Testing method of rock structural plane using digital drilling

The rock mass consists of rock blocks and structural planes,which can reduce its integrity and strength.Therefore,accurately obtaining the characteristics of the rock mass structural plane is a prerequisite for evaluating stability and designing supports in underground engineering.Currently,there are no effective testing methods for the characteristic parameters of the rock mass structural plane in underground engineering.The paper presents the digital drilling technology as a new testing method of rock mass structural planes.Flawed rock specimens with cracks of varying widths and angles were used to simulate the rock mass structural planes,and the multifunctional rock mass digital drilling test system was employed to carry out the digital drilling tests.The analysis focuses on the variation laws of drilling parameters,such as drilling pressure and drilling torque,affected by the characteristics of prefabricated cracks,and clarifies the degradation mechanism of rock equivalent compressive strength.Additionally,an identification model for the characteristic parameters of rock mass structural planes during drilling is established.The test results indicate that the average difference of the characteristics of prefabricated cracks identified by the equivalent compressive strength is 2.45°and 0.82 mm,respectively.The identification model while drilling is verified to be correct due to the high identification accuracy.Based on this,a method for testing the characteristic parameters of the surrounding rock structural plane while drilling is proposed.The research offers a theoretical and methodological foundation for precise in situ identification of structural planes of the surrounding rock in underground engineering.

Numerical analysis of the effects of downhole dynamic conditions on formation testing while drilling

Formation testing while drilling is an innovative technique that is replacing conventional pressure testing in which the fluid sampling is conducted in a relatively short time following the drilling. At this time, mud invasion has just started, mudcake has not formed entirely and the formation pressure is not stable. Therefore, it is important to study the influence of the downhole dynamic environment on pressure testing and fluid sampling. This paper applies an oil-water two phase finite element model to study the influence of mudcake quality and mud filtrate invasion on supercharge pressure, pretest and sampling in the reservoirs of different permeability. However, the study is only for the cases with water based mud in the wellbore. The results illustrate that the mudcake quality has a significant influence on the supercharge pressure and fluid sampling, while the level of mud filtrate invasion has a strong impact on pressure testing and sampling. In addition, in-situ formation pressure testing is more difficult in low permeability reservoirs as the mud filtrate invasion is deeper and therefore degrades the quality of fluid sampling. Finally, a field example from an oil field on the Alaskan North Slope is presented to validate the numerical studies of the effects of downhole dynamic conditions on formation testing while drilling.

Properties and testing of a hydraulic pulse jet and its application in offshore drilling

Offshore drilling has attracted more attention than ever before due to the increasing worldwide energy demand especially in China. High cost, long drilling cycles, and low rate of penetration （ROP） represent critical challenges for offshore drilling operations. The hydraulic pulse generator was specifically designed, based on China offshore drilling technologies and parameters, to overcome problems encountered during offshore drilling. Both laboratory and field tests were conducted to collect the characteristics of the hydraulic pulse generator. The relationships between flow rate and pressure amplitude, pressure loss and pulse frequency were obtained, which can be used to optimize operation parameters for hydraulic pulse jet drilling. Meanwhile a bottom hole assembly （BHA） for pulse jet drilling has been designed, combining the hydraulic pulse generator with the conventional BHA, positive displacement motor, and rotary steerable system （RSS） etc. Furthermore, the hydraulic pulse jet technique has been successfully applied in more than 10 offshore wells in China. The depth of the applied wells ranged from 2,000 m to 4,100 m with drilling bit diameters of 311 mm and 216 mm. The field application results showed that hydraulic pulse jet technique was feasible for various bit types and formations, and that ROP could be significantly increased, by more than 25%.

Development of a Drilling and Coring Test-bed for Lunar Subsurface Exploration and Preliminary Experiments

Drill sampling has been widely employed as an effective way to acquire deep samples in extraterrestrial exploration. A novel sampling method, namely, flexible-tube coring, was adopted for the Chang＇e mission to acquire drilling cores without damaging stratification information. Since the extraterrestrial environment is uncertain and different from the terrestrial environment, automated drill sampling missions are at risk of failure. The principles of drilling and coring for the lunar subsurface should be fully tested and verified on earth before launch. This paper proposes a test-bed for conducting the aforementioned experiments on earth. The test-bed comprises a rotary-percussive drilling mechanism, penetrating mechanism, drilling medium container, and signal acquisition and control system. For granular soil, coring experiments indicate that the sampling method has a high coring rate greater than 80%. For hard rock, drilling experiments indicate that the percussive frequency greatly affects the drilling efficiency. A multi-layered simulant composed of granular soil and hard rock is built to test the adaptability of drilling and coring. To tackle complex drilling media, an intelligent drilling strategy based on online recognition is proposed to improve the adaptability of the sampling drill. The primary features of this research are the proposal of a scheme for drilling and coring a test-bed for validation on earth and the execution of drilling experiments in complex media.

Two stages power generation test of the hot dry rock exploration and production demonstration project in the Gonghe Basin,northeastern Qinghai-Tibet plateau,China

The Hot Dry Rock(HDR)is considered as a clean and renewable energy,poised to significantly contribute to the global energy decarbonization agenda.Many HDR projects worldwide have accumulated valuable experience in efficient drilling and completion,reservoir construction,and fracture simulation.In 2019,China Geological Survey(CGS)initiated a demonstration project of HDR exploration and production in the Gonghe Basin,aiming to overcome the setbacks faced by HDR projects.Over the ensuing four years,the Gonghe HDR project achieved the first power generation in 2021,followed by the second power generation test in 2022.After establishing the primary well group in the initial phase,two directional wells and one branch well were drilled.Noteworthy progress was made in successfully constructing the targeted reservoir,realizing inter-well connectivity,power generation and grid connection,implementing of the real-time micro-seismic monitoring.A closed-loop technical validation of the HDR exploration and production was completed.However,many technical challenges remain in the process of HDR industrialization,such as reservoir fracture network characterization,efficient drilling and completion,multiple fracturing treatment,continuous injection and production,as well as mitigation of induced seismicity and numerical simulation technology.

Investigation of active vibration drilling using acoustic emission and cutting size analysis

This paper describes an investigation of active bit vibration on the penetration mechanisms and bit-rock interaction for drilling with a diamond impregnated coring bit. A series of drill-off tests(DOTs) were conducted where the drilling rate-of-penetration(ROP) was measured at a series of step-wise increasing static bit thrusts or weight-on-bits(WOBs). Two active DOTs were conducted by applying 60 Hz axial vibration at the bit-rock interface using an electromagnetic vibrating table mounted underneath the drilling samples, and a passive DOT was conducted where the bit was allowed to vibrate naturally with lower amplitude due to the compliance of the drilling sample mountings. During drilling, an acoustic emission(AE) system was used to record the AE signals generated by the diamond cutter penetration and the cuttings were collected for grain size analysis. The instrumented drilling system recorded the dynamic motions of the bit-rock interface using a laser displacement sensor, a load cell, and an LVDT(linear variable differential transformer) recorded the dynamic WOB and the ROP, respectively. Calibration with the drilling system showed that rotary speed was approximately the same at any given WOB, facilitating comparison of the results at the same WOB. Analysis of the experimental results shows that the ROP of the bit at any given WOB increased with higher amplitude of axial bit-rock vibration, and the drill cuttings increased in size with a higher ROP. Spectral analysis of the AEs indicated that the higher ROP and larger cutting size were correlated with a higher AE energy and a lower AE frequency. This indicated that larger fractures were being created to generate larger cutting size. Overall, these results indicate that a greater magnitude of axial bit-rock vibration produces larger fractures and generates larger cuttings which, at the same rotary speed, results in a higher ROP.

Motion Regular Analysis and Its Simulation of the Rodless Drilling Unit's Guiding & Positioning Board

To analyze the stress of the guiding & positioning board and the effectiveness of the guiding & positioning device,according to guiding & positioning device's operational principle and structure,the guiding & positioning board's motion regular was analyzed by diagrammatical method based on 2 postulated conditions.Considering about the working conditions' change,simulations in 5 different kinds of working conditions were done to check the correctness of the motion regulars obtained by diagrammatical method.Simulation results prove that the motion regulars are right,the postulated conditions have no effect on the obtained motion regulars.According to the simulation results,the motion processs's characters were drawn out at the same time.

Application of the monitoring and early warning system for internal solitary waves:Take the second natural gas hydrates production test in the South China Sea as an example

Internal solitary waves(ISWs) contain great energy and have the characteristics of emergency and concealment. To avoid their damage to offshore engineering, a new generation of monitoring and early warning system for ISWs was developed using technologies of double buoys monitoring, intelligent realtime data transmission, and automatic software identification. The system was applied to the second natural gas hydrates(NGHs) production test in the Shenhu Area, South China Sea(SCS) and successfully provided the early warning of ISWs for 173 days(from October 2019 to April 2020). The abrupt changes in the thrust force of the drilling platform under the attack of ISWs were consistent with the early warning information, proving the reliability of this system. A total of 93 ISWs were detected around the drilling platform. Most of them occurred during the spring tides in October–December 2019 and April 2020, while few of them occurred in winter. As suggested by the theoretical model, the full-depth structure of ISWs was a typical current profile of mode-1, and the velocities of wave-induced currents can reach 80 cm/s and30 cm/s, respectively, in the upper ocean and near the seabed. The ISWs may be primarily generated from the interactions between the topography and semidiurnal tides in the Luzon Strait, and then propagate westward to the drilling platform. This study could serve as an important reference for the early warning of ISWs for offshore engineering construction in the future.

隧道不良地质识别:方法、现状及智能化发展方向

随着隧道施工对于不良地质识别精度要求的不断提高以及人工智能技术的发展,融合多源信息的不良地质智能化识别已成为发展趋势。本文首先阐述了常见的6种隧道不良地质类型及其地质成因,回顾分析了隧道主要的不良地质识别方法及现状,详细介绍了笔者在不良地质智能化识别方面的探索性研究:基于机器学习利用图像识别技术对隧道围岩岩性与裂隙特征进行智能识别;融合图像和光谱特征进行不良地质识别;将地化分析融入到传统的超前钻探中,融合随钻参数和地化信息进行不良地质随钻识别,既可以发挥超前钻探在感知岩体质量和地层信息变化方面的优势,又可以发挥地化分析在岩性和不良地质异常识别方面的优势;基于地质与物探联合反演进行不良地质识别,旨在实现掌子面前方不良地质体“形”(位置、形态、规模)和“性”(性质和类型)的精确识别。最后,对隧道不良地质智能化识别的发展趋势进行了展望。

开采保护层与预抽煤层瓦斯防突效果分析

为比较开采保护层与预抽煤层瓦斯防突效果,以1124(3)运顺开采保护层段和预抽煤层瓦斯段煤巷掘进为试验对象,统计了试验地点煤巷掘进期间残余瓦斯含量、钻屑瓦斯解吸指标K1、钻屑量等防突指标,采用假设检验方法推断了各防突指标是否有差别,分析了开采保护层段和预抽煤层瓦斯段各防突指标产生差别的原因,验证了开采保护层区域防突措施比预抽煤层瓦斯区域防突措施更加安全可靠。

各向异性地层中随钻地层测试压力响应数值模拟

在随钻地层测试器测试过程中,钻井液动态侵入和地层各向异性会导致不同的压力响应特征,并直接影响地层压力测试结果的解释精度。为此,基于各向异性多孔介质渗流理论,建立了钻井液侵入条件下横观各向同性地层随钻地层测试压力响应数学模型,采用有限元方法对模型进行求解,通过与经典解析解对比进行了模型验证,并分析了渗透率各向异性、地层产状、抽吸间歇时间、抽吸探头半径对随钻地层测试压力响应的影响规律。结果表明:在抽吸前阶段,地层各向异性和地层产状对钻井液侵入导致的井周增压影响较大;在压力恢复阶段,由于井周地层增压作用的影响,测试压力响应初始值会高于原始地层压力,且压力呈先升高后降低的演化趋势;渗透率各向异性程度越小、地层倾角和倾向越小,抽吸压降阶段的压力响应初始值越大、压降值越大、压力恢复速率越低;抽吸间隔时间和抽吸探头半径对压力响应也有一定影响,抽吸间隔时间越小,测试初始压力越大,探头半径越大,压力恢复速率越快。揭示了渗透率各向异性对随钻地层测试压力响应的影响规律,研究结果可为随钻地层测试结果解释和地层参数反演提供理论依据。

不同品位高庙子膨润土用于钻井泥浆的试验研究

钻井泥浆是膨润土应用占比较大的市场之一,通过试验测试,研究不同品位高庙子膨润土用于钻井泥浆的可行性,以便充分开发和利用高庙子膨润土矿床。研究结果表明:不同位置开采的未经处理的高庙子天然钠基膨润土不符合钻井泥浆的使用性能要求,必须对其进行增效处理;通过添加增效剂羧甲基纤维素(CMC),发现高庙子天然钠基膨润土在添加2%的增效剂后,蒙脱石含量为70%左右的膨润土均达到国家标准规范要求的钻井级膨润土的要求。但应综合考虑天然钠基膨润土的开采成本和增效剂的成本,筛选出既满足技术要求,又能控制成本的样品类型。

超协调元

该文提出一类超协调的单元理论。不同于在普通协调元中采用的线位移协调插值格式,超协调元的单元插值函数首先引入转角自由度等线位移导数的高阶协调假设,并通过积分推导,进而获得超协调的线位移模型。基于超协调元理论,该文构造了一类新型的三结点三角形平板壳元SCT。数值算例表明:与其他类型单元相比,基于超协调元理论的单元具有计算精度高和计算效率好的优势。该文所提出单元理论构造简单,超协调元理论可以成为构造高性能数值算法的一种新的通用理论。

碳纤维复合材料层合板钻削后拉伸剩余强度研究

拉伸剩余强度是复合材料层合板的一个重要力学性能,对产品的使用寿命起着关键作用。为了研究钻削工艺参数对碳纤维复合材料(Carbon Fiber Reinforced Plastics,CFRP)层合板钻削后拉伸剩余强度的影响,将所选用的失效准则和刚度退化模式编写Vumat子程序,在Abaqus软件中建立了CFRP层合板钻削后拉伸有限元模型。通过正交试验探究主轴转速、进给量和钻头顶角对CFRP层合板钻削后拉伸剩余强度的影响。研究结果表明,主轴转速、进给量和钻头顶角都对层合板拉伸剩余强度有显著影响,提高主轴转速,减小进给量和钻头顶角都可以有效地提高层合板钻削后拉伸剩余强度,为实际加工提供参考。

水平孔多参数综合测试仪器研发与应用

为研究引大济岷工程隧洞岩体特征、岩溶发育特征、地应力特征和地下水特征等,在泸定取水中线方案的引水线路中布置水平钻孔8个,共计2300 m。为满足对水平孔综合测试的需求,研制了一套适用于水平钻孔的存储式综合测井仪器。本文分析了水平孔多参数综合测试仪器各参数测量的基本工作原理;详细阐述了各功能单元的电路构成选型,主要采用DSP微处理器和大规模集成电路,结合传感器技术实现多种参数的综合测量,包括:水平钻孔的压力、温度、自然伽马、声波波速、孔内电视图像。综合测试仪器集成了模拟传感器、模拟调理电路、数据采集、数据处理、信息存储、数据通讯、信息交换、测控软硬件、电脑显示等功能,是水平孔综合测试不可缺少的技术。在引大济岷工程的水平定向孔中成功应用,一趟起下钻解决了水平钻孔的井斜、方位角、压力、温度、自然伽马、孔内电视测试的难题,尽最大可能保证了钻孔的安全及降低了劳动强度。

数字化波浪补偿分离式液压钻机的研制

基于能源绿色、风力大等优势,海上风力发电技术近年来越来越受到重视,正由浅海向深海发展,且小型发电机逐步被大功率发电机取代。海上风力发电中风电场的选址、风机的基础设计、桩基施工、地层测试等,都离不开钻探和井内静力触探技术。为了满足海上勘察钻机的要求,研发了数字化波浪补偿分离式液压钻机,主要是在数字化、自动化、回转、波浪补偿等功能,以及模块化设计、制造工艺等方面进行了创新。通过理论参数核算、海上应用测试、深海生产施工验证,证明该钻机不仅可满足使用需求,并且比常规钻机更加方便管理、高效安全,还降低了钻探的辅助成本。

钻井液漏斗黏度和密度自动检测仪的研制与应用

近年来,国内外对钻井液性能自动检测技术的研究取得了长足进步。针对现有钻井液自动检测仪器成本高、结构复杂和工作环境受限等问题,研制了钻井液漏斗黏度和密度自动在线检测仪。使用可编程逻辑控制器、物联网模组、压力传感器、超声传感器、蠕动泥浆泵、电动球阀和隔膜泵等,搭建取浆模块、检测模块、清洗模块和控制模块,实现了对钻井液漏斗黏度和密度的自动检测、移动端设备数据查看和操作等功能。采用传感器数据融合和滤波算法等方法提高仪器精度和稳定性,对不同钻井液体系性能测试验证,漏斗黏度误差控制在±1 s,密度误差控制在±0.01 g/cm^(3),且可连续地对钻井液性能进行自动测试。室内测试和现场试验结果表明,该仪器具有操作方便、测试结果准确、可重复性高、人为测量误差小和节约人工等优点,能满足实际钻井施工过程中对钻井液性能检测的要求,具有较强的普适性和广泛的应用前景。

极地钻探用铝合金双壁钻杆结构强度的有限元分析及试验研究

为了实现钻穿冰盖、直接获取冰下基岩样品的科研目标,本文设计了一种极地钻探用铝合金双壁钻杆,使钻杆可以满足极地上覆积雪层、冰层、冰岩夹层和冰下基岩等不同地层的空气反循环、水力反循环、绳索取心钻进相配合等钻进需求。依据铝合金双壁钻杆在极限拉伸、极限拉扭组合工况下的受力情况,开展了双壁钻杆的有限元分析,并对双壁钻杆外管与钢接头连接试样进行了拉伸试验与扭转试验。双壁钻杆有限元分析结果表明:在极限拉伸和极限拉扭组合工况下铝合金双壁钻杆中产生的最大应力分别为183.8 MPa与161.9 MPa,均小于铝合金材料的屈服强度489.99 MPa。双壁钻杆外管与钢接头连接试样强度试验结果也表明:拉伸试样破坏时的极限可承载拉力为399.5 kN,远大于提升1000 m双壁钻杆所需的拉力(208.11 kN);扭转试样破坏时的极限可承载扭矩为8264.7N·m,同样大于钻杆在正常钻进过程当中所承受的最大扭矩(1990.56 N·m)。上述结果表明,极地钻探用铝合金双壁钻杆设计方案可以满足极地钻探使用要求。

蒙陕矿区内钢板-钢筋混凝土钻井井壁非均匀受力特性研究

以蒙陕矿区某煤矿风井为工程背景,利用双向不等压模型推导出水平地应力下井壁的受力形式,并得出了非均匀系数k的计算公式,确定了蒙陕矿区地层的不均匀系数范围为0.06~0.20,研判了钻井井壁全深受力关键横断面的受力破坏特征。根据有限元软件ANSYS模拟非均匀荷载条件下的井壁受力规律,井壁混凝土外缘环向应力为控制应力,井壁应力呈现非均匀分布,90°位置的不均匀程度大于0°位置,外荷载较小的90°位置受拉,而外荷载较大的0°位置受压。通过对井壁压力试验台对内钢板-钢筋混凝土进行非均匀加载试验分析,非均匀荷载对钻井井壁受力影响极为明显,在k=0.15时模型的峰值应力仅为均匀荷载条件下的23.1%~33.3%;在k=0.20时模型的峰值应力为均匀荷载条件下的20%左右,且破坏形式为混凝土先受拉破坏,随后钢筋和钢板屈服。研究结果表明,内钢板-钢筋混凝土钻井井壁对非均匀荷载较为敏感,在蒙陕矿区使用钻井法应该考虑非均匀系数的影响,且需要在井壁设计阶段重点关注井壁外荷载较小位置的受力。

一种虚实结合的工控安全实训靶场平台设计

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