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Abstract:This paper outlines the development history and current status of the drilling techniques， states the roles of drilling techniques for national economy and humans well-being life development. The drilling technique progress keeping up with times and also its undertakings combining itself characteristic with a dependence of geological science and engineering are analyzed and discussed. The reality and feasibility of the AI and green drilling techniques are expounded. The notions to the undertaking and mission of the drilling techniques used the geological science and engineering by way of high efficiency， low-energy consumption， reliability and environment friendly are presented in the paper. As the other sciences and technologies development， the drilling techniques will have to continuously develop， which are practical technologies， and must develop in accordance with practical and realistic， scientific regular patterns and better accomplishment of the mission as a development direction.

Abstract:In view of the coring problem for the China-led IODP349、367、368/368X voyage， through analyzing the coring data， the coring tools and factors affecting the core recovery， core quality and cored efficiency in sedimentary rock and hard rock are researched， the causes and degree of the influence factors such as lithology， technical tools and external environment etc. which affect the ocean drilling coring are classified and summarized. The corresponding improvement measures are put forward.

Abstract:Natural gas hydrate is an efficient and clean energy， which is widely distributed in the sedimentary strata in the South China Sea. China has successfully carried out two trial productions in 2017 and 2020 respectively. However， due to the special occurrence conditions of marine natural gas hydrate， there are still some problems with single well trial production， such as small production range and short time for high and stable production. In order to improve the exploitation range of hydrate， the two-dimensional hydraulic fracturing numerical model is studied based on cohesive units. Through simulation， the half length and width of cracks of the two models 100m×100m and 20m×20m are compared. It is concluded that at the injection pressure of 30MPa， the half length of the crack is 6m for both models， and the maximum width is 5.8mm and 5.5mm respectively. The more accurate experimental results can be obtained by constructing a larger model. Moreover， the variation law of fracture width with injection time is studied. With the continuous increase of injection pressure and injection volume， the initial fracture width increases rapidly， and then the fracture propagates “step by step” under the action of in-situ stress and injection fluid pressure. The research has been successfully applied in the hydraulic fracturing model analysis of unconventional energy reservoirs such as shale gas， coalbed methane， and provides some technical guidance for marine natural gas hydrate reservoir hydraulic fracturing .

Abstract:To provide guidance for structural design and optimization of the functional sub in the drill string， the model of the mud pulser sub in Type 675 instrument string is simplified and the finite element analysis model is created in the case of the extreme working condition under the combined load of compression， bend and torsion. Considering the structural characteristics of the mud pulser sub in Type 675 instrument string， different mesh division methods are adopted for different sections of the mud pulser sub. Fixtures are added on both sides of the model for composite loading， while equivalent loading is applied for the bend load in the combination of compression， bend and torsion load by calculating the maximum deflection under the limit dogleg. The simulation results show that under the combined load of compression， bend and torsion， the stress concentration phenomenon mainly occurs in the drill collar and the electronic framework， and weak positions such as openings， grooves. Based on the analysis results， suggestion is put forward on the structural improvement of the mud pulser sub in 675 instrument string. The analysis method and design experience presented in this paper can provide reference for the design and optimization of the functional sub of the same kind.

Abstract:Block B of Wenchang 13-2 Oilfield is located in Pearl River Mouth Basin in the west of the South China Sea， and belongs to the offshore marginal small oil field. With the limitation of the number of slots and the rig capacity， and after comprehensive evaluation and in consideration of the actual development needs of Wenchang 13-2 Oilfield， three sections of ?339.7 mm flush joint casing were simultaneously run in ?914.4 mm conductor for the first time so as to realize the drilling and completion job of three wells independently from one slot. Taking the drilling of the B20， B22 and B23 wells from the slot as example， this paper systematically introduces the key triple hole splitter wellhead technology， including design principles， slot selection， directional well trajectory design， casing program design， surface casing running， surface casing cementing， etc. These key technologies have been successfully applied in Wenchang 13-2 Oilfield， providing reference and suggestions for improving the utilization rate of slots while effectively reducing the construction cost of offshore works in offshore oil and gas development.

Abstract:In geological drilling and oil and gas drilling， PDC bits have been used widely with good technical and economic results. However， PDC bits are often abnormally worn， and even broken， which influences their further popularization and application. Russian drillers studied this problem， and suggested that new generation PDC cutting elements be used to design a new structure bit. Some progress has been made with considerable technical and economic results. Therefore it has definite reference value for Chinese drillers.

Abstract:Regarding to the technical problems of loose phosphogypsum hole wall collapse， dispersion of phosphogypsum encountering water， calcium contamination of drilling fluid and difficulty in drilling trajectory control during horizontal hole drilling in phosphogypsum formation， the research on drilling fluid technology was carried out indoors with analysis of the requirements of horizontal hole drilling in phosphogypsum formation for the performance of drilling fluid. The calcium-based film-forming environment-friendly drilling fluid was developed and successfully applied to horizontal hole drilling at a depository of phosphogypsum tailings in Guizhou. Laboratory test and field application results indicate that the system has good resistance to calcium intrusion， low filtration loss， and relatively stable rheological properties. A relatively strong protective film can be formed on the core surface， which can effectively prevent the hole wall collapse and protect core. In addition， the system consisting of non-toxic and biodegradable materials has good environment protection performance.

Abstract:According to the geological needs， XY-6B drill was used to drill a scientific experimental hole with design depth of 535m， and completion depth 540m at ?133mm in the Qipanjing coal mine area， Inner Mongolia. After drilling， geophysical exploration was needed. In order to reduce the shielding of the steel casing to the instrument signal in the drilling hole， PVC-U casing of ?90mm diameter was run into the drilling hole. A lot of preparatory work was done before setting the PVC-U casing， mainly including the diameter parameter design of the drilling hole， modification of PVC-U casing connection mode， use of the guide cone head to prevent the wear and jamming of PVC-U casing during running， processing the screen pipe to balance the buoyancy of drilling mud. As a result， the PVC-U casing was successfully run into the scientific experimental drilling hole， ensuring the smooth completion of a series of scientific experiments.

Abstract:The spiral conveyor is an important component of the rotary system of the horizontal spiral centrifuge. As the only irregular rotary part， it will rotate at a high speed with the rotary system of the centrifuge. Therefore， the dynamic balance precision of the spiral conveyor will have an important impact on the service life of the whole machine. At the same time， because of the particularity of the structure of the spiral conveyor， the selection and implementation of dynamic balancing technology has some limitations and difficulties， which will affect the precision of dynamic balancing. Based on the theoretical analysis of the dynamic balancing effect of the spiral conveyor， the key factors affecting the dynamic balancing effect include the rotor structure， rotation radius and speed， etc.； and in combination with the dynamic balance test process， an optimized dynamic balance process is proposed， mainly including the dynamic balancing machine calibration， benchmarking， selection of counterweight position and the weighting method of residual unbalance， so as to reduce the residual unbalance of the spiral propeller， improve the precision of dynamic balance. Finally， through the monitoring and comparison of the temperature and vibration of the bearing seat of the centrifuge， it is proved that the process can effectively reduce the vibration of the whole centrifuge in working and improve the service life of the bearing.

Abstract:In view of multiple requirements such as efficient drilling， rapid movement， safety and reliability due to large volume of core drilling operations， the XYT-1500 reinforced mounting trailer is designed for core drills. The trailer adopts the full trailer traction mode， the hydraulic system is equipped with an independent hydraulic pump station， and the jack leg oil cylinder is designed with a mechanical lead screw lock which works with the hydraulic lock to provide double guarantee， and the drilling tower has three states of transportation， drilling and putting-down to provide convenience for long-distance transportation and exploration drilling activities. The overall design of the XYT-1500 enhanced core drill trailer improves the reliability， advancement， economics and safety of spindle type core drills， and achieves the desired purpose.

Abstract:Sonic drill rig is high-end soil sampling equipment. The hydraulic top-drive head of the drill rig generates high-frequency exciting forces to drive the drilling tool to overcome the resistance of shallow formation so as to make the formation around the drilling tool liquefied locally， and then quickly obtain high-quality undisturbed samples from formation. Based on the main design parameters of the 50m sonic drill rig， the open hydraulic system was selected to simplify the oil circuit structure of the system through analysis of the hydraulic system design of the drill rig， The hydraulic system adopted the control plan of the main hydraulic circuit and the auxiliary hydraulic circuit， where the main hydraulic circuit drives the vibration， rotation and feeding of the top head， and crawler walking； the auxiliary hydraulic circuit drives the leveling of jack legs， putting up and putting down， and sliding of the mast. The parameters of the hydraulic system were designed and calculated with the working pressure of the hydraulic system of the drill rig selected as 21MPa， and the total flow of the main hydraulic circuit calculated as 320L/min. Therefore， the engine was determined. Then the hydraulic system was installed and debugged， and the drill rig was tested. On this basis， the sampling application and promotion of the drill rig， includes sampling with large diameter double-layered tube and split-tube and samling in complex formation， was carried out with good sampling results. The hydraulic system of the drilling rig is stable， safe and reliable， with beautiful hydraulic line layout， flexible and convenient operation， which can meet the requirements of engineering application.

Abstract:With regard to the challenges of high friction， drag force， etc. during drilling directional and horizontal wells， ??127 hydraulic oscillation friction reduction tool was developed， which is able to effectively reduce the friction force between the drill string and the wellbore or inner wall of casing， improve weight on bit transfer， extend the length of directional and horizontal sections， and increase the rate of penetration. The mechanism of hydraulic oscillation antifriction drilling technology is introduced. The main parts of the tool are analyzed， and the operating principle is studied. The feasibility and the vibration stability of the tool were verified by numerical simulation， laboratory test and field test. The results showed that the performance of the device was reliable， and the hydraulic pulse frequency， pressure fluctuation amplitude and axial vibration displacement increased with flow rates. The results can provide references for research and development of related drilling tools and technologies for friction reduction， ROP improvement， etc.

Abstract:The torsional impactor which can increase drilling rate and efficieny has seen wide use in oil and gas drilling industry. But hot dry rock drilling is quite different, where many difficulties such as high temperature, high pressure,hard rock, strong abrasiveness,deep and ultra-deep wells, are encountered. Specific design has been made on the torsional impactor in regard to these issues and trial use was conducted. A series of drilling tests were conducted on the torsional impactor with different drilling tool combinations in hard-extremely hard rock strata during two drilling trips to study its influence on drilling efficiency.The test results show that the torsional impactor can eliminate the lateral vibration of PDM caused by centrifugal inertia force， which verifies the feasibility of the combined application of the torsional impactor and PDM. ROP increased by 29.59% from the well section where the torsional impactor was not used.In addition， the roller cone bit had higher drilling advantages over the PDC bit in the combined drilling mode of the torsional impactor+PDM+the rotary table in terms of the rock fragmentation mechanism and the formation adaptability. The test results can provide theoretical basis for both the study of the matching between the torsional impactor and the cone bit and that for the coupling between the torsional impactor and PDM.

Abstract:In view of the problems with the existing cuttings flow measurement system， such as incomplete cuttings dumping in the actual working process， the risk of borehole cleanness， wellbore stability， for which the specific evaluation method has not been formed， this paper analyzes the factors affecting horizontal well borehole cleanness， and puts forward the technical scheme for cuttings flow measurement based on cuttings sweeping， solving the problem of incomplete dumping of rock cuttings in the previous process of rock cuttings flow measurement with reduction of the manual cleaning frequency. Based on the return rate of rock cuttings， the quantitative monitoring method of wellbore cleanness and wellbore stability has been established， and the risk monitoring and evaluation method of wellbore cleanness and wellbore stability formed. Through the field application test， the risk of wellbore uncleanness and wellbore instability has been successfully warned， which proves that the method established in this paper can be applied to the field construction.

Abstract:Well JZ04 is a geothermal exploration well deployed by China Geological Survey in Jizhong Depression， North China. The designed depth of the well is 4000m with the completion depth of 4016.63m at 215.9mm diameter. In view of susceptible collapse， leakage and sticking due to large diameters of the first and second well sections， research were made on the drilling assembly and the fluid formula. The coring technology was studied to resolve the problem of low core recovery. The drilling experience can provide guidance for subsequent work. In addition， the thickness， temperature， lithology， permeability， water yield and other parameters of the deep thermal reservoir in the area were obtained by analyzing the physical core data， logging data and pumping test data， so as to provide basic data for exposing the Cenozoic and Meso-Neoproterozoic carbonate strata， and investigating the carbonate reservoir distribution and deep geothermal resource evaluation in the central and southern Gaoyang Low Uplift.

Abstract:The DTH hammer drill bit used for casing while drilling is the main tool of rock breaking and it is one of the important components of air reverse circulation drilling tools. It is widely used in geological hazard control projects. During the drilling process， the drill bit is subjected to alternating impact load， which is prone to stress concentration and fatigue failure. The stress waves generated by the piston collision with the bit propagate to the contact surface of the bit and rock， and cause the superposition of stress waves， which increases the stress on the bit. In order to ensure the normal operation of the drill bit， the strength analysis of FGQ-600 large-diameter DTH hammer drill bit under impact load is carried out by the Finite Element Software. The results show that the von-mise stress increases with impact energy. The maximum equivalent stress on the bit is 808.9MPa at the impact energy of 2500J of the DTH hammer， which is less than the material yield strength and meets the strength requirements. When tripping， the stress on the pin decreases with the increase of its diameter. The maximum stress on the 40mm pin is 383.66MPa， which is less than the material yield strength of 785MPa and meets the strength requirements.The pin appears plastic deformation at the diameter of 16mm； thus， it is recommended that the diameter of the suspension pin should not be less than 20mm.

Abstract:Multi-branch horizontal well grouting technology has been widely used in coal mine water hazard control due to its low construction cost， low environmental pollution and good water isolation effect. However， the coal seam floor generally is featured of complex conditions such as fracture development， thin target layers， and aggregation of fracture zones， often leading to problems such as mud leakage， difficulty in in-seam drilling， and easy sticking through the fractures during drilling operations and affecting the effect of grouting treatment seriously. In view of these problems， taking a coal mine in Anhui as an example， based on the analysis of its geological features， this paper studies directional wellbore trajectory design， selection of directional equipment and control of wellbore trajectory. Directional drilling and geo-steering technology were combined and successfully applied to the advance grouting treatment project with multi-branch horizontal wells. The field application showed that the technology improved the accuracy of wellbore trajectory control， ensured the target layer intersection rate， and had good application effect.

Abstract:To date， the commonly used BIM software lacks foundation pit engineering related families， making it difficult for designers to create complex foundation pit models. Based on Autodesk Revit software， this paper supplements and develops Revit families related to foundation pit engineering， and tries to provide convenience for designers to apply BIM technology in foundation pit engineering. The foreign family of foundation pit engineering is constructed， the design and creation of foreign family models are carried out， and a plan is proposed for model construction and construction process simulation for various stages of foundation pit engineering . Relying on the actual project， the families developed in this paper are used to create the foundation pit support model， and the feasibility of the modeling scheme is verified. Finally， the simulation of the foundation pit construction process is realized via the Fuzor software. The result shows that BIM technology can be better applied to foundation pit engineering by the developed Revit families.

Abstract:In view of the collapse of the trench wall and the failure of conventional plugging materials such as cement in the construction of diaphragm walls in water-rich sand and gravel formations， single factor experiment was used to analyze the influence of the gel forming agent （anionic polyacrylamide）， the crosslinking agent （chromium crosslinking agent）， the reinforcing agent and clay on the properties of polymer gel （gelation time， viscosity， strength and stability） for shallow plugging； and the optimum formulation was obtained by orthogonal test. In addition， the formation mechanism of the gel material was also analyzed. The results show that the reinforcing agent can link the gel-forming agent in gel， and further enhance the strength and stability of gel. Clay can also shorten the cross-linking time and enhance the gel strength， but clay is not conducive to the stability of the slurry. The final optimized formula is： 15% chromium crosslinking agent+5% gelling agent+8% reinforcing agent+7.5% clay. Its performance can meet the plugging requirements of shallow diaphragm walls.

Abstract:This paper studies the influence of different boundaries on the conventional triaxial simulation test of granite. The particle flow code（PFC3D） was used to generate the granite model based on the method of grain?-based model. At the same time， the discrete element triaxial test models were established respectively for the three boundaries of the rigid membrane， flexible membrane and finite element （“Shell”） by using the FDM?-DEM coupling modeling technology. Test results shows that compared with the “Shell” boundary， the rigid boundary will increase the probability of stress concentration in the sample and affect the failure form of rock samples， the flexible membrane boundary will cause the actual confining pressure of the rock sample to be larger than the target confining pressure during the triaxial loading process， and significantly increase the residual strength of the rock sample. However， the confining pressure of the rock sample under the shell boundary is stable， and the probability of stress concentration is the smallest. Therefore， the shell boundary should be used in the triaxial test of discrete element simulation.