E-mail: [email protected] Whatsapp: +8613647327093 Tel: +86-731-8403-0163
E-mail: [email protected] Whatsapp: +8613647327093 Tel: +86-731-8403-0163
Complex and changeable geological conditions are the primary external factors that affect the efficiency of coring construction and the integrity of core samples. The specific manifestations, causes and solutions are as follows:
1. Manifestation: Collapse of the hole wall, block drop, resulting in stuck drill or hole failure
Influencing factors:
1) Loose formation, such as unstable structures such as silt layer, clay layer, and strong weathering zone.
2) Abundant groundwater, resulting in softening or scouring of the hole wall.
3) Excessive drilling disturbance, destroying the stress balance of the hole wall.
4) Failure to timely protect the wall or grouting reinforcement during drilling.
Solution strategy:
1) Master the formation hydrological information in advance: understand the depth and strength distribution of the aquifer through geological surveys and well logging data.
2) Use casing wall drilling or segmented wall method: especially in weak formations or broken zones, real-time advancement of casing wall.
3) Use high-performance mud system: such as bentonite + polymer combination, to improve wall protection ability and adhesion, and prevent collapse.
4) Appropriately reduce drilling speed and propulsion force to reduce disturbance to the formation.
2. Manifestation: Drilling difficulties, slow penetration, low mechanical efficiency
Influencing factors:
1) Dense hard rock formations, such as granite and quartzite, have high cutting resistance.
2) The rock formations are mixed with hard mineral particles (such as iron ore and quartz nodules), which causes the drill bit to wear quickly.
3) The drill bit type does not match the formation and cannot effectively break the rock.
4) The passivated drill tool is not replaced in time, which reduces the cutting efficiency.
Solution strategy:
1) Select high-efficiency hard rock drill bits: such as diamond composite (PDC) and metal sintered diamond drill bits to improve rock breaking ability.
2) Optimize parameter combination according to rock properties: high speed + medium propulsion force is used for hard rock to control the cutting amount.
3) Regularly check and replace the drill bit to ensure the sharp cutting edge.
4) Use of auxiliary pressure system: suitable for super-hard rock formations to improve drilling efficiency (such as top pressure system or gas lift assistance).
3. Manifestation: low coring rate, fragile or damaged core samples
Influencing factors:
1) Frequent changes in formation strength, such as alternating soft and hard layers or interlayer fault zones, resulting in uneven distribution of drilling force.
2) The core is subjected to stress concentration or flushing during drilling.
3) The drill bit jumps violently and cannot cut continuously.
4) The core tube is disconnected from the formation and cannot capture the core completely.
Solution strategy:
1) Use a double-tube or triple-tube coring system: the inner and outer tubes are independent, reducing interference with core samples and improving integrity.
2) Optimize coring parameter matching: reduce flushing fluid pressure in weak layers, stabilize the advancement speed in hard layers, and reduce disturbances.
3) Use shock absorbers or buffer joints: reduce drill bit jumps and improve cutting continuity.
4) Add stabilizing fluid or perform short-segment consolidation when necessary: prevent the loss of soft layer cores.
4. Manifestation: frequent drill jams and drill burials, interruption of construction
Influencing factors:
1) Interlayers or disintegrated fragments accumulate in the hole, forming jam points.
2) Insufficient mud carrying capacity leads to drilling debris deposition.
3) Drill rod bending or torque mutation, resulting in twisting and jamming.
4) Continuing drilling without timely cleaning the bottom of the hole.
Solution strategy:
1) Strengthen the mud carrying capacity: increase the flow rate or replace it with high-density mud to improve the efficiency of slag removal.
2) Regularly short-circuit the rotary drill to remove the drill cuttings at the bottom of the hole.
3) Use mid-course vibration or impact device: clear the blockage point.
4) Choose a drill bit structure with self-cleaning function (such as wide groove spiral, negative pressure slag removal type).
5) When encountering signs of drill jam, it should be reversed or lifted in time to prevent further jamming.
During the construction of a multifunctional coring drill, the stability of the coring quality is crucial and directly related to the reliability of geological data. The following are the manifestations of specific problems, the corresponding cause analysis, and targeted solution strategies:
1. Manifestation: The core sample is short and discontinuous, and there are "empty sections"
Influencing factors:
1) Poor matching between the drill bit and the formation, fast penetration and incomplete cutting.
2) Insufficient propulsion force causes the core sample to break or be carried away by the flushing fluid.
3) Drill rod swings or is unstable, causing the core sample to fall off.
4) During the drilling process, the core sample "slips" in the coring tube and is not effectively intercepted.
Solution strategy:
1) Select the drill bit type and structure that matches the formation: If you encounter hard rock, choose a diamond drill bit. if you encounter a broken layer, choose a large chip groove and low disturbance drill bit.
2) Reasonably adjust the propulsion parameters: increase the propulsion force to keep the drill bit cutting the rock formation continuously, but avoid excessive thrust to crush the core sample.
3) Strengthen the rigidity of the drill rod and the design of the centering mechanism: reduce the shaking of the drill rod and ensure the stable wrapping of the core tube on the core.
4) Adopt anti-slip core tube design: such as installing a spring core chuck or a one-way check device to improve the core capture ability.
2. Manifestation: The core sample is severely broken and it is difficult to restore the geological stratification
Influencing factors:
1) Excessive rotation speed or uncoordinated propulsion force causes core disturbance and crushing.
2) The impact force of the drill bit on the rock formation is too large, resulting in stratification damage.
3) The stratum itself is a broken structure or fault zone, which makes it difficult to form a complete core sample.
4) The internal structure of the core tube is too rough or has burrs, causing the core sample to break during the extraction process.
Solution strategy:
1) Optimize the drilling parameter ratio: For broken strata, reduce the rotation speed and increase the propulsion force appropriately to reduce disturbance.
2) Use special core drill bits: such as three-wing or large channel drill bits, which have good cutting stability and low crushing rate.
3) Apply pressurized stable coring technology: Stabilize the stratum structure by pressurizing with mud or air while drilling.
4) Upgrade the inner wall accuracy of the core tube: Use mirror stainless steel inner tube or coating material to avoid friction and crushing between the core sample and the tube wall.
3. Manifestation: The core sample is dispersed and contaminated by the flushing fluid, and loses its analytical value
Influencing factors:
1) The flushing fluid pressure is too high or the flow rate is uneven, which directly flushes the core.
2) The mud performance is poor and does not play an effective wall protection role.
3) The slag discharge system is blocked, resulting in the back pressure destroying the core sample.
4) The formation is easily soluble in the flushing fluid, such as gypsum, salt rock, etc..
Solution strategy:
1) Control the flushing fluid pressure and displacement: set appropriate pump pressure and flow rate parameters to avoid direct impact on the core.
2) Select high-efficiency wall protection mud or polymer flushing fluid: improve the stability of the barrier and reduce the disturbance to the core sample.
3) Clean and optimize the slag discharge system design: ensure smooth discharge of drill cuttings to avoid back pressure impact on the core.
4) Use waterless drilling or air drilling for special formations: reduce the physical and chemical damage of water to the core sample.
The multifunctional coring drill integrates complex systems such as hydraulics, power, and electronic control. It is very easy to fail in field conditions, affecting continuous operation and construction cycle. It is necessary to deal with it systematically from three aspects: problem manifestation, root cause, and system solution strategy.
1. Manifestation: Hydraulic system leakage, insufficient pressure, abnormal operation
Influencing factors:
1) Aging or improper installation of hydraulic seals causes interface leakage.
2) Hydraulic oil pollution, impurities wear the valve body and pump body precision structure.
3) Oil pipe joints are loose and broken, causing pressure loss.
4) Hydraulic pumps, reversing valves and other core components are damaged or worn.
Solution strategy:
1) Regularly replace seals, filters and hydraulic oil (such as maintenance every 500 hours).
2) Use high-quality hydraulic oil to control the impurity content and water ratio.
3) Establish a hydraulic system pressure monitoring and alarm system to identify leakage trends in advance.
4) Strengthen assembly process control, such as torque standardization and joint tightening process.
5) Key hydraulic components use imported brands or original spare parts to reduce failure rates.
2. Manifestation: Drill pipe stuck, broken, construction interrupted
Influencing factors:
1) Drill pipe material is unqualified or has not been replaced due to long-term fatigue use.
2) Improper setting of propulsion force or speed causes stress concentration in drill pipe.
3) Drill pipe thread is poorly lubricated or not tightened according to specifications, resulting in stripping or breaking.
4) Failure to take measures such as reverse driving and lifting the drill in time after the formation suddenly changes and the drill is stuck.
Solution strategy:
1) Use qualified brand drill pipes and establish a service life record sheet.
2) Set recommended parameter values for different formations to avoid misoperation (such as low speed and medium torque for hard rock, high speed and light propulsion for soft layer).
3) Check the drill pipe thread before construction and apply special high-temperature grease.
4) Configure emergency drill stuck processing tools (such as reverse circulation pump, high-pressure water flushing gun), and train operators on emergency processing procedures.
3. Manifestation: The temperature of the power head/spindle box is too high and the efficiency is reduced.
Influencing factors:
1) Continuous high-load operation, poor heat dissipation of the lubrication system.
2) Mismatched viscosity of the lubricating oil in the gearbox or aging of the oil.
3) Radiator blockage, fan failure, heat accumulation.
4) Abnormal clearance of the power head components, increased friction.
Solution strategy:
1) Set the start-up-operation-shutdown cycle to control the continuous operation time of the equipment.
2) Regularly check and replace the gearbox lubricating oil (such as every 300 hours).
3) Regularly clean the air duct and radiator fins to ensure smooth air circulation.
4) Introduce a spindle temperature monitoring sensor and set an alarm threshold (such as a prompt of over 85°C).
5) Use an automatic lubrication system instead of manual greasing to improve lubrication uniformity and efficiency.
4. Manifestation: The electronic control system is slow to respond or fails
Influencing factors:
1) Aging of control lines, loose interfaces, unstable signal transmission.
2) Water ingress, short circuit or failure of electronic control components (such as damage to PLC modules).
3) Unstable power supply voltage, resulting in control panel reset or freeze.
4) Overly simplified operation panel, lack of misoperation protection mechanism.
Solution strategy:
1) Check wiring integrity and insulation before each move or rain operation.
2) Set waterproof seals and desiccant for the electronic control box, and clean dust regularly.
3) Use voltage-stabilized power supply modules or set up UPS to protect important circuits.
4) Set misoperation locks and hierarchical control permissions for the electronic control system to reduce misoperation.
5) Strengthen on-site training and fault judgment capabilities of electricians.
5. Manifestation: Abnormal wear of equipment caused by operator misoperation
Influencing factors:
1) Lack of operator training, misjudgment of formations or parameters.
2) Lack of standardized operation procedures and working condition records.
3) Operation data is not recorded and fed back in real time, and closed-loop improvement cannot be formed.
Solution strategy:
1) Implement pre-job operation training and regular skill assessment system.
2) Establish a "construction log + parameter record + abnormal working condition reporting" three-link system.
3) Introduce human-machine interface (HMI) to record key operations and abnormal prompt information.
4) Set up "standard operation procedure cards" at the construction site as on-site reference.
5) Upload equipment abnormal operation data to the remote diagnosis system to form a big data feedback mechanism.
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