Drill Design Research Articles

A semi-analytical solution technique for predicting circulating mud temperatures

Accurate prediction of circulating fluid temperature in wellbore is required for proper drilling operations and design of the closed-loop systems. This study involves the improvement of the traditional analytical solution based on the assumption of constant input values. The presented solutions are derived from the analytical solution of the transient radial heat conduction. Application of the superposition theorem and combination of the analytical solutions established for each segment constituting the wellbore to account for temporal and positional variations are the main features of the semi-analytical solution presented in this study. In this respect, it can be asserted that the solution is also valid for variable mud/water circulation in deviated and horizontal wells.The presented solution is validated using the pertinent results of the traditional analytical solution. The results of the semi-analytical solution for realistic wellbore design reveal the possible deviations from temperature profile corresponding to analytical solution. The temperature profile as a result of the circulation with variable rate in a designed horizontal well is examined to test the presented semi-analytical solution. The trials indicate that the semi-analytical solution which is able to be implemented with plausible computational effort can be an alternative improvement for the traditional analytical solution.

Experimental study of the energy transfer efficiency and rock fragmentation characteristics in percussive drilling

This article conducted studies of percussive drilling, and revealed impact stress wave propagation mechanisms and rock fragmentation characteristics under percussion. In this study, the experimental equipment and numerical calculation platform were built based on percussive drilling system. The incident waves, reflected waves and transmitted waves during percussion were used to evaluate impact energy transfer efficiency. Simultaneously, the Scanning Electron Microscope and three-dimensional Laser Profile Scanner were used to depict the crushed craters and cracks of the rock. The key findings of this study are as follows. For percussive drilling with hemispherical teeth, when the impact velocity is increased, the energy transfer efficiency augments. For percussive drilling with stinger teeth, as the impact velocity increases, the energy transfer efficiency decreases. As the rock temperature increases, the energy transfer efficiency roughly decreases. Compared with stinger teeth, more tensile cracks of the rock are formed under percussion by hemispherical teeth. The stinger teeth tend to concentrate impact energy in the areas under teeth, which is more conducive to generating craters in the rock. The hemispherical teeth tend to spread impact energy out of the areas under teeth, which is more conducive to generation of the tensile cracks. Rocks at high temperatures are more prone to tensile cracks under percussion. This study provides a theoretical basis for the optimal design of percussive drilling based on high temperature hard rock.

Research status and development directions of intelligent drilling fluid technologies

By reviewing the current status of drilling fluid technologies with primary intelligence features at home and abroad, the development background and intelligent response mechanisms of drilling fluid technologies such as variable density, salt response, reversible emulsification, constant rheology, shape memory loss prevention and plugging, intelligent reservoir protection and in-situ rheology control are elaborated, current issues and future challenges are analyzed, and it is pointed out that intelligent material science, nanoscience and artificial intelligence theory are important methods for future research of intelligent drilling fluid technology of horizontal wells with more advanced intelligent features of “self-identification, self-tuning and self-adaptation”. Based on the aforementioned outline and integrated with the demands from the drilling fluid technology and intelligent drilling fluid theory, three development suggestions are put forward: (1) research and develop intelligent drilling fluids responding to variable formation pressure, variable formation lithology and fluid, variable reservoir characteristics, high temperature formation and complex ground environmental protection needs; (2) establish an expert system for intelligent drilling fluid design and management; and (3) establish a real-time intelligent check and maintenance processing network.

Substantiation of the specific energy intensity of drilling as a criterion characterizing the explosive destruction of rocks on the example of the Koktaszhal

Drilling and blasting operations are one of the most important components of the mining industry. Currently, further improvement and optimization of technological processes at mining enterprises are possible mainly due to the determination and constant monitoring of the mining and technological properties of the rock mass – their drillability, explosivity and exaviability. A prospective assessment of the explosivity of rocks in the massif, which is the basis for designing and calculating the parameters of the DBO, is currently possible only using the energy parameters of technological work. The article provides information on methods for studying the strength and elastic characteristics of rocks in natural occurrence. The results of the study of the relationship between the specific energy intensity of drilling and explosive destruction of rocks are presented. The correlation between the specific energy intensity of drilling and the propagation velocity of elastic longitudinal waves is also considered. A comparative analysis is carried out between the traditional calculation of the explosive index using the results of laboratory studies on the physical and mechanical properties of the rocks of the Koktaszhal deposit and the calculation of the explosive destruction index taking into account the energy parameters of drilling. The validity of the use of the specific energy intensity of drilling as a criterion characterizing the explosive destruction of rocks in the design of drilling and blasting operations is shown.

Novel crescent drill design and mechanistic force modeling for thrust force reduction in bone drilling

Bone drilling tends to cause mechanical damages and thermal necrosis in the vicinity of the drilled hole, which can deteriorate the surgery quality and patients’ recovery. Understanding the cutting forces generation mechanism is crucial in controlling thrust force and bone temperature for optimum tool design. In this study, a novel crescent drill bit featuring an improved positive rake angle distribution was designed to reduce the thrust force and temperature elevation. On this basis, a mechanistic model for predicting thrust force and torque was proposed for drill bits with different geometries (twist drill and crescent drill). The proposed model was established in the polar coordinate system to precisely calculate the curvilinear integral of the crescent cutting edges. Drilling experiments were carried out using two types of drill bit under different cutting conditions and results showed that our proposed model agrees well with the experimental data. The experimental results also demonstrated that our tool design can significantly reduce the thrust force and reduce the bone temperature below the thermal threshold without coolant, providing a clinical option for coolant free drilling.

Research on seriation design of Dynamic Kill Drilling (DKD) mixer

Abstract Automatic slurry mixing device, one of the core equipment of dynamic kill drilling (DKD) system, is the key to determine whether the drilling fluid system can provide precise density for bottom layer in time and effectively, and also the key equipment to control the operation risk of ultra-deep water drilling in the face of narrow pressure window. Based on the incompressible viscous flow characteristics of non-Newtonian fluid mixed with seawater and combined with the actual drilling fluid field situation of offshore drilling platform, a kind of tubular DKD mixer with dumbbell shaped nozzle as jet element is designed in this paper, which is verified by theoretical calculation and numerical simulation. Finally, “Y type reverse reflux (60°) + 90° cross jet element” was determined as the final structural design scheme. At the same time, the influences of inlet flow rate, length of eddy current section and incident Angle on mixing effect of mixer are studied, and a seriation design scheme of dynamic kill drilling (DKD) mixer is proposed, and a seriation design chart of product is completed.

Design and Analysis of CFRP Drilling by Electrical Discharge Machining.

The novelty of EDM machining as a drilling operation for composite materials means that there is no consensus on the influence of the parameters that optimise the final quality. For these reasons, a characterisation of the EDM drilling process of a unidirectional composite material has been developed. The influence of several cutting parameters has been related to the quality of the final hole obtained. Thus, macrogeometric aspects in terms of conicity and final diameter and microgeometric aspects in terms of surface quality have been evaluated. In addition, the final state of the material and the wear of the electrode have been evaluated by visual inspection, allowing the range of cutting parameters that offer the best performance to be established. Finally, a series of contour diagrams based on predictive models have been obtained to establish a direct relationship between input and output variables.

Ortopedik Matkaplar İçin Bozucu Gözlemci Tabanlı Kemik Doku Değişim Tahmin Yaklaşımı Benzetimi

Orthopedic drills are currently used for various operations in surgical fields such as orthopedics, ear, nose, and throat surgery. The path that orthopedic drills travel through the tissue is controlled manually by surgeons, and manual control leads to the risk of damaging areas such as nerves and tissues. In our study, an innovative approach is presented against existing drill designs and breakthrough detection problems. In the proposed model, the change in the load torque and the change in friction force caused by the tissue change in the drilling path are considered as a disturbance effect, and a disturbance observer has been developed that allows these disturbances to be observed. Observation of the disturbance effects allows the perception of the hardness of tissue change during drilling since it gives the change of load torque changes and friction coefficient, which cannot be measured under normal operation. The performance of the proposed approach has been proven by simulation study.

Temperature Changes during Implant Osteotomy Preparations in Fresh Human Cadaver Tibiae, Comparing Straight with Tapered Drills.

The success of osseointegration depends on many factors. With temperatures beyond a 47 °C threshold over 1 min, bone survival may be impaired. The purpose of the study was to evaluate, in fresh human cadaver tibiae, the temperature changes during osteotomy preparations using two straight and two tapered implant systems’ drills, external irrigation, and varying revolutions per minute (RPM). The tibiae from a fresh female cadaver were harvested bilaterally. Two tapered and two straight design drills were assessed. Two-hundred and forty osteotomies were prepared at 6 mm depth following the drill sequence of the manufacturers’ protocol for each drilling speed. Difference in temperature (ΔΤ) was calculated by subtracting the baseline from the maximum temperature (ΔT = Tmax − Tbase). Drill design and drill diameter, as independent variables or synergistically, had a significant effect on ΔΤ. Tapered drills: As the drill diameter increased, ΔΤ increased at all RPM. Straight drills: As the drill diameter increased, ΔΤ remained constant or slightly decreased at all RPM. Drill diameter and design had a significant effect on ΔΤ in human tibiae, which never exceeded the critical threshold of 47 °C. Tapered drills caused significantly greater heat production compared to straight drills.

Crusher to Mill Transportation Time Calculation—The Aitik Case

Comminution is a major contributor to the production costs in a mining operation. Therefore, process optimization in comminution can significantly improve cost efficiency. The mine-to-mill concept can be utilized to optimize the comminution chain from blasting to grinding. In order to evaluate the mill performance of the ore from a specific location of the deposit, a direct link needs to be established between the mill performance and the place of origin in the mine. Today, technology enables the accurate positioning of drilling, loading, and dumping points in the mine, making the ore flow between loading and crushing more transparent. However, the material flow from the crusher to the mill is not yet fully understood and monitored. This paper presents the development of an ore transportation model, based on the virtual silo concept, between the crusher and the mill for Boliden’s Aitik mine in northern Sweden. The proposed model helps to establish a link between in situ ore location and mill performance. Two transportation time calculations are used, one based on mass balance, and one based on momentary values. Historical data are used to test the capabilities of the model and the results are compared with the transportation time calculated from the mean capacity values, commonly used in previous studies to connect mill parameters with in situ ore location. The comparison of the results show that the mean parameter-based values can be as much as 50% lower than the transportation times, even in normal operation. In the tested times, the transportation time based on momentary values systematically underestimated the cumulated times. The developed model will also serve as a starting point to analyze the effect of geotechnical parameters, in addition to drill and blast design, on the mill performance of the blasted ore.

Temperature Performance of Stainless Steel AISI420B Orthopedic Drill Bits Simulation Study

In orthopedic and trauma surgery, the drilling of bone is the process of preparing, making, and enlarging a hole of circular crosswire in a solid anisotropic material bone structure. The failure of irreversible osteonecrosis occurs when the temperature rises to 47 °C or higher during bone drilling. Osteonecrosis is a disorder that leads to the death of bone tissue cells, resulting in weaker contact between implants and bone, and in some cases, the loss of strong and stable attachment to the bone. Previous studies had concentrated on drill bit material, design, point angle, force, speed, and feed rate. This study outlines the technique for developing a drilling-related finite element model to verify the drilling process’s efficacy using a computer simulation approach. Software LS-DYNA © 2011-2020 LST was used to conduct a drilling model based on the finite element (FE) technique. The temperature behavior of orthopedic chromium type martensitic magnetic stainless steel AISI420B twist drill bit (Ø 4.3 mm) was determined. The findings were quantified, and the outcomes of the simulated and actual evaluations were compared. The surgeon’s typical drilling technique or pattern was used in this study, with a penetration angle of no more than 30°, and performed using a battery-powered surgical hand drill. A forward-looking infrared (FLIR) camera for temperature detection was used to record drill bits thermal data throughout the experiment. The utilization of two factorial analyses in the design of experiment (DOE) and analysis of variance (ANOVA) revealed that the simulation result had higher mean performance confirmation than the actual experimental result, with a difference of 10.9102%. The AISI420B showed good heat conductivity, and minor wear than typical stainless steel drill bits in the market for bone drilling. Therefore, the AISI420B stainless steel twist drill bit tested able to perform well for bone drilling.

Computer-aided design of rational parameters for the location of blasthole charges in horizontal underground development

ABSTRACT The article substantiates a stage-by-stage physical model of destruction of a real rock mass. On its basis, the key results of an explosion in a solid medium were determined: the strength characteristic of rocks under conditions of all-round explosive loading, the relative limiting radius of the blast cavity, the radii of the zones of fine crushing and radial cracks, and the principle of the rational arrangement of charges in the blasted block was formulated. Using this principle, an analytical method has been developed for determining the rational parameters of the location of charges in the face of preparatory workings and their computer-aided design. Experimental explosions carried out in the underground mines of Kazakhmys Corporation LLP confirmed the operability of the proposed automated design of drilling and blasting operations in horizontal underground workings. The proposed results are in good agreement with the data presented in the works of a number of world authors.

Thermal changes during implant site preparation with a digital surgical guide and slot design drill: an ex vivo study using a bovine rib model.

In this study, we aimed to evaluate the degree of heat generation when a novel drill design with an irrigation slot was used with metal sleeve-free (MF) and metal sleeve-incorporated (MI) surgical guides in an environment similar to that of the actual oral cavity. A typodont with a missing mandibular right first molar and 21 bovine rib blocks were used. Three-dimensional-printed MF and MI surgical guides, designed for the placement of internal tapered implant fixtures, were used with slot and non-slot drills. The following groups were compared: group 1, MI surgical guide with slot drill; group 2, MI surgical guide with a non-slot drill; and group 3, MF surgical guide with a slot drill. A constant-temperature water bath at 36°C was used. The drilling was performed in 6 stages, and the initial, highest, and lowest temperatures of the cortical bone were measured at each stage using a non-contact infrared thermometer. There were no temperature increases above the initial temperature in any drilling procedure. The only significant difference between the non-slot and slot groups was observed with the use of the first drill in the MI group, with a higher temperature in the non-slot group (P=0.012). When the heat generation during the first and the second drilling was compared in the non-slot group, the heat generation during the first drilling was significantly higher (P<0.001), and there was no significant difference in heat generation between the drills in the slot group. Within the limitations of this study, implant-site preparation with the surgical guide showed no critical increase in the temperature of the cortical bone, regardless of whether there was a slot in the drill. In particular, the slotted drill had a cooling effect during the initial drilling.

Calculation of the Gas Injection Rate and Pipe String Erosion in Nitrogen Drilling Systems

Detailed information is provided for the design and construction of nitrogen drilling in a coal seam. Two prototype wells are considered. The Guo model is used to calculate the required minimum gas injection rate, while the Finnie, Sommerfeld, and Tulsa models are exploited to estimate the ensuing erosion occurring in pipe strings. The calculated minimum gas injection rates are 67.4 m3/min (with water) and 49.4 m3/min (without water), and the actual field of use is 90–120 m3/min. The difference between the calculated injection pressure and the field value is 6.5%–15.2% (formation with water) and 0.65%–7.32% (formation without water). The results show that the Guo model can more precisely represent the situation of the no water formation in the nitrogen drilling of a coal seam. The Finnie, Sommerfeld, and Tulsa models have different sensitivities to cutting densities, particle size, impact velocity and angle, and pipe string hardness.

A robust and efficient method to geometrically calculate the minimum bit stick-out in a deepwater conductor jetting project

The length of the bit protruding from the running conductor assembly (i.e., bit stick-out), a key factor in deepwater drilling design, directly affects the efficiency of the injection process and the bearing safety of the conductor after installation. To improve the efficiency and safety of conductor installation, it is necessary to establish a reasonable theoretical model of the bit stick-out to provide a feasible scheme for field applications. In this study, geometric judgment criteria of the reasonable bit stick-out location are proposed that determine whether the diameter of the nozzle jet circle is smaller than that of the conductor. These judgment criteria are applied to obtain the reasonable position of the minimum bit stick-out for different diameters of conductors and tricone bits. According to these judgment criteria, we propose a mathematical model of the minimum bit stick-out during deepwater conductor jetting, which considers the influence of the heterogeneity in the nozzle space. Through theoretical analysis and experimental research, combined with on-site cases, the results indicate that if the diameter of the nozzle jet circle is larger than that of the conductor, the reasonable bit stick-out location occurs where the upper boundary of the nozzle jet beam is tangential to the inner boundary of the lower end of the conductor. Conversely, the reasonable bit stick-out location occurs where the jet beam originating from the nozzle can reach the intersection of the jet trajectory and the curved surface formed by the main and secondary cones of the cone bit at the bottom of the well. A numerical simulation study reveals that when the bit stick-out is greater than 150 mm, the hole can be enlarged during the jetting process, thus increasing the installation depth of the conductor and affecting the stability of the conductor. In addition, the models established in this work are applied in the field. In 12 wells, the average value of the calculated results is 114.76 mm, which is close to the lower limit of the interval. Overall, the research results provide a more accurate theoretical basis for bit stick-out design in deepwater conductor jetting projects. This study can maximize the jetting depth, considering that the size of the created hole optimally matches the casing size to achieve wellbore stability. In addition, the developed procedure based on the proposed mathematical model can be applied more conveniently to different combinations of conductor and bit sizes in the field.

Production of water-based mud for drilling operation application

A successful drilling operation is heavily dependent on the effectiveness of the drilling fluid's design in use. This study attempts to evaluate the rheological and filtration properties of water-based drilling mud (WBDM) upon the addition of Stearyl Acrylate-Behenyl Acrylate (SABA) copolymer, silicon dioxide (SiO2), and nickel (III) oxide (Ni2O3) nanoparticles. This SABA copolymer-nanofluid was prepared by dissolving the nanofluid in a SABA polymer solution and homogenizing it using ultrasonication. The properties were studied using mud balance, viscometer, and low-pressure low-temperature (LPLT) filter press. The rheological and filtration properties of SABA copolymer were found to imply that it could improve drilling fluid performance. However, the addition of nanoparticles gave a better performance of rheological and filtration properties on WBDM. SABA copolymer with 5000 ppm concentration shows the best performance due to showing the highest viscosity compared to basic drilling fluid. Also, the addition of 800 ppm of Ni2O3 concentration into 5000 ppm of SABA shows the lowest fluid losses. The experimental results indicate that SABA copolymer shows a great potential application and the addition of nanoparticles shows that nanotechnology has a lot of potentials to improve WBM performance

Study on Distribution of Wellbore Temperature in Gas Drilling with Gradient Equations

Precise calculation of gas temperature profile is the key to gas drilling design. It is traditionally assumed that the gas temperature distribution in the wellbore is equal to the formation temperature, without considering the influence of fluid flow and Joule-Thomson cooling effect. This paper puts forward a gradient equation method for gas temperature distribution in wellbore considering gas flow and Joule-Thomson local cooling of the bit. The method applies pressure, temperature, density, and velocity equations to gas flow in drillstrings and annulus. The solution of the gradient equation is in the form of the fourth-order Runge-Kutta equation. Bottom wellbore temperatures measured at depths of 700 to 2000 m in an actual well are consistent with those predicted by the gradient method. Due to the Joule-Thomson cooling effect at the bit nozzle, the temperature drops by about 30°C. The sensitivity analysis is carried out by gradient method, and the results show that the temperature drop range of different nozzle sizes can reach 60°C due to the Joule-Thomson cooling effect. Stable temperature curves can be established within a few minutes of the gas cycle. Due to the influence of gas flow and Joule-Thomson cooling, the gas temperature in the wellbore deviates significantly from the geothermal temperature in the formation under the flow condition. The temperature of the gas in drillstrings increases as the drill depth increases and then decreases rapidly near the bottom of the hole. As the gas flows upward along the annulus, the gas temperature rises first, surpasses the formation temperature, and then decreases gradually along the geothermal gradient trend.

Modeling Dynamical Positional Physical Data on Field Zones Occupied by Playing Positions in Elite-Level Futsal: A Comparison Between Running Velocities, Accelerations, and Decelerations.

Serrano, C, Felipe, JL, García-Unanue, J, Vicente Gimenez, J, Jiménez-Linares, L, Ibáñez, E, Hernando, E, Gallardo, L, and Sánchez-Sánchez, J. Modeling dynamical positional physical data on field zones occupied by playing positions in elite-level futsal: a comparison between running velocities, acceleration, and deceleration. J Strength Cond Res 37(1): 200-206, 2023-The aim of this study was to analyze the influence of playing positions on the physical demands and the specific court zones occupied during official futsal games. The total number of observations were 188, corresponding to 8 matches from the first division of the Spanish Futsal League during the 2019-2020 season. All dynamic motion representations were recorded using an 18 Hz device with ultra-wideband technology and local positioning system installed on the futsal pitch for each position. Python Data Analysis Library, Matplotlib, and Python programming language were applied as computational tools to generate visual analysis of figures to represent every physical demand analyzed. An analysis of variance test showed differences between playing positions, specifically, for winger position (p < 0.05). Based on eta-square coefficients, all variables showed large effects, except acceleration distance zone 1 (1-2 m·s-2). Accordingly, the visual representation of positional dynamic motion data showed differences in the physical demands and the court zone occupied by the different playing positions. This innovative visual analysis allows fitness coaches to associate the physical demands with court zones occupied by different playing positions, and it aids in the design of training drills associated with futsal competition requirements.

Mr Influence of clinical and technical parameters on accuracy of guided implant placement. Systematic review and meta-analysis

Aim The aim of the present review was to assess scientific literature on influence of clinical and technical parameters of guided implantation on implant position deviations. Methods Two reviewers conducted electronic searches on Cochrane and PubMed databases and manual search in databases of relevant scientific journals. The date range was limited to from 2009 through 2019. Results In total 36 publications were included for review and subgroup analysis. Meta-analysis revealed mean deviation of 1.14 mm (95% CI: 1.016, 1.268, SE: 0.064) at implant neck, 1.42 mm (95% CI: 1.275, 1.575, SE: 0.072) at implant apex as well as 0.415 mm (95% CI: 0.317, 0.514, SE: 0.096) of mean vertical error and 3.49° (95% CI: 3.228, 3.756, SE: 0.135) of mean angular error. Significantly lower deviations in one or more measurement points were determined in subgroups of partial edentulism, single implantation per guide, mechanical vertical control, mounted drill design and teeth-supported guides. Conclusion With respect to limitations of the study, it can be concluded that type of edentulism, size of defect, type of vertical control, guide design and type of guide support influence accuracy of computer-assisted guided implantation. Future research should focus on analyzing the advantages of technical parameters of individual static guides in distinct clinical subgroups.

A new analysis model for borehole stability in gas drilling

Gas drilling is one of the main underbalanced drilling techniques, which has a significant effect on the ROP (rate of penetration) improvement in hard formation. However, because the circulating medium in drilling process is gas instead of liquid, the fluid column pressure of gas drilling cannot provide enough support force for the rock around borehole as that of conventional overbalanced drilling. Due to the combination influence of engineering and geological factors, the borehole rock is prone to instability during gas drilling, which can lead to rock blocks falling from the well wall and the formation of irregular borehole shape. To avoid the occurrence of complex underground accidents caused by too many falling rock blocks, such as the borehole instability and pipe-sticking, it is necessary for gas drilling to take into consideration the true triaxial stress state of the rock in the deep formation and the possibility of the borehole breakout. Based on the permitted breakout angle of borehole and true triaxial strength theory of rock, an analysis model of borehole stability has been developed for the engineering of gas drilling. The theory of linear elasticity, involved in this analysis model, is used to analyse the stress state of rock around a cylindrical hole under lower wellbore pressure. The failure of the rock around borehole is determined by the Mogi-Coulomb criterion, which considers the intermediate principal stress effect on rock material. The results show that the model is as simple and practical as the traditional model, which takes no account the effect of the intermediate principal stress or the permitted borehole breakout, and it can provide an accurate analysis for the borehole stability of gas drilling. Therefore, the results of this study, combined with the related work such as the prediction of water formation, can guide the adaptability evaluation for the engineering design of gas drilling.