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Aim Methodology Results Conclusion High‐quality, prospective clinical studies are needed to increase evidence for guided endodontics. This study aims to assess the clinical outcome of guided endodontics for treatment of teeth presenting with pulp canal obliteration (PCO) in comparison with freehand treatment.This trial was registered in the ISRCTN.com registry (ISRCTN75277265) and designed as a controlled clinical trial: Single arm trial, prospective, nonrandomized, single‐centre study (ethical approval number S64630). Inclusion criteria were; tooth presenting with PCO and symptoms and/or signs of apical periodontitis (AP). An external control group was selected from clinical records of patients presenting the same criteria but treated freehanded. Guided root canal treatments were performed by the same operator on all patients. Freehanded treatments were performed by a specialist in endodontics under microscope with pre‐operative CBCT available. Primary outcome for both groups was evaluated as: canal found, canal not found, or perforation. As secondary outcome, the qualitative accuracy of the drill path was assessed as: optimal precision, acceptable precision or technical failure. Patients were followed up yearly. Descriptive statistics on the study patient's demographics and healing outcome were performed and specific statistical analysis was performed on each outcome variable.A total of 133 teeth were included (n = 60 guided, n = 73 freehanded) from 128 patients (n = 59 guided, n = 69 freehanded). The primary outcome for the guided group was: 59 teeth canals found and 1 tooth canal not found. No perforations were recorded. In the freehanded group, the root canal was successfully found in 59 teeth, seven were not found, and seven had a perforation. An analysis of all data showed that guided endodontics presented statistically significant better outcome than freehand treatment (p < .05).Guided endodontics showed a statistically significant better outcome than freehanded treatment resulting in less technical failures. However, it is a complex procedure which should be carried out by an experienced endodontist with the aid of a dental microscope. [ABSTRACT FROM AUTHOR]

With the increased directional drilling activities in the oil and gas industry, combined with the digital revolution amongst all industry aspects, the need became high to optimize all planning and operational drilling activities. One important step in planning a directional well is to select a directional tool that can deliver the well in a cost-effective manner. Rotary steerable systems (RSS) and positive displacement mud motors (PDM) are the two widely used tools, each with distinct advantages: RSS excels in hole cleaning, sticking avoidance and hole quality in general, while PDM offers versatility and lower operating costs. This paper presents a series of machine learning (ML) models to automate the selection of the optimal directional tool based on offset well data. By processing lithology, directional, drilling performance, tripping and casing running data, the model predicts section time and cost for upcoming wells. Historical data from offset wells were split into training and testing sets and different ML algorithms were tested to choose the most accurate one. The XGBoost algorithm provided the most accurate predictions during testing, outperforming other algorithms. The beauty of the model is that it successfully accounted for variations in formation thicknesses and drilling environment and adjusts tool recommendations accordingly. Results show that no universal rule favors either RSS or PDM; rather, tool selection is highly dependent on well-specific factors. This data-driven approach reduces human bias, enhances decision-making, and could significantly lower field development costs, particularly in aggressive drilling campaigns. [ABSTRACT FROM AUTHOR]

In orthopedic surgery, precise bone screw insertion is crucial for stabilizing fractures, necessitating a preliminary cortical bone drilling procedure. However, this process can induce temperatures exceeding 70 °C due to the low thermal conductivity of cortical bone, potentially leading to thermal osteonecrosis. Furthermore, significant cutting forces and torque pose risks of tool breakage and bone damage, underlining the need for high precision and optimal processing parameters. Traditionally, drilling relies on the surgeon's experience and often results in imprecise outcomes due to inconsistent feed rates. Therefore, this study proposes the use of a 6-axis robot for controlled drilling, offering precise control over angular velocities and consistent feed rates. Additionally, explore the use of cryogenic liquid nitrogen (LN2) as a novel cooling method compared to conventional saline solutions, examining its efficacy under various cutting conditions. The results demonstrate that LN2 cooling conditions lead to a reduction in thrust and torque under specific processing conditions, and facilitate smoother chip evacuation. Additionally, LN2 significantly lowers the peak temperature around the drilling site, thus minimizing the risk of thermal osteonecrosis. Consequently, the use of a 6-axis robot provides consistent feed rates, and LN2 cooling achieves optimal processing conditions, enabling a more controlled and effective drilling process. [ABSTRACT FROM AUTHOR]

Accurately determining the flow direction of drilling fluid in maxi-horizontal directional drilling (maxi-HDD) is essential for the precise calculation of parameters such as the minimum pressure required for drilling fluid circulation, volume of return drilling fluid, drag force of the drilling fluid, and borehole pressure. We propose a novel method for determining the flow direction and computing these physical parameters in maxi-HDD using the Bingham plastic model. An engineering case study was conducted to validate the applicability of the method. We analyzed the variation patterns of the minimum pressure required for drilling fluid circulation, flow rate, the drag force of the drilling fluid, and borehole pressure during the pipeline installation process. Furthermore, a parametric study was conducted to assess the influence of factors such as reaming, reaming differential, bentonite concentration, and the elevation difference between the bore entry and exit points on drilling fluid flow. The proposed method considers a wide range of parameters, including flow direction, elevation difference, and other relevant parameters. It offers a comprehensive tool for analyzing drilling fluid flow in maxi-HDD. [ABSTRACT FROM AUTHOR]

Modern satellite positioning and navigation technologies are not applicable in specific areas such as the exploration of oil and gas deposits by means of directional drilling techniques. Here, we can rely solely on natural geophysical fields, such as the Earth's magnetic field. The precise underground navigation of borehole drilling instruments requires a seamless, near-real-time access to operational geomagnetic data. This paper describes the MAGNUS BD hardware-software system, deployed at the Geophysical Center of the Russian Academy of Sciences, that provides the efficient accumulation, storage, and processing of geomagnetic data. This system, based on the Big Data (BD) technology, is a modern successor of the MAGNUS processing software complex developed in 2016. MAGNUS BD represents one of the first cases of the BD technology's application to geomagnetic data. Its implementation provided a significant increase in the speed of information processing and allowed for the use of high-frequency geomagnetic satellite data and expanding the overall functionality of the system. During the MAGNUS BD system's deployment on a physically separate dedicated cluster, the existing classical database (DB) was migrated to the Arenadata database with full preservation of its functionality. This paper gives a brief analysis of the current problems of directional drilling geomagnetic support and outlines the possible solutions using the MAGNUS BD system. [ABSTRACT FROM AUTHOR]

The Geomagnetism Group at the National Centers for Environmental Information (NCEI), in collaboration with the Cooperative Institute for Research in Environmental Sciences (CIRES), along with various government and industry partners, specializes in developing and providing access to Earth's internal magnetic field models. These models are crucial for applications such as compass navigation and wellbore positioning, offering reference values for the geomagnetic field (total field, dip or inclination, and declination) at any location across the Earth. This study assesses the Weimer geomagnetic perturbation model, proposed by Weimer in 2013, which is an empirical model of magnetic field variations at high latitudes driven by solar wind measurements, as a candidate for capturing geomagnetic field variations in high‐latitude areas. We compare the geomagnetic field variations predicted by the Weimer model against data from the INTERMAGNET and SuperMAG observatory networks. Our findings indicate that the Weimer model achieves a reduction in the standard deviations of high‐latitude magnetic field variations by approximately 20%–30% once quiet‐time baselines are removed from the data set. Furthermore, we compare the performance of the Weimer model against the Space Weather Modeling Framework's Geospace model during specific geomagnetic storms in 2017 and 2018, and we find that the Weimer model is more effective in predicting magnetic variations at high latitudes than the Geospace model during these storms. Additionally, comparisons to magnetometer data collected from high‐latitude directional‐drilling operations align with the trends observed in comparisons with INTERMAGNET and SuperMAG observatory data, confirming the Weimer model's reliability and effectiveness for such applications. Plain Language Summary: The Geomagnetism Group at the National Centers for Environmental Information (NCEI), in collaboration with the Cooperative Institute for Research in Environmental Sciences (CIRES), along with various government and industry partners, develops geomagnetic models that are used for navigation and oil drilling applications. At high latitudes, geomagnetic variations caused by the interaction between the solar wind and the Earth's magnetic field increases uncertainty in the models. This study assesses the Weimer geomagnetic perturbation model as a candidate to compensate for these geomagnetic variations. We compare the model to scientific ground observatories, and show that the model captures 20%–30% of the variation. We also demonstrate that the model is useful in applied setting by comparing the model to data collected from oil drilling operations. Key Points: The Weimer Geomagnetic Perturbation Model is evaluated for real‐time prediction of geomagnetic disturbances at high latitudesThe Weimer model reduces geomagnetic reference errors at high latitudes by 20%–30% based on comparisons to observatory dataMeasurement‐while‐drilling data show that the Weimer model can save valuable rig time by reducing geomagnetic reference model errors [ABSTRACT FROM AUTHOR]

DDWC (Directional Drilling with Casing) is an effective wellbore construction technique, particularly suitable for soft marine formations. In DDWC, the casing replaces the drill pipe for sliding drilling operations, and the passability of the drill string through the casing has become one of the primary challenges in applying DDWC. This study uses ANSYS Workbench to simulate the strain and bending behavior of the casing under various geological conditions. Simulations were conducted for different wellbore trajectories, casing specifications, and materials to evaluate the feasibility of the drill string passing through the casing under different conditions. The results show that, when the dogleg severity reaches 18°/30 m and the casing's inner diameter is 315 mm, the maximum radial strain of the casing is 4.2 mm, which cannot guarantee the successful passage of a drill string assembly with a 311 mm outer diameter. For other casing specifications, with a minimum inner diameter of 317 mm, the drill string can pass through under the maximum dogleg severity. Additionally, since the elastic modulus and Poisson's ratio of the casing materials are identical, the strain behavior is consistent across different materials, meaning that the material does not affect the passability of the casing. Moreover, the study optimized the selection of casing specifications and materials. From the perspective of ensuring drill string passability and resource conservation, a casing with an inner diameter of 319.4 mm was chosen. To ensure the longevity of the casing and the stability of the wellbore, N80 steel was selected as the material. A sensitivity analysis was conducted on the factors affecting casing strain, and the results aligned with the simulation findings, showing that wellbore trajectory and casing specifications have a significant impact on casing strain. Verifying the passability of the drill string through the casing is critical for the development and application of DDWC technology. [ABSTRACT FROM AUTHOR]

Featured Application: This study presents a new pullback load calculation model from the perspective of pipe–borehole wall contact. Pipeline pullback load is a crucial basis for drill rig selection and pipeline strength design. This paper presents a new pullback load calculation model from the perspective of pipe–borehole wall contact. The pipe–borehole wall contact analysis includes the distribution of contact pressure and the relationship between the external load and compressive displacement. The friction force between the pipe and the borehole wall was calculated based on the pipe–borehole wall contact analysis and adhesion theory without depending on the empirical friction coefficient. The effects of the eccentricity were also considered when calculating the fluid drag force. Through case studies, we verified the applicability of the model and discussed the possible reasons for the errors between the theoretical and field-measured results. This study can provide a helpful tool for analyzing the pipe–borehole wall contact and pullback loads for horizontal directional drilling. [ABSTRACT FROM AUTHOR]

ABSTRACT Evaluating the cathodic protection (CP) effectiveness of horizontal directional drilling (HDD) pipe is a significant technical challenge, due to the feasibility of testing only in shallow buried areas at entry/exit extremities, and not in deeply buried areas or the crossing section of the pipe. Numerical simulation provides a method to evaluate the CP effectiveness of HDD pipes. To improve the accuracy of potential distribution along the HDD pipe, it is necessary to adopt appropriate boundary conditions of the HDD pipe and accurate holiday models of coating. A specialized deep well polarization test device was designed and employed in the field to obtain the actual polarization characteristics as the boundary condition of the HDD pipe at buried depths ranging from 2 to 25 m. The result revealed that the polarization characteristics of HDD pipe in various depths were different and the potential distribution of the actual situation was greatly different from the potential distribution of the shallow aerobic soil. The potential distribution along the HDD pipe was analyzed in two types of holiday models. The results could be used as a reference for the CP effectiveness evaluation of HDD pipes. [ABSTRACT FROM AUTHOR]

Underground cavities have complex spatial structures and geological settings, their arrangement is dense and crisscrossed. The construction system involves multiple work surfaces, levels, and processes. The close integration of construction simulation with actual production conditions is crucial for enhancing the guidance that simulation results provide for practical engineering. Therefore, from the perspective of optimizing construction organization and management, this article comprehensively considers various factors in the construction process, innovatively introduces the principle of production line balance and the concept of rule cycle, and combines technology and management, an underground cavities construction simulation system (UCCSS) is developed. In UCCSS, a hierarchical model is built and calculation are performed on models with different construction methods by modifying the parameters as per the actual engineering characteristics. The simulation results are comprehensively analysed to determine the optimal construction programme. An application case is proposed based on the construction organisation design of the long and parallel diversion tunnels at the CB Hydropower Station. The results show that the system has good practicality and credibility and can provide guidance for the construction organisation design of underground cavities with various features. [ABSTRACT FROM AUTHOR]

Copyright of Coal Geology & Exploration is the property of Xian Research Institute of China Coal Research Institute and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract With the increased directional drilling activities in the oil and gas industry, combined with the digital revolution amongst all industry aspects, the need became high to optimize all planning and operational drilling activities. One important step in planning a directional well is to select a directional tool that can deliver the well in a cost-effective manner. Rotary steerable systems (RSS) and positive displacement mud motors (PDM) are the two widely used tools, each with distinct advantages: RSS excels in hole cleaning, sticking avoidance and hole quality in general, while PDM offers versatility and lower operating costs. This paper presents a series of machine learning (ML) models to automate the selection of the optimal directional tool based on offset well data. By processing lithology, directional, drilling performance, tripping and casing running data, the model predicts section time and cost for upcoming wells. Historical data from offset wells were split into training and testing sets and different ML algorithms were tested to choose the most accurate one. The XGBoost algorithm provided the most accurate predictions during testing, outperforming other algorithms. The beauty of the model is that it successfully accounted for variations in formation thicknesses and drilling environment and adjusts tool recommendations accordingly. Results show that no universal rule favors either RSS or PDM; rather, tool selection is highly dependent on well-specific factors. This data-driven approach reduces human bias, enhances decision-making, and could significantly lower field development costs, particularly in aggressive drilling campaigns.

In order to solve the problems of wall deformation mechanism of gob-side entry retaining, unclear air leakage flow field in goaf and poor gas control effect in thick coal seam, taking 20107 working face of Qincheng Coal Mine in Shanxi Province as the engineering background, mechanical modeling and theoretical analysis are used to study the influence of roof fracture position on stress concentration and propagation path in gob-side entry retaining. It is pointed out that when the fracture line is located outside the retaining roadway, the support stress can be effectively transferred and the pressure can be relieved. The calculation method of the key position of roof cutting by staged fracturing is proposed. By means of unit method measurement, the distribution law of air leakage flow field and gas concentration in goaf of gob-side entry retaining is revealed from two aspects of air leakage volume distribution in goaf and air leakage channel in gob-side entry retaining, furthermore, the multiple prevention and control technology of goaf gas in gob-side entry retaining is put forward, that is, the directional drilling staged fracturing roof cutting pressure relief-strengthening gas drainage advanced collaborative governance, weakening the transfer of roof pressure to avoid wall deformation and fracture air leakage, and improving the efficiency of goaf gas drainage. Silicate composite materials were used to spray and plug the existing wall crack development area ( at the junction of the roof and around the outer wall of the intubation ) to plug the air leakage channel of the roadway. With the optimization of the intubation parameters of the retaining roadway and the air volume ratio of the working face, the air leakage and gas emission in the goaf are further reduced, and verified by field investigation. The results show that : ①In 20107, the air leakage in 20107 goaf is mainly caused by the positive pressure leakage of the inlet air flow in the belt roadway, and the return air side is mainly caused by the leakage of high concentration gas into the gob-side entry retaining. The positive pressure air leakage in the 0-36 m section of the working face is 332.84 m3/min, accounting for 58.17%. The leakage air volume of the 36-108 m section of the retaining roadway is 408.45 m3/min, accounting for 87.09%. ②After optimization, the average gas drainage purity of directional drilling (fracturing hole+ pumping hole) in fracture zone is 7.46 m3/min, and the average gas concentration in gob-side entry retaining is gradually reduced from 0.59% to 0.34%. After fracturing and roof cutting, the deformation and fracture control of the retaining wall are greatly improved, and the efficient production of the working face is realized.

It is an effective hole protection measure to ensure the effect of gas drainage in the mining process of the working face by using the screen pipe to complete the borehole after the directional long hole drilling in the coal seam roof. In order to study the feasibility of using the large-diameter drill pipe re-entered into the drill hole and the hydraulic transportation of the grouping screen pipe automatic docking in the drill pipe to complete the full-hole section screen pipe protection, the hydraulic transportation and automatic docking simulation tests of the grouping screen pipe in the drill pipe were carried out using the designed hydraulic transportation screen pipe testing device and the grouping screen pipe docking device, and the hydraulic transportation differential throttling pressure and transportation force of the grouping screen pipe under different pump volumes were obtained, and compared with the theoretical calculation results. At the same time, the docking reliability of the grouping screen pipe docking device and the automatic docking success rate of the grouping screen pipe are analyzed and tested. The test results show that the measured values of differential throttling pressure and hydraulic transportation force are close to the theoretical values and show an exponential growth trend under different pump volumes. When the pump volume is 390 L/min, the measured differential throttling pressure and hydraulic transportation force of the grouping screen pipe with ϕ82 mm throttling booster pipe in the ϕ102/ϕ83 mm large-diameter drill pipe reach 1.29 MPa and 6 860 N respectively, and the single docking success rate of the grouping screen pipe docking device and the automatic docking success rate of the grouping screen pipe are not less than 94.18% and 82.23% respectively.

In the process of mining, a large area of hard roof will be exposed above a goaf and may suddenly break. This can easily induce rock burst and has a significant impact on production safety. In this study, based on the engineering background of the hard roof of the 2102 working face in the Balasu coal mine, the spatial and temporal characteristics of the strain energy of the roof during the initial mining process were explored in depth. Based on a theoretical calculation, it is proposed that hydraulic fracturing should be carried out in the medium-grained sandstone layer that is 4.8–22.43 m above the roof, and that the effective fracturing section in the horizontal direction should be within 30.8 m of the cutting hole of the working face. The elastic strain energy fish model was established in FLAC3D to analyze the strain energy accumulation of the roof during the initial mining process. The simulation and elastic strain energy results show that, as the working face advances to 70–80 m, the hard roof undergoes significant bending deformation. The energy gradient increases with the rapid accumulation of strain energy to a peak value of 140.54 kJ/m3. If the first weighting occurs at this moment in time, the sudden fracture of the roof will be accompanied by the release of elastic energy, which will induce rock burst. Therefore, it is necessary to implement roof cutting and pressure relief before reaching the critical step of 77 m. To this end, the comprehensive hydraulic fracturing technology of 'conventional short drilling + directional long drilling' is proposed. A field test shows that the hydraulic fracturing technology effectively weakens the integrity of the rock layer. The first weighting interval is 55 m, and it continues until the end of the pressure at the 70 m position. The roof collapses well, and the mining safety is improved. This study provides an important reference for hard roof control. [ABSTRACT FROM AUTHOR]

In order to ensure the smooth implementation of the water pipeline during the submarine laying process, taking the submarine pipeline laying from Damen Island to Luxi Island in the first phase of the Dongtou Land Diversion Project as an example, in view of the problems such as long pipeline laying distance, different buried depths, complicated navigation conditions, and various types of submarine light (electricity) cables in the laying areas, the construction process of using a combination of bottom towing and directional drilling for submarine pipeline laying was adopted. The bottom towing method was used to lay the pipeline outside the navigable area, and the directional drilling process was used to lay the submarine pipeline in the navigable area, which can improve the efficiency and safety of submarine pipeline laying. At the same time, the process optimization of the pipeline weight process was optimized. The final decision was to increase the pipeline wall thickness as the weight scheme for this project through comparison, which improved the corrosion resistance of the pipeline and effectively controlled the construction cost. [ABSTRACT FROM AUTHOR]

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UBCTD (Under Balance Coiled Tubing Drilling) is one of the most prospective unconventional well drilling techniques. It allows reducing the time of connecting and dismantling pipes and increasing the Rate of penetration. It depends on continuous coil of tubes and downhole motor. Also provides better well control using the strippers as the well is already shut-In while drilling operations. The use of ECoil with downhole orienteer directs this technology to achieve upcoming rig-less drilling operations. This study was done on a multilateral well in, XC reservoir to check the feasibility of applying UBCTD. The main parameters in the technical feasibility are designing the Aerated Mud, WOB deliverability and the lock-up problem. The optimum gas-liquid flow Rate window (GLFRW) design is based on Guo-Ghalambor Method. The mechanical design including tubing selection to overcome coil buckling in hole, due to mechanical forces available at the drilling bit. UBCTD is found to be the optimum technique to drill mature reservoirs and heterogeneous reservoirs with many pressure barriers. The use of PDC Bit with its different shapes based on the design will be the best solution as it doesn't require WOB as much as tri-cone bit. Also shallow wells will encounter less buckling and lock-Up problems. With regard to the cost and Achieve the rigless operation. A hybrid design of CT Units will provide light mast to make the deployment of downhole tools. The cost of the injected gas like nitrogen and air is a major cost parameter and shall be designed with optimum GLFRW. The aforementioned cost parameters shall be studied in detail against the benefits of UBCTD with regards contingency factor to achieve optimal cost effective drilling operation. [ABSTRACT FROM AUTHOR]

The compound directional drilling process, including slip and rotation, is the key to realizing long-hole drilling in coal mines. First, a compound directional drilling process control scheme is proposed to realize intelligent control of the directional drilling process. An intelligent drilling process optimization method was designed to improve drilling efficiency. A robust controller for the drilling rate based on gain scheduling was designed to achieve stable control of the drilling rate during sliding deflection drilling. A robust controller based on hybrid sensitivity was designed to achieve stable control of the drilling rate during rotary inclined stabilization drilling. The results of this study can provide a theoretical basis for realizing the intelligent optimization and control of compound directional drilling in coal mines. [ABSTRACT FROM AUTHOR]

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Copyright of Coal Science & Technology (0253-2336) is the property of Coal Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Coalbed methane (CBM) is the only unconventional gas in Poland with estimated recoverable resources. The prospects for developing deep CBM have been explored in recent years by drilling deep exploration wells within the depocenter of the Upper Silesian Coal Basin. The purpose of this study is to analyze the occurrence and potential for CBM extraction in this area of the basin, which can be considered prospective due to the confirmed presence of significant amounts of gas and thick coal seams at depths > 1500 m. The study examined the vertical and horizontal variability of the gas content in the studied area, the coal rank in the seams, thermal conditions, and coal reservoir parameters. The gas content in the seams, reaching more than 18 m3/t coaldaf at a depth of 2840 m, and indicative estimated gas resources of 9 billion m3 were found. The high gas content is accompanied by positive thermal and coal rank anomalies. The permeability and methane saturation of the coal seams are low, and therefore, potential methane production may prove problematic. However, the development of CBM extraction technologies involving directional drilling with artificial fracturing may encourage gas production testing in the study area. [ABSTRACT FROM AUTHOR]

OBJECTIVE The objective of this study is to compare drilling variables and torsional mechanical properties of rabbit femora after bicortical drilling with a 1.5-mm standard surgical drill bit, acrylic drill bit, and K-wire. SAMPLES 24 pairs of rabbit femora. METHODS After drilling under controlled axial displacement rate, each bone was biaxially loaded in compression followed by rapid external torsion to failure. Maximum axial thrust force, maximum drill torque, integral of force and displacement, change in temperature, maximum power spectral density of the torque signal, torque vibration, and torque and angle at the yield and failure points were collected. Pre- and postyield stiffness, yield and failure energies, and postyield energy were calculated. RESULTS The work required to drill through the cis- and transcortices (integral of force and displacement) was greater for the K-wire, followed by the acrylic and then standard drill bits, respectively. The K-wire demonstrated higher maximum torque than the drill bits at the ciscortex, and the force of drilling was significantly greater. The vibration data was greater with the acrylic and standard drill bits than the K-wire. There was no difference in torsional strength between drilling types. CLINICAL RELEVANCE Mechanical differences exist between different drill bits and K-wire and demonstrate that the K-wire is overall more damaging than the surgical drill bit. [ABSTRACT FROM AUTHOR]

The study considers gas compression properties, gas slippage, back pressure (BP), phase transition (PT), well depth, and differences in gas-liquid physical properties. A new temperature model for multiphase flow is proposed by considering phase transition in the drilling process. The mathematical model of multiphase flow is solved using the finite difference method with annulus mesh division for grid nodes, and a module for multiphase flow calculation and analysis is developed. Numerical results indicate that the temperature varies along the annulus with the variation of gas influx at the bottom of the well. During the process of controlled pressure drilling, as gas slips along the annulus to the wellhead, its volume continuously expands, leading to an increase in the gas content within the annulus, and consequently, an increase in the pressure drop caused by gas slippage. The temperature increases with the increase in BP and decreases in gas influx rate and wellbore diameter. During gas influx, the thermal conductivity coefficient for the gas-drilling mud two phases is significantly weakened, resulting in a considerable change in temperature along the annulus. In the context of MPD, the method of slightly changing the temperature along the annulus by controlling the back pressure is feasible. [ABSTRACT FROM AUTHOR]

Copyright of Iraqi Journal of Chemical & Petroleum Engineering is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This article provides a general description of the potential for increasing hydrocarbon production in Ukraine through the restoration of oil and gas wells by drilling sidetracks, based on an analysis of the fields resource potential. The main factors for selecting candidate wells for sidetracking are described. Each stage of well selection set during the design and direct drilling operations is supported by practical results. The main technical and technological solutions for well rehabilitation are described, taking into account the possibility of minimizing the cost of sidetrack drilling. The approaches to selecting and designing a sidetracked well profile are analyzed in detail. The technological scheme for drilling a sidetrack and the layout of the bottom of the drill string are substantiated. An algorithm for calculating the required length of weighted drill pipes and the length of the casing exit for sidetracking is presented. The peculiarities of using drilling fluids for deepening wells with an assessment of the impact on the coefficient of core permeability recovery are presented. The requirements for high-quality well casing are analyzed on the basis of an assessment of the possibility of running the casing in certain areas of sharp changes in the curvature parameters when drilling a well with a small-sized rock-destroying tool. The main functional criteria of the applied buffer systems are characterized and the necessity of using sedimentation-stable dispersion-reinforced grouting systems for high-quality cementing of sidetracks in conditions of small annular gaps is substantiated.

Tunnel-boring machines (TBMs) are widely used in urban underground tunnel construction due to their fast and efficient features. However, shield-tunnel construction faces increasingly complex geological environments and may encounter geological hazards such as faults, fracture zones, water surges, and collapses, which can cause significant property damage and casualties. Existing geophysical methods are subject to many limitations in the shield-tunnel environment, where the detection space is extremely small, and a variety of advanced detection methods are unable to meet the required detection requirements. Therefore, it is crucial to accurately detect the geological conditions in front of the tunnel face in real time during the tunnel boring process of TBM tunnels. In this paper, a 3D-ERT advanced detection method using source-position electrode excitation is proposed. First, a source-position electrode array integrated into the TBM cutterhead is designed for the shield-tunnel construction environment, which provides data security for the inverse imaging of the anomalous bodies. Secondly, a 3D finite element tunnel model containing high- and low-resistance anomalous bodies is established, and the GREIT reconstruction algorithm is utilized to reconstruct 3D images of the anomalous body in front of the tunnel face. Finally, a physical simulation experiment platform is built, and the effectiveness of the method is verified by laboratory physical modeling experiments with two different anomalous bodies. The results show that the position and shape of the anomalous body in front of the tunnel face can be well reconstructed, and the method provides a new idea for the continuous detection of shield construction tunnels with boring. [ABSTRACT FROM AUTHOR]

Increasing regulatory and market changes that decouple fossil fuels from the built environment will require existing trade practitioners to upskill. However, the structure of the construction sector, which includes short-term contracts, tight deadlines, high reliance on contingent labor, and a large proportion of small-business contractors who are responsible for their own training makes upskilling challenging. Consideration of the industry's structure and the characteristics of small trade business learning practices is necessary for any upskilling program. Plumbing is a key example of a trade requiring upskilling for a low-carbon economy. The gas fitting component of plumbing work will change dramatically with the phasing out of carbon-producing natural gas and substitution with alternatives such as hydrogen. This study used a survey of 1,001 Australian plumbers, informed by the theory of planned behavior (TPB), to understand the learning contexts and needs of plumbers in upskilling and ascertain attitudinal, social, and structural enablers for training behavior. The results show that attitudes to training, including the perceived benefits of training for skills development and end-user safety, are the key motivator for plumbers' training behavior, whereas social norms and behavioral controls such as time and cost are somewhat influential. The findings provide insight into training behavior enablers that can be leveraged to support the roll-out of upskilling for low-carbon technologies and ongoing trades training programs more broadly. [ABSTRACT FROM AUTHOR]

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Copyright of Geology & Exploration is the property of Geology & Exploration Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Studying profound samples from celestial entities like the Moon and Mars offers a gateway to comprehending the chronicles of our solar system. These samples encapsulate the authentic geological insights from its inception. Nonetheless, procuring these invaluable scientific specimens demands attaining the desired depths and surmounting the formidable hurdle of penetrating through the extensive regolith layers. This study presents a novel concept for an autonomous self-burrowing drilling system based on the Archimedes screw principle. The drilling robot is designed in a mole-type configuration and employs an innovative dual-Archimedes screw (or dual-screw) regolith conveying method. A prototype of the robot is developed, designed, and manufactured. To assess the robotic system's performance, a model is formulated to represent the drilling load within the regolith and is derived accordingly. A ground test platform is established to validate both the analytical model and the mechanical capabilities of the robotic system, using in-house lunar regolith simulants CSU-LRS-1. The robot undergoes a parametric analysis under specific manipulation modes. The experimental results unveil the intricate nature of the drilling load, influenced by the varying kinematic states of the conveyed regolith. Additionally, the mechanical specific energy approach is introduced to enhance the understanding of how controlled dual-screw rotation affects the robot's drilling resistance and operational efficiency. The proposed drilling load model concurs with the observed trend of drilling load changes as depth increases. The research, covering theory and experimentation, is dedicated to overcoming critical obstacles in the envisioned lunar deep drilling system. This will propel the advancement of multi-depth sampling technology and deep directional drilling or locomotion capabilities. • A dual-Archimedes-screw lunar subsurface drilling robotic mole is developed. • Proposed design and its modeling are experimentally validated with lunar simulant. • Drilling reactions are strongly related to rotational speed ratio of dual screws. • This design consumes less energy than single-screw coring tube for penetration. [ABSTRACT FROM AUTHOR]

Gas extraction is a major technique for regional gas regulation and coal and gas comining in China. Assuring effective gas extraction operations is a crucial step in ensuring the supply of energy. The effect range of extraction drilling, pressure relief degree, and standard period of gas extraction are all constrained because of the geological constraints affecting coal gas permeability and occurrence. Combined with the advantages of directional drilling and high-efficiency pumping technology and antireflection enhanced pumping technology of hydraulic fracturing, directional long-drilling hydraulic fracturing can effectively improve the efficiency of gas control and expand the scale of gas control. The present study focuses on the exploration of directional long-hole hydraulic fracturing technique in thick coal seams with high gas content using Dafosi Mine as a case study. The research findings demonstrate that hydraulic fracturing contributes to the enlargement of pore size, pore density, and pore connectivity in coal seams. In-depth research was conducted on the expansion of coal seam fractures during the hydraulic fracturing process using the RFPA3D-flow numerical simulation program. Additionally, a comprehensive analysis of stress distribution around the fractures under the flow-solid coupling condition was performed. To further improve the effectiveness of hydraulic fracturing technique, the research team optimized the fracturing tools and construction processes in the four coal seams of Dafosi Mine. The impact of segmented hydraulic fracturing in coal seam bare hole drilling was also studied. Furthermore, an investigation method specific to the coal seam bare hole segmented hydraulic fracturing effects applicable to Dafosi Mine was developed. The maximum fracture extension pressure, minimum fracture closure pressure, and fracture morphology change characteristics during drilling and fracturing were measured, and the fracturing influence radius of coal seam was determined to be 46−58 m, the gas extraction concentration after fracturing increased by 2.20–4.22 times, and the 100-m extraction flow increased by 4.93–11.03 times. It gives other mines technical assistance so they can keep advocating and utilizing the horizontal directional long-drilling stage hydraulic fracturing technique. [ABSTRACT FROM AUTHOR]

The purpose of this study was to optimise directional drilling of exploration wells in the Caspian Sea area of Turkmenistan to improve efficiency and reduce environmental impact. The methods employed include the analytical method, classification method, functional method, statistical method, and synthesis method. The study analysed the experience of drilling a directional exploration well in the North Goturdepe field in South-West Turkmenistan with a bottom hole offset of more than 1000 m from the wellhead under anticentral intracavity pressure conditions. The findings of the study confirmed the effectiveness of the new methods to increase hydrocarbon production, reduce time costs, and mitigate the negative impact on the natural environment. This study emphasised not only the significance of modern technological solutions in the energy industry but also their substantial contribution to the sustainable development of the region and energy security. [ABSTRACT FROM AUTHOR]

Aiming at the technical problem of abnormal gas outflow caused by collapsed holes in the process of directional drilling and sleeve milling in broken-soft coal seams, a gas prevention technology was proposed for directional drilling and sleeve-milling salvage in broken-soft coal seams. On the basis of the existing casing milling salvage technology, the gas drainage pipeline system in the casing milling salvaging drilling tool is optimized, and a large amount of gas accumulated in the salvaging drilling tool during the casing milling salvage process is drained and relieved. The salvage orifice airtight gas pumping system and the sleeve milling salvage rod anti-gas device can realize negative pressure extraction, airtight slag discharge and sealing rod addition in the whole process of sleeve milling salvage. The technology was used to successfully deal with a directional drilling stuck accident of crushed soft coal seam with hole depth of 362 m. In the treatment of the accident, the gas gathered in the fishing drill was extracted and pressure relieved through the gas extraction pipeline system in the fishing drill, and the gas gushing out of the hole and the end of the fishing drill pipe was realized through the closed gas extraction system in the hole and the anti-gas device in the rod. There was no over-limit gas accident in the whole salvage process.

The outcrop fire area in Rujigou Coal Mine in Ningxia, China has been burning continuously for over 100 years. This not only results in wastage of resources but also poses significant damage to the ecological environment. Previous research on open fire detection has mainly focused on coalfield fire areas, using single method such as infrared remote sensing or surface temperature measurement, magnetic method, electrical method, radon measurement and mercurimetry. However, the outcrop fire area has migrated to deeper parts over the years, conventional single fire zone detection methods are not capable of accurately detecting the extent of the fire zone, inversion interpretation is faced with the problem of many solutions. In fire management, current research focuses on the development of new materials, such as fly ash gel, sodium silicate gel, etc., However, it is often difficult to quickly extinguish outcrop fire areas with a single technique. Considering this status quo, unmanned aerial vehicle (UAV) infrared thermal imaging was employed to initially detect the scope of the outcrop fire area, and then both the spontaneous potential and directional drilling methods were adopted for further scope detection in pursuit of more accurate results. In addition, an applicable fire prevention and extinguishing system was constructed, in which three-phase foam was injected for the purpose of absorbing heat and cooling. Furthermore, the composite colloid was used to plug air leakage channels, and loess was backfilled to avoid re-combustion. The comprehensive detection and control technologies proposed in this study can be applied to eliminating the outcrop fire area and protecting the environment. This study can provide guidance and reference for the treatment of other outcrop fire areas. [ABSTRACT FROM AUTHOR]

Due to the creep and weak mechanical strength of the salt, perturbations or anomalies of stress and pore pressure often occur in the sediments around salt, leading to the risk of wellbore drilling and even drilling failure. The drilling problem near salt structures still has not been well solved, and has become a challenge in petroleum drilling engineering. To study the effects of stress field in salt basins on wellbore stability and drilling trajectory, we built a three-dimensional conceptual salt hemisphere finite element model to simulate stress fields of the salt structure under different background stress environments, investigate these stress fields and their perturbations around salt, and analyze their effects on the safe mud weight window in the salt system. The results show that the safe mud weight window is the widest under thrust-fault background stress environment, but the narrowest under normal fault background stress environment; it is in the middle under strike-slip fault background stress environment. For a subsalt reservoir under the strike-slip fault background stress environment, the use of directional well can not only avoid the stress anomaly area at the top of the salt sphere, but also improve the drilling stability because of a wider safe mud weight window for the inclined well than that for the vertical well. Our results also suggested that in the Keshen 10 Block of Tarim Basin, the directional well drilling and the inclined well drilling in the regions to the south of the salt structure are the preferred well trajectory. Highlights: A geomechanical finite element model is developed and used to simulate stress field around salt structures. The safe mud weight window of vertical and inclined wells in salt systems is calculated by using modeled stresses and both the M–C and the Mg–C fracture criteria. Inclined wells and directional wells can improve the stability of salt structure drilling. In the Keshen 10 Block of Tarim Basin, the directional well drilling and the inclined well drilling in the regions to the south of the salt structure are the preferred well trajectory. [ABSTRACT FROM AUTHOR]

A case study from eastern Australia is used to demonstrate methods for subsurface high-grading and development-concept optimisation in Coal Seam Gas resource plays. We discuss two aspects of subsurface high-grading: (1) improved prediction of net coal using 2D seismic data, and (2) structure-geological analysis and mapping of the fracture network. Net-coal predictions across the study area focused on the upper Juandah Coal Measures interval of the Jurassic Walloon Coal Measures. There is a positive relationship between extracted and normalised upper Juandah Coal Measures seismic-amplitude strength and net coal in the wells. Areas with considerable amplitude dimming commonly coincide with reflector 'washout' areas mapped from seismic data and are interpreted as channel incisions into otherwise continuous coal seams. Integration of seismic and well data can improve the mapping of net coal and help optimise the placement of appraisal wells, reducing the number of unexpected or difficult-to-interpret well finds. It may also guide delineation of resource-classification domains in a more robust manner than mapping from well data alone. Fractures in coal seams of the study area are mostly bed-perpendicular joints and cleats. Three sets of fractures/cleats are identified in the coal beds: a dominant set and two more localised sets. Fracture intensity was mapped per set using well data and then combined. Fracture maps are deemed useful as an indication of permeability anisotropy, and hence the expected shape of well drainage areas, as opposed to indicating a range of permeability values. Based on the fracture interpretations, it may be possible to optimise the development concept of specific areas, i.e. varying well spacing and/or drilling wells slanted perpendicular to dominant fracture strike. Use of 2D seismic data to qualitatively indicate net-coal trends in the Walloon Coal Measures. The correlation coefficient between seismic amplitude and net coal is strong enough to guide well placement and resource delineation. Fracture intensity mapping from borehole images may indicate permeability anisotropy of the coals rather than absolute permeability values. [ABSTRACT FROM AUTHOR]

The theoretical study of sound field formation in an acoustic interference array presented in this article is motivated by an analysis of the physical principle of operation of a highly directional interference microphone. One of the objectives of the study is to determine the sound pressure acting on the microphone membrane inside the array. The sound field inside the interference array is analyzed using a matrix method, similar to the reverberation matrix method. The solution is formally represented as a Schwarzschild series. The result calculated by this method agrees well with the experimental data. [ABSTRACT FROM AUTHOR]

In order to realize the efficient development of unconventional oil and gas, the measurement accuracy of wellbore spacing in the drilling of parallel horizontal wells is more and more required. Although the Rotating Magnet Ranging System or Magnetic Guidance Tool is used to achieve a good ranging effect in the drilling of dual horizontal wells, the position measurement of the magnetic sub leads to a large ranging error. A new ranging algorithm for the Two Sensor Packages-Rotating Magnet Ranging System is presented in this paper. The algorithm takes the magnetic signal generated by the rotation of the magnetic sub at a fixed position, the tilt measurement data of the two wells, the length of the magnetic sub, and the distance between the two fluxgate sensors as input parameters to avoid measuring the position of the magnetic sub and to reduce the influence of the degree of non-parallelism and the length of the magnetic sub. The simulation and experiment demonstrate that the inclination and azimuth angles of the two wells have a significant impact on the magnetic ranging results when the ranging well sections are not parallel and that the distance between the bottom of the drill bit and the center of the magnetic sub cannot be ignored. Moreover, the accuracy of the relative distance calculated by this new algorithm can reach 97%, and the error of direction calculation is less than 3°. Applying this algorithm in the field can successfully aid in controlling the spacing of cluster horizontal wells more accurately. [ABSTRACT FROM AUTHOR]

Abundant industrial experiences have shown that directional air drilling technology is effective for gas drainage when drilling broken and soft coal seams. In this paper, the Eulerian–Eulerian model was used to simulate the gas–solid two-phase flow behavior of compressed air transporting coal dust in broken soft coal seams. The relationship between the degree of coal dust deposition, annular air pressure law, transportation of coal dust, aforementioned factors of rotational speed, particle size, and air volume could be determined. The results indicate that the particle size plays a significant role in the transport capacity of coal dust. Smaller particle sizes and a higher airflow result in a lower deposition degree of coal dust. When the particle size of coal dust is 1.69 mm and the airflow is 300 m3/h, in the case of coal dust generation at a rate of 0.24 m3/h, the deflection angle of the coal dust collection zone is increased by 130% as the rotational speed of the drill rod is increased from 0 to 120 rpm. Similarly, the deflection angle of the coal dust collection zone is increased by 12.8% in a 500 m3/h airflow under the same condition. Additionally, fine particle-sized coal dust is transported in a spiral line. The coal dust with larger particle sizes tends to be in the middle and lower parts of the hole and move along a specific trajectory. Industrial experiences of medium-air-pressure drilling confirm that a rotary drilling speed between 80 and 120 rpm, with a minimum air volume of 400 m3/h and preferably 500 m3/h, can promote a smooth hole drilling effect and enhance the construction safety in the gas drainage process. [ABSTRACT FROM AUTHOR]

Currently, drilling of directional oil and gas wells under complex technical-technological and mining-geological conditions requires the use of drill pipes made of various materials. In turn, to choose rational modes of strengthening drill pipes and drill string layouts, information on the contact forces and friction forces of the drill string pipes on boreholes is necessary. Drill pipe curved sections friction with boreholes and drill bit resistance moment changes are the main causes of uneven rotation of a drill string during rotary or combined drilling methods and the occurrence of parametric oscillations. To reduce the cost of mechanical energy for well wiring, it is necessary to take into account the "drill string–borehole rocks" force interaction to estimate the magnitude of the frictional forces and their influence on the technological parameters of the drilling process. To solve this problem, mathematical models of "conventionally vertical and inclined drill string sections–borehole" were built. Based on the industrial data, an analysis of the force interaction of a deformed drill string composed of pipes made of different materials (aluminum, titanium, steel) was carried out. Analytical dependences were obtained for determining the contact forces and friction of the pipes on boreholes. A numerical study of the change of these power factors depending on the depth of the well under conditions of intensive vibration loading was carried out. The amplitude values of these forces, the frequency of their change for good sections, as well as the places for the most rational installation of drill pipes in the layout of the drill string were estimated. It was established that the intensity of contact and friction forces for steel drill pipes is greater than for titanium or aluminum ones. It is shown that the greater impact of a solid steel string on contact forces and frictional forces compared to a layout with sections of titanium or aluminum pipes in the range of vibration frequencies of 8–22 Hz corresponds to a bit rotation frequency of 70–80 rpm. The practical application of the obtained research results will contribute to the improvement of technical and economic indicators of the well drilling process. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this paper is to propose a disruption claim management (DCM) life cycle and a risk management framework to provide comprehensive guidance to construction practitioners for facilitating effective and efficient DCM. Design/methodology/approach: DCM life cycle was initially developed through a focus group discussion (FGD) with the participation of the construction practitioners who have diverse experiences about DCM. The life cycle is comprised of 6 phases and also includes proper reactions of the owners and contractors. Then, 42 risk factors that can impact the deliverables of DCM were identified through a literature review and an additional FGD session. This was then followed by a Fuzzy Analytical Hierarchy Process (FAHP) which was performed to evaluate the importance of each risk factor in terms of the factor's impact on the success of DCM. Additionally, consistency analysis was performed to further maximize the reliability of the results. Findings: Findings revealed that a proactive and systematic approach should be adopted and DCM practices should be initiated before any disruption event is triggered. Accordingly, the proposed framework recommends DCM practices to be initiated early in the contract development phase since compensation for the disruption might be recovered only to the extent that the contract permits. The contract-related risks were given top priority by the experts so that the results of the fuzzy AHP analysis also verified the significance of the contract development phase. Besides contract-related risks, risks related to insufficient site observation, ignorance of the project team, cognitive bias and conflict of interest were determined as the most significant DCM risks, needing an urgent and sophisticated risk response plan. Lastly, results suggested that "Site observation and record-keeping" is the most formidable phase since the phase's implementation on a continuous basis could create unforeseen organizational challenges such as mismanagement of project records, especially in the dynamic and turbulent environment of the construction projects. Originality/value: Disruption – which is caused mostly by change – is inevitable in construction projects due to their sophisticated nature. DCM, therefore, becomes crucial to compensate losses of contractors and eliminate or diminish the prolonged dispute resolution process. Existing studies, however, do not provide a comprehensive theoretical basis for the DCM life cycle and DCM life cycle's potential risks so that DCM life cycle's promising benefits can hardly be materialized. Thus, developing a DCM life cycle and associating DCM life cycle with risk management, this study is highly believed to make a promising theoretical contribution to the DCM domain since this is one of the earliest attempts in the literature. Additionally, this research provides construction practitioners with an insight into the effective implementation of DCM practices in construction projects. [ABSTRACT FROM AUTHOR]

The relevance of the study of construction of directional deep wells in Turkmenistan lies in the application of innovative drilling methods for efficient oil production from hard-to-reach horizons, which is becoming a strategic necessity in the context of the development of the oil industry in this country. The purpose of this study was to analyse the effectiveness of the simultaneous separate operation method in the context of hydrocarbon production in one of the fields of Turkmenistan. In the course of the work the statistical method, comparative method and analysis were used. The results of the study indicated that the introduction of advanced technologies and equipment in the process of drilling and well development in the region of Turkmenistan had a profound impact on oil production. It has led not only to increased efficiency and reduced well construction time, but also increased oil production. The demand for this technology is of particular importance in western Turkmenistan, where directional drilling has become a key factor in the region's economic development and energy security. The gamma ray logging results show fluctuations in natural radiation levels corresponding to different geological formations. Pressure curves plotted as a function of depth demonstrate fluctuations in reservoir pressure. The results of the work are of direct practical significance, allowing to accelerate the development of fields in difficult geological conditions, offshore shallow waters, as well as to reduce drilling costs without requiring changes in oil recovery factor. [ABSTRACT FROM AUTHOR]

Copyright of Natural Gas Industry is the property of Natural Gas Industry Journal Agency and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Coal Science & Technology (0253-2336) is the property of Coal Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)