to the surface of the drilling tool or the borehole wall to form a mud ring and wrap the drilling tool. After the mud ring is formed, the annular space becomes smaller and the debris removal is not smooth, and the debris continues to gather at the mud ring to form a mud bag, which completely blocks the borehole in severe cases, causing sticking and burying accidents.
cause analysis
Formation factors: micro-gushing water and wet formation. The formation micro-gushing water forms liquid film on the borehole wall and makes rock powder wet. The liquid film on the borehole wall and rock powder bond to form rock cuttings. When the rock cuttings cannot be completely taken out of the wellbore by air, they adhere and gather at the borehole wall and hammer head to form mud rings, and the phenomenon of mud mass adhering and gathering into mud rings is particularly serious.
Solution measures
(1) Replace the drilling process. When the formation is wet and a small amount of water seepage is encountered during drilling, the limestone, dolomite and other rock formations are drilled by atomization (diluted by water injection).
(2) Discharge chips frequently. For every 0.5~1m of drilling, the drilling tool is pulled away from the bottom of the well for slag discharge.
(3) increase the air compressor. Increase the air supply, improve the wind speed, enhance the sand discharge effect.
(4) Reasonable allocation of drilling tools. Select reasonable drill collar and drill pipe.
(5) Short-range trip to draw the borehole wall. Prevent the forming and thickening of mud rings on the shaft wall.
6. Card and buried drill
Stratigraphic factors: geologic structure, dissolution, cracks produced by joints and development of faults lead to loose rock mass and weak bonding force, as well as water inflow which leads to water-absorbing expansion and disintegration of some rock strata, well wall falling off, collapse and burying down-the-hole hammer. Process technology: drilling medium and high frequency shock destroys the overall structure of rock mass, high-speed airflow scouring (stripping) destroys the rock wall structure, circulating medium has no balanced wall protection function, and water gushing soak reduces the structural force of mud shale to cause block sticking hammer head and collapse buried down-the-hole hammer.
Technical measures
(1) Observe frequently.
(2) Operate drilling tools frequently.
(3) Timely stop drilling.
(4) channeling and unblocking.
(5) Infusion of foam agent for strong chip removal and resistance removal.
(6) Short-rise the borehole wall.
(7) foam drilling.
(8) Replace the process protection wall and drill.
(9) Mud injection for wall protection.
(10) Milling card.
This article is reproduced from the drill set network, infringement will be deleted.
Key words:
Technology, Hammerhead, Drilling, Blockage, Formation, Inverted suction, Cuttings, Measures, Solution, Fracture
