The maximum internal tangential stress is a critical parameter for the design of the PDC (polycrystalline diamond compact) die that has been widely applied to offshore oil drilling. A new simple equation for the cal...The maximum internal tangential stress is a critical parameter for the design of the PDC (polycrystalline diamond compact) die that has been widely applied to offshore oil drilling. A new simple equation for the calculation of the stress is developed, and verified by the test data from Kingdream Corp. of China, the largest bit Company in China. An opti- mum method for the design of the PDC die is presented and demonstrated in detail, and software for the design and FEM analysis of the die is developed on the basis of the method. This software has been used in oil industry in recent years.展开更多
The lunar surface and its deep layers contain abundant resources and valuable information resources,the exploration and exploitation of which are important for the sustainable development of the human economy and soci...The lunar surface and its deep layers contain abundant resources and valuable information resources,the exploration and exploitation of which are important for the sustainable development of the human economy and society.Technological exploration and research in the field of deep space science,especially lunar-based exploration,is a scientific strategy that has been pursued in China and worldwide.Drilling and sampling are key to accurate exploration of the desirable characteristics of deep lunar resources.In this study,an in-situ condition preserved coring(ICP-Coring)and analysis system,which can be used to test drilling tools and develop effective sampling strategies,was designed.The key features of the system include:(1)capability to replicate the extreme temperature fluctuations of the lunar environment(-185 to 200℃)with intelligent temperature control;(2)ability to maintain a vacuum environment at a scale of 10^(-3) Pa,both under unloaded conditions within Ф580 mm×1000 mm test chamber,and under loaded conditions using Ф400 mm×800 mm lunar rock simulant;(3)application of axial pressures up to 4 MPa and confining pressures up to 3.5 MPa;(4)sample rotation at any angle with a maximum sampling length of 800 mm;and(5)multiple modes of rotary-percussive drilling,controlled by penetration speed and weight on bit(WOB).Experimental studies on the drilling characteristics in the lunar rock simulant-loaded state under different drill bit-percussive-vacuum environment configurations were conducted.The results show that the outgassing rate of the lunar soil simulant is greater than that of the lunar rock simulant and that a low-temperature environment contributes to a reduced vacuum of the lunar-based simulated environment.The rotary-percussive drilling method effectively shortens the sampling time.With increasing sampling depth,the temperature rise of the drilling tools tends to rapidly increase,followed by slow growth or steady fluctuations.The temperature rise energy accumulation of the drill bits under vacuum is more significant than that under atmospheric pressure,approximately 1.47 times higher.The real-time monitored drilling pressure,penetration speed and rotary torque during drilling serve as parameters for discriminating the drilling status.The results of this research can provide a scientific basis for returning samples from lunar rock in extreme lunar-based environments.展开更多
With the innovation and development of offshore oil drilling technology, drilling wells in deep waters areas have become an important activity for the development of new hydrocarbon reservoirs in this type of environm...With the innovation and development of offshore oil drilling technology, drilling wells in deep waters areas have become an important activity for the development of new hydrocarbon reservoirs in this type of environment. CNOOC (China National Offshore Oil Corporation) won the rights to exploit two unexplored deepwater blocks in the Gulf of Mexico, in a bid realized by the Mexican Government (CNH), in 2016. The challenge to combine the newest technology with the oil industry experienced knowledge to lead the exploration and development of these deep-water blocks in Mexico is around the corner. Therefore, the basic techniques for deep waters wells drilling and the main potential risks are expounded in this paper. A set of deep waters wells drilling processes and methodologies are previously designed, and a specific case is demonstrated next, which provides a referential model for deep waters wells drilling in the Gulf of Mexico.展开更多
Theories established from engineering fundamentals have been of great value in supporting the design and execution of drilling operations in gas drilling where gas is used as a drilling fluid.This work presents an ove...Theories established from engineering fundamentals have been of great value in supporting the design and execution of drilling operations in gas drilling where gas is used as a drilling fluid.This work presents an overview of new theories developed in recent years for special gas drilling operations including horizontal wells.These new theories are found in the areas of gas-mixture flow hydraulics in deviated and horizontal boreholes,hole cleaning of solids accumulation,hole cleaning of formation water,flow diverging for washout control,bit orifice optimization,and depression of formation water influx.This paper provides drilling engineers with updated mathematical models and methods for optimizing design to improve gas drilling performance.展开更多
One of the most important factors influencing on a tunnel blast efficiency is the proper design of blasting pattern. Among blasting parameters, blasthole diameter and tunnel face area are more significant so that any ...One of the most important factors influencing on a tunnel blast efficiency is the proper design of blasting pattern. Among blasting parameters, blasthole diameter and tunnel face area are more significant so that any change in these parameters could finally affect on specific charge and specific drilling. There are mainly two groups of methods for tunnel blast design categorized based on the parallel cuts and angular cuts. In this research, a software for tunnel blast design was developed to analyze the effect and sensitiveness of blasthole diameter and the tunnel face area on blasting results in different blast design models. Using the software, it is quickly possible to determine specific charge, specific drilling and number of blastholes for each blast design model. The relations between both of blasthole diameters and the tunnel face area with the above parameters in different blast design models were then investigated to yield a set of equations with the highest correlations to compare the methods. The results showed that angular method requires more blasthole numbers than parallel method in similar condition(blasthole diameter and tunnel face area). Moreover, the specific charge values yielded by the two methods are approximately the same and very close together.展开更多
High strength reinforced concrete drilling shaft linings have been adopted to solve the difficult problem of supporting coal drilling shafts penetrating through thick top soils. Through model experiments the stress an...High strength reinforced concrete drilling shaft linings have been adopted to solve the difficult problem of supporting coal drilling shafts penetrating through thick top soils. Through model experiments the stress and strength of such shaft linings are studied. The test results indicate that the load beating capacity of the shaft lining is very high and that the main factors affecting the load bearing capacity are the concrete strength, the ratio of lining thickness to inner radius and the reinforcement ratio. Based on the limit equilibrium conditions and the strength theory of concrete under multi-axial compressive stressed state, a formula for calculating the load-beating capacity of a high strength reinforced concrete shaft lining was obtained. Because the concrete in a shaft lining is in a multi-axial compressive stress state the compressive strength increases to a great extent compared to uni-axial loading. Based on experiment a formula for the gain factor in compressive strength was obtained: it can be used in the structural design of the shaft lining. These results have provided a basis for sound engineering practice when designing this kind of shaft lining structure.展开更多
With the continuous increase in vertical depths and horizontal displacements of directional wells,the difficulties of drilling operations continue to increase,and more accurate methods of drilling difficulty evaluatio...With the continuous increase in vertical depths and horizontal displacements of directional wells,the difficulties of drilling operations continue to increase,and more accurate methods of drilling difficulty evaluation are needed.In this paper,a drilling difficulty evaluation method is built by combining drilling limit model and expert evaluation.Firstly,the concept of drilling difficulty index is introduced,and the method to calculate drilling difficulty index is established.Next,the meanings of five drilling difficulty levels are explained and the optimization design method with drilling difficulty as the target is built.At last,the theoretical model is applied to the extended-reach drilling of the Liuhua oilfield in the South China Sea,in which drilling difficulties are evaluated and the relationship between drilling difficulty and development control radius is revealed.The results indicate that extended-reach drilling in the Liuhua oilfield is on the“normal”difficulty level on average,rotary drilling in 8_(1/2)-in.section is the most difficult,and the main constraint conditions are excessive torque and high friction.Through technology upgradation,the drilling difficulties are decreased,the development control radius increases from 6.6 to 11.4 km,and the maximum horizontalto-vertical ratio increases from 5.3 to 8.7.Then,the development wells in marginal oilfields and adjustment wells in old oilfields can be drilled on“normal”difficulty level.Therefore,technology upgradation,especially drilling rig upgradation,is the most important development direction for extended-reach drilling in the South China Sea.展开更多
Development of unconventional tight oil and gas reservoirs such as shale pays presents a huge challenge to the petroleum industry due to the naturally low permeability of shale formations and thus low productivity of ...Development of unconventional tight oil and gas reservoirs such as shale pays presents a huge challenge to the petroleum industry due to the naturally low permeability of shale formations and thus low productivity of oil and gas wells.Shale formations are also vulnerable to the contamination of the water in the drilling and completion fluids,which further reduces reservoir permeability.Although gas-drilling(drilling with gas)has been used to address the issue,several problems such as formation water influx,wellbore collapse,excessive gas volume requirement and hole cleaning in horizontal drilling,still hinder its application.A new technique called gas-lift drilling has recently been proposed to solve these problems,but the optimal design of drilling operation requires a thorough investigation of fluid flow field below the asymmetric drill bits for evaluating the fluid power needed to clean the bottom hole.Such an investigation is conducted in this work based on the Finite Element Method(FEM)implemented in an open source computational framework,FEniCS.Pressure and flow velocity fields were computed for three designs of drill bit face characterized by radial bit blades and one eccentric orifice of discharge.One of the designs is found superior over the other two because it generates relatively uniform flow velocities between blades and provides a balanced fluid power needed to clean all the bit teeth on each bit blade.To quantify the capability of borehole cleanup presented by three drill bit designs,the energy per unit volume is calculated in each region of drill bit and compared with the required value suggested by the literature.In addition,the developed FEM model under FEniCS framework provides engineers an accurate tool for optimizing drill bit design for efficiently gas-lift drilling unconventional tight oil and gas reservoirs.展开更多
The household drill is named 90 Degree, designed by Industrial Design Pilot Program Center(Hereinafter referred to as IDPPC) of Luxun Academy of Fine Arts(Hereinafter referred to as LAFA), which is the only national p...The household drill is named 90 Degree, designed by Industrial Design Pilot Program Center(Hereinafter referred to as IDPPC) of Luxun Academy of Fine Arts(Hereinafter referred to as LAFA), which is the only national pilot program center in Chinese industrial design field. 90 Degree is designed for home environment, it helps inexperience users, such as women and the elderly, complete the operation easily, and it makes sure that safe operation and assistance users solve the precise punching, location, storage trash and other operations. According to research among users who can understand or manipulate a drill, the designers find problems of users from the user central perspective, and then they integrate product innovative design methods to propose solutions. When the designers intend to design 90 Degree, they attempt using the user behavior record and analysis system, and start ergonomics study in subjects by double hands operation analysis, using gesture analysis, details of work analysis, time and motion study, etc; meanwhile taking advantages of user experience analysis, behavior intention analysis to do user subjective perceptual evaluation. The functions, structure, shape, color, material, details of 90 Degree should be consistent with the standard of usability evaluation. There are two characteristics in 90 Degree, the first one is a transparent cover installed in front of the drill, which can collect the dust, rubbish when drilling and keep the work environment clean. So it is applicable for households. When the transparent cover of the drill is removed, it also can be used as a normal hand drill; the second one is the shape of 90 Degree makes it and the operating surface fitting together, thus enhancing the stability in operation, so it is best for inexperienced users. When 90 Degree contacts with the operating surface, it can emit the laser ray which helps the user to punch accurately, and make array punch more easily. After obtaining the data, charts, creating Shadow observation by the designers, they make a comprehensive evaluation on research results; verification advantages of 90 Degree meet the requirement of usability, reducing operating failure rate; and increasing safety factors. 90 Degree, in 2011, wined German Red Dot Design Award, which had become a representative excellent design example to resolve several drilling difficulties. The designers introduce ergonomics theory into design practice, and use scientific program and methods to evaluate the products which is useful to the development and promotion of products.展开更多
Based on the mechanical model of an elastic rod,a new trajectory design method was established.The advantages of the suspender line trajectory in reducing drag and torsion were compared,and the main controlling factor...Based on the mechanical model of an elastic rod,a new trajectory design method was established.The advantages of the suspender line trajectory in reducing drag and torsion were compared,and the main controlling factors of drag and torque and their influence rules were analyzed.Research shows that the suspender line trajectory reduces drag and torque more effectively than the conventional trajectory in a certain parameter interval and has more controllable parameters than that of the catenary trajectory.The main factors affecting the drag reduction and torque reduction of the suspender line trajectory include the friction coefficient,vertical distance,horizontal distance,and deviation angle at the initial point in the suspended section.The larger the friction coefficient and deviation angle,the less the drag reduction and torque reduction.The suspender line trajectory has the best drag reduction effect when the horizontal and vertical distances are more than 3000 m and the ratio is close to 1.5.The drag in sliding drilling can be reduced up to 60%,and the torque in rotary drilling can be reduced by a maximum of 40%.Therefore,the trajectory design of the suspender line has unique application prospects in deep extended-reach wells.展开更多
Titanium alloys are widely used in the aerospace industries because of their excellent strength-to-weight ratio, high resistance to corrosion, high chemical reactivity and low thermal conductivity and ability to withs...Titanium alloys are widely used in the aerospace industries because of their excellent strength-to-weight ratio, high resistance to corrosion, high chemical reactivity and low thermal conductivity and ability to withstand high temperatures. However, these properties make titanium alloys difficult to machine. Drilling of titanium alloy may generate high temperature and high cutting forces. This paper is aimed at determining the suitable cutting parameters in the drilling of titanium alloys to minimize the cutting temperature and cutting forces. A finite element 3D model of the drilling process is simulated in this research. A combination of drilling speeds and feed rates are simulated to obtain the resulting responses of cutting force and temperature. The central composite design (CCD) is used to generate different combinations of cutting parameters to reduce the number of experiments and optimize the temperature and cutting force responses. Results show at the drilling speed of 5000 rpm with a feed rate of 0.1 mm/rev, temperature and cutting force significantly reduced.展开更多
文摘The maximum internal tangential stress is a critical parameter for the design of the PDC (polycrystalline diamond compact) die that has been widely applied to offshore oil drilling. A new simple equation for the calculation of the stress is developed, and verified by the test data from Kingdream Corp. of China, the largest bit Company in China. An opti- mum method for the design of the PDC die is presented and demonstrated in detail, and software for the design and FEM analysis of the die is developed on the basis of the method. This software has been used in oil industry in recent years.
基金supported by the National Natural Science Foundation of China(Nos.52225403,U2013603,52434004,and 52404365)the Program for Guangdong Introducing Innovative and Entrepreneurial Teams(No.2019ZT08G315)+2 种基金the Shenzhen National Science Fund for Distinguished Young Scholars(No.RCJC20210706091948015)the National Key Research and Development Program of China(2023YFF0615404)the Scientific Instrument Developing Project of Shenzhen University。
文摘The lunar surface and its deep layers contain abundant resources and valuable information resources,the exploration and exploitation of which are important for the sustainable development of the human economy and society.Technological exploration and research in the field of deep space science,especially lunar-based exploration,is a scientific strategy that has been pursued in China and worldwide.Drilling and sampling are key to accurate exploration of the desirable characteristics of deep lunar resources.In this study,an in-situ condition preserved coring(ICP-Coring)and analysis system,which can be used to test drilling tools and develop effective sampling strategies,was designed.The key features of the system include:(1)capability to replicate the extreme temperature fluctuations of the lunar environment(-185 to 200℃)with intelligent temperature control;(2)ability to maintain a vacuum environment at a scale of 10^(-3) Pa,both under unloaded conditions within Ф580 mm×1000 mm test chamber,and under loaded conditions using Ф400 mm×800 mm lunar rock simulant;(3)application of axial pressures up to 4 MPa and confining pressures up to 3.5 MPa;(4)sample rotation at any angle with a maximum sampling length of 800 mm;and(5)multiple modes of rotary-percussive drilling,controlled by penetration speed and weight on bit(WOB).Experimental studies on the drilling characteristics in the lunar rock simulant-loaded state under different drill bit-percussive-vacuum environment configurations were conducted.The results show that the outgassing rate of the lunar soil simulant is greater than that of the lunar rock simulant and that a low-temperature environment contributes to a reduced vacuum of the lunar-based simulated environment.The rotary-percussive drilling method effectively shortens the sampling time.With increasing sampling depth,the temperature rise of the drilling tools tends to rapidly increase,followed by slow growth or steady fluctuations.The temperature rise energy accumulation of the drill bits under vacuum is more significant than that under atmospheric pressure,approximately 1.47 times higher.The real-time monitored drilling pressure,penetration speed and rotary torque during drilling serve as parameters for discriminating the drilling status.The results of this research can provide a scientific basis for returning samples from lunar rock in extreme lunar-based environments.
文摘With the innovation and development of offshore oil drilling technology, drilling wells in deep waters areas have become an important activity for the development of new hydrocarbon reservoirs in this type of environment. CNOOC (China National Offshore Oil Corporation) won the rights to exploit two unexplored deepwater blocks in the Gulf of Mexico, in a bid realized by the Mexican Government (CNH), in 2016. The challenge to combine the newest technology with the oil industry experienced knowledge to lead the exploration and development of these deep-water blocks in Mexico is around the corner. Therefore, the basic techniques for deep waters wells drilling and the main potential risks are expounded in this paper. A set of deep waters wells drilling processes and methodologies are previously designed, and a specific case is demonstrated next, which provides a referential model for deep waters wells drilling in the Gulf of Mexico.
基金financially supported by the National Natural Science Foundation of China through Grants No. 51221003, No. 51134004 and No. 51274220
文摘Theories established from engineering fundamentals have been of great value in supporting the design and execution of drilling operations in gas drilling where gas is used as a drilling fluid.This work presents an overview of new theories developed in recent years for special gas drilling operations including horizontal wells.These new theories are found in the areas of gas-mixture flow hydraulics in deviated and horizontal boreholes,hole cleaning of solids accumulation,hole cleaning of formation water,flow diverging for washout control,bit orifice optimization,and depression of formation water influx.This paper provides drilling engineers with updated mathematical models and methods for optimizing design to improve gas drilling performance.
文摘One of the most important factors influencing on a tunnel blast efficiency is the proper design of blasting pattern. Among blasting parameters, blasthole diameter and tunnel face area are more significant so that any change in these parameters could finally affect on specific charge and specific drilling. There are mainly two groups of methods for tunnel blast design categorized based on the parallel cuts and angular cuts. In this research, a software for tunnel blast design was developed to analyze the effect and sensitiveness of blasthole diameter and the tunnel face area on blasting results in different blast design models. Using the software, it is quickly possible to determine specific charge, specific drilling and number of blastholes for each blast design model. The relations between both of blasthole diameters and the tunnel face area with the above parameters in different blast design models were then investigated to yield a set of equations with the highest correlations to compare the methods. The results showed that angular method requires more blasthole numbers than parallel method in similar condition(blasthole diameter and tunnel face area). Moreover, the specific charge values yielded by the two methods are approximately the same and very close together.
基金Project 050440502 supported by the Natural Science Foundation of Anhui Province
文摘High strength reinforced concrete drilling shaft linings have been adopted to solve the difficult problem of supporting coal drilling shafts penetrating through thick top soils. Through model experiments the stress and strength of such shaft linings are studied. The test results indicate that the load beating capacity of the shaft lining is very high and that the main factors affecting the load bearing capacity are the concrete strength, the ratio of lining thickness to inner radius and the reinforcement ratio. Based on the limit equilibrium conditions and the strength theory of concrete under multi-axial compressive stressed state, a formula for calculating the load-beating capacity of a high strength reinforced concrete shaft lining was obtained. Because the concrete in a shaft lining is in a multi-axial compressive stress state the compressive strength increases to a great extent compared to uni-axial loading. Based on experiment a formula for the gain factor in compressive strength was obtained: it can be used in the structural design of the shaft lining. These results have provided a basis for sound engineering practice when designing this kind of shaft lining structure.
基金the financial support from the Natural Science Foundation of China(Grant Nos.51904317 and 51821092)Science Foundation of China University of Petroleum,Beijing(Grant No.ZX20180414)other projects(ZLZX2020-0107-01)
文摘With the continuous increase in vertical depths and horizontal displacements of directional wells,the difficulties of drilling operations continue to increase,and more accurate methods of drilling difficulty evaluation are needed.In this paper,a drilling difficulty evaluation method is built by combining drilling limit model and expert evaluation.Firstly,the concept of drilling difficulty index is introduced,and the method to calculate drilling difficulty index is established.Next,the meanings of five drilling difficulty levels are explained and the optimization design method with drilling difficulty as the target is built.At last,the theoretical model is applied to the extended-reach drilling of the Liuhua oilfield in the South China Sea,in which drilling difficulties are evaluated and the relationship between drilling difficulty and development control radius is revealed.The results indicate that extended-reach drilling in the Liuhua oilfield is on the“normal”difficulty level on average,rotary drilling in 8_(1/2)-in.section is the most difficult,and the main constraint conditions are excessive torque and high friction.Through technology upgradation,the drilling difficulties are decreased,the development control radius increases from 6.6 to 11.4 km,and the maximum horizontalto-vertical ratio increases from 5.3 to 8.7.Then,the development wells in marginal oilfields and adjustment wells in old oilfields can be drilled on“normal”difficulty level.Therefore,technology upgradation,especially drilling rig upgradation,is the most important development direction for extended-reach drilling in the South China Sea.
基金This research was supported by the Open Fund(PLN201704)of the China State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation at the Southwest Petroleum University and the China National Natural Science Foundation Founding Nos.51874252,51534006 and 51674044.This research was also supported by the China Scholarship Council Founding No.201808510219.
文摘Development of unconventional tight oil and gas reservoirs such as shale pays presents a huge challenge to the petroleum industry due to the naturally low permeability of shale formations and thus low productivity of oil and gas wells.Shale formations are also vulnerable to the contamination of the water in the drilling and completion fluids,which further reduces reservoir permeability.Although gas-drilling(drilling with gas)has been used to address the issue,several problems such as formation water influx,wellbore collapse,excessive gas volume requirement and hole cleaning in horizontal drilling,still hinder its application.A new technique called gas-lift drilling has recently been proposed to solve these problems,but the optimal design of drilling operation requires a thorough investigation of fluid flow field below the asymmetric drill bits for evaluating the fluid power needed to clean the bottom hole.Such an investigation is conducted in this work based on the Finite Element Method(FEM)implemented in an open source computational framework,FEniCS.Pressure and flow velocity fields were computed for three designs of drill bit face characterized by radial bit blades and one eccentric orifice of discharge.One of the designs is found superior over the other two because it generates relatively uniform flow velocities between blades and provides a balanced fluid power needed to clean all the bit teeth on each bit blade.To quantify the capability of borehole cleanup presented by three drill bit designs,the energy per unit volume is calculated in each region of drill bit and compared with the required value suggested by the literature.In addition,the developed FEM model under FEniCS framework provides engineers an accurate tool for optimizing drill bit design for efficiently gas-lift drilling unconventional tight oil and gas reservoirs.
文摘The household drill is named 90 Degree, designed by Industrial Design Pilot Program Center(Hereinafter referred to as IDPPC) of Luxun Academy of Fine Arts(Hereinafter referred to as LAFA), which is the only national pilot program center in Chinese industrial design field. 90 Degree is designed for home environment, it helps inexperience users, such as women and the elderly, complete the operation easily, and it makes sure that safe operation and assistance users solve the precise punching, location, storage trash and other operations. According to research among users who can understand or manipulate a drill, the designers find problems of users from the user central perspective, and then they integrate product innovative design methods to propose solutions. When the designers intend to design 90 Degree, they attempt using the user behavior record and analysis system, and start ergonomics study in subjects by double hands operation analysis, using gesture analysis, details of work analysis, time and motion study, etc; meanwhile taking advantages of user experience analysis, behavior intention analysis to do user subjective perceptual evaluation. The functions, structure, shape, color, material, details of 90 Degree should be consistent with the standard of usability evaluation. There are two characteristics in 90 Degree, the first one is a transparent cover installed in front of the drill, which can collect the dust, rubbish when drilling and keep the work environment clean. So it is applicable for households. When the transparent cover of the drill is removed, it also can be used as a normal hand drill; the second one is the shape of 90 Degree makes it and the operating surface fitting together, thus enhancing the stability in operation, so it is best for inexperienced users. When 90 Degree contacts with the operating surface, it can emit the laser ray which helps the user to punch accurately, and make array punch more easily. After obtaining the data, charts, creating Shadow observation by the designers, they make a comprehensive evaluation on research results; verification advantages of 90 Degree meet the requirement of usability, reducing operating failure rate; and increasing safety factors. 90 Degree, in 2011, wined German Red Dot Design Award, which had become a representative excellent design example to resolve several drilling difficulties. The designers introduce ergonomics theory into design practice, and use scientific program and methods to evaluate the products which is useful to the development and promotion of products.
基金Supported by the National Science and Technology Major Project(2016ZX05060-014)PetroChina Major Science and Technology Project(ZD2019-183-005)。
文摘Based on the mechanical model of an elastic rod,a new trajectory design method was established.The advantages of the suspender line trajectory in reducing drag and torsion were compared,and the main controlling factors of drag and torque and their influence rules were analyzed.Research shows that the suspender line trajectory reduces drag and torque more effectively than the conventional trajectory in a certain parameter interval and has more controllable parameters than that of the catenary trajectory.The main factors affecting the drag reduction and torque reduction of the suspender line trajectory include the friction coefficient,vertical distance,horizontal distance,and deviation angle at the initial point in the suspended section.The larger the friction coefficient and deviation angle,the less the drag reduction and torque reduction.The suspender line trajectory has the best drag reduction effect when the horizontal and vertical distances are more than 3000 m and the ratio is close to 1.5.The drag in sliding drilling can be reduced up to 60%,and the torque in rotary drilling can be reduced by a maximum of 40%.Therefore,the trajectory design of the suspender line has unique application prospects in deep extended-reach wells.
文摘Titanium alloys are widely used in the aerospace industries because of their excellent strength-to-weight ratio, high resistance to corrosion, high chemical reactivity and low thermal conductivity and ability to withstand high temperatures. However, these properties make titanium alloys difficult to machine. Drilling of titanium alloy may generate high temperature and high cutting forces. This paper is aimed at determining the suitable cutting parameters in the drilling of titanium alloys to minimize the cutting temperature and cutting forces. A finite element 3D model of the drilling process is simulated in this research. A combination of drilling speeds and feed rates are simulated to obtain the resulting responses of cutting force and temperature. The central composite design (CCD) is used to generate different combinations of cutting parameters to reduce the number of experiments and optimize the temperature and cutting force responses. Results show at the drilling speed of 5000 rpm with a feed rate of 0.1 mm/rev, temperature and cutting force significantly reduced.