Drill Bit Research Articles

Kirschner wire creates more microdamage than standard or acrylic drill bits in the rabbit (Oryctolagus cuniculi) femur

Abstract OBJECTIVE Histologically evaluate damage to rabbit femur after the creation of bicortical 1.5-mm-diameter holes using a standard surgical drill bit, an acrylic drill bit, and a Kirschner wire (K-wire). METHODS 10 femora (5 pairs) from skeletally mature female intact New Zealand white rabbits were used. The bone diaphyses were divided into 4 locations, systematically undergoing each test (surgical drill bit, acrylic drill bit, K-wire, and intact control). Four pairs were drilled using a mechanical testing machine, and 1 pair was drilled by hand. Cross-sections of the bone were stained en bloc with basic fuchsin for undecalcified histological evaluation. Damaged bone was reported as a percentage of a standardized area and categorized by location (cis- or transcortex), drill contact (entrance or exit of the cortex), and total damage (both cortices). RESULTS The drilling method (hand vs mechanical testing machine) had no effect on histologic damage, so results were analyzed by combining all data. The K-wire demonstrated the greatest area of cracks/damage compared to both standard surgical and acrylic drill bits, whereas no difference in damage was noted between the 2 drill bits for all variables. CONCLUSIONS The K-wire and drill bits caused microdamage; K-wire drilling created more microdamage than drill bits. CLINICAL RELEVANCE The rabbit bone cortex is thin and brittle relative to dogs and cats, leading to failure during and after fracture fixation. The clinical failure of rabbit bone is at least partially caused by drill bits or K-wires causing microcracks.

Investigation of cutting forces of glass sphere reinforced polymer composites

AbstractIn this study, the effects of reinforcement ratio, drill bit material, and drilling process parameters on the cutting forces generated during the drilling of glass sphere‐reinforced polypropylene composites were investigated experimentally. Test specimens were produced by conventional injection‐moulding of glass sphere reinforced polypropylene composite materials at 5 %, 10 % and 20 % wt. ratios. High speed steel, titanium‐coated high‐speed steel, and carbide drill bits with 4 mm diameter were preferred for drilling. In addition, the drilling process was carried out on a 3‐axis computer numeric control milling machine. Three different feed rates of 0.05 mm/rev, 0.10 mm/rev, and 0.15 mm/rev and cutting speeds of 12 m⋅min−1, 16 m⋅min−1, and 20 m⋅min−1 were determined for the drilling process. In addition, Taguchi experimental optimization method, analysis of variance and scanning electron microscopy were used to investigate the morphology of the drilled surface and the wear mechanisms occurring on the drill bit due to the drilling process. The test findings showed that the maximum torque value was 54.64 N⋅mm and the maximum thrust force was 100.43 N. The optimum test parameter for cutting forces was observed as C1D3FR1CS3. Drill parameter had an effect of 40.96 % on thrust force and 36.11 % on torque.

Analysis of failure modes and impact resistance factors of PDC cutters

The service life of PDC cutters directly affects the overall drilling performance. In hard and heterogeneous formations, PDC cutters often fail prematurely due to dynamic impacts, leading to short footage and slow penetration rates. Enhancing the dynamic impact resistance of PDC cutters is crucial for achieving one-run drilling and reducing costs. This paper systematically studies the main factors influencing and optimizing the impact resistance of PDC cutters. First, the failure modes of hundreds of returned PDC drill bits were statistically analyzed, revealing that dynamic impact failure, wear failure, thermal damage, and erosion are the primary failure modes. Among these, dynamic impact failure is the most prevalent, with dynamic impact load being the main cause. Following the successful practices of leading international drill bit companies, a set of dynamic impact test and evaluation devices for PDC cutters was designed, and corresponding testing standards were established. Based on this, 19 types of PDC cutters were tested for impact resistance, exploring the effects of cutter diameter, diamond layer thickness, chamfer, cobalt removal, and cutter design on impact resistance. An optimized design methodology to enhance impact resistance was summarized, leading to the proposal of a new arch-axe cutter design. Indoor impact test data verified the superiority of this cutter. The research results indicate that cutter design (non-standard cutters) can significantly improve the dynamic impact resistance of PDC cutters. Additionally, increasing the cutter diameter and chamfer size while reducing the diamond layer thickness also enhances the dynamic impact resistance of PDC cutters. Through the optimization of the arch-ridge design, the independently developed arch-axe cutter improved the dynamic impact resistance by 106.45% and 71.43% compared to flat circular cutters and axe-shaped cutters, respectively.

Natural H2 Transfer in Soil: Insights from Soil Gas Measurements at Varying Depths

The exploration of natural H2 is beginning in several countries. One of the most widely used methods for detecting promising areas is to measure the H2 percentage of the air contained in soils. All data show temporal and spatial variabilities. The gradient versus depth is not usually measured since the standard procedure is to drill and quickly install a tube in the soil to pump out the air. Drill bits used do not exceed one meter in length. These limitations have been overcome thanks to the development of a new tool that enables percussion drilling and gas measurements to be carried out with the same tool until 21 feet deep. This article shows the results obtained with this method in the foreland of the Colombian Andes. The variation of the gradient as a function of depth provides a better understanding of H2 leakage in soils. Contrary to widespread belief, this gradient is also highly variable, and, therefore, often negative. The signal is compatible with random and discontinuous H2 bubbles rising, but not with a permanent diffusive flow. Near-surface bacterial consumption should result in a H2 increase with depth; it may be true for the first tens of centimeters, but it is not observed between 1 and 5 m. The results show that, at least in this basin, it is not necessary to measure the H2 content at depths greater than the conventional one-meter depth to obtain a higher signal. However, the distance between the measured H2 peaks versus depth may provide information about the H2 leakage characteristics and, therefore, help quantify the near-surface H2 flow.

Remediation of LWD data lag with hybrid real-time data using self-attention-based encoder-decoder model

This study aims to address the lag issue in Logging While Drilling (LWD) data, which is crucial for real-time decision-making in subsurface resource exploration. The primary objective is to enhance the accuracy of LWD measurements, which suffer from a positional discrepancy due to the tools being positioned several meters behind the drill bit. This lag can lead to delayed responses and misinterpretations during drilling operations. To achieve this, we introduce a novel Self-Attention-Based Encoder-Decoder (SABED) model that compensates for the time/depth lag by utilizing hybrid real-time data, including drilling engineering and LWD data. Our methodology involves training and validating the SABED model using data from the Volve field in the North Sea. The model's architecture is designed to effectively capture the complex relationships between drilling data and LWD measurements. Experimental results demonstrate that the SABED model can predict gamma ray values up to 45 m ahead with a Mean Relative Error (MRE) of less than 1.5% in the primary test well (F7), outperforming conventional sequential deep learning models. Further evaluations on an auxiliary test well (F10) indicate robust performance and generalization capabilities, even with noisy drilling data. The model also meets real-time operational requirements, processing predictions in approximately 4.5 s per 300-step interval (30 m) on both CPU and GPU. Notably, the SABED model maintains predictive accuracy despite data loss, using linear interpolation for missing segments. These findings underscore the SABED model's effectiveness in mitigating LWD data lag and its potential as a valuable tool for real-time geological information prediction. This research contributes novel insights to the field by providing an advanced methodology for improving data accuracy in LWD operations, thereby enhancing decision-making in the petroleum industry.

The Geysers Is a Unique Geothermal Resource Presenting Equally Unique Challenges to Drillers

_ For drillers, The Geysers is a unique sort of hell. It is one of the only places on Earth where a shallow well can reach a highly fractured reservoir so hot that it only produces steam. That steam powers 18 power plants generating 835 MW of electricity, making this 45-square-mile area the world’s most prolific geothermal power producer. High drilling costs there also stand out. Drilling a well requires 60 days or so and generates a lot of damaged drill bits and drillpipe. The drilling rigs have the size and power of modern onshore rigs, but a close look reveals there’s no topdrive. Below the rig floor there is a rotary table, known as a Kelly drive because it can spin drilling pipe without being in the line of fire of the steam flowing out when running slotted casing into the steam-production zone. When they get to that zone, they switch from drilling fluid and mud to injecting a high-pressure stream of air because of the enormous fluid losses anticipated when they reach that highly fractured level. A drill bit that lasts 500 ft in this harsh, highly fractured rock has had a long run. And the rugged terrain—mountains to a Texan but hills to a Californian—makes this a hard place to move a rig. “The Geysers is its own animal, for sure,” said Sam Noynaert, a Texas A&M professor who was a key member of a team of drilling experts and scientists that drilled a well in The Geysers to test if faster drilling methods from the oil business could work there. The two upper sections went pretty well, considering. As they went deeper, they repeatedly had to deal with severe fluid losses. Still, they had shaved nearly 6 days off the average drilling time. But when they reached the highly fractured steam-producing payzone and their drilling method changed to air drilling, things got worse with drill bits failing after runs as short as 21 ft. As a Geysers drilling paper presented at the Stanford Geothermal Workshop earlier this year delicately put it: “The air section proved to be more challenging.” The Blob The Geysers has a long history. The heat source is “a large blob of silica-rich magma (which) forced its way through Earth’s crust beneath the Coast Range,” according to the description of an image from NASA. That flow about 1.3 million years ago from deep within the earth heated the overburden, making the rock brittle and prone to fracturing. Over time, water seeped into those hot fissures, creating hot springs that were awed by Native Americans and later attracted tourists to a nearby resort hotel. By the 1960s drillers were tapping the steam in those payzones for commercial power generation, which peaked at 2,000 MW in 1987. It declined from there as steam production depleted the reservoir. Eventually, the output was stabilized at its current level by injecting water from sewage-treatment plants into the production zone.

Vibration analysis of push-the-bit rotary steerable bottom hole assembly

With the development of oil and gas fields to the deep-sea, the rotary steerable system is widely used. Downhole vibration is an important factor affecting the performance of rotary steerable system. Currently, the lack of research on vibration during operation of rotary steerable system has affected the development of deep-sea oil and gas field development technology. In this paper, the dynamic model of the push-pull rotary steerable system is established based on the similarity principle. The model includes Bit-rock interaction model, Drillstring-borehole contact model and guiding force model of rotary steerable system, the trajectory and vibration of drill bit under different guiding forces are simulated. Then, the actual drilling experiment of the full-scale Push-The-Bit Rotary Steerable System (PTB-RSS) in the horizontal section is carried out. The acceleration and speed signals of the push-pull rotary steerable system in the process of applying guiding force are collected and verified with the calculation results of the dynamic model. It is found that the vibration frequency and amplitude of the Bottom Hole Assembly (BHA) gradually increase with the increase of the guiding force of the PTB-RSS during the drilling stage, which induce high-frequency torsional vibration to a certain extent. In addition, the dynamic simulation shows that when the guiding force of the rotary steerable system is increased to a certain extent, the vibration of the BHA gradually stabilizes, but the vibration amplitude does not decrease.

Detection of effective prestressing of 1860-grade strands based on the microporous method

Existing tensioning cable prestress ensures bridge safety. This work presents the micro-hole release technique, which accurately measures the effective prestress of strands in existing prestressed concrete bridges. The strand drilling model was produced in Solidworks and Abaqus. The effect of drilling depth, diameter, deflection angle, and hole edge distance on strand stress release was then examined. The findings indicate that strand drilling tension relief is directly related to hole depth and diameter. As aperture size increases, stress alleviation decreases. The stress release error rate increases as the strand drilling deflection angle increases from 0° to 15°. Portable electric drill bits are 1.5 mm. A 5.0 mm hole was bored into the steel wire. The steel strand drilling wire is 3.0 mm from the hole’s edge. The drill bit is designed to maintain a drilling deflection angle of less than 5°, ensuring accuracy and ease of testing. After that, the 1860 grade strand drilling test was used to compare stress release and associated circumstances between P-T and T-P operating conditions. The strain-tension fitting equations for strand release were compared to finite element simulation results under P-T and T-P operating conditions. We found that the formula for fitting the strain-tension force of strand release under T-P condition matches finite element simulation results. It also matches real-world engineering methods.

Modeling of drilling tool vibration in the process of drilling blast wells

Purpose. To determine the characteristic features and model bit vibration during its interaction with rock in the process of drilling technical (blast) wells in open pit mines. Methodology. The following methods were used in the work: analysis of scientific and practical solutions; statistical methods for processing the results of experimental studies; methods of analytical synthesis; computer modeling methods for synthesis and analysis of mathematical models. Findings. The process of interaction between a drill bit and a rock was analyzed. The conditions and causes of vibration of drilling equipment are determined. The spectral analysis of the vibration signal, the formation and analysis of the map of the order of rotation of the rotating parts of the drilling rig during the drilling of technical (blast) wells were performed to identify the bit in the frequency domain of the measured concomitant integrated vibration signal as a source of high-amplitude vibration. The modulated signal measured in the time domain at the specified frequency carries information about the physical and mechanical characteristics of the drilled rock and the state of the bit. The analysis of the experimental studies and modeling of the process of interaction of the bit with the rock allows us to conclude that the obtained statistical indicators of the accompanying vibration signal really adequately characterize the process of well drilling. Originality. A method for determining the characteristics of the interaction of a drill bit with rock in the process of drilling technical (blast) wells based on measuring the parameters of the accompanying vibration signal is proposed. The method differs from the known ones in the fact that in the process of changing the operating mode of the drive of the rotating parts of the drilling rig, an order map is formed over the entire range of its revolutions, the frequency of high-amplitude vibration of the bit is determined, which corresponds to a certain peak order of revolutions, and at this frequency the statistical parameters of changes are measured. Practical value. This approach to the process of drilling wells in open pit mines makes it possible to quickly determine the physical and mechanical characteristics of the drilled rock and adjust the process parameters accordingly to increase its productivity and energy saving.

Optimization of Drill Bit Geometries for Minimum Thermal Damage in Bone Drilling

Thermal injury is a common post-operative effect in bone drilling surgeries. The extreme heat generated during the drilling process kills bone cells, which causes irreversible bone death. This bone death loosens medical fixations—screws, plates, and implants—and subsequently refractures the bone. Research on drill bit geometries in bone drilling has attracted interest from engineering and medical researchers. However, previous research has mainly focused on the simulation of bone drilling, which could generate an incorrect approximation of thermal bone damage if the simulation model is not validated. For this reason, this study focuses on the optimization and parametric analysis of the bone temperature elevations induced by customized drill bit features—point angle (60-180°), web thickness (25-50 %), and helix angle (10-55°)—in comprehensive ex-vivo bone (bovine) experimental drilling tests. The L9 Taguchi optimization method was then applied to determine the optimal design to minimize maximum bone temperature rise. Results from the parametric analysis revealed that the optimal setup for the drill point features can be obtained with the ranges of point angle of 160-180°, web thickness of 25-30 %, and helix angle of 30-40°. Based on the Taguchi optimization results, the minimum thermal damage is produced with the point angle of 180°, web thickness of 25 %, and helix angle of 35°. This work offers a promising solution for reducing thermal injury and preventing thermal osteonecrosis in bone drilling surgeries.

Optimization of hydraulic structure and well flushing parameters of a truncated cone drill bit for drilling shaft sinking

ABSTRACT Based on a research method combining numerical simulations and model testing, a numerical model and test platform for gas lift reverse circulation multiphase coupling in well washing were developed. The hydraulic structure and well washing parameters of a φ5 m truncated cone bit used in the Beifeng well at Taohutu Coal Mine were optimized, and the distribution law of the well washing flow field was determined. The findings revealed that: (1) with a bit taper of 40 and a length-diameter ratio of 0.32 for the truncated cone, the hydraulic structure was optimal. Compared with the original bit structure, the axial speed of mud at the slag suction port increased by 15.9%, and the average sliding speed of mud at the inclined rock surface increased by 63.2%. (2) The multiphase fluid in the slag discharge pipe flowed successively in the form of “low-speed stable two-phase flow” and “high-speed disordered three-phase flow,” while the multiphase fluid in the horizontal and inclined bottom holes flowed predominantly in radial and tangential patterns, respectively. (3) The optimal parameter combination for efficient well washing with the truncated cone bit included a bit rotation speed of 8 r/min, a gas injection rate of 5600 m3/h, an air duct sinking ratio of 0.79, and a mud viscosity of 176 mPa·s, with bit rotation speed being the most significant factor affecting effective washing efficiency. These results could provide a valuable reference for improving the efficiency of drilling and well flushing in Jurassic strata of western China.

Development of Specialized PDC Drill Bits for the Interaction of Soft and Hard Strata in Igneous Rocks

In response to the technical challenges of low mechanical drilling speed and severe drill bit wear caused by the development of some igneous rocks in the Dongying and Shahejie formations of the Bozhong 34-9 oilfield, it is urgent to develop a specialized PDC drill bit suitable for the soft hard interaction formation of the BZ-34-9 oilfield. The PDC drill bit is required to have strong aggressiveness, as well as good impact resistance and abrasion resistance, in order to meet the drilling requirements of the soft hard interaction formation of the BZ34-9 oilfield. Through on-site use, the mechanical drilling speed has been significantly improved.

Control strategies for mitigating torsional and axial vibrations in rotary oilwell drilling systems

Abstract This paper examines a nonlinear dynamics model to explore the significant factors influencing the coupled torsional-axial vibrations of a drill string. The primary focus lies in effectively modeling, analyzing, and controlling both torsional and axial vibrations occurring in a rotary oil well drilling system. The model employed incorporates a wave equation with a damping term (PDE) connected to an ordinary differential equation (ODE) through a nonlinear function representing the interaction between the drill bit and the rock. We proceed to establish the well-posedness of the coupled PDE-ODE in an appropriate functional space. As a PDE-ODE coupled system, we specifically investigate the stability problem concerning the velocity at the bottom extremity, considering both the presence and absence of the damping term in the wave PDE. To address this, we propose a systematic method based on a Lyapunov approach for designing feedback controllers. These controllers ensure system stability and effectively suppress harmful vibrations.

Gray relational analysis for parametric optimization of micro-EDM of thermo-mechanically processed AA7075 and AA7075/SiC/Gr composite

The AA7075 alloy and AA7075/SiC/Gr hybrid composite prepared by the stir-casting method have been further thermo-mechanically processed through unidirectional hot rolling and hot cross-rolling routes to eliminate casting defects like voids, blow holes etc. Three initial sample temperatures, that is, 350℃, 400℃, and 450℃, have been considered for the hot cross-rolling. The Al alloy and its hybrid composite prepared at different rolling temperatures are studied to investigate their micro-machining behavior through micro-electric discharge machining (µ-EDM). The micro-holes are made on the rolled samples along the rolling direction of the final rolling pass using a tool with twist drill bit geometry. Further, multi-objective optimization of the µ-EDM process parameters considering the response parameters viz. material removal rate (MRR) and tool wear rate (TWR) has been carried out using the gray relational analysis (GRA) technique. The µ-EDM parameters chosen to optimize in this study are voltage, pulse on time, and tool rotation. The obtained GRA results are further analyzed through normality and equal variance tests. The R-squared values of 95.02% and 95.53% for AA7075 alloy and hybrid composite, respectively, indicate that the data fit well with the statistical model. In material removal, the different electrical and thermal characteristics of the Al matrix and the reinforcements possibly generate sparks with a different characteristic that ultimately affects the MRR of the composite. Through scanning electron microscopy (SEM), the morphological study confirmed the presence of globules and voids on the machined surface. The formation of globules and voids is more significant in the AA7075 alloy than in the composite.

Studies on surface roughness and axial thrust force of drilled holes in Mg-Zn-Ca bio-medical alloy

Mg-Zn-Ca alloy is a promising candidate for orthopaedic implants such as bone plates and screws, as it has a similar mechanical strength and elastic modulus to bone, and it degrades in the body without causing toxicity or inflammation. Drilling studies are necessary to optimize the drilling process parameters, to evaluate the machinability and surface integrity of Mg-Zn-Ca alloy, and to ensure the effective and efficient drilling for various applications in the medical and engineering fields. The present experimental study emphasizes the influence of Ca content, biofriendly coolants and their combined effect with standard drill bits on the surface quality and axial thrust force in the drilling operation of Mg-Zn-Ca alloy. The drilling parameters such as cutting speed, feed rate, standard tools, bio-compatible coolants were optimized with respect to the amount of Ca in the Mg-Zn alloy. The axial thrust force and average surface roughness of drilled holes were considered as response of the experiments. The drilled surfaces were measured for average surface roughness in the transverse direction along the centre path of the drilled hole and a qualitative analysis was also carried out using advanced confocal microscope. The results revealed that the cutting speed among continuous factors significantly influenced the axial thrust force and average surface roughness. The effect of categorical factors was assessed using a regression based ranking method. The results of statistical analysis revealed that high speed steel, and vegetable oil offered improved surface quality, whereas the coconut oil showed low axial thrust force. The liquid nitrogen showed high value of axial thrust force and average surface roughness due to the brittleness induced by cryogenic coolant before drilling operation.

Drill bit hydraulic system for oil and gas boreholes

We set out to improve the existing design of a polycrystalline diamond bit with a steel or matrix body with the purpose of creating a hydro-monitoring effect. The research object was the hydraulic system of a diamond bit with a near-bit jet pump. The near-bit ejector system was studied by a theoretical analysis of the operation of the bit hydraulic system by means of canonical dependencies and hypotheses. A hydraulic system for a polycrystalline diamond bit is proposed. This system includes a high-pressure jet pump, which enhances the hydro-monitoring effect at the bottomhole. The main hydraulic characteristics of the bit flushing system with a jet pump are as follows: at a drilling pump feed of 18.4 l/s and a drilling fluid density of 1180 kg/m3, the working coefficient of jet pump injection equals 0.34; the working nozzle diameter equals 10.3 mm; the mixing chamber is 11.9 mm, bit hydromonitor nozzles are 11.1 mm; the number of hydromonitor nozzles is 3; the velocity at the exit of hydromonitor nozzles is 85.0 m/s; the pressure drop at the bit is 15.7 MPa. The possibility of using the hydro-monitoring effect enhanced by a near-bit jet pump was substantiated, since the velocity at the exit from the hydro-monitoring nozzles is sufficient to destroy most rocks (sandstone, limestone, dolomites, rock salt, gypsum stone, basalt, marble, granite). The jet pump in the proposed design of a polycrystalline diamond bit creates an additional circulation circuit above the bottomhole, injects cuttings from the annular space and feeds them to the hydro-monitor nozzles. This enables a more efficient destruction of the bottomhole rock. The power of hydro-monitor jets is sufficient to improve drilling performance.

A novel method for identifying rock interfaces and fragmentation zones based on drilling response characteristics

The rapid measurement and acquisition of the fracture characteristics and strength of the surrounding rock are crucial for evaluating the stability of underground engineering. In this study, a laboratory/coal mine universal drilling test platform was developed to enable real-time measurement of drilling parameters. The testing results demonstrate that under identical rotation speed conditions, both thrust force and torque increase exponentially with increasing drilling speed, while under identical drilling speed conditions, both thrust force and torque decrease linearly with increasing rotation speed. In intact rock layers, variations in torque, thrust force, and drilling speed with depth remain relatively stable, in rock layer interfaces and fragmentation zones, sudden changes occur within a drill displacement range of approximately 3–7 mm, which become more pronounced as strength differences between adjacent rock layers increase.Based on the cutting mechanics model of drill bit, the evaluation index of drilling energy consumption of unit rock mass (Eη) is derived. Subsequently, based on drilling speed, rotation speed, thrust force, torque and energy index, a machine learning model for predicting rock strength is established using the LS-SVM nonlinear regression approach. Field practice has shown that drilling platform can effectively identify both the rock interface and range of fragmentation areas. The experimental results are of great value to the selection of supporting types in the process of coal mine roadway excavation.

An automatic workflow for the quantitative evaluation of bit wear based on computer vision

As global oil exploration ventures into deeper and more complex territories, drilling bit wear and damage have emerged as significant constraints on drilling efficiency and safety. Despite the publication of official bit wear evaluation standards by the International Association of Drill Contractors (IADC), the current lack of quantitative and scientific evaluation techniques means that bit wear assessments rely heavily on engineers' experience. Consequently, forming a standardized database of drilling bit information to underpin the mechanisms of bit wear and facilitate optimal design remains challenging. Therefore, an efficient and quantitative evaluation of bit wear is crucial for optimizing bit performance and improving penetration efficiency.This paper introduces an automatic standard workflow for the quantitative evaluation of bit wear and the design of a comprehensive bit information database. Initially, a method for acquiring images of worn bits at the drilling site was developed. Subsequently, the wear classification and grading models based on computer vision were established to determine bit status. The wear classification model focuses on the positioning and classification of bit cutters, while the wear grading model quantifies the extent of bit wear. After that, the automatic evaluation method of the bit wear is realized. Additionally, bit wear evaluation software was designed, integrating all necessary functions to assess bit wear in accordance with IADC standards. Finally, a drilling bit database was created by integrating bit wear data, logging data, mud-logging data, and basic drilling bit data.This workflow represents a novel approach to collecting and analyzing drilling bit information at drilling sites. It holds potential to facilitate the creation of a large-scale information database for the entire lifecycle of drilling bits, marking the inception of intelligent analysis, design, and manufacture of drilling bits, thereby enhancing performance in challenging drilling conditions.

Research on Drillpipe Stick-slip Vibration and Its Suppression Mechanism in Deep Well Drilling

Abstract During drilling deep wells, stick-slip vibration(SSV) is a reciprocating vibration form of drill bit adhesion, sliding, re-adhesion, and re-sliding. If not suppressed, it can cause serious drilling accidents, such as accelerated wear of drilling equipment, which lead to decreased drilling safety, reduced drilling efficiency, and prolonged drilling cycle. This article establishes a SSV model of the drill string system, considering the three degrees of freedom of the rotary table/top drive, hammer, and drill bit, and analyzes the SSV characteristics of the drill bit during deep well drilling. The SSV analysis of the drill string system was carried out for well XX-X-4, and the sensitivity of rotational speed, viscous damping, drilling pressure, drill bit length, and friction torque coefficient was analyzed. The results showed that the friction torque coefficient and rotational speed are the main factors affecting stick reduction efficiency, while the length of the drill collar is a secondary factor. The WOB and viscous damping have the least impact on stick reduction efficiency. The parameters were optimized to reduce SSV as the target. This article has certain guiding significance for deep well drilling operations.

Experimental study on rock drilling vibration of PDC bit in interbedded formations

Mastering the vibration characteristics of PDC bit, especially in interbedded formations, can help to explore reasonable bit failure control measures, achieve bit optimization and drilling optimization. This work used single rocks to construct different types of vertical and horizontal interbedded rocks with different interbedded properties, the experimental study obtained the bit vibration characteristics under single rock, sudden-changed rock, and alternating rock conditions. The vibration acceleration of a single rock is consistent with the rock strength. The acceleration increases with the increase of weight-on-bit and rotary speed, the influence of weight-on-bit is greater than that of rotary speed. The maximum amplitude of accelerations always occurs in the low frequency range of 0∼300 Hz, the difference between rocks is mainly reflected in the high frequency range greater than 400 Hz. When the drill bit suddenly crosses from soft rock to hard rock in the vertical interbedded formation, the acceleration increases rapidly, causing direct impact. When the drill bit suddenly crosses from hard rock to soft rock, the impact and acceleration attenuates slowly, which could cause fatigue damage to the drill bit and induce high-frequency vibration. The rapid and significant change in depth-of-cut is the fundamental reason for the impact generated when the bit crosses through the interlayer, and both the maximum and minimum depth-of-cut occur in the transition region. PDC bit alternately encountered soft and hard rocks in the horizontal interbedded formation, causing intensified vibration. The acceleration is consistent with rock difference. The influence of weight-on-bit on acceleration increases with the increase of rotary speed for horizontal interbedded formation with small rock differences. However, with the increase of weight-on-bit, the influence trend and degree of rotary speed on acceleration remain basically unchanged. The increase in weight-on-bit /rotary speed weakens the effect of rotary speed/ weight-on-bit on acceleration in horizontal interbedded formations with significant rock differences. The research results illustrate that the reason for the abnormal bit failure in interbedded formations is the frequent changes in depth of cut caused by rock mutation and alternation, and the resulting impact. This provides theoretical guidance for the implementation of effective measures such as reasonable cutter arrangement design, pertinent setting of auxiliary structures, and appropriate adjustment of drilling parameters.