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| 1 | Crack stop holes in steel bridge decks:Drilling method and effects显示文摘Force analysis using a compact tension model, as recommended by ASTM, was carried out on a crack stop hole. The stress before, and after, drilling the hole was compared in terms of stress concentration and stress gradient. The optimum drilling location and diameter were studied through analysis of different locations and diameters. By analyzing the effects of flank holes and an additional hole, drilling advice was proposed and fatigue testing of the cracks in a steel bridge deck with a crack stop hole was conducted. The results show that the stress at the crack tip with a crack stop hole decreased, and the major principal stress around the hole was distributed accordingly. The optimum position of the crack stop hole centre was where the centre of the crack stop hole was situated behind the crack and the hole edge coincided with the crack tip. Therefore, hole diameters larger than 8 mm, or those weakening the section by 10%, were suggested as the best diameters. In terms of multi-hole crack stopping, a flank hole was not recommended. The optimum horizontal position of flank holes was at a distance of 1/4 of a single hole diameter from, and in front of, the single hole. Besides, the experiment showed that crack stop hole could only prevent cracks from growing and had no influence on crack growth rate. | 傅中秋 吉伯海 谢曙辉 刘天笳 | 2017 | Journal of Central South University2017，24，10： | 16 |
| 2 | 国外石油钻井软件的发展现状显示文摘在钻井工程设计软件方面,国外从20世纪80年代开始研究,目前已推出多种商业化的软件产品。这些钻井工程软件系列全、覆盖面广,经过长期现场应用改进,模型计算准确、运行稳定,用户认可程度高。文章详细阐述了Landmark、Drilling Office、Paradigm、DrillNET等几款主流钻井软件产品,以及部分针对特殊工艺的专业钻井软件的功能特点和特色技术,分析了我国钻井软件研发与国外的差距,指出开发具有自主知识产权的产品已势在必行,今后发展趋势应是信息集成一体化、三维可视化和钻井智能化。 | 张冬梅 周英操 蒋宏伟 赵庆 霍宗强 项德贵 连志龙 宋鹏 赵亦朋 周泊奇 王倩 | 2012 | 石油科技论坛2012，31，3： | 16 |
| 3 | Desorption-diffusion model and lost gas quantity estimation of coalbed methane from coal core under drilling fluid medium显示文摘The differences of coalbed methane(CBM) desorption-diffusion from coal drilling-core under various drilling fluid medium are not considered in the present calculating methods of lost CBM quantity,which leads possibly to the inaccuracy of CBM quantity in coal seam.Here we took the desorption of CBM from coal core under drilling fluid medium as a pressure-swing process,and based on the Langmuir equation and Fick-first law,established the desorption-diffusion model and numerical modeling method of lost gas(including free CBM) calculation in coal core under various drilling fluid mediums through physical simulation test and by considering comprehensively primary factors.The results showed that the physical simulated t-Qt curves can be rightly fitted by the numerical modeling data,which indicated the ultimate desorption quantity from the numerical modeling was adjacent to that from the physical simulation as a whole.It was found that the lost CBM quantity from the modeling method was generally higher than that from the direct method when lost time was relatively long.Thus,we sug-gest that it is necessary to emend the active China national standard through further investigation,since the lost CBM quantity from coal drilling-core was generally underestimated using the method in the current standard. | Geoff WANG | 2010 | Science China Earth Sciences2010，53，4： | 13 |
| 4 | Effect of hydrophilic silica nanoparticles on hydrate formation: Insight from the experimental study显示文摘Invasion of drilling fluid into natural gas hydrate deposits during drilling might damage the reservoir,induce hydrate dissociation and then cause wellbore instability and distortion of the data from well logging. Adding nanoparticles into drilling fluid is an effective method in reducing the invasion of drilling fluid and enhancing borehole stability. However, the addition of nanoparticles might also introduce hydrate formation risk in borehole because they can act as the 'seeds' for hydrate nucleation. This paper presents an experimental study of the effect of hydrophilic silica nanoparticle on gas hydrate formation in a dynamic methane/liquid-water system. In the experiment, the ultrapure water with and without1.0 wt%–6.0 wt% concentrations of silica nanoparticles, grain sizes of 20 and 50 nm, were pressurized by methane gas under varied conditions of temperature and pressure. The induction time, the gas consumption, and the average rate of gas consumption in the system were measured and compared to those in ultrapure water. The results show that a concentration of 4.0 wt% hydrophilic SiO_2 particles with a grain size of 50 nm has a relatively strong inhibition effect on hydrate formation when the initial experimental condition is 5.0 °C and 5.0 MPa. Compared to ultrapure water, the hydrophilic nano-SiO_2 fluid increases the induction time for hydrate formation by 194% and decreases the amount and average rate of hydrate formation by 10% and 17%, respectively. This inhibition effect may be attributed to the hydrophilicity,amount and aggregation of silica nanoparticle according to the results of water activity and zeta potential measurements. Our work also elucidates hydrophilic, instead of hydrophobic, nanoparticles can be added to the drilling fluid to maintain wellbore stability and to protect the hydrate reservoir from drilling mud damage, because they exhibit certain degree of hydrate inhibition which can reduce the risk of hydrate reformation and aggregation during gas hydrate or deep water drilling if their concentration can be controlled properly. | Ren Wang Tianle Liu Fulong Ning Wenjia Ou Ling Zhang Zhen Wang Li Peng Jiaxin Sun Zhichao Liu Tianshu Li Huicui Sun Guosheng Jiang | 2019 | Journal of Energy Chemistry2019，28，3： | 12 |
| 5 | An analytical model for estimating rock strength parameters from small-scale drilling data显示文摘The small-scale drilling technique can be a fast and reliable method to estimate rock strength parameters. It needs to link the operational drilling parameters and strength properties of rock. The parameters such as bit geometry, bit movement, contact frictions and crushed zone affect the estimated parameters.An analytical model considering operational drilling data and effective parameters can be used for these purposes. In this research, an analytical model was developed based on limit equilibrium of forces in a Tshaped drag bit considering the effective parameters such as bit geometry, crushed zone and contact frictions in drilling process. Based on the model, a method was used to estimate rock strength parameters such as cohesion, internal friction angle and uniaxial compressive strength of different rock types from operational drilling data. Some drilling tests were conducted by a portable and powerful drilling machine which was developed for this work. The obtained results for strength properties of different rock types from the drilling experiments based on the proposed model are in good agreement with the results of standard tests. Experimental results show that the contact friction between the cutting face and rock is close to that between bit end wearing face and rock due to the same bit material. In this case,the strength parameters, especially internal friction angle and cohesion, are estimated only by using a blunt bit drilling data and the bit bluntness does not affect the estimated results. | Sajjad Kalantari Alireza Baghbanan Hamid Hashemalhosseini | 2019 | Journal of Rock Mechanics and Geotechnical Engineering2019，11，1： | 9 |
| 6 | Numerical Analysis of Wellbore Instability in Gas Hydrate Formation During Deep-Water Drilling显示文摘Gas hydrate formation may be encountered during deep-water drilling because of the large amount and wide distribution of gas hydrates under the shallow seabed of the South China Sea. Hydrates are extremely sensitive to temperature and pressure changes, and drilling through gas hydrate formation may cause dissociation of hydrates, accompanied by changes in wellbore temperatures, pore pressures, and stress states, thereby leading to wellbore plastic yield and wellbore instability. Considering the coupling effect of seepage of drilling fluid into gas hydrate formation, heat conduction between drilling fluid and formation, hydrate dissociation, and transformation of the formation framework, this study established a multi-field coupling mathematical model of the wellbore in the hydrate formation. Furthermore, the influences of drilling fluid temperatures, densities, and soaking time on the instability of hydrate formation were calculated and analyzed. Results show that the greater the temperature difference between the drilling fluid and hydrate formation is, the faster the hydrate dissociates, the wider the plastic dissociation range is, and the greater the failure width becomes. When the temperature difference is greater than 7℃, the maximum rate of plastic deformation around the wellbore is more than 10%, which is along the direction of the minimum horizontal in-situ stress and associated with instability and damage on the surrounding rock. The hydrate dissociation is insensitive to the variation of drilling fluid density, thereby implying that the change of the density of drilling fluids has a minimal effect on the hydrate dissociation. Drilling fluids that are absorbed into the hydrate formation result in fast dissociation at the initial stage. As time elapses, the hydrate dissociation slows down, but the risk of wellbore instability is aggravated due to the prolonged submersion in drilling fluids. For the sake of the stability of the wellbore in deep-water drilling through hydrate formation, the drilling fluid with low temperatures should be given priority. The drilling process should be kept under balanced pressures, and the drilling time should be shortened. | ZHANG Huaiwen CHENG Yuanfang LI Qingchao YAN Chuanliang HAN Xiuting | 2018 | Journal of Ocean University of China2018，17，1： | 8 |
| 7 | Investigation on the interface damage in drilling low-stiffness CFRP/Ti stacks显示文摘Carbon fiber reinforced plastic and titanium alloy(CFRP/Ti) stacks have been widely used as aerospace structures because of their excellent combination of physical properties. Interface damage caused by interface gaps, significantly different from that of metal/metal stacks, is a common problem in the through-hole drilling of CFRP/Ti stacks with low stiffness. In this study, a force–deformation coupling model was developed to further examine the formation mechanism and the control method of interface damage. Firstly, the coupling model was built considering the interaction between the thrust force and the deformation. To solve this model, a numerical method was proposed in which specific cutting coefficients were calibrated using only the thrust force of rigid stacks. Secondly, drilling experiments were performed with different feed rates and bending stiffness. Experimental results indicate that interface damage mainly includes interlayer chips and surface damage of CFRP layers. The surface damage, which is irreparable, is caused by the rotary extension of metal chips along the interlayer gap. Thirdly, variations of the interface gap were calculated with the coupling model that had been verified by measured thrust forces. The damage area was found to have a linear dependence relation with the interlayer gap. However, in conditions of large gap sizes, the interface damage areas increased with the interlayer gap at high feed rates, while decreasing slightly at low feed rates. This phenomenon was satisfactorily explained by the presented model. Finally, a method was proposed to determine the appropriate pressure exceeding which no interlayer damage will occur. Additional drilling experiments proved the method effective. This study leads to further understanding of the forming mechanism of interlayer damage and of selecting appropriate parameters in drilling low-stiffness composite/metal stacks. | Bin LUO Kaifu ZHANG Shunuan LIU Hui CHENG Runxiao WANG | 2019 | Chinese Journal of Aeronautics2019，32，9： | 7 |
| 8 | Rock fracture density characterization using measurement while drilling(MWD) techniques显示文摘Accurate determination of rock mass properties is a critical part of open-pit mine planning activities to enable more prescriptive blast designs to achieve improved loading and hauling and downstream process efficiency. Better and more accurate blast practice that delivers enhanced outcomes(better fragmentation, improved diggability, less dilution, etc.) is a critical and fundamental element of being able to achieve an effective Mine-Mill approach at a mining operation. Based on previous work, it has been demonstrated that an accurate representation of the rock mass properties can be obtained from the analysis of variations in blasthole drill performance as derived from measurement while drilling(MWD) systems when using tricone bits. This paper further investigates how monitored rate of penetration,pulldown force, rotary torque, rotary speed and bailing air pressure responses can be used to determine the presence of open and partially open fractures having varying dip angles. Based on a correlation of geophysically measured fracture logs and monitored drill performance variables in the same blastholes, the results show that the latter responses can accurately determine open versus closed fractures. The results also identified that variations in rate of penetration and rotary torque show the most sensitivity in the presence of open fractures that intersect a vertical blasthole at near orthogonal angles. | Mohammad Babaei Khorzoughi Robert Hall Derek Apel | 2018 | International Journal of Mining Science and Technology2018，28，6： | 6 |
| 9 | Establishment and application of drilling sealing model in the spherical grouting mode based on the loosing-circle theory显示文摘There are quite a few studies that have been done on borehole sealing theory both domestically and internationally.The existing researches usually consider drilling of the surroundings as a dense homogeneous elastic body which does not meet the characteristics of real drilling of the fractured body.Based on the loosing-circle theory and analyses of the surrounding rock stress field,cracks and seepage fields,combined with Newtonian fluid spherical grouting model,we deduced the dynamic relationship between the seepage coefficient and rock or grouting parameters of the drilling sealing fluid mode of spherical fissure grouting.In this experiment,mucus was injected in the simulated coal seam and the permeability coefficient of the sealing body was calculated by using the model.To verify the validity of the model,the calculated sealing body number was compared with the extreme negative pressure that the sealing body could withstand.The theoretical model revealed the drilling sealing fluid mechanism,provided a method for the quantitative calculation of the drilling sealing fluid effect by grouting mode and a reference for the subsequent research of sealing mechanism. | Hao Zhiyong Lin Baiquan Gao Yabin Cheng Yanying | 2012 | International Journal of Mining Science and Technology2012，22，6： | 6 |
| 10 | Theoretical and experimental study of the pulling force of jet bits in radial drilling technology显示文摘Radial drilling technology,of which the jet bit is the key device,is a research focus in the field of oil drilling and production.This paper establishes mechanical equations for jet bits and analyzes the hydroseal of backward jets in bottom holes.Meanwhile this paper establishes a mechanical equation for a high pressure hose and analyzes the axial force distribution.Laboratory experiments indicate that the flow rate,the angle between the backward nozzle axis and the jet bit axis,and the hole diameter are the major influencing factors;the generation of the pulling force is mainly due to the inlet pressure of the jet bit;the backward jets can significantly increase not only the pulling force but also the stability of jet bits.The pulling force would reach 8,376 N under experimental conditions,which can steadily pull the high-pressure hose forward. | Ruichang Guo Gensheng Li Zhongwei Huang Shouceng Tian Xiaoning Zhang Wei Wu | 2009 | Petroleum Science2009，6，4： | 5 |
| 11 | Research on High-Speed Drilling Performances of Austenitic Stainless Steels显示文摘Due to specific properties arising from their structure (high ductility, high toughness,strong tenacious and low heat conductivity), the stainless steels have poor machinability. The drilling of the stainless steels becomes the machining difficulty for their serious work-hardening and abrasion of tools. In this paper, the austenitic stainless steel is used as the work-piece to perform the contrastive experiments with the TiN coated and TiAlN-coated high-speed steel drills. The cutting force, torque, cutting temperature, and the abrasion of drills and tool life are tested and analyzed in the process of high-speed drilling. Experiment results show the effect of drilling speed on cutting force, cutting temperature, and drill wear. TiAlN-coated drills demonstrate better performances in high speed drilling. The research results will be of great benefit in the selection of drills and in the control of tool wear in high speed drilling of stainless steels. | J.W.Zhong Y.P.Ma F.H.Sun M.Chen | 2004 | 上海交通大学学报2004，38，z2： | 5 |
| 12 | Exploring the deep South China Sea: Retrospects and prospects显示文摘Rapid developments of deep-sea researches in China over the past 20 years have promoted the South China Sea(SCS) into the international deep-sea frontiers. The 'three deep technologies', namely scientific drilling, long-term seafloor observation and deep submersible vehicles implemented successively in SCS studies helped to achieve a number of scientific breakthroughs. Over the 20 years, five international ocean drilling expeditions to the SCS recovered nearly 10 km of sediment cores from sites at 3–4 km water depths, and drilling into the magmatic basement at 6 sites shed light on the genesis of the SCS basin. Coupled with other deep-sea short core sediments from the SCS, these records demonstrate evidence that water and carbon cycling in the low latitude regions can directly respond to the orbital forcing, and subsequently nurture a new concept of lowlatitude forcing of climate changes, which challenges the classical wisdom of the overwhelming role played by the Arctic icesheet in climate changes. The exploration in the continent-ocean transition zone also reveals a number of specific features that characterize the SCS as a marginal basin formed at the subduction zone in the Western Pacific. The features include active magmatism and rapid rupture of lithosphere through the basin formation process, and imply that 'the SCS is not a mini-Atlantic'as they can be distinguished as 'plate-edge rifting' and 'inner-plate rifting' respectively, thus challenging the universality of the Atlantic model for passive margins. Many more discoveries can be assembled from long-term mooring observations and deep diving cruises in the deep SCS, such as the cyclonic nature of the deep-water circulation, deep-water sediment transport by contour currents and turbidites, manganese nodules, extinct hydrothermal vents, and cold-water coral forests. In addition,prominent progress achieved in microbiology and biogeochemistry includes the microbial carbon pump and the coupling of carbon and nitrogen cycles. Clearly, most achievements of the deep-sea explorations in the SCS over the last 20 years have always been of international scale and impact. However, the contributions from Chinese scientists are most prominent, particularly with the research activities undertaken from the major program 'Deep Sea Processes and Evolution of the South China Sea(2011–2018)' supported by the National Natural Science Foundation of China. | Pinxian WANG Zhimin JIAN | 2019 | Science China Earth Sciences2019，62，10： | 5 |
| 13 | Deep Continental Scientific Drilling Engineering Project in Songliao Basin:progress in Earth Science researcha显示文摘The Songke No.2 well (eastern hole)(referred to as Well SK-2),one of the 'two wells and four holes'of the Deep Continental Scientific Drilling Engineering Project in the Songliao Basin,is in Anda City, Heilongjiang Province,and was officially completed on May 26,2018.Tlie scientific goals of Well SK-2 cover four aspects:paleoclimate research,resource and energy exploration,primary geological research, and development of deep earth exploration techniques.Since the official commencement of drilling in 2014,the Well SK-2 scientific drilling engineering team has organized and implemented drilling for coring,in situ logging,chemical analysis of core elements,and deep structural exploration around the well.Currently,the following preliminary scientific research progress has been made:4334.81 m in situ core data has been obtained;the centimeter-level high-resolution characterization of the most complete and continuous Cretaceous continental strata ever unearthed has been completed,and the standard profile of continental strata has been initially established;the unconventional natural gas resources and basin-type hot dry rocks in the deep Songliao Basin were found to have good prospects for exploration and development;the climatic evolutionary history of the Cretaceous continental strata was rebuilt for the first time,covering hundreds of thousands to millions of years,and the major events of Cretaceous climate fluctuations have been discovered;all these reveal strong evidence for the subduction and aggregation of paleo-ocean plates,providing a theoretical basis for the re-recognition of the genesis of the Songliao Basin and for deep earth oil and gas exploration.The implementation of the Deep Continental Scientific Drilling Engineering Project in the Songliao Basin is of great significance for exploring the mysteries of the Earth and solving major problems such as those related to the deep energy environment.It is a solid step along the road of 'going deep into the Earth'. | He-sheng Hou Cheng-shan Wang Jiao-dong Zhang Feng Ma Wei Fu Pu-jun Wang Yong-jian Huang Chang-chun Zou You-feng Gao Yuan Gao Lai-ming Zhang Jin Yang Rui Guo | 2018 | China Geology2018，1，2： | 5 |
| 14 | Main technical innovations of Songke Well No.2 Drilling Project显示文摘Songke Well No.2,one of the main part of the scientific drilling project in Songliao Basin,which was drilled 7018 m and acquired the part of cores continuously from the Low Cretaceous to the Carboniferous and the Permian from the 2843 m deep,can be considered as the deepest continental drilling project in Asia.Aiming at the features of longer well sections,larger diameters and multiple spud-ins for coring of Songke Well No.2,this project broke through the 'coring in small diameter and reaming in large diameter'spud-in drilling-completion procedures which are always used in large-diameter-well coring for continental scientific drilling projects in domestic and overseas and the drilling method of short-singlecylinder roundtrip footage.At the same time,'coring in the same diameter and completing drilling at one single diameter'was achieved at all φ311 mm and φ216 mm coring sections of more than one thousand meters long,high-efficient operation with 'drilling long footage with drill tools combined in multicylinders'was achieved at deep coring section.Four world drilling records were created which include more than a thousand meters continuous coring at φ311 mm,and the footage per roundtrip footage at φ311 mm,φ216 mm and φ152 mm is all more than 30 m,all of these breakthroughs reduced at least 300 days for this project;moreover,considering the characteristics of formations that the geothermal gradient is high in the drilled sections and the inside-well temperature is over 240℃ after drilling completion,a formate-polymer water-based mud system was developed by compounding attapulgite and sodium bentonite and by adding independently developed high-temperature stabilizer,which can provide critical technical support for successful well completion at 7018 m in the super-high-temperature environment It is the first time that the water-based mud is operated at the working temperature higher than 240℃ in China;Besides,considering the high-quality requirement on cores imposed by the project,the method 'mechanical cored is charge'to discharge core nondestructively on the ground was worked out,and more than 4000 m scatheless cores were discharged out of the drill pipes while maintaining original stratum structures. | Yong-yi Zhu Wen-shi Wang Xiao-ming Wu Heng-chun Zhang Jie Xu Jia Yan Long-long Cao Heng-qian Ran Jin-chang Zhang | 2018 | China Geology2018，1，2： | 5 |
| 15 | Reliability-based maintenance scheduling of hydraulic system of rotary drilling machines显示文摘Hydraulic system has a critical and important role in drilling machines.Any failure in this system leads to problems in power system and machine operation.Since the failure cannot be prevented entirely,it is important to minimize its probability.Reliability is one of the most effcient and important method to study safe operation probability of hydraulic systems.In this research,the reliability of hydraulic system of four rotary drilling machines in Sarcheshmeh Copper Mine in Iran has been analyzed.The data analysis shows that the time between failures(TBF)of Machines A and C obey the Weibull(2P)and Weibull(3P)distribution,respectively.Also,the TBF of Machines B and D obey the lognormal distribution.With regard to reliability plots of hydraulic systems,preventive reliability-based maintenance time intervals for 80%reliability levels for machines in this system are 10 h. | Mohammad Javad Rahimdel Mohammad Ataei Reza Khalokakaei Seyed Hadi Hoseinie | 2013 | International Journal of Mining Science and Technology2013，23，5： | 4 |
| 16 | Use of drilling performance to improve rock-breakage efficiencies:A part of mine-to-mill optimization studies in a hard-rock mine显示文摘In a hard-rock mine,blasting is an important rock-breakage process that impacts energy consumption both in downstream comminution processes and mine productivity.Optimizing the blast fragmentation to improve rock-breakage efficiencies during crushing and grinding is key to mine-to-mill(MTM)optimization.This study explores the use of monitoring while drilling(MWD)data to achieve this goal.Representative penetration rates(PRs)were extracted from blastholes to estimate intact rock properties and predict the breakage efficiencies that directly affect comminution energy consumption.Two intact rock properties,tensile strength(TS)and Bond work index(BWI),were correlated with the PR data to predict these efficiencies in crushing and grinding,respectively.Because of the complexity of the raw MWD data and effects of various disturbances,the MWD data was preprocessed and normalized to achieve a representative PR value at each blasthole.This preprocessing entailed defining valid PR ranges from the MWD data that could eliminate the noise related to discontinuity features in the rock mass structure as well as errors in operator behaviors.The PR data was also normalized using the adjusted penetration rate(APR)to minimize the effects of mechanical factors such as drill feed force,torque,and rotational speed.To correlate the representative APR value with intact rock properties,TS and BWI,various laboratory experiments were conducted:drilling tests using a high-precision coring machine,Brazilian disc tests,and Bond grindability tests.Based on the results of these experiments,models were developed to predict rock-breakage efficiencies during crushing and grinding based on APR.The result of this study can be used to obtain blast energy designs that consider comminution energy consumption and efficiency in the downstream rock-breakage processes. | Junhyeok Park Kwangmin Kim | 2020 | International Journal of Mining Science and Technology2020，30，2： | 4 |
| 17 | Effect of aluminum content on machining characteristics of AZ31 and AZ91 magnesium alloys during drilling显示文摘Magnesium(Mg)and its alloys are now becoming the promising choice for various structural applications due to their low density and high specific strength compared with other light metals such as aluminum and its alloys.Among all Mg alloys,AZ(aluminum and zinc)series is the most widely used alloy system for various structural applications.But,machining of magnesium and its alloys involves certain issues due to their brittle nature and risk of inflammability unlike other nonferrous metals.Particularly,alloys with considerable amount of secondary phase may exhibit different machining characteristics during metal cutting operations.In the present study,two AZ series alloys AZ31 and AZ91 were selected and drilling operation was performed to assess the effect of the secondary phase amount and distribution on machining characteristics.Drilling operation was carried out at different sets of process parameters and cutting forces were obtained and the chips which have been produced during drilling were analyzed.From the results,it can be clearly understood that the presence of secondary phase(Mg_(17)Al_(12))has a significant influence on cutting forces.Increase in cutting speed has reduced the required cutting force and load fluctuations in all the cases. | B.Ratna Sunil K.V.Ganesh P.Pavan G.Vadapalli Ch Swarnalatha P.Swapna P.Bindukumar G.Pradeep Kumar Reddy | 2016 | Journal of Magnesium and Alloys2016，4，1： | 4 |
| 18 | Investigations into the coiled tubing partial underbalanced drilling (CT-PUBD)technique for drilling hard formations显示文摘To improve the rate of penetration(ROP) in drilling deep and hard formations, this paper proposes a new drilling method called coiled tubing partial underbalanced drilling(CT-PUBD). As a preliminary investigation into the new drilling method, this paper presents predictions of hole cleaning efficiency, drilling speed, cuttings migration and pressure loss in the drilling process with CT-PUBD. Based on numerical simulation and full-scale experimental studies, we conclude that using CT-PUBD, an underbalanced drilling condition can be achieved near the bit while maintaining wellbore safety at the same time. This condition can be achieved using a cuttings discharge device, a rotary packer and a backflow controller.According to the numerical simulations performed in this study, CT-PUBD can achieve high efficiency of hole cleaning.Along the cuttings migration process, the fluid velocities can reach the maximum values in the backflow holes. A full-scale laboratory experimental system was used to test the hydraulic characteristics and obtain the drilling performance of the new technology. The result shows that CT-PUBD significantly improves the ROP compared to the conventional drilling method. | Huai-Zhong Shi Zhao-Sheng Ji He-Qian Zhao Heng-Yu Song Zhen-Liang Chen | 2018 | Petroleum Science2018，15，4： | 4 |
| 19 | Seismic response to natural gas anomalies in crystalline rocks显示文摘According to the geological and seismic reflection data of the Chinese Continental Scientific Drilling (CCSD) main-hole (MH), and the anomalies of CH4, CO2, and He are correlated to the three-component seismic reflectors, especially in horizontal component profiles. However, the seismic response is dif-ficult to be explained as the porosity of crystalline rocks is only about 1% in well section where the gas anomalies occur. Seismic velocity measurement of the MH cores indicated that compared with wa-ter-saturated rock samples, seismic velocity (especially the S-wave) could be distinctly decreased by gas contained in tiny cracks despite of the low porosity, and then notable seismic response could be induced in gas-filled crystalline rocks. It could be predicated that if the porosity of certain rocks in the middle crust rose due to water-rock interaction and had natural gas filled, then there would be more probability for natural gas in top of the mid-crust to fill in the crystalline rocks with increased porosity. In such case, based on the decrease of Swave velocity in crystalline rocks, seismic method could be applied in the future to explore natural gas reservoirs in the middle crust. | YANG WenCai JIN ZhenMin YU ChangQing | 2008 | Science China Earth Sciences2008，51，12： | 4 |
| 20 | Optimized design of drilling and blasting operations in open pit mines under technical and economic uncertainties by system dynamic modelling显示文摘Drilling and blasting are the two most significant operations in open pit mines that play a crucial role in downstream stages. While previous research has focused on optimizing these operations as two separate parts or merely in a specific parameter, this paper proposes a system dynamic model(SDM) for drilling and blasting operations as an interactive system. In addition, some technical and economic uncertainties such as rock density, uniaxial compressive strength, bit life and operating costs are considered in this system to evaluate the different optimization results. For this purpose, Vensim simulation software is utilized as a powerful dynamic tool for both modelling and optimizing under deterministic and uncertain conditions. It is concluded that an integrated optimization as opposed to the deterministic approach can be efficiently achieved. This however is dependent on the parameters that are considered as uncertainties. | H.Abbaspour C.Drebenstedt M.Badroddin A.Maghaminik | 2018 | International Journal of Mining Science and Technology2018，28，6： | 4 |
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