Numerical simulation of rock-breaking and influence laws of dynamic load parameters during axial-torsional coupled impact drilling with a single PDC cutter

Axial and torsional impact drilling technology is used to improve the drilling efficiency of hard rock formation in the deep underground.Still,the corresponding theory is not mature,and there are few correlative research reports on the rock-breaking mechanism of axial and torsional coupled impact drilling tools.Considering the influence of the impact hammer geometry and movement on the dynamic load parameters(i.e.,wavelength,amplitude,frequency,and phase difference),a numerical model that includes a hard formation and single polycrystalline diamond compact cutter was established.The Riedel-Hiermaier-Thoma model,which considers the dynamic damage and strength behavior of rocks,was adopted to analyze the rock damage under axial and torsional impact loads.The numerical simu-lation results were verified by the experimental results.It was found that compared with conventional drilling,the penetration depths of axial,torsional,and axial-torsional coupled impact drilling increased by 31.3%,5.6%,and 34.7%,respectively.Increasing the wavelength and amplitude of the axial impact stress wave improved the penetration depth.When the bit rotation speed remained unchanged,increasing the frequency in the axial and circumferential directions had little effect on the penetration depth.However,as the frequency increased,the cutting surface became increasingly smooth,which reduced the occurrence of bit vibration.When the phase difference between the axial and circumfer-ential stress waves was 25%,the penetration depth significantly increased.In addition,the bit vibration problem can be effectively reduced.Finally,the adjustment of engineering and tool structure parameters is proposed to optimize the efficiency of the axial-torsional coupled impact drilling tool.

Design and Fluid-Dynamic Analysis of a Flushing Nozzle for Drilling Applications

The actuator is a key component of the creaming tool in drilling applications.Its jet performances determine the effective reaming efficiency.In this work,a new selective reaming tool is proposed and the RNG k-εturbulence model is used to calculate its internal and externalflowfields.In particular,special attention is paid to the design of theflushing nozzle.The results show that the jet originating from theflushing nozzle has a significant influence on rock cutting and blade cooling effects.In turn,the jet performances depend on geometric structure of the creaming actuator.In this framework,a conical-cylindrical nozzle with a diameter of 7 mm is initially considered as a basis to implement a strategy to optimize the structural parameters of the reaming actuator,and improve the related side tracking reconstruction technology.

Recent Advances in Drilling Tool Temperature:A State‑of‑the‑Art Review

Drilling is regarded as the most complex manufacturing process compared with other conventional machining processes.During the drilling process,most of the energy consumed in metal cutting is converted to heat and increases temperature considerably.The resulting thermal phenomena are important since they influence the mode of deformation,the final metallurgical state of the machined surface,and the rate of tool wear.Hence,understanding the temperature characteristics in the drilling process is crucial for enhancing the drill performance and process efficiency.Extensive efforts have been conducted to measure and control the drilling tool temperature successively.However,very few studies have been conducted from a comprehensive perspective to review all the efforts.To address this gap in the literature,a rigorous review concerning the state-of-the-art results and advances in drilling tool temperature is presented in this paper by referring to the wide comparisons among literature analyses.The multiple aspects of drilling tool temperature are precisely detailed and discussed in terms of theoretical analysis and thermal modeling,methods for temperature measuring,the effect of cutting parameters,tool geometries and hole-making methods on temperature and temperature controlling by different cooling methods.In conclusion,several possible future research directions are discussed to offer potential insights for the drilling community and future researchers.

Analysis of secondary makeup characteristics of drill collar joint and prediction of downhole equivalent impact torque of Well SDTK1

Based on the three-dimensional elastic-plastic finite element analysis of the 8"(203.2 mm)drill collar joint,this paper studies the mechanical characteristics of the pin and box of NC56 drill collar joints under complex load conditions,as well as the downhole secondary makeup features,and calculates the downhole equivalent impact torque with the relative offset at the shoulder of internal and external threads.On the basis of verifying the correctness of the calculation results by using measured results in Well GT1,the prediction model of the downhole equivalent impact torque is formed and applied in the first extra-deep well with a depth over 10000 m in China(Well SDTK1).The results indicate that under complex loads,the stress distribution in drill collar joints is uneven,with relatively higher von Mises stress at the shoulder and the threads close to the shoulder.For 203.2 mm drill collar joints pre-tightened according to the make-up torque recommended by American Petroleum Institute standards,when the downhole equivalent impact torque exceeds 65 kN·m,the preload balance of the joint is disrupted,leading to secondary make-up of the joint.As the downhole equivalent impact torque increases,the relative offset at the shoulder of internal and external threads increases.The calculation results reveal that there exists significant downhole impact torque in Well SDTK1 with complex loading environment.It is necessary to use double shoulder collar joints to improve the impact torque resistance of the joint or optimize the operating parameters to reduce the downhole impact torque,and effectively prevent drilling tool failure.

Two-Layer Contact Nonlinear Mechanical Analysis of Flexible Drilling Tool in the Wellbore

The lack of research on flexible drilling tool leads to limited application of ultra-short radius horizontal wells.The flexible drilling tool is different from the conventional drilling tool.The flexible drilling pipe involves a mutual transition between the structure and the mechanism during the deformation process.At the same time,the flexible drilling pipe and the eccentric guide tube,the guide tube and the wellbore generate random contact.In this paper,3-D beam elements,universal joint elements,rigid beam elements and the beam-beam contact elements are combined to establish a two-layer contact nonlinear finite element model of the flexible drilling tool in the wellbore.The dynamic relaxation method is introduced for numerical solution.The feasibility of the model and the algorithm is verified by an example.The mechanical analysis of flexible drilling tool under the four hole inclinations in the oblique section is carried out.It is found that the flexible drilling pipe has a“folded line”deformation.The contact force between the flexible drilling pipe and the guide tube is randomly distributed.The contact force between the guide tube and the wellbore in the oblique section is greater than that in the vertical section.As the hole inclinations increase,the torque and axial force transmitted to the drill bit gradually decrease.

Analysis of Tool Wear Rate in Drilling Operation using Scanning Electron Microscope (SEM)

Hole making had long been recognized as the most prominent machining process, requiring specialized techniques to achieve optimum cutting condition. Drilling can be described as a process where a multi-point tool is used to remove unwanted materials to produce a desired hole. It broadly covers those methods used for producing cylindrical holes in the work piece. However, high production machining and drilling with high cutting velocity, feed and depth of cut is inherently associated with generation of large amount of heat and high cutting temperature. Such high cutting temperature not only reduces dimensional accuracy and tool life but also impairs the surface integrity of the product. In this case, high pressure coolant (HPC) is very effective to reduce temperature. When temperature is increased a large amount of tool wear appears at the drill bit. In this situation, high temperature either affects roundness of the hole or chip shape and color of chip. HPC is applied in the same direction as the drill bit. HPC has reduced temperature as well as improving roundness and also provide lubrication in the tool tip and surface interface.

Tillage Effect and Development Prospect of Fenlong Farming Tools with"Drill"

In this paper,farming and crop cultivation effects of farming tools with"drill"which are invented independently in China are clarified firstly,containing horizontal cutting of soil,super deep ploughing,deep loosening and not disturbing soil layer,granular soil,soil not easy to bond and harden,and one-time land preparation.It is a significant path to deeply develop and use the"five natural resources"not fully utilized by human beings(soil resources at plough bottom and below,saline-alkali land,natural rainfall,solar energy,oxygen)and realize"mitigation"of five natural disasters(flood,drought,high temperature,low temperature and climate warming).In the past 10 years,the farming tools have been applied in 40 kinds of crops in 26 provinces of China.Compared with vertical breaking of soil by traditional"plow",the amount of loose soil,water storage and dissolved oxygen in cultivated land increased by more than one time,and yield increased by 10%-50%.They have been applied in transformation of saline-alkali land in 10 provinces,and yield increased by 30%-150%.After Fenlong treatment for 1 and 2 years,biomass of sugarcane increased by 68.9%and 50.1%respectively.Net photosynthetic rates of Gramineous crops were improved by 6.82%-11.94%,while net photosynthetic rates of Legume crops were improved by 20.32%-32.08%.After"spiral drill","vertical two-knife drill","vertical three-knife drill"and other hollow series of Fenlong farming toolss were invented newly.They were the most advanced farming tools with large soil discharge and small resistance,and could be equipped in large-,medium-and small-size modern Fenlong agricultural machinery as key technology,thereby setting up a new"standard stalk"for world agricultural reform and bringing benefit to mankind.

Advancing electrochemical drilling process via coupling of flow field and electric field in pulsating state generated by a novel tube tool

This paper introduces an improvement to electrochemical drilling process by coupling flow field and electric field in pulsating state. A novel tube with half-wedged shape at the end(HW-tube) is prepared, with both sidewall and wedged part of the HW-tube insulated. Only the flat part is utilized to provide electric field for electrochemical drilling. By rotating the HW-tube, both flow field and electric field in pulsating state are generated, alternating in different positions within the inter-electrode gap(IEG). The pulsating flow field enhances the mass transfer process, while pulsating electric field disperses material dissolution process and distribution of electrolytic byproducts. Both pulsating fields are coupled at the same frequency, further enhancing the electrochemical drilling process. Simulation results indicate that both flow field and electric field in pulsating state are generated. Compared to the traditional tube, the HW-tube significantly reduces the number of residual particles in IEG, and this number is further reduced by increasing the rotation speed. Experimental results reveal that the surface quality and dimensional uniformity of small hole are improved with HW-tube. With feed rate of 2.22 mm/min, a small hole with diameter of 1.52± 0.017 mm is drilled, resulting in a surface roughness of 0.331 μm.

Drilling study on lightweight structural Mg/SiC composite for defence applications

Heat energy generated during machining has been found to have a greater influence on determining the machinability of the materials.In this work,magnesium-based silicon carbide composite,which has been identified as a suitable lightweight application material,is prepared with the weight ratio of 90:10 by a stir casting process.Conventionally available HSS drill tools with different diameters of 4,6 and 8 mm are used to perform the drilling operations with governing parameters of spindle speed,feed rate and constant depth of cut.Thermal image camera of the FLIR E60 series is used to measure the temperature variation in the cutting zone at different operating conditions.The influences of machining temperature on chip morphology,tool wear and surface profile of the machined samples are investigated.Spindle speed has been found to have a significant effect on machining temperature.When spindle speed increases,the diameter of drill tool increases the tool wear and surface profile,respectively.Both abrasion and adhesive type of wears are observed in the drill tool.Further,change from abrasion to adhesive wear is noticed with the increase of the diameter of the drill tool.Surface plots are drawn with respect to the interaction of governing parameters along with the working temperatures obtained under different machining conditions.

Failure analysis of 18CrNi3MoA drilling tails

The fracture of a drilling tail made of 18CrNi3MoA steel in the exchanging water hole was analyzed in terms of inclusions, prior austenite grain size, carburized layers, and fatigue fracture morphology by means of optical microscopy, quantitative metallography, and scanning electron microscopy （SEM）. Fatigue crack initiation and propagation on the drilling tail were also studied. The results showed that the fracture on the drilling tail was not induced by inclusions and the distribution inhomogeneity of prior austenite grain size. Instead, be- cause the outside surface of the exchanging water hole was not continuously geometric, there was a great deal of stress concentration in those areas under continuous twisting, axial impact, and corrosion of mineral water. Thus three crack sources emerged in these areas. Initial cracks centered on these sources spread from the outside surface to the inside surface, and eventually the drilling tail ruptured. Furthermore, the fractograph of the region around the crack sources exhibited a typical ductile dimple fracture pattern, and cracks initiated on the outside sur- face of the carburized layers of the exchanging water hole. Three crack sources could be the sources of fatigue crack propagation. Based on the analysis of fatigue crack propagation, it was further demonstrated that fatigue damage originated from the outside surface of the ex- changing water hole.

万米深井上部大尺寸井眼钻柱动力学特性研究

油气勘探已向更深、更复杂的超深层的万米勘探新领域推进,但上部大尺寸井眼给万米深井的钻井提出了巨大挑战:岩石硬和返速低导致钻速慢,大尺寸井眼内剧烈振动导致钻具裂纹多发,钻压小则钻速慢,钻压稍大则下部振动快速加剧从而导致大尺寸钻具使用寿命远低于预期。为此,在对比研究了深地川科1井(以下简称SDCK-1井)和毗邻8000 m超深井上部井段钻柱振动问题基础上,基于全井钻柱系统动力学模型和数值仿真方法,针对性研究了大尺寸井眼中的钻柱动力学特性。研究结果表明:①井眼尺寸越大,钻头和下部钻具的振动越剧烈,SDCK-1井二开大尺寸井眼与邻井中等尺寸井眼相比(井深500 m处),其钻头及下部钻具振动强度均值分别增加了48.0%和41.5%,比SDCK-1井三开中等尺寸3000 m井深的钻头及下部钻具振动强度均值分别高了29.0%和2.9%;②相同井眼尺寸和岩石特性情况下,下部钻具组合比钻柱整体长度对钻头振动的影响更大,优化下部钻具组合能够明显改善钻头振动,保护钻头,同时还可以提高钻头破岩能量利用效率实现钻井提速;③在大尺寸井眼中钻头破岩激励向上传播,横向振动衰减慢于轴向振动衰减,大尺寸钻头扭矩更大且钻压和扭矩波动更加明显,因此从保护下部钻具的角度出发,大尺寸井眼钻具组合对抑制横振更加有效;④大尺寸井眼中下部钻具弯矩和弯矩波动更大,现场频繁出现的钻具裂纹除受控于整体振动强度较大以外,交变弯矩是裂纹发生的重要原因。结论认为,该研究成果揭示了超深井大尺寸井眼中钻柱的动力学特性,指出了应着重控制横振和交变弯矩,该认识可以为超深井上部大尺寸井眼钻井提供技术指导。

煤矿防冲钻孔机器人全自主钻进系统关键技术

针对高地应力矿井钻孔卸压作业智能化程度低的技术难题,总结分析了国内外钻孔卸压技术和装备的研究现状,指出研发高性能、高可靠、高效率的防冲钻孔机器人全自主钻进系统是破解冲击地压防治难题的重要发展方向。为此,凝练了影响钻进系统性能的“孔位精准识别、钻具姿态精确感知、无线电磁随钻智能检测、钻具运行状态智能识别和钻进系统精确控制”五大关键技术,并给出了解决思路和方法。针对在复杂恶劣环境下卸压孔的精确识别问题,设计了融合图像尺寸调节和多阶段训练模式的卸压孔图像样本扩充SinGAN模型,引入多层特征融合优化的FasterRCNN,构建了基于改进SqueezeNet轻量级网络架构的孔位识别模型,以实现卸压孔位的准确快速识别;针对钻具姿态精确感知问题,提出了基于改进梯度下降法算法优化无迹卡尔曼滤波的惯性测量单元(Inertial Measurement Unit,IMU)初始对准方法,设计了多个IMU的空间阵列布局方式,研究了基于BP神经网络的钻具姿态误差补偿方法,旨在提高钻具姿态的解算精度,实现精准钻孔卸压;针对复杂地质环境下钻进工况的精确检测问题,搭建了煤矿井下随钻测量无线电磁传输系统架构,探讨了微弱电磁波信号自适应调制和随钻高速双向电磁传输技术原理,研究了孔底地质参数、几何参数和工程参数的测量原理和实现过程;针对钻进系统运行状态识别问题,构建了钻进信号时域、频域、时频域的多域特征和深度网络高级特征提取架构,提出了钻进系统关键零部件健康状态评估和故障诊断技术,构建了基于改进蝙蝠优化长短期记忆网络的卡钻风险因子预测模型,实现对卸压钻具卡钻状态的准确预测;针对钻进系统的精确控制问题,分析了钻进系统的液压系统工作原理,构建了考虑煤岩性状的钻进系统精确控制方案,探讨了基于转矩和位置的钻进系统最优控制参数求解原理,旨在实现钻进回转系统和给进系统的智能协同控制和并行作业。

SDTK1井钻铤接头二次上扣特性分析与井下等效冲击扭矩预测

基于8"(203.2mm)钻铤接头三维弹塑性有限元模型,分析复杂载荷条件下NC56钻铤接头内、外螺纹的受力特征和井下二次上扣特性,通过有限元分析,根据接头内、外螺纹台肩处相对偏移量计算井下等效冲击扭矩,形成井下等效冲击扭矩的预测模型,利用塔里木盆地GT1井井下实测结果验证该模型正确性,并应用于中国第1口超万米特深井——深地塔科1井(SDTK1井)。结果表明:复杂载荷作用下钻铤接头应力分布不均匀,台肩处和靠近台肩的螺纹牙处vonMises应力水平相对较高;对于按API(美国石油学会)标准上扣的203.2mm钻铤接头,当井下等效冲击扭矩超过65 kN·m时,钻铤接头的上扣预紧平衡被打破,钻铤接头发生二次上扣;随井下等效冲击扭矩的增大,内、外螺纹台肩处相对偏移量增加。SDTK1井井下存在较大冲击扭矩,井下载荷环境复杂,需要采用双台肩钻铤接头以提高接头的抗冲击扭矩能力或优化作业参数来降低井下冲击扭矩,从而有效防止钻具失效。

水平井尾管完井与钻井一体化设计控制技术

针对水平井尾管导向钻井技术存在的钻机旋转系统负载大、地面扭矩传动效率低、使用与维护成本高等问题,提出了水平井双管柱尾管差速旋转钻进新方法,揭示了相应的技术原理,设计了双管柱差速旋转传动、复合旋转导向及悬挂器等井下专用工具,优化了相关工艺流程;提出了导向钻具组合工具面控制方法,建立了水平井双管柱尾管差速旋转钻进延伸极限计算模型。结果表明:水平井双管柱尾管差速旋转钻进技术配备常规随钻测量仪器和螺杆钻具,通过调节钻柱转速可以控制导向钻具组合的工具面,实现了水平井双管柱尾管差速旋转导向钻进;基于鄂尔多斯盆地东缘深部煤层气水平井工程案例计算水平井双管柱钻进延伸极限,与常规尾管钻井方式相比,采用双管柱尾管差速旋转钻进方式显著增大了水平井延伸极限,为水平井尾管完井与钻井一体化设计控制提供了参考。

BH-N型不提钻换钻头钻进技术研究与应用

地质钻探施工时起下钻更换钻头,需要占用大量时间,且存在一定的安全隐患,大大影响钻探效率,采用不提钻换钻头钻进技术可以很好的解决这个问题。以N规格绳索取心钻杆为使用平台,沿用BH-75钻具基本结构,并针对其存在问题,研制BH-N规格的不提钻换钻头钻具,同时根据N规格钻具的具体结构完善BH-75钻具,提高了钻具的承压能力和钻具收敛(投送)稳定性,增设了自动除沙机构等。在山东乳山金青顶金矿ZK43-1钻孔进行了现场应用,在孔深2081.20~2211.40米实现了不提钻换钻头,钻具岩心采取率达到100%,岩心质量好,最大限度减少起下钻次数,有效预防起下钻引发孔内事故。不提钻换钻头钻进技术为深孔地质勘探中钻进强研磨性、打滑、软硬频繁交替等地层,提供了及时优化钻头使用方案,降低能源消耗,有效的保护孔壁安全和减少劳动强度。

全旋转指向式导向钻井工具结构设计与仿真

为了提高全旋转指向式导向钻井工具的设计效率,缩短研发周期,笔者首先设计了该钻井工具的导向执行机构,简化导向执行机构的空间机构模型,通过自由度的计算,得出了该机构具有确定的运动。再对该钻井工具的结构组成和导向原理进行分析,得到了其导向控制方法是通过控制全旋转指向式导向钻井工具的双偏心环和旋转外套的角位移关系,调节其工具角和工具面角,实现导向钻井。最后利用SolidWorks和ADAMS软件对钻井工具虚拟样机进行三维实体建模及运动仿真,仿真结果表明该钻井工具可以实现工具面角(0~360)°和工具角(0~5)°的无级调节,验证了所设计的全旋转指向式导向钻井工具结构和导向原理的可行性,为原理样机的加工奠定了基础。

顺北油气田二叠系火成岩钻井技术研究与应用

塔里木盆地顺北区块二叠系火成岩地层厚度大、硬度高、裂缝发育、非均质性强,导致机械钻速低与堵漏耗时长,相比邻区平均钻井周期增加达1.5倍。近几年,通过持续强化钻井液堵漏技术与优选高效钻井工艺,漏失量与堵漏时间逐步缩短,钻井指标逐年提高。本文分析了影响堵漏时间长与机械钻速低的主控因素,提出堵漏浆中加入竹纤维、变形颗粒以改善堵漏工艺技术,明确了冲击工具的适用条件,优选攻击性与抗冲击性的PDC钻头,改进混合钻头结构以及配套大扭矩、长寿命螺杆等技术对策,提速降本成效显著,为加快顺北油气田的高效勘探开发提供了指导。

旋冲钻具凸轮-滚轮冲击机构工作特性分析

旋冲钻具能有效提高深层、硬地层的破岩效率,具有广阔的应用前景。凸轮-滚轮是实现冲击动作的关键机构,但复杂多变的井下环境导致机构损伤严重,进而影响破岩效率。基于旋冲钻具多井次的试钻数据,建立凸轮-滚轮动力学模型,通过显式动力学(Autodyn)分析不同冲程、转速、钻压下的工作特性,总结机构的形变特征提出优化方法。分析结果与试验数据和理论数值对比,验证了计算模型的准确性。结果表明:冲程增大可提高冲击效果,但高于10 mm冲程的滚子实际运动轨迹受钻速、滚轮尺寸、凸轮轮廓曲率影响其轨迹将变平缓。转速在9~18 rad/s时轴向加速度波动幅度较大,对钻具的稳定性具有一定影响。钻压增大凸轮内缘处形变特性明显,其形变量与钻压成正比,25 kN钻压下凸轮的形变量约是10 kN的2.6倍。凸轮齿顶、滚轮内缘处为易变形点,在齿顶处安装可换滚筒同时改变滚轮为鼓轮构型并对抛物线-直线-抛物线、2次多项式、摆线、7次多项式4类凸轮轮廓线型进行特性分析。选用摆线及7次多项式凸轮座轮廓和鼓轮可提高冲击效果,计算结果可为旋冲钻具设计提供参考依据。