Design Of Drill Bit Research Articles

Research and practice of high-speed spiral composite drilling technology in complex and weak coal seams

In response to the difficult slag discharge and low hole formation rate encountered in the Wangpo Coal Mine, a study was conducted on high-speed spiral composite drilling technology. This study was integrated with the performance characteristics of the ZDY6000LR-type high-speed pit rig, resulting in the design of drill bits in three different specifications: Φ110/63.5 mm, Φ95/60.3 mm, and Φ88/50 mm. Additionally, the study optimized the three-wing drill pipe's feed speed, rotation speed, and airflow volume. The industrial field test, conducted on the 3206 working face of the Wangpo Coal Mine, resulted in the design of three drill bit combinations that exhibited high strength and stiffness. This design improvement led to enhanced hole integrity, elevated slag removal efficiency, and extended service life for both the drill pipe and bit. The high-speed spiral composite drilling technology, alongside the supporting equipment, effectively addresses the challenges of slag discharge and nozzle top drilling encountered during operations. It significantly improves the deep hole drilling rate, achieving a drilling depth of over 100 m with a success rate exceeding 70%. This technology provides vital support for the extraction of gas from coal seams within the mine. Notably, the Φ95/60.3 mm screw pipe and its corresponding drill bit demonstrated the optimal holeforming effect, with an average hole depth of 111.2 m and a hole formation rate of 90.9%. These findings offer valuable insights for drilling operations under similar conditions of complex and weak coal seams.

Technology Focus: Bits and Bottomhole Assemblies (December 2023)

As bottomhole-assembly and drill-bit design and operation have embraced new technologies such as artificial intelligence, new materials and manufacturing techniques, and improved design software, the industry continues to research methods of optimizing delivery and understanding of already globally used technologies. It is this approach that has long allowed service companies, operators, and drilling contractors alike to improve drilling performance, as highlighted in the papers summarized here. In the first of these papers, paper SPE 210723, finite element fatigue simulation has been used to minimize the risk of twistoffs in jars, something that many of us in the drilling community have experienced. This paper can help us reduce those unplanned events and lost time. Many rigs worldwide have moved to using autodriller-type control systems, and, in many cases, these systems have shown improved performance. In the second paper, paper SPE 214997, the optimization of these systems is discussed in the review and modification of driller procedures to minimize damage to bottomhole assemblies and the drill bit during drilling. Finally, while many papers have discussed high-frequency torsional oscillations and their effect on the bottomhole assembly and drill bit from an operational or a theoretical view point, the final paper, paper SPE 212566, discusses full-scale laboratory experiments to qualify the drill bit’s influence on this effect. All three of these papers highlight increased understanding in the operation and evolution of existing technologies to improve drilling delivery. In the evolving world of drilling where the final objectives and uses of wells are changing—whether for repurposing; carbon capture, use, and storage; or geothermal uses—these approaches to optimizing existing technologies in conjunction with the introduction of new technologies can help oilfield drilling teams pivot into this adjacent energy environment to deliver successful wells. Recommended additional reading at OnePetro: www.onepetro.org. SPE 212438 Building a System To Solve the Challenges of Drilling Hot Hard Rock for Geothermal and Oil and Gas by Anthony Pink, NOV, et al. SPE 212559 Machine Learning-Based Drilling System Recommender: Toward Optimal BHA and Fluid-Technology Selection by Gregory Skoff, SLB, et al. SPE 212109 World’s First Application of Steel Body Bit in High-Chloride Formation With Water-Based Mud by Bekbolat Uandykov, Zhigermunaiservice, et al.

Optimum Design of Large-Diameter Reverse Circulation Drill Bit for Drilling Rescue Wells Using Orthogonal Experimental Method and CFD Simulation

Down-the-hole (DTH) hammer drilling with reverse circulation is a novel, mobile, high-speed drilling system suitable for the specific requirements of mine rescue. This technology can be applied to shorten the rescue time during mine accidents. The performance of reverse circulation (RC) drilling depends on the structural design of the drill bit. An orthogonal experimental design is executed to investigate the effect of the structural design parameters of the large-diameter drill bit for drilling rescue wells on the cutting carrying capacity and reverse circulation performance. This study employs computational fluid dynamics (CFD) software to solve the Navier–Stokes equation for three-dimensional steady flow and calculate the flow field around the drill bit to evaluate the RC efficiency. Six key geometric parameters were proven to have a direct influence on the RC performance, including the diameter of suction nozzles Dn, the length of nozzles L, the quantity of nozzles N, the diameter of the pilot hole Dg, the inclination angle of nozzles θs, and the deflection angle of nozzles θd. The CFD simulation experiments were implemented according to the orthogonal array L18(37) and were analyzed using the range, variance, and regression analysis. A mathematical model was developed for the RC efficiency to understand the effect of the factors. The results show that the diameter of suction nozzles Dn has an essential effect on the RC performance of the drill bit. An ideal combination is Dn = 20 mm, L = 50 mm, N = 3, Dg = 50 mm, and θs = 35°, θd = 10°, which was obtained through variance analysis and validated via CFD simulation for higher efficiency. To verify its real performance, a large-diameter RC drill bit with a diameter of 1.2 m was manufactured and tested in the field. The result demonstrated that the drill bit had excellent cutting transport and reverse circulation performance.

Big Data and Machine Learning Optimize Operational Performance and Drill-Bit Design

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 202243, “Use of Big Data and Machine Learning To Optimize Operational Performance and Drill-Bit Design,” by Simon Cornel, SPE, Baker Hughes, and Gonzalo Vazquez, Senex Energy, prepared for the 2020 SPE Asia Pacific Oil and Gas Conference and Exhibition, originally scheduled to be held in Perth, Australia, 20–22 October. The paper has not been peer reviewed. Time savings and bit longevity are major challenges in coal-seam gas (CSG) unconventional fields onshore Queensland. Maximizing rate of penetration (ROP) on the basis of optimal drilling parameters was the key to tackling these issues. A formal process for optimizing performance was developed, with a focus on optimizing polycrystalline diamond compact (PDC) bit design and drilling hydraulics and developing a drillers’ road map. As a result, ROP increased from 50 to 150 m/h. Time savings of more than 150 hours for the drilling campaign was achieved. Background The drilling campaign encompassed two areas for development. Field A is a CSG acreage 45 km southwest, and Field E 30 km northeast, of Wandoan, Queensland. Eighty vertical wells would be drilled across the two fields. This would provide the opportunity to trial the data-mapping concept to increase ROP and fine-tune bit designs to improve longevity. In addition, the rig-sensor data set provided the basis for creating a machine-learning model to help improve drilling parameters during the production-drilling phase. Drilling Challenges The three primary challenges to be addressed included the following: - Economics for unconventional fields, specifically delivering time savings in order to lower the average cost per well - Control vibrations to avoid twistoffs and bottomhole-assembly fatigue - Consistent performance The benchmark for the initial project was an on-bottom ROP of 80 m/h. Therefore, the target for this campaign was to achieve an average on-bottom ROP of over 100 m/h and drilling-time savings of 1 hour per well. Methodology Bit optimization typically has been an iterative process, taking bit-record information to make assumptions about bit performance before providing recommendations for the next well. A more-detailed approach may include the use of log data (i.e., gamma ray and sonic) to estimate rock strength and overlay the depth-based well data to identify key incidents that affected performance (both positive and negative) so such incidents can be mitigated in future wells. This approach, while exhaustive, takes time to complete and is open to subjective interpretation of the engineer performing the analysis. When drilling CSG wells, typical well duration is 3–5 days. With short turn-around times between wells to analyze the data, the goal in this study was to develop an automated approach using real-time data gathered from the rig and present it to the field and rig crew in a visualized method. A two-step approach was devised in which data from the rig was used, followed by a real-time model.

ЗАЛЕЖНІСТЬ СТАТИЧНОЇ МІЦНОСТІ КРУПНИХ КРИСТАЛІВ СИНТЕТИЧНОГО АЛМАЗУ ТИПУ Ib ОКТАЕДРИЧНОГО ГАБІТУСУ, ПІСЛЯ ХІМІКО-ТЕРМІЧНОЇ ОБРОБКИ, ВІД ЇХНЬОГО РОЗМІРУ

The use of large single crystals of diamond, grown by HP-HT with the latest technologies in drilling tools, can improve the productivity of the drilling process, increase the penetration rate, reduce wear of the main matrix, and provide a safe working environment when drilling solid rocks.For an informed choice or design of the working part of the drilling equipment, an analysis of the functional purpose is important.The main role here is played by the factor of complexity of geodetic conditions: the angle of drilling, fracture toughness and class of rocks, their changes with the depth of drilling.Analysis of studies and publications on functional analysis showed that diamonds should not only have high hardness and static strength, they should have a high value of thermal strength and chemical resistance, which will allow them to be used with sufficient efficiency when developing wells in difficult geological conditions. However, the main indicator of the suitability of such single crystals is still strength. It has been experimentally proven that the main type of diamond wear during drilling is partial or complete chipping of the protruding part of the crystals. Thus,the bits are equipped with harder diamonds, they will allow to process harder rocks without chips, reduce wear of the matrix itself, provide higher drilling speeds alongwith a decrease in energy consumption and consumption of consumables, for example, drilling mud.The purpose of the article is to analyze the effect of chemical-thermal exposure, as an integral part of the technological process of manufacturing drill bits, on the tensile strength of synthetic diamonds of octahedral habit type Ib obtained by HP-HT technology.Based on the data obtained experimentally, the work shows the suitability of synthetic diamonds as part of a functional cutting tool for drilling and geological exploration. The optimal size of crystals was determined, at which a sufficient level of strength is provided. The falling dependence of the strength on the edge length of the investigated diamond single crystals is graphically demonstrated.For the first time, the paper presents a study of the effect of chemical-thermal treatment as part of the technological process of manufacturing a drilling tool on the strength of non-magnetic single crystals of synthetic diamond type Ib. The presented materials can be used for a reasonable choice or design of drill bits impregnated with largesingle crystals for drilling and geological exploration.

Drill Bit Deformations in Rotary Drilling Systems under Large-Amplitude Stick-Slip Vibrations

In oil and gas industry, rotary drilling systems are used for energy exploration and productions. These types of systems are composed of two main parts: mechanical and electrical parts. The electrical part is represented by rotating motor called top drive; however, the mechanical part of the system is composed of tool string with many pipes, at the bottom end of these pipes the bit is attached to cut the rock during their contact. Since the bit is in a direct contact with rock characteristic variations, it can be under risk for heavy damage. The latter is principally caused by the fact that the rock–bit interaction term is highly nonlinear and unpredictable. In literature, many mathematical models have been proposed for rock–bit interaction, but they do not reflect the dynamic of the bit under vibrations since torsional and axial vibrations are strongly coupled and synchronized with it. In industrial development, the design of drill bit has faced many improvements in order to overcome these vibrations and mitigate unpredictable phenomena. Even though, the practical use of these drill bits confirmed that there are still many failures and damages for the new designs; moreover, bits’ virtual life become shorter than before. The objective of this study is to analyze the drill bit deformations caused by the stick-slip vibration phenomenon which is characterized by high-frequency high-amplitude in rotary drilling systems. The obtained results were validated through a case study of MWD (measurement while drilling) data of well located in a Southern Algerian oil field.

Evaluation of the parameters affecting bone temperature during drilling using a three-dimensional dynamic elastoplastic finite element model.

A three-dimensional dynamic elastoplastic finite element model was constructed and experimentally validated and was used to investigate the parameters which influence bone temperature during drilling, including the drill speed, feeding force, drill bit diameter, and bone density. Results showed the proposed three-dimensional dynamic elastoplastic finite element model can effectively simulate the temperature elevation during bone drilling. The bone temperature rise decreased with an increase in feeding force and drill speed, however, increased with the diameter of drill bit or bone density. The temperature distribution is significantly affected by the drilling duration; a lower drilling speed reduced the exposure duration, decreases the region of the thermally affected zone. The constructed model could be applied for analyzing the influence parameters during bone drilling to reduce the risk of thermal necrosis. It may provide important information for the design of drill bits and surgical drilling powers.

THE STUDYLOAD OF THE CUTTERSOF DRILL BITS

To assess the reliability and durability of certain elements of the weapons of drilling cone bits and support assemblies of cutters and bits in General, it is necessary to know the magnitude of the forces acting on the elements of cutting structures of rolling cutter drill bits in the process of its interaction with the bottom. The method and results of direct measurement of these forces with the help of a special measuring device to measure the amount of force acting on each tooth of each cutter in the interaction with the indestructible face. Found that the greatest axial forces acting on the teeth of the secondary cutters. The obtained results can be used to optimize the design of drill bits.

Unconventional Polycrystalline-Diamond-Bit Design Allows Significant Performance Gains

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 156961, ’Departure From the Norm in Polycrystalline-Diamond-Bit Design Allows Significant Performance Gains in Highly Erosive and Abrasive Formations,’ by Aron Deen, Jason Maw, Craig Knull, and John Clegg, SPE, Ulterra Drilling Technologies, prepared for the 2012 SPE Annual Technical Conference and Exhibition, San Antonio, Texas, USA, 8-10 October. The paper has not been peer reviewed. This paper discusses the design, manufacture, and application of a contiguous blade of polycrystalline diamond (PCD). This bit has full-length, contiguous PCD coverage, without gaps between cutters on each blade, as in a conventional PCD-compact (PDC) bit design. The implementation of this bit represents a step change in bit design. Drill-Bit Damage The traditional view has been that PCD cutters are the most important part of the PDC bit because they are required to engage the formation and maintain their geometrical properties long enough for shear drilling to be economical. The bit body, then, is necessary only in order to hold the cutters in their arranged layout, and to convey mechanical and hydraulic power to remove the rock in their path. PCD cutters are very hard and resistant to abrasion, but are susceptible to damage from their relative lack of toughness. Bit-body materials, whether made of steel or tungsten carbide composite hard facing or infiltrated matrix, are more prone to failure in the drilling environment. One drill-bit design limitation is a requirement for sufficient body material to exist to create a pocket to which the PCD cutter will be brazed. In the case of the webbing be-tween the cutters, depicted in Fig. 1, this puts the body material in a position where it is likely to engage either the formation or high-velocity fluid flow. Invention and Hypothesis The premise that there has to be enough body material to constitute a braze pocket leads to the conclusion that there has to be a webbing between the cutters. The resulting engineering problem was to optimize this webbing, on the basis of the need for cutter exposure and material strength of the body material. But does a braze pocket need to be constructed entirely from body material? Erosion and Abrasion. The first obvious benefit of this new design philosophy should be that, given that there is no weak point of webbing subjected to abrasive or erosive wear, intercutter or cross-blade abrasion and erosion will be mitigated. The webbing between the cutters is the area most susceptible to this mechanism along the fluid path. Abrasion occurs because of the same design weakness—the webbing—but be-cause of a different mechanism. As illustrated in Fig. 2, abrasion is more uniform because of the rotation of the bit. It occurs when the bit body contacts the formation and is worn away. The result, though visibly different from erosion, shares a similarity in terms of location.

Challenges and developments of micro drill bit for printed circuit board: a review

PurposeThe purpose of this paper is to present a clear picture of the challenges of micro drill bit and the developments of novel micro‐drill bits for flexible circuit boards, environmental‐friendly printed circuit boards (PCBs), high aspect ratio drill bit and ultra‐small micro drill bit, as well as the developments of geometry design of micro drill bit.Design/methodology/approachThe paper details the developments trend and challenges of micro drill and PCBs first. Then the current research status of novel micro drill bits for flexible circuit boards, environmental‐friendly PCBs, high aspect ratio drill bit, ultra‐small micro drill bit are described. Finally, the developments of geometry design and drilling process are reviewed.FindingsTo achieve excellent performance for drilling flexible PCB, a large helical angle, large flute/land ratio and small web thickness that guarantee the sharp evacuation capability, are adopted in drill bit design. A small helix angle and an appropriate primary face angle are employed for drill bit to process environmental‐friendly printed circuit boards. It is beneficial to implement big helix angle, small primary face angles and small point angles in the design of ultra‐small micro drill bit. An optimum web thickness and step feed should be taken into consideration in high aspect ratio drill bits design.Originality/valueThe paper reviews different solutions of micro drill bits for the state‐of‐the‐art PCB and the developments of geometry design of drill bit for printed circuit boards.

Experimental Investigations on Drilling GFRP Epoxy Composite Laminates Using Specialized and Conventional Uncoated Cemented Carbide Drills

The growing demand of the fiber reinforced plastics (FRPs) in lightweight engineering has led to a need for assessing and quantifying the workpiece material defects, like hole exit delamination, during their drilling process. This article presents the experimental investigations on in-process drilling load profiles and a quantitative analysis of the induced hole exit delamination in drilling glass fiber reinforced plastic (GFRP) epoxy composite laminates, using various uncoated carbide drill bits (two specialized and a conventional one). The aim of studying and analyzing the in-process load profiles, in this work, is necessary in better comprehending the interaction between the tool and the workpiece material, with respect to the induced peak loads. It may further be helpful for determining and assessing the root cause of the induced delamination damage. Moreover, it is shown that the design and geometry of a particular drill bit also plays a vital role regarding its cutting loads and delamination results. The specialized tools were found to be much better than their conventional counterpart. Furthermore, subsequent drilling was conducted onto some predrilled pilot-holes using the same specialized drills, to test the chisel edge effect. The research emphasizes a need to pay attention to the quality and design of a drill bit (cutting edge corner).

Computational simulation of frictional drill-bit movement in cemented granular materials

The main purpose of this paper is to simulate computationally the kinematical motion of the frictional drill-bit of an automatic mining machine in the underground consisting of cemented granular materials. Although the finite element method has become a powerful tool for the design and analysis of many kinds of engineering products, it cannot be used, both effectively and efficiently, for dealing with the frictional drill-bit design problem that involves discrete-mechanics characteristics in nature. Thus, the particle simulation method is employed for mimicking the kinematical motion of a frictional drill-bit, which is fundamental to the design of an automatic mining machine in cemented granular materials. In order to simulate the driving force mechanism of a frictional drill-bit, both the designed velocity and the actual velocity concepts of the frictional drill-bit are proposed. This enables the particle simulation method to be used as a potential tool for the design of an automatic mining machine, which can be used as a new mining technology in some particular mining environments. To illustrate the usefulness and applicability of the proposed driving mechanism associated with the particle simulation method, it has been used for mimicking the frictional drill-bit movement of an automatic mining machine in cemented granular materials under several working conditions. The related computational simulation results have demonstrated that (1) the particle simulation method, together with the proposed driving mechanism of a frictional drill-bit, can provide a useful tool for the design of an automatic mining machine and (2) the vibrating frequency of a frictional drill-bit may have considerable effects on the motion of the frictional drill-bit in the underground consisting of cemented granular materials.

Drilling Force and Temperature of Bone by Surgical Drill

Drilling force and temperature of tibia at the high speed drilling for improving the design of surgical drills are very important. In this paper we describe experiments using pig tibia bones, measuring the drilling force and temperature of a new design of drill bit and compare the results against a twist drill. The result shows that the drilling force and temperature are affected by the feed rate and drilling speed, which vary with the drilling depth into the bone. The new surgical drill with three top cutting edges can achieve lower temperature below 47oC and lower drilling force than with the stainless steel twist drill and carbide twist drill.

Delivering Steering Success in Problematic Soft-Formation Directional Wells

Abstract Development and diversification of directional-drilling tools continues, as do the applications in which they operate. As a result, there is continual demand for development and refinement of drill bits and string tools to meet the latest challenges and issues faced. One such challenge is the ability to reliably deliver consistent directional performance in very soft formation applications. Issues such as hole washout, inappropriate drilling parameters, stabilization, and hole quality can all contribute to poor directional-drilling performance. Several commercial projects are reviewed where technical merit has justified use of rotary steerable systems (RSSs), but because of the very soft lithologies, these systems have been unable to deliver the required directional control. In each example, a separate engineered solution is introduced. These include An innovative concentric string reamer (CSR), featuring a mid reamer section that enables effective stabilization of the reamer even if the pilot borehole is of poor quality or is over gauge.A soft formation fixed-cutter drill-bit design with an engineered hydraulic configuration to avoid hole washout and extended circumferential gauge geometry.A near-bit stabilizer incorporating a full ring gauge that delivers 360° circumferential coverage, thus providing greater contact with the wellbore and higher potential for deviation.A specific bicenter design that uses a secondary component configuration on the face of the pilot to enable appropriate drilling parameters to be used for efficient directional control. The gauge geometry and profile is also tailored to suit soft formation drilling. Global case studies document where these solutions, in combination with both push and point RSSs, have proven extremely successful. These have provided greater flexibility with regard to tool selection, well planning options, and delivering lower cost per foot in rotary-steerable projects.

Technological Breakthroughs Advanced Upstream E&P's Evolution

Throughout the history of the petroleum business, advancements in technology have transformed the upstream sector of the industry. Between the early 1900s and mid-1950s, the rotary rig, roller-cone bit, blowout preventer, electric well log, and walking beam pump were invented, just to name a few. All of these inventions, as well as others not cited above, were responsible for quantum leaps that led to huge changes in the way the industry evolved. Of the numerous technologies invented or developed since SPE came into its own 50 years ago, many have continued that evolution of technology, often changing the business by making it easier, faster, more efficient, and more cost-effective to find and produce hydrocarbons. Many of these breakthroughs and incremental changes resulted from either the direct or indirect work of members of SPE. Of all the inventions and technologies developed since the mid-1950s, industry veterans surveyed for this article unanimously agreed that the computer has had the most overall and lasting impact on the industry. The subsequent invention of the microprocessor and integrated circuit paved the way for further development of computer technology, thereby opening the door for additional advancements in communication technology, including both wired and wireless. Today, it seems almost impossible to imagine an energy industry (or any other industry, for that matter) without computers. During the past 50 years, they have evolved into the energy industry's workhorse, transforming every facet of the business, from seismic acquisition and interpretation through drilling simulation and drill-bit design to completion design and execution. Reservoir planning, management, and production depend on computers, as do offshore rig and platform design. Production facilities are controlled and managed from remote locations using computer software and communications hardware. Administratively, computers help manage every facet of energy companies' accounting, inventory, payroll, and related functions. Seemingly, computers are every where, performing tasks that get the job done faster, cheaper, and more efficiently. Early Computers Adopted Eagerly Engineers eagerly adopted the first computers as they saw the potential of devices that could crunch numbers quickly. One of the areas in which the computer enjoyed early influence was in reservoir simulation, a discipline that requires large volumes of mathematical calculations. Although nothing more than electromechanical calculating machines, early computers were much faster than the widely used mechanical calculators of the period. Those who used the first computers remember them as crude and rudimentary, but better than alternatives available at the time. "Our job (in reservoir simulation) was to model the flow of gas through the porous rock of a field," recalled Donald J. Peaceman, a retired ExxonMobil researcher and industry consultant. "We had nothing that you could call a computer, but we did have access to some accounting machines that the accounting department would let us use at night.

Overview: Bit Technology (December 2006)

Drilling activity has increased in the last couple of years, with wells being drilled deeper and into harder and more-abrasive formations. These drilling environments present serious challenges for drill bits in terms of rate of penetration (ROP) and bit durability. The high drilling-activity level and increased demand led to increased rig rates. To reduce drilling costs, drilling engineers have had to re-evaluate bottomhole-assembly designs, drilling processes, drilling fluids, and applications. Drill bits, although insignificant in terms of price, have huge effects on operational costs. To improve drilling performance, considering the challenges, drill bits must drill faster and last longer. These targets are what drilling engineers have come to expect and what bit companies are delivering to the industry. Several types of drill bits are available for different applications and drilling challenges—polycrystalline-diamond-compact (PDC), impregnated, and roller-cone bits. To reduce drilling costs substantially in the current environment, technology development must expand and permeate into all the different bit types. For PDC bits, new modeling tools and bit designs are being developed on a continuous basis. Bit-behavior analysis, especially the characterization of the different vibration modes, has become a standard in the bit-design process. New PDC cutters with very high abrasion-resistance properties continue to be developed. These cutters stay sharper for longer periods of time, thus improving ROP and durability. Substantial ROP and durability improvements are also being seen with impregnated bits. These improvements resulted from detailed evaluations that focused on the effects of drive tools (rotation speed and power regime), down-hole-pressure environment, and depth of cut on impregnated-bit development and performance. For roller-cone bits, new technologies are improving seal reliability and cutting-structure durability. In addition, new developments in metal-seal-bearing technology have drastically increased the on-bottom drilling time of roller-cone bits, especially in directional wells. Drill-bit companies have accepted the challenges, and they do not plan on slowing down. Bit Technology additional reading available at the SPE eLibrary: www.spe.org SPE 102182 "Coupling of Downhole-Dynamics Recorder Enhances System-Matched Approach to Drill-Bit Design and Application With a Specific Rotary-Steerable System" by S. Barton, SPE, ReedHycalog, et al. SPE 102134 "Vibration Analysis, Model Prediction, and Avoidance: A Case History" by G. Robello Samuel, Halliburton Drilling, Evaluation, and Digital Solutions, et al. SPE 99193 "Real-Time Downhole Torsional Vibration Monitor for Improving Tool Performance and Bit Design" by D.C.-K. Chen, Halliburton Sperry Drilling Services, et al.

The Disc Bit - A Tool for Hard-Rock Drilling

SummaryThis paper traces the development of a radically different design of drill bit, describing its concept, laboratory work, and the latest field trials.Disc-bit technology is based on the single-rolling disc cutter. This cutter was first used successfully in rock on a tunnel-boring machine in 1956. By the early 1970s, virtually every rock-tunneling machine in the world had evolved from picks, tungsten carbide button cones, or multirow tapered cutters to the single-row disc. By then, practical field experience had demonstrated the superior performance of tunneling machines. Further, the Colorado School of Mines (CSM) began scientific studies and published data comparing the specific energy of excavation of various tools on the basis of full-scale laboratory testing. These studies clearly showed that the single-row disc cutter required less energy than conventional cutters used in roller cones to excavate a given volume of rock. With energy at the cutting face always a limited commodity, a lower energy requirement translated to a higher rate of penetration (ROP).Not until the mid-1990s was the concept of the single-rolling disc cutter applied to drill bits. Very small—3¼-in. Mini-Disc™— cutters were evaluated at CSM and found to be extremely efficient and sufficiently robust to be used on drill bits as small as 7⅞ in. An evaluation of an 8½-in. disc bit was performed at the Gas Research Inst. (GRI) Catoosa Test Facility in Oklahoma. The U.S. GRI sponsored an effort to develop the concept through laboratory and field testing. Other field trials were sponsored by private and government grants, including the most recent test funded by a joint industry project (JIP) and managed by Petrobras.

Eggbeater PDC Drillbit Design Eliminates Balling in Water-Based Drilling Fluids

Summary This paper describes a novel polycrystalline-diamond-compact (PDC) -bit concept based on insights into PDC-bit cutting mechanism and rock behavior during drilling. The design comprises a hydraulic layout that optimizes bit cleaning and cuttings removal in soft and sticky formations. Significant improvements in performance have been achieved in Cretaceous and Triassic formations drilled with water-based muds.

On Fractures Produced by Low-Velocity Impact In Plexiglas Rods Simulating Drill Bits

Introduction The purpose of the present study was to arrive at a better understanding of the stress fields developed within drill bits under dynamic loading and the influence that these stress fields could have on the failure of the drill bits. Particular emphasis has been given to the influence that bit shape has on the establishment of highly localized, potentially destructive stress inhomogeneities within the bit. This paper covers one phase of a broad study involving three velocity regimes: impacts at very low velocities, 0 to 20 ft/sec, a velocity range in which dynamic effects are just beginning to be found; impacts at velocities ranging from 20 to several hundred ft/sec, a range commonly encountered in practical drilling operations; and impulsive loading through the detonation of explosives, a velocity range in which the dynamic effects are greatly exaggerated and made more identifiable. Specifically, fracturing which develops at the end of a cylindrical bar undergoing a shock produced by impact was experimentally investigated, the impacted area being the face of a truncated cone terminating the cylindrical bar. Fracture characteristics were looked at as a function of impact velocity, area of impacted face and cone angleparameters of considerable importance in the design of drill bit. EXPERIMENTS The specimens were made of Plexiglas, which enabled the fracture pattern to be easily observed. In Plexiglas, the velocity of a longitudinal wave is about 8,700 ft/sec, and the velocity of the transverse wave about 4,200 ft/sec. The specimens were impacted by a steel cylinder whose lower face was parallel to the terminal face of the experimental bit, as shown in Fig. 1. The impacting mass was shifted up and down on two steel rods, dropping from a maximum height of 11 ft, with the velocity varied between 0 and 6.5 m/sec. The initial mass of the cylinder was 4.1 kg, which could be increased by steps up to 8.8 kg by addition of steel plates. The velocity of the steel cylinder was determined by using an electric circuit; as the cylinder dropped, it contacted two steel wires, the first one starting and the second one stopping an electronic counter. Two similar counters connected in parallel were used to corroborate each other. The velocity was checked at each drop as it had been observed to vary somewhat from drop to drop. The two contact wires were located just above the top of the specimen so as to give a value of the instantaneous velocity of the steel cylinder at impact. The distance between the wires was 40 0.5 mm and the discrepancy between the counters was never more than 0.1 m/sec. Thus the velocity was known to within 3.25 per cent. This precision was sufficient with respect to the precision of the machining of the specimens. A very small lack of parallelism between the face of a specimen and that of the impacting hammer resulted in an oblique impact which required a much lower velocity to break the specimen. SPEJ P. 203^

On Axial Fractures Produced by Explosively Induced Shocks in Plexiglas Rods Simulating Drill Bits

Introduction Some time ago a study was initiated at the Colorado School of Mines in an effort to arrive at a better understanding of the stress fields developed within drill bits under dynamic loading and the influence that these stress fields could have on the failure of the bits. Particular emphasis has been given to the influence that bit shape has on the establishment of highly localized, potentially destructive stress inhomogeneities within the bit. The study has been divided into three phases involving three velocity regimes: impacts at very low velocities, 0 to 20 ft/sec, a velocity range in which dynamic effects are just beginning to be found; impacts at velocities ranging from 20 to several hundred ft/sec, a range commonly encountered in practical drilling operations; and impulsive loading through the detonation of explosives, a region in which the dynamic effects are greatly exaggerated and made more identifiable. The ultimate objective is to provide basic data which will enable the mitigation through judicious design of the frequency and severity of these transient concentrations of intense stress, thereby prolonging and increasing drill efficiency. This paper presents results of the third phase of this study the development of a better understanding of the dynamics and mechanics of failures caused by transient stress-wave interactions. The impulsive loading or transient waves in these experiments were generated by detonating small explosive charges placed on the ends of Plexiglas cylindrical rods terminating in truncated cones. Under such intense loading, dynamic effects are greatly exaggerated and, hence, made more identifiable. The explosion generates a high-intensity transient stress disturbance which moves through the rod, reflects from surfaces which lie in its path, and establishes momentarily narrow regions of high concentrations of stress where failure of fracture may occur. The peregrinations of these waves, their interactions and their effects have already been described in the literature (see, for example, Refs. 1 and 2). The locations and extent of the regions quite apparently are strongly dependent on specimen shape, making it possible through judicious shaping of specimens to relocate the highly stressed regions, minimize their extent, or eliminate them entirely. These experiments were designed, first, to identify more clearly the vulnerable regions in geometries relevant to drill-bit design and, then, to modify these regions in a predictable way by changing specimen shape. Through this latter process, it is anticipated that better bit design might evolve. The specimens used in the experiments were cylindrical rods, 1 1/2 and 1 1/8 in. in diameter, ended by a truncated cone, with the cone angles ranging from 45 degrees to 130 degrees. Upper cone face diameters were 1/2, 3/4, or 1 in. A small plastic-covered electric blasting cap detonated on the axis of the specimen produced the spherical shock wave. The detonators used were Olin Mathieson No. 6, which induced into the rod a transient saw-toothed stress disturbance of about 3-microseconds duration, corresponding to a wave length of 0.3 in. in the Plexiglas. Five distinct systems of fracture were observed:along the axis of the rod, a lower system of fractures, the cracks focusing around one point for specimens having cone angles of 80 degrees and 90 degrees and, as the cone angle was increased, spreading downward;just above these fractures, an upper system of fractures composed of horizontal cracks observable in some specimens but not of any appreciable extent;a third system of axial cracks still above the latter, observable in the small cone angle specimens:in the upper part of the specimen, a system of radial fractures extending from the blasting point; andcircular spalling due to reflection of the wave on the boundary of the cylinder. Only the first three systems, the axial fractures, are examined here. LOWER TENSILE FRACTURE SYSTEM The first, lower system of tensile fractures, shown in the photograph of Fig. 1, was observed in almost all of the specimens. It was due to the reflected tensile wave coming in from the boundary of the cylinder as shown in Fig. 2. SPEJ P. 207^