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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]

Horizontal well drilling is a powerful means of exploring and developing unconventional oil and gas reservoirs. However, cuttings are easily deposited at the bottom of the annulus of the horizontal well section. They, thus, form a cuttings bed and affect the wellbore flow and heat transfer during drilling. Currently, no wellbore heat transfer model considers the impact of cuttings beds. Therefore, a coupling model of wellbore heat transfer and cuttings bed height was established and validated using field data in this study. Despite the model's accuracy being dependent on the precise distribution of the cuttings bed height, it better aligns with the wellbore heat transfer characteristics during horizontal well drilling. Using this model, the influences of the circulation time, circulation flow rate, drill pipe rotation speed, rate of penetration, and inlet temperature on the wellbore heat transfer were investigated. Subsequently, measures to reduce the downhole temperature were proposed. In a case study, in comparison with models that do not consider the cuttings bed, the downhole temperature calculated by the new model was 1.3 °C higher. By increasing the circulation flow rate, controlling the drill pipe rotation speed and rate of penetration, and reducing the drilling fluid inlet temperature, we lowered the downhole temperature by 13.3 °C. This provided support for achieving one-trip drilling in a 215.9 mm borehole. [ABSTRACT FROM AUTHOR]

The safety and efficiency of drilling engineering are greatly impeded by destructive vibrations of drill string in air drilling, such as stick-slip, bit-bounce and their coupled vibrations. To avoid or suppress these vibrations improving the stability of drilling operations, revealing the occurrence mechanisms of abovementioned harmful vibrations are indispensable by investigating dynamics characteristics of drill string system. In this paper, an axial-torsional coupled dynamics model that can capture the motion behaviors of bottom hole assembly (BHA) is established adopting the lumped parameter method. Subsequently, a rate of penetration (ROP) model appropriating for air drilling is obtained firstly by linear fitting means. Meanwhile, a novel discontinuous support model is established to describe the bit-formation interactions. Then, BHA dynamics are discussed using numerical simulations under different vibration scenarios: normal operation; stick-slip; bit-bounce; bit-bounce and stick-slip combination. Subsequently, in two drilling modes: the continuous and intermittent drilling, the vibration mitigation strategies and dynamics sensibility study of BHA are carried out based on the parametric analysis. The results show that increasing torsional stiffness of drill-pipes, appropriately adjusting rotation speed of top driven system and dynamic weight on bit (WOB) are deemed as an effective strategy suppressing or eliminating stick-slip and bit-bounce vibrations of BHA. Suggest that the rotation speed of top driven system and dynamic WOB are 5 rad/s and 3.5 kN, respectively. Finally, the constructed probability maps allow to driller to choose reasonable mechanical parameters, thereby realizing smooth drilling operation in the air drilling. [ABSTRACT FROM AUTHOR]

To evaluate the fatigue reliability of different types of drill pipes during an offshore short-radius sidetracking process, the fatigue life and limit of G105, S135, and V150 steel and a new titanium alloy drill pipe were studied in air, high-temperature conditions, drilling fluid, and drilling fluid containing H2S. First, the chemical composition, microstructure, and tensile properties of four kinds of drill pipe materials were tested. Secondly, the fitting effects of different S-N models were evaluated and identified, a fatigue test of four kinds of drill pipe under different environments (air, high temperature, drilling fluid, and H2S drilling fluid) was carried out, and the S-N curves and fatigue limits of different drill pipes under different environments were obtained. Finally, the fatigue sensitivity of drill pipes to different factors was studied, and the potential corrosion fatigue mechanism was explained. The research results show that the fatigue life of a drill pipe in a non-corrosive environment (air and high temperature) is mainly related to steel grade, and the fatigue life of a titanium alloy drill pipe is better than that of a steel drill pipe in a corrosive environment. The dense passivation film on the surface of a titanium alloy drill pipe is an important reason for its better corrosion fatigue life than that of a steel drill pipe. This study provides important data support for selecting drill pipes in offshore short-radius sidetracking. [ABSTRACT FROM AUTHOR]

A finite element model for analysing the sealing performance of three types of wellhead rotary blowout preventer rubber ring structures in use on site was established. By using this model, the stress, deformation and contact pressure distribution of the passive rubber ring during pre-tightening conditions were calculated when the inner annulus of the passive rubber ring passed through the 5-inch drill pipe body and the 7-inch joint. The distribution position, length, and magnitude of contact pressure on the contact surface between the three types of rubber rings and the outer wall of the drill string under different pressure penetration loads under rated working conditions were calculated. Overall, the sealing performance of the active rubber ring is the best while the sealing performance of the passive rubber ring is the worst. However, the passive rubber ring has a simple structure and does not require a hydraulic system, which makes it impossible to adjust the sealing strength of the rubber ring in real time based on the actual fluid pressure on site. On the other hand, the I-type rubber ring uses part of the rotating blowout preventer structure as the hydraulic chamber wall, which can thicken the rubber layer in contact with drill pipe. Therefore, passive rubber rings are more suitable for low fluid pressure drilling operations. When the fluid pressure at the lower part of the rubber ring exceeds the rated maximum fluid pressure, it will lead to a sharp decrease in the sealing performance of the rubber ring. Therefore, stricter control of the use of the rubber ring is needed during on-site use, especially in drilling conditions with wellhead fluid pressure. The research methods and achievements in the article provide theoretical guidance for the safety evaluation of rotary blowout preventers used in ultra deep wells unbalanced drilling. [ABSTRACT FROM AUTHOR]

Rotating cylinders submerged in the fluid have many practical applications such as offshore wind turbines and drilling pipes. These rotating cylinders are usually subjected to vortex-induced vibrations, and heat transfer has a great effect on their efficiency. Therefore, it is very important to investigate the heat transfer from the rotating cylinder undergoing vortex-induced vibrations. The present study investigates the flow-induced vibration (FIV) of a rotating circular cylinder, along with the related convective heat transfer, for various mass ratios (mr), rotating rates (α), and a range of reduced velocity (3.0 ≤ ur ≤ 15). The cylinder is modeled as a two-degree-of-freedom system, whereby it is free to oscillate both in the streamwise and transverse directions. The results indicate that the rotational motion of the cylinder significantly enhances the cylinder's displacements in both directions. Furthermore, the displacement amplitude in both directions decreases with an increase in mr. For higher reduced velocities, the displacement amplitude becomes constant. Also, it is observed that increasing mr leads to an improvement in heat transfer for high reduced velocities. Also, the maximum value of the Nusselt number is 15.25 for the non-rotating cylinder and 14 for the rotating cylinder with α = 1. The FIV of a rotating circular cylinder exhibits several vortex patterns, including 2S, 2P, P + S, and 2T. [ABSTRACT FROM AUTHOR]

Copyright of China Mining Magazine is the property of China Mining Magazine Co., Ltd. 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 Journal of Mine Automation is the property of Industry & Mine Automation Editorial Department 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 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.)

Rotary drilling rigs are extensively used in foundational construction, with main components including the mast, drill rods, drill bits, power head, and cockpit. The mast, a critical component, must be of high quality to ensure operational reliability. To ensure the reliability of the mast during operation, it is necessary to detect defects in the most stress-prone areas. Based on finite element analysis and practical engineering experience, the welds on the large circular disc of the drill mast are identified as the most vulnerable to damage. Accordingly, this paper prepared test specimens specifically from these weld locations and conducted X-ray inspections, obtaining images for analysis. Given the inevitable presence of noise due to objective conditions, the images first underwent median filtering. For effective subsequent defect detection, edge detection was performed on the images. Among various edge detection operators, the Scharr operator was found to be highly effective. To further enhance the edge detection performance, this paper introduces an improved Scharr edge detection algorithm that incorporates dynamic thresholds and Markov Random Field (MRF) techniques. The enhanced algorithm was evaluated using signal-to-noise ratio and edge localization accuracy as metrics, and it was found to significantly improve performance. [ABSTRACT FROM AUTHOR]

The effect of microstructure on fatigue properties and fracture mechanisms in drill pipes made of aluminum alloys 1953 and 2024 (D16) has been studied experimentally. It is shown that the more hardened α-solid solution and the presence of reinforcing intermetallics MgZn2 and Al2CuMg in the structure of alloy 1953 provide more effective resistance to fatigue crack nucleation as compared to alloy 2024 with Al2CuMg and Al2Cu intermetallics and a less hardened matrix α-solid solution. Accordingly, the fatigue limit of the pipe made of alloy 1953 is 192 MPa, and that of alloy 2024 is 179 MPa. However, the ratio of the fatigue limit to the yield strength of the aluminum alloy 2024 is 40%, while for the 1953 alloy it is 32%. This is explained by a higher fracture toughness of alloy 2024 as compared to 1953, a greater degree of deformation and uniformity of the structure of alloy 2024. [ABSTRACT FROM AUTHOR]

The increased demand for energy has led to the development of innovative drilling methods and technologies in the oil and gas industry. Inefficient transportation of cuttings causes downhole cleanliness issues, which have drawn widespread attention. One way to overcome cuttings transport inefficiency is to use suitable modeling methods to determine capable drilling parameters that will ensure the effective removal of cuttings particles. In this paper, Computational Fluid Dynamics (CFD) and Discrete Element Method (DEM) are combined to deeply investigate the impact of various drill parameters on cutting transport. The effects of cuttings particle size, eccentricity, fluid velocity, drill pipe/bit rotation speed, and bit offset angle are analyzed by studying the velocity of cuttings particles and the spatial distribution of particles in the annulus and bottom-hole. The results show that an increase in eccentricity and particle size reduces the velocity of cuttings particles, with the velocity decreasing more significantly when the eccentricity is greater than 0.5 and the particle size exceeds 2 mm. An increase in fluid velocity and speed of drill pipe/bit significantly increases the velocity of cuttings particles, which has a positive feedback effect on the migration of cuttings particles in the downhole. Bit offset angle leads to changes in the bottom-hole spatial structure and reduces the cuttings transport efficiency. These findings provide a useful strategy for improving cuttings migration and downhole cleaning. [ABSTRACT FROM AUTHOR]

To address the problems of wall collapse, cuttings slurrying, and scaling on the inner wall of the drill pipe, which often occur in small-diameter diamond wireline core drilling, the inhibition properties of polyvinyl alcohol (PVA) was investigated, and the formulation of solids-free drilling fluid with PVA as the inhibitor were completed. PVA has the advantages of fast adsorption and easy regulation of rheological properties Firstly the inhibition effect of PVA was compared with that of common inorganic salts (sodium chloride, NaCl, potassium chloride, KCl) by bentonite dispersion test, linear swelling test, shale rolling recovery test and mud ball immersion test in this study. Then, the inhibition mechanism of PVA was analyzed with potentiometric particle size tests, Fourier transform infrared (FT-IR) and X-ray Diffraction (XRD) measurements. Based on the outstanding inhibition performance of PVA, tackifiers and filtration reducers were preferred through the compatibility test. And finally, the effects of various contaminants on the comprehensive performance of the formulated solids-free drilling fluids were evaluated. The results showed that PVA exhibited better inhibition of clay hydration and dispersion in shale recovery and linear swelling compared to NaCl and KCl, which was particularly evident in the mud ball immersion test. FT-IR and XRD tests revealed that the inorganic salts were used to replace the cations with larger radius and high degree of hydration in the clay layer by ion exchange ti achieve the effect of clay de-watering by reducing the spacing of the clay interlayer and the electrostatic repulsion between the particles. However, PVA is strongly adsorbed on the clay surface in the form of hydrogen bonds due to its unique multi-hydroxyl chain structure, forming a hydrophobic barrier to prevent water molecules from entering the clay layer, thus inhibiting the hydration and swelling of the clay. Using PVA as an inhibitor, compounded with xanthan gum, sulfonated lignite resin and sulfonated gilsonite (FT-1), the solids-free drilling fluid is promising for use in diamond wireline core drilling in complex formations. [ABSTRACT FROM AUTHOR]

The transient temperature of the wellbore plays an important role in the selection of downhole tools during the drilling of deep shale gas horizontal wells. This study established a transient temperature field model of horizontal wells based on the convection heat transfer between wellbore and formation and the principle of energy conservation. The model verification shows that the root mean squared error (RMSE) between the measured annular temperature neat bit and the predicted value is 0.54 °C, indicating high accuracy. A well in Chongqing, China, is taken as an example to study the effects of bottom hole assembly (BHA), drill pipe size, drilling fluid density, flow rate, inlet temperature of drilling fluid, and drilling fluid circulation time on the temperature distribution in wellbore annulus. It is found that the increase in annular temperature is about 1 °C/100 m in the horizontal section when a positive displacement motor (PDM) is used. A Φ139.7 mm drill pipe is more favorable for cooling than Φ139.7 mm + Φ127 mm drill pipe. Reducing drilling fluid density and flow rate and inlet temperature is beneficial to reduce bottom hole temperature. Bit-breaking rock, bit hydraulic horsepower, and drill pipe rotation will increase the bottom hole temperature. The research results can provide theoretical guidance for temperature prediction, selection of proper drill tools, and adjustment of relevant parameters in deep shale gas horizontal wells. [ABSTRACT FROM AUTHOR]

The load spectrum of rotary drilling rig's drill pipe is used for drill pipe design, simulated fatigue testing, and reliability assessment. However, the proper extrapolation of the drill pipe double load is challenging, especially to meet the requirements of both load sequence and load strengthening. In this paper, an extrapolation technique for a double load of drill pipe is proposed. The time sequence rainflow counting technique is proposed to keep the torque and pressure sequence. Meanwhile, the individual distributions of the loads are accurately estimated. Finally, the torque and pressure are simulated and extrapolated by the percentile extrapolation method. The results show that the proposed extrapolation method for maintaining the load sequence enriches the dynamics and diversity of the loads while ensuring the load sequence. [ABSTRACT FROM AUTHOR]

Obtaining real natural gas hydrate pressure-retaining samples is challenging, necessitating the study of in-situ condition preserved coring (ICP-Coring) technology. In this paper, we simulated the in-situ formation of natural gas hydrate natural gas hydrate using a high pressure cooling method within a self-developed formation environment simulation chamber. Drilling experiments were conducted to examine the influence of drilling parameters on low disturbance drilling processes. Our findings indicate that the feed rate of the drill pipe primarily affects the force magnitude on the drill pipe, while the rotational speed of the drill pipe significantly impacts the stability of this force, with slightly higher rotational speeds resulting in less disturbance. [ABSTRACT FROM AUTHOR]

Drilling deviated wellbores has raised concerns about proper cutting transport. Cuttings settling downhole can create stationary cutting beds, causing drilling mishaps like stuck pipes. High fluid velocity is typically required to efficiently erode a stationary bed, but this is constrained by hydraulic and wellbore geometry. When this occurs, pipe rotation can erode the bed mechanically and enable efficient cutting transport even with lower fluid velocities. Therefore, this study formulated water-based mud (WBM) with hydroxyapatite nanoparticles (n-HAp) to examine the effect of pipe rotation on cutting transport in deviated wells. It was compared with copper II oxide nanoparticles (CuO NP) in terms of rheology, filtration, and cutting transfer efficiency (CTE). The CTE of n-HAp amounts (0.4–2.0 g) in moving cuttings with diameters of 0.80 to 3.60 mm through deviated wellbores of 40 to 65° at a 3.5 m/s fluid velocity with 60 and 120 rpm pipe rotation speeds was determined. Compared with CuO NP, n-HAp findings demonstrated enhanced rheology and CTE. However, for fluid loss control, n-HAp was slightly less effective compared to CuO NP. For all deviated angles, n-HAp increased the CTE by 9.5–50%, while CuO NP increased it by 3.4–38.7% at 120 rpm. Compared with 60 rpm, a higher CTE occurred at 120 rpm. Moreover, CTE occurs in the following manner: 40° > 65° > 45° > 60° > 50° > 55°. It suggests that stationary bed formation is more likely to occur at inclinations of 50–55°. These findings are crucial for drilling deviated wells. [ABSTRACT FROM AUTHOR]

For Ti alloys used in oil drilling pipe, the fatigue crack propagation (FCP) resistance is one of the key properties for petroleum industrial applications. In this work, the fatigue crack propagation behaviors of bimodal, equiaxed, lamellar, and Widmanstatten microstructures have been systematically investigated and characterized by SEM and EBSD. The results show that the Widmanstatten microstructure containing α colonies has higher yield strength (877 MPa), moderate elongation (9.3%), and better FCP resistance compared to other specimens. During the process of crack propagation, the large α colonies can effectively deflect the cracks and induce secondary cracks, which significantly impedes the main crack propagation. Additionally, 101¯2<101¯1¯> tensile twinning can occasionally occur within the large α colony along the crack, improving the plasticity of the crack tip and resulting in a decrease in fatigue crack propagation rate (FCPR). Highlights: Fatigue crack propagation behaviors of different microstructures were investigated.The Widmanstatten exhibits good tensile properties and crack propagation resistance.The 101¯2<101¯1¯> tensile twinning was found inside the large α colony along crack. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Applied Mechanics is the property of Chinese Journal of Applied Mechanics 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.)

Copyright of Steel Pipe is the property of Steel Pipe Magazine 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.)

Slim hole drilling as an important technology is more and more used in developing deep oil and gas resources. In slim hole drilling, the much higher annular pressure losses impose a challenge to the annular pressure control. Accurate prediction of the annular pressure losses under the condition of eccentric rotation of drill string is an important theoretical and practical base for slim hole drilling. Conventional prediction models for this purpose have limited applicability and often omit the influences caused by the tool joints, thus cannot satisfy the requirements for accuracy in field operation. To solve this problem, a method of constructing empirical models with pressure loss correction factors is established based on the analyses of the effects of the tool joints on the flowfield and pressure losses in annular spaces using numerical simulation. The analyses show that the extra pressure losses produced by the tool joints are affected by the type of drilling fluid, rotary speed of drill pipe, eccentricity of drill pipe and annular flow velocity. Thus, when determining the pressure loss correction factor, the coupling of these effects should be taken into account. Using the result of numerical simulation of 152 sets of data, a model for predicting the annular pressure losses of the slim holes drilled in the Mahu oilfield in Xinjiang is established. The calculation using this model shows that there is a critical rotary speed at low drill pipe eccentricity, at which the annular pressure loss reaches maximum. At high drill pipe eccentricity, the annular pressure losses increase with rotary speed. The effects of the drill pipe eccentricity on the annular pressure losses will become complex because of the rotary speed. Using the annular pressure loss prediction model developed, the equivalent circulation density of the well MHHW-X in the Mahu oilfield was calculated and compared with the PWD data, the average error was only 1.18%, indicating that the model has high accuracy. The results of the study show that, the model established through numerical simulation for calculating annular pressure losses in slim holes, which takes into account the effects of tool joints, is able to satisfy the requirement of accuracy for field prediction of annular pressure losses, and to provide guidance to the annular pressure control in field operation. [ABSTRACT FROM AUTHOR]

Titanium alloys have been widely used for drill pipes in complex structural wells and ultra-deep wells because they can provide great benefits in cost and operation in drilling systems due to their excellent properties such as high strength, low density, exceptional corrosion resistance and inherent flexibility. However, their wear behaviors during drilling have not been well understood by the communities. In this work, the effect of the impact force on the wear performance of titanium alloy drill pipes against steel casings was investigated through using a modified wet impact-sliding pin-on-disk test system, in which ZSA-3 titanium alloy was used for the pins and J55 steel was for the disks. The tests were conducted under simulated drilling mud conditions. As the impact force increases, the coefficient of friction tends to become stable and fluctuates slightly, and thus the wear rate of the tribo-pairs decreases gradually. The wear mechanism of J55 steel disks presents a transition from plastic deformation to plastic deformation accompanied by adhesive wear, while that of the titanium alloy pins changes from the plowing effect with adhesive wear to plastic deformation and adhesive wear. In addition, complex oxides will be formed on the surfaces of the tribo-pairs due to the oxidation of Ti and Fe during the wear process. The present results could provide as a fundamental guide for the drilling engineers in related industries for reducing casing wear in the drilling environment. [ABSTRACT FROM AUTHOR]

In this study, the fatigue strength of polished drill pipe specimens was investigated and compared with previous test results of corroded and not-corroded pipes. The resonant fatigue test rig, which was designed and implemented by the University of Pisa, is initially presented by providing a detailed description of the set-up of the machine, the calibration of the strain gauges, the control system, and the correct identification of the vibrational node locations. A polishing rig was also designed and put into operation to remove the corrosion pits from the outer surface of almost the entire length of the drill pipe specimens. After the fatigue tests with the resonant rig, and the observation of the fatigue fracture of the specimens, a few samples were extracted from different zones (corroded and not corroded) of the failed drill pipe specimens. This allowed for investigations to be carried out using a scanning electronic microscope. The obtained results were analyzed using the Murakami model, and a discussion is presented about the effect of the corrosion pits on the fatigue strength. [ABSTRACT FROM AUTHOR]

PROSPECT is a comprehensive payload package developed by the European Space Agency which will support the extraction and analysis of lunar surface and subsurface samples as well as the acquisition of data from additional environmental sensors. The key elements of PROSPECT are the ProSEED drill and the ProSPA analytical laboratory. ProSEED will support the acquisition of cryogenic samples from depths up to 1m and deliver them to the ProSPA instrument. ProSPA will receive and seal samples in miniaturized ovens, heat them, physically and chemically process the released volatiles, and analyze the obtained constituents via mass spectrometry using two types of spectrometers. Contextual information will be provided by cameras which will generate multi-spectral images of the drill working area and of acquired samples, and via temperature sensors and a permittivity sensor that are integrated in the drill rod. The package is designed for minimizing volatile loss from the sample between acquisition and analysis. Initially developed for a flight on the Russian Luna-27 mission, the payload package design was adapted for a more generic lander accommodation and will be flown on a lunar polar lander mission developed within the NASA Commercial Lunar Payload Services (CLPS) program. PROSPECT targets science and exploration in lunar areas that might harbor deposits of volatiles, and also supports the demonstration of In-Situ Resource Utilization (ISRU) techniques in the lunar environment. PROSPECT operations are designed to be automated to a significant degree but rely on operator monitoring during critical phases. Here, we report the PROSPECT flight design that will be built, tested, and qualified according to European space technology engineering standards before delivery to the lander provider for spacecraft integration. The package is currently in the hardware manufacturing and integration phase with a target delivery to the NASA-selected CLPS lander provider in 2025. [ABSTRACT FROM AUTHOR]

The air-lift reverse circulation drilling method enables efficient and continuous core extraction. However, the flow characteristics of gas–liquid–solid mixtures during core mass transport are complex, and developing a model to predict performance remains challenging. The flow characteristics of gas–liquid–solid mixtures inside the drill pipe are numerically analyzed by calculating the mixing transport of the core during the airlift process. By solving the momentum equations for multiphase flow, the distribution of physical quantities of three phases and pressure along the depth was calculated, and the laws of influence of the operating parameters on the transport characteristics of the core were analyzed. The results show that the drilling performance is related to the geometric parameters of the pipe and core, drilling speed, and depth. When the submergence ratio is increased to 0.9 , the maximum liquid-phase superficial velocity is increased by 109 % compared with that when the submergence ratio is 0.6. The size of the annular space gap 67 formed between the core and the pipe wall is the key to the core's mechanical properties, and the differential pressure gradient force increases with increasing core diameter. An increase in well depth reduces the fluid flow. In addition, increasing the pipe diameter improves drilling performance due to reduced friction losses, which elevates the air flow rate required for air-lift reverse circulation operation. [ABSTRACT FROM AUTHOR]

It is well known that the type of drill pipe motion has an important effect on the cuttings transportation process and pressure loss gradient in the annular space, in particular for horizontal and deviated wells. For that, it is needed to understand more about the effect of planetary motion on the pressure loss gradient during circulation of the drilling mud in the bottom hole of explored wells. In the present paper, the influence of the drill pipe planetary motion on the pressure loss gradient of a mixture (Ostwald-de Waele fluid with solid particles) in a turbulent regime during its circulation through an annular space is evaluated for different drilling parameters including eccentricity, rate of penetration, and solid particles size. In addition, the effect of drill pipe planetary motion for various conditions of temperature and pressure is evaluated for two types of muds water-based and oil-based. The numerical analysis revealed that an angular speed of 120 rpm of planetary motion can be considered as an optimal value in terms of pressure loss gradient. In addition, it was observed that the effect of the planetary motion on the pressure loss gradient depends mainly on the fluid temperature for both types of mud. [ABSTRACT FROM AUTHOR]

A flexible drilling tool is a special drilling tool for ultrashort-radius radial horizontal wells. This tool is composed of many parts and has the characteristics of a multibody system. In this paper, a numerical method for the dynamic analysis of flexible drilling tools is proposed. The flexible drill tool is discretized into spatial beam elements, while the multilayer contact of the flexible drilling tool is represented by the multilayer dynamic gap element, and the dynamic model of the multibody system for the flexible drilling tool's multilayer contact is established, considering the interaction force between the drill bit and the rock. The nonlinear dynamic equation is solved using the Newmark method and Newton–Raphson method. An analysis of the dynamic behavior of a flexible drilling tool is conducted. The results indicate that the flexible drilling tool experiences vortex formation due to the interaction between the flexible drilling pipe and the guide pipe, leading to increased friction and wear. This situation hinders safe drilling operations with flexible drilling tools. The collision force of the flexible drilling tool near the bottom of the hole is more severe than that of the other tool types, which may lead to failure of the connection. [ABSTRACT FROM AUTHOR]

In this paper, based on the non-linear mechanics theory of the drill pipe, a mechanical model of stick-slip vibration of the drill pipe has been established by considering the torsional properties of the drill pipe, kinetic energy and the motion law of the bit. The example calculations and sensitivity analysis of the parameters are carried out. The results show that increasing the rotational speed, viscous damping, length of the drill collar and de-creasing the weight of bit have the effect of suppressing the stick-slip vibration. [ABSTRACT FROM AUTHOR]

Multi-gradient drilling is a new offshore drilling method. The accurate calculation of the related wellbore temperature is of great significance for the prediction of the gas hydrate formation area and the precise control of the wellbore pressure. In this study, a new heat transfer model is proposed by which the variable mass flow is properly taken into account. Using this model, the effects of the main factors influencing the wellbore temperature are analyzed. The results indicate that at the position where the separation injection device is installed, the temperature increase of the fluid in the drill pipe is mitigated due to the inflow/outflow of hollow spheres, and the temperature drop of the fluid in the annulus also decreases. In addition, a lower separation efficiency of the device, a shallower installation depth and a smaller circulating displacement tend to increase the temperature near the bottom of the annulus, thereby helping to reduce the hydrate generation area and playing a positive role in the prevention and control of hydrates in deepwater drilling. [ABSTRACT FROM AUTHOR]

A small‐diameter nuclear magnetic resonance (NMR) technology optimized for use with direct push (DP) and cone penetrometer test (CPT) drilling has been developed. The DP NMR tool can be deployed through 2.25‐in. diameter DP and CPT drilling rods allowing high‐resolution NMR logging measurements to be acquired during retraction of drill rods. DP NMR technology runs from a person‐portable battery‐powered control unit and provides significantly higher resolution in both the spatial (vertical) dimension and in the time domain of the NMR measurement than previously available NMR technology. In this study, we summarize the development of two different DP NMR tools and demonstrate their application at different sites within the United States. We believe that this technology can provide a leap forward in adoption of NMR technology for high‐resolution hydrological and geophysical investigations in groundwater resources and environmental remediation applications. [ABSTRACT FROM AUTHOR]

Objectives: This article investigates the corrosion behavior and mechanical-property changes of S135, G105, and V150 drill pipe materials in a high-temperature-resistant, potassium amino poly-sulfonate drilling fluid, which has good lubrication performance and contains CO2/H2S, by applying an 80% yield-limit-load simulation. The results show that the CO2-corrosion behavior of G105, S135, and V150 drill pipes are obvious under the simulated constant-load-stress-corrosion environments at the wellhead, well-middle, and bottomhole positions. Compared to uncorroded drill pipes, S135 and V150 drill pipes have increased strength and yield ratios, decreased fracture elongation, and increased sensitivity to hydrogen embrittlement under H2S action, and V150 has a greater risk of stress-hydrogen embrittlement. The strength and yield ratios of G105-material drill pipes decrease, while the fracture elongation increases; the intensity-change amplitude levels are ranked V150 > G105 > S135, and the fracture-elongation-change amplitude is ranked G105 > S135 > V150. The tensile-performance-change amplitude and the SSCC (Sulfide-Stress-Corrosion Cracking) sensitivity of G105 and V150 drill pipes were the highest at the bottomhole. S135 drill pipe materials were most affected by pitting and tensile action at the wellhead, and they had the with the largest SSCC sensitivity. [ABSTRACT FROM AUTHOR]

A S135 drill pipe experienced severe corrosion failure only after several cycles in a well. In this paper, a series of experiments were conducted to analyze the causes of corrosion failure of drill pipe, including nondestructive testing, chemical and physical properties, macroscopic and microscopic analysis, and X-ray diffraction (XRD) analysis. The results showed that the corrosion failure of the external thread joint and pipe body of the S135 drill pipe belonged to oxygen corrosion, and a large amount of Cl− in the environmental medium accelerates the corrosion. The external threaded joint of the drill pipe was more severely corroded than pipe body due to the following two reasons. Firstly, vortexing flow was easy to form at the drill pipe joints with single shoulder threads. Secondly, the drill pipe external thread joint had 3.0-grade banded structure segregation, forming a local small electrode potential difference. [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]

Cutting transport is difficult in horizontal borehole regions due to the limited axial velocity distribution. This causes transported cuttings to gravitate to the bottom, generating cutting beds and leading to drilling mishaps. Water-based mud (WBM) that includes nanoparticles (NPs) to determine the cutting transport ratio (CTR) performance using copper II oxide (CuO), aluminium oxide (Al2O3), magnesium oxide (MgO), and silicon dioxide (SiO2) in a horizontal borehole needs further investigation. These NPs ability to transport 0.80-3.60 mm cutting sizes was tested using concentrations of 1.0 and 2.0 g circulated through a horizontal annulus at 3.5 m/s and 120 rpm. With 2.0 g, MgO lowered the viscosity by 60%, whereas SiO2, CuO, and Al2O3 increased it by 49%, 10%, and 87%, respectively. CuO NP decreased the fluid loss (FLAPI) the best, followed by MgO, SiO2, and Al2O3. The FLAPI of the WBM, which was 9.4 mL, dropped to 4.8, 5.1, 7.4, and 8.2 mL with CuO, MgO, SiO2, and Al2O3 NPs, respectively. The CTR performance of the NPs increased with concentration and decreased with increasing cutting size. CuO, having less viscosity than Al2O3 and SiO2, carried the most cutting at all concentrations and sizes. It increased the CTR by 28.8-31.1%, whereas Al2O3 and SiO2 increased it by 22.7-26.7% and 16.7-22.2%, respectively. The lowest increase was 13.6-17.8% for MgO NP. This study demonstrates the favourable impact of NP concentrations on the performance of drilling fluids while presenting many choices for the selection of NPs. [ABSTRACT FROM AUTHOR]

The drill pipe of a rotary rig is subject to the dynamic influence of non-stationary loads, including rotation torque and applied force. In order to address the challenge of simultaneously extrapolating multiple non-stationary loads, a novel extrapolation framework is proposed. This framework utilizes rainflow counting to obtain mean and amplitude sequences of the loads. The extreme values of the amplitude sequence are fitted using the Generalized Pareto Distribution (GPD), while the median values are fitted using the Double Kernel Density Estimation (DKDE). By extrapolating the Inverse Cumulative Distribution Function (ICDF) based on the fitted distribution, a new amplitude sequence can be derived. The combination of this extrapolated amplitude sequence with the original mean sequence forms a new load spectrum. The results of applying the proposed extrapolation method to the drill pipe of a rotary rig demonstrate the ability of the method to yield conservative extrapolation results and accurately capture the variations in damage under the original working conditions. [ABSTRACT FROM AUTHOR]

Transportation of the drilled cuttings to the surface is required to ensure optimum hole cleaning condition that is needed to fasten the drilling process. Transportation of these cuttings is challenging regardless of the well trajectory because of the several parameters controlling the performance of the drilling mud to raise these cuttings, and the severity of the hole cleaning problems is increased for the deviated and horizontal wells due to the increase in the wellbore inclination. All of the currently available parameters considered for evaluating the hole cleaning condition do not include the effect of some of the influential factors affecting the hole cleaning condition. This study evaluates the hole cleaning factor (HCF) which is a new hole cleaning parameter developed by modifying the cutting carrying index. HCF considers the impact of all parameters affecting the hole cleaning conditions, which involve the impact of the drilled hole size and inclination, the size of the drill pipe, the drilling fluid rheology, mud density, and its flowrate, and rate of penetration. The developed HCF is applicable to evaluate the hole cleaning in the vertical and deviated wells on real time while drilling. The HCF model was applied to evaluate the hole cleaning situation in vertical and deviated wells. The results showed an excellent correlation between the conditions predicted with the HCF and the daily drilling reports. The crew members reported an increase in the torque with fluctuation in the drilling parameters followed by stuck pipe condition at the sections identified by the HCF. [ABSTRACT FROM AUTHOR]

Titanium drill pipe have promising application prospects in ultra-deep drilling, but the nonlinear dynamic characteristics of composite drill strings are very complex. It is very important to use titanium drill pipe safely, economically, and effectively in the drilling process. In this paper, different schemes of the titanium/steel drill pipe composite drill string was designed, and the statics and dynamics characteristics of these composite drill strings were analyzed. The design scheme of titanium/steel composite drill strings were optimized by using whirling characteristics, dynamic stress and vibration acceleration. The results show that the titanium drill pipe can effectively improve the tensile allowance of the wellhead and reduce the whirling velocity, dynamic stress and vibration acceleration of the drill string. By comparing and analyzing the dynamic characteristics of 3 kinds of composite drill strings, the use of titanium drill pipe for the lower 2000 m of the 4′′ drill pipe have the smaller dynamic stress and lateral vibration, and less collision with the wellbore. Based on the analysis of vibration and dynamic characteristics, an optimal scheme of drilling operation parameters for the titanium/steel composite drill string was formed finally, which can provide guidance for the use of the drill string composed of titanium/steel drill pipe in natural gas drilling of ultra-deep well. [ABSTRACT FROM AUTHOR]

A wellbore's cleanliness affects drilling efficiency, economy and drilling safety directly in extended-reach drilling operations. Wellbore cleaning in extended-reach drilling has always been a tough problem. Field experience has shown that inefficient transport of small cuttings is a main factor for excessive drag and torque during extended-reach drilling. However, very little is known about the transport of small cuttings. In this paper, we use the data fitting method of dimensional analysis and regression analysis to establish a wellbore cleaning model for high-inclination sections, then use water and Polyanionic Cellulose (PAC) as a drilling fluid to analyze the settlement cleaning of small cuttings in the wellbore. The data from the example wells were used for field simulations to finally derive many factors like drilling fluid density, drilling fluid displacement, drill pipe rotation speed, diameter of cuttings and annulus hydraulic diameter, which affect the thickness of the dimensionless cutting bed. The results show that the dimensionless cutting thickness decreases with increasing drilling fluid density, drilling fluid displacement and drill pipe rotation speed; and increases with increasing cutting size and annular hydraulics diameter. Meanwhile, the effect of drilling fluid discharge, drill pipe rotation speed and cutting size on the thickness of the dimensionless cutting bed decreases as their values increase. This model can be utilized to design parameters in drilling and to predict the transport of cuttings in high-inclination sections. The successful establishment of the wellbore cleaning model for small cuttings in high-inclination sections of extended-reach drilling wells is highly innovative, which is a successful combination of theory and practice and has important guiding significance for promoting the development of wellbore cleaning technology. [ABSTRACT FROM AUTHOR]

A new type of parallel operation unit for excavating and supporting anchors is proposed to address the issue of imbalanced excavation anchor ratio in coal mines. By equipping a straddle type anchoring drilling rig group, the synchronous parallel and fast operation mode for excavating and supporting anchors is achieved; Consider the problem of poor drilling stability of drill pipes in coal mines due to the coupling vibration between surrounding rock and anchoring equipment. Firstly, taking the multi drilling rig anchoring system as the research object, considering the influence of the equipment itself as an influencing factor on the vibration of the drill pipe, a dynamic model of the system is constructed using Lagrangian equations, and analytical solutions for the vibration displacement of each mass block are obtained; In order to more intuitively represent the vibration process of the drill pipe, Ansys is used to conduct modal analysis on the key components of the anchoring drilling rig system, and obtain the natural frequencies and vibration modes of each order of the key components; Using Adams to solve the rigid flexible coupling dynamic model of the anchoring drilling rig system, the vibration response laws of the drill pipe under different operating states were obtained. Secondly, Abaqus was used to simulate the drilling process of the drill pipe and obtain the vibration response law generated by the interaction between the drill pipe and the surrounding rock; The results indicate that the anchoring equipment has a greater impact on the vibration of the drill pipe, and the surrounding rock has a more stable impact on the vibration of the drill pipe. Due to the short body and large span structure of the anchoring system crossbeam expansion frame, the vibration response of the drill pipe is significantly greater than that of the retracted state of the drilling rig due to being in an unstable cantilever state when the drilling rig is extended. The theoretical reliability of the vibration response law of the drill pipe under different states has been further verified through drilling experiments of the anchoring system prototype. The relevant theories can provide a theoretical basis for the implementation of automatic anchoring technology in the anchoring system. [ABSTRACT FROM AUTHOR]

With the exploration and development of oil and gas resources moving towards deeper areas, there is an increasing number of high-temperature wells being drilled. However, during drilling, the temperature of the drilling fluid at the bottom of the well may exceed the temperature limits of the rotary steerable system, logging while drilling, and other downhole tools. This poses a significant risk to the safety of the drilling operation. Therefore, it is urgent to study temperature control technology for drilling fluids in high-temperature wells. Inner-coating thermal insulation drill pipe is a new technology with significant application prospects. In order to study the thermal insulation performance of inner-coating thermal insulation drill pipe and consider the influence of the insulation coating, an equation for the wellbore temperature field during drilling with inner-coating thermal insulation drill pipe was established. Through case analysis, the thermal insulation performance of inner-coating thermal insulation drill pipe was evaluated, and the sensitivity of parameters was analyzed. An optimization method was developed for determining the installation length of inner-coating thermal insulation drill pipe. The installation length was optimized for various temperature-resistant conditions through case calculations. The research results show that inner-coating thermal insulation drill pipe has a positive impact on controlling the temperature of drilling fluid at the bottom of the well and has promising potential for widespread application. Only by installing 3500 m of inner-coating thermal insulation drill pipe can we meet the requirement for tools that can withstand temperatures of 150°C. This study can provide valuable insights for the design and application of inner-coating thermal insulation drill pipes in high-temperature wells. It is of significant importance for ensuring safe drilling operations in such conditions. [ABSTRACT FROM AUTHOR]

To optimize and improve the impact performance of a hydraulic rock drill, it is helpful to test the stress waves of the drill and analyze the impact energy, impact frequency, and energy utilization rate. For this study, a stress wave test bench was designed and built, according to international standards, in order to study the impact process of a hydraulic rock drill under the working pressures of 18 MPa and 23 MPa. The impact energy, impact frequency, and energy utilization rate of two different hydraulic rock drill pistons in low, middle, and high gear were analyzed using a control variable method. The results demonstrate that the impact stress waves of the rock drill periodically occur in the drill rod, and then decay exponentially until they become close to zero. Moreover, the amplitude of the incident stress wave determines the rock-breaking ability of the drill. The impact energy of the short piston is greater than that of the long piston, with a maximum average value of 346.1 J; the impact frequency of the long piston is higher than that of the short piston, with a maximum average value of 62 Hz; and the energy utilization rate of the short piston is higher than that of the long piston, with a maximum average value of 56.92%, which is close to the theoretical ideal efficiency. Therefore, it can be concluded that the impact performance of a hydraulic rock drill can be effectively tested using the proposed horizontal bench, and that piston characteristics and the working pressure are the main factors affecting impact performance. Accordingly, when developing a hydraulic rock drill, it is advisable to select a shorter piston and a higher working pressure, thus allowing the drill to provide good impact performance. [ABSTRACT FROM AUTHOR]

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