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WANG Ying, LI Yuxiao, ZHANG Kai, LI Fuqiang, LIU Xiao
2024,51(5):1-11, DOI: 10.12143/j.ztgc.2024.05.001
Abstract:
With the continuous development of the exploration, development and utilization of deep mineral resources, the bottom environment of the hole is more complex. Pregnant diamond bit, as a special tool for geological drilling, the complex deep hard rock geological environment also puts forward higher requirements for the performance of pregnant diamond bit. The efficiency and life of crushed rock of pregnant diamond bit are closely related to the performance of broken rock unit. This paper summarizes the research status of drilling wear response of pregnant diamond bit in deep hard rock drilling. At present, the research is not perfect, so further in-depth analysis is needed to clarify the response mechanism. On this basis, discusses the innovation of broken rock unit in recent years, the emphasis from the internal structure and the analysis of different reinforcement way of the cutting unit strength, wear, drilling efficiency, the results show that it can effectively improve the deep hard rock pregnant drill cutting efficiency and working life. From the perspective of prolonging lifespan and increasing efficiency, this paper discusses the direction of strengthening the broken rock unit of impregnated diamond drill bits suitable for deep hard rock drilling, providing reference for the design and manufacturing of impregnated diamond drill bits for deep geological drilling.
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LIU Shu, LI Wenjie, LI Lijia, LUO Yongjiang, TAO Rui, LI Xiaoxuan, YANG Yahui
2024,51(5):12-23, DOI: 10.12143/j.ztgc.2024.05.002
Abstract:
Natural gas hydrate is a type of solid clean energy with huge reserve, which is therefore considered as a substitute for traditional fossil fuels and have attracted much attention around the world. Due to its occurrence in low-temperature and high-pressure marine and permafrost environments, the key to achieving commercial exploitation is to find out economical and efficient exploitation methods. Based on the current research status of laboratory research, numerical simulation, and on-site experiments, the exploitation effects of methods such as depressurization, heat injection, chemical inhibitor injection, CO2 displacement and combination method were analyzed, and the advantages and limitations of each method were discussed. The existing exploitation methods are mainly limited by low reservoir permeability and poor thermal conductivity, and have not been able to achieve long-term continuous gas production. To address the above issues, the in-situ resistance heating method for reservoirs is proposed to improve thermal utilization efficiency, and it is believed that hydraulic fracturing and permeability enhancement technology is an effective measure to increase reservoir permeability and assist in efficient gas production through production methods such as depressurization; Regarding the potential instability of reservoirs caused by hydrate exploitation, it is believed that the use of CO2 replacement method can strengthen the reservoir, and the use of supercritical CO2 injection technology can improve the CO2 replacement rate.
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GAO Ke, LIU Zhenghao, QIN Xiaolin, WEN Yumin, ZHANG Zongzheng, LI Xu, ZHAO Yan
2024,51(5):24-35, DOI: 10.12143/j.ztgc.2024.05.003
Abstract:
With the gradual depletion of shallow underground resources, people gradually seek energy from deeper parts of the earth. In order to coping with the harsh environment of underground formations during drilling, a self-balancing drilling system and a bionic self-propelled drilling tool feeding system are proposed to move the pressure drive unit underground. In this paper. In order to solving the problems of how to increase the efficiency of the support mechanism in the self-propelled feed system, the surface of the drag-enhancing mechanism of the self-propelled feed system is designed bionically by analysing the non-smooth structure of the head surface of the dung beetle. The drag-enhancing performance and the damage to the well wall are simulated, and the friction and wear performance is tested experimentally to study the drag-enhancing and wear-reducing effects of different bionic structures. The results show that the ratio of the spacing of the dung beetle head bumps to the diameter of the dung beetle head is around 1.50, the ratio of the diameter of the middle bumps to the length of the corresponding dung beetle head ranges from 1:142 to 1∶133, with a higher probability near 1∶138, the ratio of the diameter of the two side bumps to the length of the corresponding dung beetle head ranges from 1∶173 to 1∶158, with a higher probability near 1∶167. The proportion of the bumps in the middle part was about 45%, and on both sides was basically the same; the spacing of the bionic structure design had a good drag-enhancing effect when the ratio of the spacing to the diameter of the bionic structure was around 1.50. Under the condition of the same diameter of the convex packs, the larger the spacing was, the greater the damage to the wall of the wells. The orthogonal triangular layout was the best layout for the drag-enhancing effect of bionic units, and a rectangular layout increased the damage to the wall of the wells, at the same time, reduced the drag-enhancing effect; Concentric circular arrangement has the greatest damage to the well wall and the worst drag-enhancing effect.
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CHEN Xiaojun, SONG Gang, WANG Shijun, HAN Zelong, ZHAO Ming, ZHANG Xin, TIAN Yingying
2024,51(5):36-43, DOI: 10.12143/j.ztgc.2024.05.004
Abstract:
Aiming at the problems of low drilling efficiency and low coring efficiency of hard rock coring tools in ocean drilling, this paper introduces the basic development and land test of ?185mm hollow screw motor bottom hole power rope coring tool developed by the Institute of Exploration Techniques, CAGS. In the development process, through theoretical calculation and Ansys Workbench finite element simulation, the spiral structure of the hollow screw motor is optimized and the dynamic analysis is carried out. The force safety analysis of the universal joint is carried out, and the material is optimized. The key technologies such as multi-head small offset short pitch hollow rotor and flexible hollow universal joint are overcome. The feasibility of the working performance of the prototype of the coring tool is verified by the coring test of granite block on land, which provides the guidance of working parameters and the optimization of matching drill bit for the engineering application of this coring tool. It can provide hard rock coring technical support for ocean drilling and deep scientific drilling in China.
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ZHANG Qi, GAN Chao, CAO Weihua
2024,51(5):44-51, DOI: 10.12143/j.ztgc.2024.05.005
Abstract:
Ocean drilling is a major means for the exploration and development of marine energy resources and the study of crustal tectonic evolution, which is often faced with problems such as large disturbances in complex sea state and strong uncertainty in seafloor formation. This paper proposes an online interval prediction method for ROP during the ocean drilling process, and carry out the validation of the method with the indoor simulation experiment of micro drilling ship as an example, so as to lay an important foundation for the engineering application. Firstly, methods such as data resampling, data time-depth matching and data filtering are applied to pre-process the multi-source ocean drilling data. Secondly, methods such as Extreme Learning Machine (ELM) and Particle Swarm Optimization (PSO) are applied to establish a point prediction model of ROP. Furthermore, nonparametric estimation method is utilized to construct confidence intervals, establish ROP interval prediction model, and carry out ROP interval prediction. Finally, the interval prediction model parameters are updated online by moving window to realize online learning and optimization of the model. The comparative results of the indoor simulation experiments on the micro drilling ship verify that the proposed method has strong ROP prediction capability and robustness, and can provide a new engineering solution for the optimization and control of ROP during the ocean drilling process.
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QIN Rulei, CHEN Haowen, LI Yunjun, GAO Jieyun, HE Guolei, XU Benchong, YIN Guoyue, LIANG Nan, SU Xianghui, LIU Xin, QIN Bowen
2024,51(5):52-57, DOI: 10.12143/j.ztgc.2024.05.006
Abstract:
The deep sea mud lifting system plays a critical role in the Riserless Mud Recovery (RMR) drilling process. In order to enhance the safety redundancy and adaptability of the lifting system, in-depth research on the multi pumps series parallel mechanism was conducted, including the detailed study of the series parallel structure design and working principle of the mud lifting pump, and the relationship between flow rate and lift during series and parallel operation, as well as the mathematical method and graphical method for series parallel operating points of the pump group. Furthermore, by utilizing the measured characteristic curve of the model pump, the Q-H characteristic curve and operating points of the dual pumps series parallel operation were obtained using graphical method. Finally, suggestions for dual pumps collaborative control were proposed.
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WANG Zufan, LI Yazhou, YANG Gansheng, ZHANG Kai, WANG Jin, ZHOU Zheng
2024,51(5):58-66, DOI: 10.12143/j.ztgc.2024.05.007
Abstract:
It is of great significance to carry out subglacial bedrock core drilling in polar regions for studying subglacial geology, revealing the evolutionary history of ice sheets and evaluating future climate change. The temperature of the drilling fluid may rise above 0°C after circulating at the bottom of the hole When drilling subglacial bedrock in polar regions, which may cause the wall of the icy hole to be melted during upward return, resulting in the instability of the wall, and even triggering the stuck drilling accident. It is necessary to design a drilling fluid cooling system that cooling the drilling fluid to a lower temperature before injecting it into the borehole, thereby keeping the drilling fluid below 0℃ at all times during circulation. The heat exchanger is the core component of the drilling fluid cooling system. The paper selects plate heat exchanger as the heat exchange component to cool drilling fluid, and uses the average temperature difference method to determine the heat exchange area and basic parameters, then numerical simulation of the heat exchange performance of the plate heat exchanger is using COMSOL Multiphysics 6.0 software. The research results show that the heat exchanger can cool the drilling fluid to -4~-3℃. Further, the simulation results show that the outlet temperature of the drilling fluid decreases with the decrease of the carrier refrigerant injection temperature and the increase of the carrier refrigerant flow rate, the type of drilling fluid has a great influence on the heat transfer performance of the heat exchanger, while the material of the heat exchanger plate has little influence.
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DENG Yingying, SUN Pinghe, XIA Yuhongye, XU Yong, PU Yingjie, ZHANG Xinxin, ZHANG Chen, ZHANG Hangsheng, ZHANG Shaohe
2024,51(5):67-76, DOI: 10.12143/j.ztgc.2024.05.008
Abstract:
The fracture leakage channel in fractured formation usually has multi-scale characteristics and uncertainty. The drilling fluid leakage problem is particularly prominent in the construction of geological drilling in fractured formation. Shear Thickening Fluid (STF), as a new type of intelligent material, has excellent properties such as self-sensing, self-adaptation and self-repair, and has been widely used in many fields. In this study, shear thickening fluid was used as a plugging material, and the plugging characteristics of shear thickening fluid were investigated under different dispersed phase concentrations (56.9vol%, 59.2vol% and 61.7vol%), slit widths (1,2,3,4,5mm) and pressure conditions through the plugging test of API plugging instrument. The plugging test results show that the amount of leakage increases with the increase of seam width and time. When the concentration of nano silica increases in the range of 56.9%~61.7%, the leakage rate will be reduced and the effect of the gap width on the leakage rate will be weakened. When the leakage pressure is 0 MPa, the shear thickening fluid does not produce thickening effect, but leaks out from the seam in the form of liquid. When the pressure increases slightly, the thickening effect will be stimulated, and agglomeration particles will be generated to seal the seam pipe and reduce the leakage rate. When the pressure further increases beyond the bearing capacity of the sealing layer, the shear-thickening fluid is extruded out of the fracture in a plate form. The application of shear-thickening fluid in plugging field is expected to provide innovative solutions for plugging in fractured formation.
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BAI Jun, WANG Sheng, LAI Kun, XU Shiyi, ZHANG Jie, ZHANG Jie
2024,51(5):77-84, DOI: 10.12143/j.ztgc.2024.05.009
Abstract:
Under the dual influence of the extremization of drilling construction conditions and the industrial transformation brought about by the development of new-generation information technologies, the intelligence of drilling technology has become an inevitable trend in the development of drilling technology. Intelligent drilling, in line with the needs of the Fourth Industrial Revolution, utilizes the theories and methods of information technology to transform and enhance traditional drilling models and technical systems, achieving digital empowerment and digital transformation of drilling projects, thereby becoming the core driving force for the development of drilling technology. In this context, this paper focuses on the critical issue of intelligent rock mass recognition based on real-time drilling key parameters, providing a comprehensive overview of non-core sampling in-situ rock mass testing technology based on the drilling process. Finally, it offers an outlook on the intelligent development of drilling engineering. By reviewing the latest technologies and research progress in this field, a new recognition system for deep fusion of process-physical multimodal information during drilling is proposed, aiming to realize intelligent identification of rock and soil masses during the drilling process and improve the quality and efficiency of major infrastructure engineering investigation.
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CAO Zhicheng, CHEN Qiu, CUI Junyan, XIE Jingyu, ZHANG Weiqiang, JIANG Guosheng
2024,51(5):85-92, DOI: 10.12143/j.ztgc.2024.05.010
Abstract:
Hydraulic fracturing of hot dry rock(HDR) reservoirs to form a complex network of seams is essential for the construction of enhanced geothermal systems (EGS). In order to deeply understand the mechanism of hydraulic fracture extension in HDR reservoirs and reveal the influence of engineering and geological parameters on hydraulic fracture extension, in this paper, a HDR reservoir in the Gonghe Basin of Qinghai Province is taken as the research object, and based on the extended finite element method (XFEM) numerical simulation software ABAQUS, a field-scale HDR reservoir model is established to realize the thermo-hydro-mechanical coupling and to analyze the extension mechanism of the hydraulic fracture. The results show that: (1) In the normal fracture-type stress state, the crack undergoes a very obvious turning toward the Z-axis, in the strike-slip-type stress state, the crack expands mainly along the horizontal direction with a slight tendency to turn toward the Z-axis, and in the thrust-type stress state, the crack expands along the horizontal direction. (2) With the increase of elastic modulus crack initiation pressure decreases, the injection pressure of crack extension also decreases; the larger the elastic modulus the earlier the crack initiation time; the larger the Poisson ratio the greater the rupture pressure of hydraulic cracks; the rupture pressure as a whole shows a normal fracture-type>strike-slip-type>thrust-type. (3) The hydraulic fracture rupture pressure decreases with the increasing temperature, by about 2~3MPa or so, showing the same trend for all three stress states. This paper inriches the numerical simulation methods of hydraulic fracturing extention for HDR, the relavant research results can also provides technical supports for the prediction of the hydraulic fracturing extention and the influences affected by different perameters for HDR reservoirs.
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YE Huibing, ZHANG Suobang, HU Shenghua, HONG Yi, LIU Hangming, CHEN Weibao, LIANG Wubao, WAN Yuhang
2024,51(5):93-100, DOI: 10.12143/j.ztgc.2024.05.011
Abstract:
In the process of geothermal well exploitation, the transient high temperature caused by wellbore thermal fluid has a great impact on the mechanical properties of casing. This paper calculates the wellbore temperature and pressure field based on the steady-state heat conduction mathematical model of casing cement sheath formation rock, establishes the mathematical model for the mechanical evaluation of the interaction between middle-deep layer geothermal exploitation heat release and casing, and carries out the finite element calculation and experimental simulation of the influence of geothermal exploitation heat release on casing damage. The following conclusions are obtained: under the action of geothermal exploitation wellbore heat release, the casing has a large ovality, which weakens the collapse strength of the casing. When the internal pressure reaches 90MPa and the temperature in the casing is 30℃, the stress distribution on the inner wall is extremely uneven under the condition of different formation radial pressures, with the maximum difference of 560MPa. The stress is distributed in layers along the circumference, and a large range of stress concentration areas appear on the side subject to the formation radial pressure. With the increase of temperature, the displacement contour of casing changes little, and the maximum displacement increases slightly. When the temperature reaches 120℃, the casing is in a relatively harsh thermal environment. The increase of thermal stress leads to serious plastic deformation of the casing. At the same time, when the internal pressure increases to 120MPa, the inner wall of the casing is in a high stress state as a whole, which is more likely to lead to plastic failure of the wall
. The research results can provide guidance for the influence of heat release from geothermal exploitation on casing damage, and for the evaluation of casing stress environment, cement sheath strength, cement sheath micro gap width and other parameters. -
YUE Yongdong, TAN Chunliang, RAN Lingjie, ZHU Qiang, SU Xingtao
2024,51(5):101-107, DOI: 10.12143/j.ztgc.2024.05.012
Abstract:
The new round of strategic action for mineral exploration breakthrough has put forward higher requirements for drilling technology, and the shallow drilling technology is of great important for rapid verification in shallow cover area. Moreover, the multi-technique drilling technology can provide technical supports for green and efficient drilling in complex formations. Based on this requirement, the TGQ-200RC multi-technique automatic drill is developed. The overall schedule of the drill is formulated, and the main components of the drill are designed such as the multi-techniques power head, clamping and unscrewing device, 6-DOF drill rod swinging mechanism, vehicle-mounted integrated hydraulic rod storage, electro-hydraulic control and parameter monitoring system. Furthermore, the process of multi-mechanism collaborative action during automatic adding and removing drill rods was planned. The field test shows that the TGQ-200RC drilli has high drilling efficiency, good sampling quality, and features of multi-technique capability, mobility, automation, and digitization, the average time for a single automatic adding or removing of drill rods is about 90s. With the wireless remote control, it can achieve unmanned operation in the wellhead, effectively reducing labor intensity and improving operational safety. The TGQ-200RC multi-technique automatic drill can provide solid support for building a green, efficient and economical rapid verification drilling technology system, and useful reference for promoting the automated upgrading of domestic shallow drilling equipment.
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Study of drilling trajectory control for improving exploration accuracy in Xuefenghu structural belt
PAN Deyuan, HE Qianping, CAI Jun, ZHOU Chengjian, LAI Xiaobin
2024,51(5):108-114, DOI: 10.12143/j.ztgc.2024.05.013
Abstract:
With the increase of mineral resources exploration requirements in resent years, the depth of core drilling is rising and the encountered formations are more and more complex. In order to get the ore body in the target area accurately to realize the geological purposes, the requests to control the drilling trajectory is higher. In some working areas of the Xuefenghu structural belt, the dip angle is large with frequent alternation of the soft and hard layers and broken strata. The stratum deflection is serious during the practical construction. As the hole depth increases, the deviation from the ore body in the target area become larger, which affects the exploration accuracy and quality of the mineral resources. In this paper, through deeply analysing the formation deflection, the primary directional technology and the full-hole drilling tool technology are used in the ZK1001 drilling construction, which greatly improves the quality of the borehole and better controlling the drilling trajectory. Moreover, different core drilling tool combinations in different hole sections are tested, some opinions and suggestions for optimizing drilling tool assemblies are put foward, which provides technical reference of drilling trajectory control for coring hole in the working area.
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WANG Pengfei, GUO Yaoxin, ZHAI Yufeng, WANG Luzhao, YANG Fang, SONG Baojie, WANG Xiuhui
2024,51(5):115-121, DOI: 10.12143/j.ztgc.2024.05.014
Abstract:
The 3500m extra-deep hole (ZK001 hole) in Xiaoqinling gold mine field is located in Lingbao City, Henan Province. It is the first full-hole continuous coring extra-deep hole in the Xiaoqinling tectonic belt. The formation lithology of this hole is very complicated, with soft, hard and broken strata appearing interactively, and the wall protection is extremely difficult. There are many complicated conditions in drilling, such as hole wall collapse, block loss, hydration decomposition and pulping, high in-situ stress gouge shrinkage and micro-fracture water loss. In this paper, the flushing solution system is adjusted according to the formation changes. The upper part uses low solid phase flushing solution and the lower part uses low solid phase polymer anti-collapsing flushing solution system. The flushing solution formula is constantly optimized, the performance parameters are timely maintained and adjusted, and various problems in the hole are effectively solved. It provides a reliable flushing fluid technology for deep hole core drilling in Xiaoqinling area.
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CHENG Yuehan, ZHANG Tongde, ZHAO Zhan, FAN Lasheng, QIAN Feng
2024,51(5):122-129, DOI: 10.12143/j.ztgc.2024.05.015
Abstract:
Well Chuanmaye 1 is a shale gas parameter well deployed in Mabian, Sichuan. When drilling to 3437.58m, there were drilling complexs and sealed with cement after the first stage of treatment was unsuccessful. This article proposes a three hole open hole section sidetracking technology scheme for the complex situation of Well Chuanmaye 1. Based on the analysis of the factors affecting the sidetracking force near the drill bit position, combined with the actual situation, the sidetracking point, sidetracking method, and sidetracking tool combination were optimized, and the sidetracking technical measures were determined. After two rounds of sidetracking construction, the construction difficulties such as lack of adjacent well data, large sidetracking depth, complex formation prone to collapse, high temperature and formation strength in the sidetracking section, small inclination of the original wellbore, and limited sidetracking direction were overcome. Finally, a new wellbore was drilled and reached the predetermined depth. Provided reference for subsequent drilling construction and complex treatment in the region.
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2024,51(5):130-137, DOI: 10.12143/j.ztgc.2024.05.016
Abstract:
The accumulation of cuttings bed in the wellbore is one of the main factors restricting the safe and efficient drilling of horizontal wells. Research has shown that the spiral flow of drilling fluid in the annulus can effectively improve the efficiency of cutting removal. For this purpose, a rock debris removal tool capable of generating annular spiral flow was designed using CFD numerical simulation and experimental methods, and on-site application was also carried out. The results showed that the promoting effect of the V-shaped blade on cutting transport and disturbance ability on the cutting bed is stronger than that of the spiral and straight edged blades, making it the preferred structural form for generating annular spiral flow. There is an optimal range for the length of V-shaped blades, and the higher the blade height, the better the effect, while the number of blades has a weaker impact. The on-site application shows that the cutting removal tool meets the requirements of shale gas horizontal well operation in terms of strength, hardness, and blade wear resistance. The tool can destroy and remove the cutting bed while drilling. Combined with reaming operations on key sections where the cutting bed accumulates during the tripping process, it can effectively remove the stubborn large particle cuttings and improve the borehole cleaning effect.
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2024,51(5):138-144, DOI: 10.12143/j.ztgc.2024.05.017
Abstract:
The directional drill pipe in coal mine is subjected to bending, torsion, vibration, tension and other loads in the hole, and the fracture accident often occurs in the construction process. The main reason for the fracture of drill pipe is stress concentration. Based on the resistance strain measurement, this paper builds a full-size physical stress test platform for directional drill pipe, conducts tensile stress tests on drill pipe joints, and plots each experimental data into stress distribution curves. The results show that the stress of drill pipe pin is greater than that of drill pipe box, and the maximum stress of drill pipe pin and box is at the position of tooth 3. The correctness of the simulation model is verified by the stress distribution trend and the stress value of each tooth, and a method to verify the drill pipe simulation model is provided. The experimental data and stress distribution curve in this study provide reliable data support for the finite element simulation of drill pipe.
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TONG Zhaojun, LIU Heng, LUAN Baokun, QIAO Hongguo, JIANG Shan, ZHANG Hai, HAN Hailiang
2024,51(5):145-153, DOI: 10.12143/j.ztgc.2024.05.018
Abstract:
With the deepening of exploration and development of deep geological resources in China, deep mineral deposits have become the focus of geological prospecting work. In the process of deep prospecting and drilling, the problem of maintaining the straightness of the vertical well section in the high steep structure has been a major problem for drilling technicians, which seriously affects the exploration efficiency of deep mineral deposits. In the inclined section, the single bend bistable screw drill is the most commonly used anti-deviation and correction drill assembly. In this paper, a mechanical model of BHA is established based on the crossbar bending beam method and the principle of equilibrium trend. The influence law of each factor on the deviation correction ability is analyzed through the model, and the main control factor is determined by the orthogonal test design method. Finally, based on the theory of multi-objective optimization, a multi-objective optimization method for control parameters of fast drilling is established to obtain the optimal parameter combination. Based on the above research, a set of anti-skew and straightening optimization design method is developed to improve the drilling efficiency of the vertical well section of the high steep structure, and promote the efficient and low-cost drilling and development of deep mineral deposits.
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2024,51(5):154-162, DOI: 10.12143/j.ztgc.2024.05.019
Abstract:
The potential for uranium exploration in the Miaoershan area of Guangxi is enormous, but part of the formations are complex, with large thickness of water-sensitive and broken formations. During drilling construction, difficulties such as hole wall collapse and excessively large bore diameter occur frequently, leading to frequent accidents in the hole, which seriously affect the construction progress. Therefore, mineral composition and microscopic characteristics of water sensitive cores in the area were analyzed. The analysis results show that there are a large amount of clay minerals such as montmorillonite, kaolinite, hydromica, etc. in the water-sensitive formations, and the microcracks are developed with serious hydration expansion. To solve above problems, new materials with film forming and wall protecting functions were optimized through indoor evaluation experiments, and a drilling fluid system with good wall protection performance was further developed, which consists of 5% film-forming agent A, 3% film-forming agent B, 1.5% modified asphalt, 1% plugging agent while drilling, 1%sealing agent, 0.6% viscosifier, 0.2% coating agent. The API filtration loss of this drilling fluid is 5~8mL, and the relative expansion reduction rate reaches over 87%. This drilling fluid can effectively inhibit hydration expansion of the water-sensitive formations, and the wall protection effect is significant. This technology has been successfully applied in three boreholes in the Miaoershan area, smoothly drilling through water-sensitive formations without any problems such as core dispersion or hole wall collapse. Good application results have been achieved, and a film forming and wall protection drilling fluid technology has been preliminarily formed for water-sensitive formations in this area.
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SUN Sishi, LI Qiaobin, ZHONG Jiu’an, ZANG Peng
2024,51(5):163-168, DOI: 10.12143/j.ztgc.2024.05.020
Abstract:
The strata where the receiving end of air shaft shield is located in a subway section of the North China Plain is mainly silty clay, clayey silt and silty fine sand from top to bottom, with high underground water level and strong liquidity. After being reinforced by high-pressure rotary jet grouting at the receiving end, it was found that there is still a risk of water and sand inrush using horizontal exploration holes. The water and sand surging is easy to happen in the gap between the tunnel doors when the cutterhead of the shield tunneling machine break through the tunnel door. To ensure the shield machine smoothly passing out of the tunnel, the method of surface sleeve valve pipe grouting is adopted, and the GX modified silicon grouting material is used to consolidate the fine sand. Targeted reinforcement grouting is carried out in the receiving end of the interval air shaft within the water-rich fine sand formation. After treatment by such technology, the shield machine successfully excavated without any water or sand inrush.
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WANG Yuewei, WANG Wen, LIU Zhi, LIANG Jian, GAO Pengju, XUE Qianbing, QI Liqiang, LIANG Nan
2024,51(5):169-175, DOI: 10.12143/j.ztgc.2024.05.021
Abstract:
Among various drilling methods, hydraulic impact rotary drilling is characterized by its high efficiency, good quality, long cycle times, few accidents, and low costs. The hydraulic down-hole hammer is the technological core of hydraulic impact rotary drilling. This article organizes the structural features of various hydraulic down-hole hammers and explores the various drilling tools which derived from the combination of hydraulic down-hole hammers, wireline coring and downhole motor drilling tools. The typical application cases of this technology are briefly introduced, and the the future development direction and technical challenges are also summarized in order to popularizing the application and promoting the advancement of hydraulic impact rotary drilling technology.
Volume 51,2024 Issue 5
综述
支撑新一轮找矿突破战略行动专题
钻探技术与装备
工程实践与应用
地学科普
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Research on geothermal reservoir types and formation damage mechanism
LU Wei, WANG Jinliang, GU Chao, wanguangnan, ZHANG Han
Abstract:
The research on the formation damage mechanism of conventional petroleum reservoirs is relatively well-established, but there has been a lack of attention towards the type classification and formation damage mechanism of geothermal reservoirs. Currently, only two types of geothermal reservoirs - sandstone and karst - are recognized in the exploration and development of geothermal resources. Because of the unclear concept and type of reservoir, the incorrect drilling method, drilling fluid selection and wrong resource assessment are caused. Furthermore,there is no formation damage mechanism and damage assessment criteria, so that the geothermal well completion process is missing, and leads to small water volume, low temperature, and even abandonment.On the basis of a large number of geothermal engineering, this paper focuses on the research of geothermal reservoir types and formation damage mechanism, aiming at the outstanding problems and referring to the conventional petroleum reservoirs research results. Researches show that: (1) Geothermal reservoirs can be categorized into four types: porous, fissure, karst, and compound type; this categorization allows for more accurate drilling methods, selection of drilling fluids,and resource assessment.(2) The main modes of thermal reservoir damage are porosity blockage or failure in the structure; among these factors,damage caused by intrusion from drilling fluid as well as staticand dynamic pressure from liquid column within wells are inevitable common problems.
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Construction Technology Discussion of Ultra-long Horizontal Directional Pre-grouting Boreholes
WANG Yihong, YANG Zengzhi, SHAO Dongmei, WANG Zhaoyang, LI Longbiao, CHANG Xishun, CHEN Xiaojun
Abstract:
In the periphery of long and deeply buried tunnels of water conservancy projects, along the tunnel axis of a wide range of fracture zones and water-rich areas, the use of the ground more than 1,000 meters of horizontal directional drilling pre-grouting ahead of the management, to achieve a good effect of the surrounding rock reinforcement and gushing water blocking, is a successful attempt in the water conservancy industry. This paper introduces the successful experience of drilling ultra-long horizontal directional pre-grouting holes with screw drilling tools in a project, and discusses the difficulties of powder removal in ultra-long horizontal drilling holes, coping with the problem of “back pressure”, the interference of strong magnetic field with the drilling measurement system, the measures of green exploration, as well as the problems of insufficient adaptability of drilling rigs, low efficiency of hard-rock drilling, and the influence of grouting on drilling in operation, etc. and the measures to solve them. and measures to solve the problems. The project has 4 main holes and 6 branch holes, the longest hole is 1427m, and the drilling workload is 8737.89m. The implementation of the project proves that the current directional drilling technology has the ability to drill accurately over long distances, which can provide a guarantee for the pre-grouting and over-treatment of the complex strata of the ultra-long tunnels and the related drilling projects.
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Synthesis and evaluation of highly absorbent resin plugging agent for drilling in loose broken formation
YANG Kuancai, MENG Yanjie, Xu Quanwei, YANG Xianyu, CAI Jihua
Abstract:
There are many challenges in the process of geological drilling, among which the problem of leakage is particularly prominent, especially in fractured formations, which occurs more frequently. Therefore, it is of great practical significance to develop a drilling fluid system suitable for loose broken formation to maintain rapid drilling in broken formation. Through the [ ]optimization experiment, the inert material and formula suitable for plugging in the broken formation were determined. Meanwhile, Super-absorbent Polymer (SAP) was prepared by aqueous solution polymerization, and the particle size and concentration of SAP were optimized by non-permeable leakage meter. 0.3% 4-8 mesh SAP was the optimal choice. The formula of the drilling fluid system is: water +8% bentonite +0.5% sodium carbonate +0.1% xanthan gum +0.6%HV-CMC+2% walnut shell +1% mica sheet +2% special fiber +0.3% SAP of 4 ~ 8 mesh. The drilling fluid system can completely plug the sand filling bed of 10~20 mesh, the loss is 0 mL at 0.69MPa pressure, and has good rheological stability in the range of 0~60℃. The apparent viscosity is between 25~48 mPa·s, the dynamic shear force is 6~18 Pa, the API filtration loss is 7~11 mL, and the lubrication coefficient μ is 0.311.
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Progress of intermediate-depth and deep ice-core drilling projects in polar regions and its enlightenment for China
LI Yazhou, SUN Youhong, ZHANG Nan, FAN Xiaopeng, LI Bing, GONG Da
Abstract:
It is of great significance to carry out intermediate-depth and deep ice-core drilling projects in polar regions for obtaining paleoclimate information and predicting future ice sheet evolution. Since the 1960s, countries around the world have completed 26 intermediate-depth ice- core drilling projects and 14 deep ice-core drilling projects in polar regions. At present, there are still five deep ice core drilling projects in progress, which are Dome A, Beyond EPICA, MYIC, Dome Fuji and Hercules Dome. Russia is also planning a deep ice core drilling project at Dome B.At present, China has only implemented one intermediate-depth ice drilling project, and the depth of the deep ice-core drilling project has just broken through 800m. Compared with Europe, the United States, Japan, Russia, China has less drilling experience, low degree of equipment independence, and relatively backward technical level in the field of intermediate-depth and deep ice-core drilling technology. Therefore, China should actively develop deep ice-core electromechanical drill with independent intellectual property rights, accelerate the implementation of Dome A deep ice-core drilling project, carry out intermediate-depth ice-core drilling and ancient blue ice drilling projects, break through key technologies such as rapid ice drilling and directional ice-core drilling technology, so as to promote the development of China's polar ice-core drilling technology and improve its influence in the field of polar ice core science.
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Research on a Drill Rate Prediction Model Based on Feature Selection Integrated with Particle Swarm Optimization
XU Zhihua, JIANG Jie, ZHOU Changchun, LI Qian, REN Jun
Abstract:
Traditional drilling speed prediction models have often been constrained by issues such as high data dimensionality and feature correlation, resulting in limited efficiency and accuracy of drilling speed prediction. To address these issues, a drilling speed prediction algorithm model based on Particle Swarm Optimization (PSO) with integrated feature selection has been proposed in this paper. Based on data preprocessing, three key parameters, threshold_1, threshold_2, and threshold_3, have been chosen as optimization targets, and a fitness function has been constructed by combining historical data and the Particle Swarm Optimization algorithm, thereby establishing the drilling speed prediction model. Subsequently, the proposed drilling speed prediction method has been validated using actual drilling data and compared with traditional machine learning algorithm models. Experimental results have shown that the proposed Particle Swarm Optimization-based integrated feature selection algorithm has achieved higher efficiency and accuracy in feature selection. The accuracy of the four machine learning drilling speed prediction models trained using the optimized integrated feature selection results has been improved by 59%, 1%, 3%, and 1%, respectively, compared to before optimization, and by 24%, 2%, 4%, and 3%, respectively, compared to models trained using all features. This paper has provided an effective feature selection method for cases where too many feature parameters have been extracted in drilling engineering, and it offers significant guidance for the practical application of feature selection algorithms in the engineering field.
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Development and performance characterization of PVA modified PLA fiber composite geothermal temporary sealing cement
CUI Xiyue, TAN Huijing, CHEN Yao, ZHENG Yuntian, WANG Yuhao, YE You
Abstract:
Formations with developed fractures are more likely to receive better water supply, and severe leakage during drilling requires the use of cement for sealing, but this can easily cause reservoir damage problems. In this paper, a geothermal temporary plugging cement is developed based on degradable fibers, which has a low permeability during drilling, plays the role of wall protection and plugging, and partially degrades to provide a channel for the output of geothermal fluids after the completion of the well. Based on the preparation, modification and characterization of PVA-coated PLA fibers (PVA-PLA), the effects of the modified fibers on the performance of the cement paste and the performance of cemented cement stone before and after high-temperature hot-water immersion was investigated and the mechanism. The results showed that: the regulation of the degradation properties of polymer fibers can be achieved by coating, heat treatment and silane modification; the compressive strength of PVA-PLA fiber cementite at 60℃ was 19.8MPa at maximum, and the porosity was 28.88% at maximum after immersion at 90℃, which was most in line with the requirements of low-temperature plugging and high-temperature unplugging; the coating of PVA at 60℃ reduced the contact between PLA and cement matrix, and the PVA-PLA fiber cementite at 90℃ was more suitable to the requirements of low-temperature plugging and high-temperature unplugging. The PVA membrane dissolved and PLA exposed to cement alkaline environment was hydrolyzed and consumed during hot water immersion at 90℃, which resulted in the formation of more >200nm pores in the cement stone. The PVA-PLA fibers remain intact and plug with the cement stone at low temperature, and the fiber degradation at high temperature forms a channel inside the cement stone and unblocking, which can support the broken pore wall and at the same time, realize partial unblocking of geothermal wells under high temperature hydrothermal conditions.
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Application about "Inner Support Ring of Inclined Brace" in High and Steep Dangerous Rock Treatment Engineering
liuwu, Fan Jingui, Hao Long, ]Liu Yanpeng, Xu Linshan, Jin Shanshan
Abstract:
The dangerous rock mass at this disaster point is located in the foundation part under a small ancient pavilion,Under the premise of protecting ancient buildings,The difficulty of controlling dangerous rock mass increases obviously,in addition,The location of the dangerous rock mass is high and steep, and a top-down "inverted pyramidal collapse rock cavity" has been formed below it.The existence of this kind of rock cavity greatly restricts the choice of treatment methods.Second, at the foot of the steep rock face where the dangerous rock mass is located,It is the landscape path of "Shijingshan ancient construction Mountain characteristic landscape Park".The combination of these three factors greatly limits the choice of treatment methods for this dangerous rock mass. After comparing and selecting many schemes,Finally, it is decided to adopt the measures of "inner support ring of I-steel inclined brace" under the dangerous rock mass.After implementation and observation upon completion, It has a good effect on the protection and treatment of small ancient pavilion foundation.The author believes that for the dangerous rock treatment project under this special condition,
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Research on the Pick Arrangement Pattern of Rotary Drilling Buckets Based on Pick Cutting Test
maning, huyawei, xiezhiyong, xiaodangui
Abstract:
During the construction of rotary drilling rig, the efficiency of rock drilling is closely related to the pick arrangement of core barrel. The key pick arrangement parameters of core barrels are studied by using pick cutting test system. Three-dimensional load, crushing volume, deformation displacement, broken morphology and other data were collected during the test process. From multiple dimensions such as crushing specific power, cutting resistance, load fluctuation, and pick spin, the controlled variable method is applied to conduct pick cutting experiments, quantitatively evaluating the effects of cutting angle, tooth deviation angle, cutting sequence, tooth tip height difference, and tooth tip trajectory spacing on rock cutting. Research has shown that there is an optimal combination of tooth arrangement parameters that match the geological properties. Taking drilling into granite formations as an example, the optimal range of tooth arrangement parameters was determined, which are: cutting angle 68-72 °, tooth deviation angle 5-15 °, skip cutting, tooth tip height difference of about 3 mm, and tooth tip trajectory spacing of about 30 mm. According to the test results, the drilling efficiency is increased by 13.64% and the cost of unit footage is reduced by 39.13%. The research results are of great significance for guiding the arrangement of the core barrels, reducing the gear loss and improving the drilling efficiency.
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Stability study of open-pit slope rock mass based on Oriented core and OTV/ATV survey
Abstract:
The stability of the slope of an open-pit mine is mainly affected by geological structures such as faults and joint of rock mass. In order to identify the distribution characteristics of the rock mass structural, the Reflex ACT III tools were used to unify the core orientation of 4 geotechnical survey holes. However, the proportion of highly reliable core orientation data for each borehole only 8.05-34.29%, due to the rock mass fragmentation and joint development near the contact zone between granite intrusions and sedimentary rocks, which affects the accuracy of core orientation. Therefor, this article took OTV/ATV survey to obtain lithology and structural characteristics, relationships and direction data effectively and improve the accuracy of geological structure information data of core orientation, through high-resolution, continuous and oriented 360° borehole wall images. Based on this, failure mode of the open pit mine was studied by equatorial polar projection theory and dynamic analysis. According to the result, the main failure mode is wedge sliding failure, with a probability of 12.66%-34.99%, followed by plane sliding, with a probability of 3.40%-20.36%, which provides the foundation for open-pit mining slope control.
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Research progress on wellbore instability mechanics of deep stratified weak face reservoirs
Abstract:
Deep reservoir gas reserves are abundant. However, due to complex geological conditions, such as the development of holes and fissures, the existence of weak bedding surface and other factors, shaft wall instability has always hindered the safe and efficient exploitation of deep oil and gas reservoirs. A series of problems such as stuck drilling, well collapse and leakage caused by shaft wall instability will bring huge losses to the project. Therefore, it is very important to have a comprehensive understanding of the mechanism and research progress of borehole instability. In this paper, starting from the stability of borehole, the mechanical mechanism and development history are summarized. It is found that the development of weak bedding surface, multi-factor ground stress, rock physical and mechanical parameters, the existence of pore cracks and other factors are the main factors that lead to the weakening of mechanical strength and the instability of deep reservoir wall. For strata with weak bedding surface, the wellbore instability is more obvious, and the mechanical strength of rocks at different inclination angles is greatly different, and the rocks are more prone to hydration expansion along the bedding surface. Therefore, drilling engineering parameters and drilling fluid density should be reasonably optimized. This paper systematically summarizes the research of borehole stability mechanics and related aspects, in order to better understand the mechanical mechanism of deep reservoir borehole stability, and provide reference for practical production and engineering practice.
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Design of deepwater pressure simulation testing system based on KingView and PLC
LIU Xiaolin, GAO Jieyun, WANG Jiarui, CHEN Haowen
Abstract:
In deep-sea drilling, deepwater instruments’ water tightness and pressure resistance should be verified by pressure simulation testing system before launched. So deepwater pressure simulation testing system is often used. This article improves the traditional deepwater pressure simulation testing system, the improved system"s electrical control part is mainly composed of King View and PLC. The system uses PLC as the lower computer, and through its built-in A/D module, combined with pressure sensors, it can collect pressure signals. Users can set parameters and preset programs, and control the on-off of the pump and the valves through digital outputs, contactors, etc. The system provides auto-manual dual-mode. By combining the PLC serial port with the Bluetooth serial port transmission module, remote device display can be achieved. KingView was developed as the upper computer, to communicate with the lower computer via serial port based on Modbus RTU protocol, develops a human-machine interaction interface through configuration programming, realizes pressurization, pressure holding, and unloading setting for the entire process of pressure simulation testing, as well as monitoring the testing process, displaying pressure curves, and reporting forms. The deepwater pressure simulation testing system has the advantages of friendly Human-Machine interface, intuitive simulation monitoring, complete functions, reliable performance, convenient operation, safety, and scalability.
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Experimental Research on Drilling Parameters of Eccentric Percussion Rotary Drilling and Development of the Drill Bit Used for
Abstract:
Rotary percussion drilling is an important method of drilling and widely used in geological exploration. Traditionally in rotary percussion drilling application of impact pulse is centric,but not eccentric. Russian experts have put award fragmentation of rock by application of eccentric impact pulse in order to improve the result of the fragmentation. That is a new concept and an innovation. They have done experimental research on it. It has been proved, that in rotary percussion drilling by eccentric impact pules in rock noy only vertical normal stress are created、but also tangential shear stress created and it is beneficial to improve the result of rock fragmentation and rising of drilling rate. In drilling dolerite and marble at eccentricity E=1mm-2 mm the mechanical drilling rate and bit penetration per revolution are increased substantially in comparison with E=0 mm. Matching with the mentioned above the drill bit for eccentric rotary percussion drilling has been developed and the bit patent obtained, strengthening the result and role of the eccentric rotary percussion drilling further in geological exploration.
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Mechanical Characteristics of Flexible Shaft in Flexible Motor Load Transfer
GUO Qiang, ZHANG Delong, YANG Peng, WENG Wei, WU Shuo, JIN Bo
Abstract:
Flexure shaft is a key component for torque transfer between the joints of ultra-short radius flexible motor units. Aiming at the failure phenomena such as fracture of flexure shaft in the drilling process of ultra-short radius flexible motor, this paper carries out mechanical modelling and design strength checking of the internal flexure shaft of the flexible motor, uses finite element simulation to carry out stress analysis on the stress state of the flexure shaft in the torque transmission process of the flexible motor, and tests the mechanical properties of the flexible motor through indoor tests to analyse the mechanical properties of flexure shafts. The results show that the root and spline contact surfaces of the flexure shaft are the stress concentration areas in torque transmission, and the fatigue life of the flexure shaft can meet the requirements of continuous downhole operation. The finite element analysis and indoor tests show that the flexure shaft can transmit torque of 500N·m, which can realise the internal torque load transmission of the flexible motor under alternating bending and torsional stresses. This provides an important theoretical basis for the drilling process of ultra-short radius flexible motors in the development of horizontal wells, and provides a new type of technical means to improve the drilling length and drilling efficiency of the horizontal section of ultra-short radius horizontal wells.
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Efficient Drilling Technology for Oil and Gas survey in Sanmenxia Basin
zhao hongbo, zhang long, shen lina, zhang jiaodong, liu xufeng, li dayong, hu hao, meng xianglong, zhu disi
Abstract:
【Background】The Paleogene sedimentary thickness in the Lingbao Sag of the Sanmenxia Basin is large and continuously distributed, with developed dark mudstone. Through the deployment of drilling projects, new discoveries of oil and gas in small and medium-sized basins can be assisted. However, the geological environment for drilling in this type of reservoir is complex, with frequent sand and mudstone interlayers, which can easily cause engineering difficulties such as bit mud entrapment, wellbore collapse, block falling, coexisting risks of leakage, and difficulty in drilling. 【Research method】 Through the optimization of drilling tool combination and wellbore structure, research on drilling fluid technology in different sections, development of PDC irregular tooth drill bits, and research on the drilling process of "low speed+medium drilling pressure+screw+high-efficiency PDC drill bits", 【Research results】effectively solved the problems of wellbore stability and drill bit selection. In the actual drilling of YXD 1 well, the average mechanical drilling speed of comprehensive drilling reached 5.67 m/h, which shortened the drilling cycle by 10 days compared to the design. 【Conclusions and suggestions】Innovations have formed a "new, superior, and fast" drilling and completion technology system for sand and mudstone interlayers in the Sanmenxia Basin, including a mud pack drilling fluid technology system, a long open hole wellbore protection drilling fluid technology system, an efficient PDC shaped tooth drill bit acceleration technology for sand and mudstone interlayers, and a "two low and one high" variable density cement slurry cementing technology that can be promoted. This can provide useful reference for drilling engineering design and construction in similar regions.
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Study on Cement Slurry System in Ultra-high temperature well
高元, LI Xiaojiang, LIU Rengguang
Abstract:
Aiming at the strength of set cement with sand degradation leads to the annular seal failure at 200℃, rich silica-aluminum material with hydration activity was developed, and when the adding amount for 30% to70% of cement ,the compresssive strength of cement are stable at 200℃×20.7MPa×30d. Based on the rich Silica-aluminum material as a high temperature stabilizer, selecting matching additives, the rich silica-aluminum ultra-high temperature cement slurry was developed, the API water loss is less than 50 mL at 100~200℃, the thickening time can be adjustable between 150~500min, the comprehensive performance is good. Compressive strength of set cement cured for 10d, 60d, 120d, 180d under 200℃×20.7MPa are all greater than 26MPa, and high temperature strength decline was not observed. The ultrasonic strength curve shows that the strength of set cement grows steady within 600h. The SEM and XRD shows that, the rich silica-aluminum material participate in the cement hydration reaction, and eliminate the calcium hydroxide, and generate aluminum-oxide tetrahedron and silica-oxide tetrahedron inter-bonding three-dimensional network structure with good high temperature performance, and together with tobermolite calcium silicate bauxite to maintain the stability of the high temperature strength of cement stone. The cement slurry system has been applied in hot dry rock cementing for 1 well, and the cementing quality is good. As so far, the cement ring has been well sealed for 1000 days.
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Numerical Simulation Analysis and Optimization of Process Parameters in the Cementing Process of Gas Hydrate-bearing Sediments in Deep Water Oil and Gas Wells
WANG Xiaoyu, ZHENG Mingming, WU Shuang, YAN Shichun, MA Ting, TANG Chengxiang
Abstract:
The South China Sea has been confirmed to be rich in oil and gas resources as well as natural gas hydrate resources. However, hydrate-bearing formations are often encountered during the drilling of oil and gas wells. Cementing is a critical step in oil and gas development. In deepwater drilling, the heat released during cement hydration can potentially induce hydrate decomposition, compromising formation stability and even affecting cementing quality. This study utilized numerical simulation methods, focusing on the hydrate-bearing formation at the SH7 site in the Shenhu area of the South China Sea GMGS-1 project. A numerical model for cementing was established to analyze the issues caused by cement slurry invasion into hydrate-bearing formations and the impact of cementing process parameters. The study found that an increase in cement hydration heat release rate significantly advanced the onset of gas and water influx, as well as increased its volume. The cementing pressure differential had a minor impact on the influx phenomenon, but it suppressed the influx when exceeding a certain threshold. Prolonging the pressure maintenance period significantly delayed the initiation of influx and reduced its volume. Therefore, it is recommended in practical engineering to use low-heat cement, extend the pressure maintenance period, and avoid excessively high cementing pressure differentials in the early stages to minimize hydrate decomposition and mitigate the occurrence of influx. This research provides a theoretical foundation for the cementing of hydrate-bearing formations, which is of great significance for enhancing the safety and efficiency of cementing operations.
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Finite element numerical simulation analysis of packer-type expansion pipe
Liyunpeng, Yinfei, sunxiao, Fengjianyue, Liuyi, Chenzhiang, Zhengyunfei
Abstract:
The packer expansion tube technology has been developed for the hydrogeological exploration of wall protection and the repair of damaged well pipes. It has the characteristics of low cost and simple process. In order to make the packer meet the requirements of the expansion pipe, the expansion mechanism of the packer is improved. The packer is used to test the pipes with different properties. According to the test results, 316L stainless steel is selected as the expansion pipe. In order to study the relationship between the expansion pressure and the change of the length and thickness of the expansion tube during the two expansions of the packer-type expansion tube, the expansion process of the expansion tube with Φ219 mm and wall thickness of 4 mm was numerically simulated by Abaqus software to obtain the change of stress and strain during the expansion process, and field tests were conducted on the expansion tube with the same specifications. Then comparing the simulation results with the test results, it is concluded that the simulation results are basically the same as the actual demonstration results, indicating that the numerical simulation results can be used as a reference for the actual construction.
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Experimental study on the thermal characteristics of dry drilling of diamond coring bits
SHEN Lina, LI Chun, ZHAO Yi, LIU Hailong, WU Haixia, ZHANG Jianyuan
Abstract:
Dry drilling has little impact on the environment. In the absence of cooling medium, it can effectively solve the problem of borehole coring when drilling some water or drilling fluid reacts or produces new pollution, so this method is one of the important means of exoplanets sampling. However, exoplanets object drill bits were mostly alloy drill bits, which had certain limitations for drilling into hard rock formations. Diamond drilling is a relatively advanced rotary drilling technology, which is widely used in oil and gas exploration and geological exploration, and is a powerful tool for drilling hard rock formations. In this paper, the dry drilling tests of diamond drill bits were carried out for hard granite, and the influences of drilling parameters and bit types on the thermal characteristics during the drilling process is discussed. The results show that: (1) The heating rate of PDC drill bits is lower than that of conventional diamond coring bits, which is about 1/2 of that of impregnated diamond bits; (2) PDC coring bits can be a way for the dry drilling of granite under suitable process parameters; (3) The rotary speed has a great influence on the temperature rise of diamond bits in dry drilling, and it shows a nonlinear growth trend; (4)The cooling curves of drill bits in air show an exponential downward trend. During the cooling from 300°C to 100°C, the cooling rate ≥ 60°C/min. The research results can provide a basis for the scientific design and rational use of dry drilling bits.
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Research on dual liquid plugging method based on thixotropic slurry
龚浩宇, Ren peigang, Zhang furong, Ma di, Xie bingxi, Fan haijiao
Abstract:
Aiming at serious leakage problems such as crack type and karst cave type, a dual liquid method is proposed for plugging. Specifically, it is a new type of plugging technology that injects two or more fluids with different properties into the wellbore at the same time, and uses the thixotropy generated by the mixed fluid to seal the lost circulation layer. In order to study the plugging performance of mixed fluid and obtain the best plugging formula, organic gel solution is used to prepare cement slurry indoors, and mixed with Bantu slurry in different proportions. The thixotropy of mixed slurry is measured by hysteresis loop method to evaluate its plugging performance. The results show that when the dosage of organic gel is 0.08% bwoc, the cement slurry prepared by organic gel solution and 0.25% Bantu slurry are mixed at a ratio of 10:1.8, the slurry has the best plugging performance, and the compressive strength after curing can meet the requirements of on-site construction.Field application shows that the combination of cement slurry prepared with organic gel solution and bentonite slurry has good plugging effect.
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Development and Application of Impregnated Diamond Bit for Horizontal Directional Drilling in Hard Formation
Abstract:
Aiming at the low efficiency of horizontal directional drilling in hard formation, the self-sharpness of the bit was improved by the hard brittleness of FeCoCu pre-alloy matrix and the hard silicon carbide particle to weaken the matrix. The layered structure design is used to alternate the high and low wear resistance layers along the radial direction of the bit. The thickness of low wear resistance and high wear resistance were designed to be 1.0 ~1.5 mm and 2.5 ~3.5 mm respectively, to realize simultaneous wear of high wear resistance layers and low wear resistance layers and improve drilling efficiency. The bits have been successfully applied to horizontal directional drilling in hard potassium feldspar granite formation, using the combination of FeCoCu pre-alloy matrix and stratified matrix structure, with the average ROP of 0.8 ~1.5 m/h and the drilling life of 30 ~40 m. Compared with the ordinary concentric sharp tooth bit, the ROP has been increased by about double, and the drilling life has been increased by more than 30%.
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Long open hole and long-immersion formation drilling technology
Zhu Di-si, Meng Xiang-Long, Wang Sheng-jian, Wang Xiao-ming, Chen Zhao-ming, Chi Huan-peng, Zhao Hong-bo, Gao Yong-jin, Li Da-yong, Yue Wei-min
Abstract:
Well Xinsudi-2 is an oil and gas geological survey well deployed in the Xinjiang Tarim Basin. The well was drilled to 2468.50m with an open hole section of 2009.24m. After geological assessment, it was designed to be Deepen drilling to 3168m. This article takes the 500-600m well section as an example to analyze the wellbore stability. The wellbore is soaked in drilling fluid for a long time, which causes the water content of the wellbore to increase. The cohesion and internal friction angle of the mudstone and other strength indicators decrease, resulting in the wellbore not having Pressure-bearing capacity, slight disturbance will cause the well wall to become unstable. The project team adopted a new anti-pollution polymer anti-collapse drilling fluid system, a drilling tool assembly with a drill-while-drilling jar to relieve stuck conditions under complex well conditions, and the target layer was drilled using low drilling pressure\low rotational speed\low-displacement parameter combination drilling and other technical methods has solved a series of complex situations caused by long open-hole sections and long time soaked formations, ensured the smooth completion of the project and achieved the geological purpose, and accumulated the experience and technology of drilling long open hole and long-immersion formations.
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SStudy On the Design and Hydraulic Characteristics of the Submarine Mud Lift Pump
Qin Rulei, Gao Jieyun, Chen Haowen, He Guolei, Xu Benchong, Su Xianghui, Yin Guoyue
Abstract:
The mud lift pump, as the core functional unit of riserless mud recovery drilling, drives the cutting-bearing mud stored in the suction module to flow back to the drilling platform along the upward return pipeline. This paper takes centrifugal pumps as the research object, constructs a computational model of the pump through CFD-EDM, conducts full-scale flow field simulation, and studies the impeller design, flow field and particle transport distribution, and hydraulic performance tests of the sample pump. The research results show that the pump has good working characteristic indicators, and its hydraulic performance meets the design requirements, the pump can be applied to deep-sea riserless drilling operations. And it also shows that the design method and experimental process of the pump are reasonable and feasible.
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Study on Simulation Characteristics of Phase Change Materials for High Temperature Resistant Vacuum Flask
liu dan, chen jian yao, hou yue, he nan, LIU Jingtao, zhou shao wu
Abstract:
With the continuous improvement and expansion of the application scope of active magnetic measurement technology represented by SmartMag Drilling Target-Hitting Guide System, it will be more applied in high-temperature underground environments such as geothermal well development and deep-sea mineral resource exploration in the future. High temperature often becomes a bottleneck problem that restricts the normal operation of instruments.In order to further improve the temperature resistance performance of the SmartMag system, this article adopts passive thermal management method and uses finite element method to simulate the phase change heat storage characteristics of the vacuum flask. It explores the optimal coupling length of the heat absorbing body and compares the phase change materials with the best temperature control ability horizontally. It analyzes the changes in axial temperature and phase state of the heat absorbing body inside the vacuum flask over time.The results show that the optimal coupling lengths are 400mm for the upper absorber and 250mm for the lower absorber. After operating the insulation cylinder at 150 ℃ for 6 hours, the utilization rate of phase change latent heat of the upper absorber is 96.7%, and the utilization rate of phase change latent heat of the lower absorber is 70.5%. The minimum temperature of the circuit board is 63.48 ℃, and the temperature control effect of low melting paraffin is the best.