Reliability analysis of retractable drill bit with air reverse circulation used for drilling while casing

Casing-while-drilling(CWD)with down the hole(DTH)hammer drilling technology has been widely used in unconsolidated formations,due to its advantages in protecting the borehole wall,excellent rock cuttings capacity,and fast penetration rate in hard rock.As an important component of the CWD system,the structure of the retractable drill bit needs not only to ensure to form stronger reverse circulation,but also to be expandable or retractable as needed,otherwise the drill bit cannot be lift and put down smoothly in the casing,and may lead to drilling accidents.This paper developed a new type of reverse circulation DTH hammer drill bit used for CWD drilling technology.The retractable performance of this type of drill bit is studied using ADAMS software.The results show that it is smoothly expandable and retractable as designed under the conditions of the weight of the bit(WOB)of 0.5–2.0 t and the rotation speed of 30–60 r/min.To investigate the reverse circulation effect of the drill bit,Fluent software was used to simulate the flow characteristic inside it.The simulation results indicated that it can form strong reverse circulation,and the entrainment ratio h can reach 9.5%.

Reverse Circulation DTH Hammer Drilling Technique

The technical characteristics and operational principal of the reverse circulation DTH hammer drilling technology is integrated introduced in this paper. Using simulation technology to assist the drilling tool design, the optimum designed DTH hammer gets stable performance, and the bit has reverse circulation ability, and further more, it has already developed serial products. The reverse circulation DTH hammer drilling technique has been fully applied in field such as the geological core exploration in complex strata, water well drilling, and large diameter rock embedding piles drilling in hard rock, and obviously, it is achieved favorable economic and social benefits.

Air flow calculation of reverse circulation drilling technique with air DTH hammer

Air DTH hammer has been successfully applied in minor-caliber solid mineral exploration,water-well drilling and other drilling areas. In order to expand the applications of the technology,the authors further studied the principle and analyzed the mechanism of reverse circulation drilling technique with air DTH hammer to get the perfect assembles of equipments by optimizing working parameters. No parameter seemed more important than the air volume because it could maintain the working performance stability. The minimum air volume is related to the parameters such as depth and pressure,which was calculated under the actual conditions. It was solved for the air injection flow tables of the air DTH Hammer working at the different pressures. According to the data tables,operators could adjust the air volume to meet the demand on this technique,which had a realistic guiding significance. So it could build up a set of systematic and complete hi-technique.

Calculation of flow distribution in air reverse circulation bit interior fluid field by simplifying air flow model

By simplifying the characters in the air reverse circulation bit interior fluid field, the authors used air dynamics and fluid mechanics to calculate the air distribution in the bit and obtained an equation of flow distribution with a unique resolution. This study will provide help for making certain the bit parameters of the bit structure effectively and study the air reverse circulation bit interior fluid field character deeply.

Finite Element Investigation of Flow Field Below Asymmetric Drill Bits for Reverse Circulation in Drilling Tight Oil and Gas Reservoirs

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.

Development of experimental apparatus about reverse circulation bit

A set of experimental apparatus on reverse circulation bit are developed, in order to lucubrate the mechanism of the new type reverse circulation bits, and the structure of the bits influencing the ability of taking core and carrying powder.Both the major structure of the equipment and the procession of experiment are described.

On measures to improveeffectiveness of pump suc-tionreverse circulation drillin,

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Optimization of reverse circulation bit based on field experiment

By field experiment in Sandaozhuang W-Mo mining area in Luanchuan of Henan Province, the authors analyzed the Experimental result of reverse circulation bit on the basis of different structures and obtained the following conclusion: the design parameter of reverse circulation bit, the number, diameter and angle of the spurt hole can influence on the reverse circulation effect. The bit with inner spurt hole is better obviously than that one without inner spurt hole in reverse circulation, one or two right and the best choice of inner spurt hole is that the diameter is Φ8, the angle is 30° dip up and the suitable number is two to three.

Numerical simulation and experimental research on air reverse circulation bit interior fluid territory

By using fluent fluid engineer emulator software to simulate negative pressure formed inside the injector added in the reverse-circulation sampling drilling bit, at six angles of 15, 30, 45, 60, 75 and 90 degrees. The pressure distributing nephogram and the corresponding numerical value gotten compared with the experiment data received by an injector with 6 angles designed by emulation the conclusion. It has been found that the two values are coincident essentially. The article shows that using emulator technology to design optimizely is credible and simple. The cost is low and the design cycle is short compared with the method through experience and test.

Repacking practice for G-3 engineering driller power unit with drive shaft of dual channel reverse circulation

In order to satisfy operating requirements for constant core drilling technology in reverse circulation with hollow-through DTH,the power unit of G-3 engineering driller was ameliorated. The new one with dual channel drive shaft, achieved the perfect assemble with transmission structure of the original power unit. It could interconvert according to need by using two sets of drive shafts with direct and reverse circulation. The repacked G-3 engineering driller carried on experiment in the field test in Luanchuan molybdenum mine of Henan, whose effect was very good.

Main coolant pump resistance influence on single phase water reverse flow in the inverted U-tubes under natural circulation

Based on nuclear power plant(NPP) best-estimate transient analysis with RELAP5 / MOD3 code,the reactor point kinetics model in RELAP5 / MOD3 code is replaced by the two-group,3-D space and time dependent neutron kinetic model,and two-fluid model is replaced by drift flux model.A coupled three-dimensional physics and thermal-hydrodynamics model is used to develop its corresponding computing code,thus simulating natural circulation of single-phase flow for the PWR.In this paper,we report the forward and reverse flow distribution in the inverted U-tubes of the steam generator(SG) under some typical operating conditions in the natural circulation case, and analyze the influence of main coolant pump resistance on the forward and reverse flow distribution.The calculation results show that,the pressure drop between SG inlet and outlet plenum decreases,and the SG inlet and outlet mass flow decrease with an increased main coolant pump resistance,but net mass flux of reverse flow in inverted U-tubes,and the ratio of mass flow in all reverse flow tubes to that of main coolant pipeline increase, meanwhile,the secondary steam load is invariable in this process.

钻井法凿井气-液-固耦合排渣流场及刀盘吸渣口优化

针对西部地区侏罗系地层煤矿立井钻井法施工中出现的气举反循环洗井排渣与钻进效率低下问题,以陕西可可盖煤矿中央回风立井ϕ4.2 m超前钻井为工程背景,基于CFD-DEM(计算流体力学和离散单元法耦合)研究方法,建立了气-液-固多相耦合排渣数值模型,揭示了排渣管内、井底流场的速度及压力分布规律,并基于自研的气举反循环排渣试验装置,采用PIV(粒子图像测速法)测试技术对流场分布的正确性进行验证;提出了优化刀盘吸渣口评判指标和方法,对吸渣口的数量、长径比、面积比、总面积占比进行优化,得到了超前钻头刀盘吸渣口布置的最佳方式和相关参数;讨论了钻头转速、注气量、风管没入比和泥浆黏度等主要因素对排渣流场的影响。研究结果表明:(1)排渣管内流体的运移以轴向流动为主,且途经注气端时,流速发生跳跃式剧增;井底流体的运移主要以水平流动为主,流体的垂直上返仅存在于吸渣口附近;井底流体的水平流动以切向流动为主,径向流动仅在吸渣口两侧较为明显,且远离吸渣口处,径流速度较小易产生岩屑沉积;(2)当刀盘吸渣口数量为2,长径比为0.4,面积比为1,总面积占比为1.94%时,吸渣口的布置方式最佳,且清渣率较现行吸渣口布置方式提高66%;(3)增大钻头转速可显著增强吸渣口的吸附作用,注气量、风管没入比与井底和排渣管内流体的轴向速度均呈正相关关系,低黏、低密度的泥浆易获取高流速,但携岩能力较差。研究结果可为破解侏罗系地层深大立井钻井法洗井排渣与钻进效率低下技术难题,提供有益的理论参考。

Detection of hepatocellular carcinoma cells in the peripheral blood with reverse--transcription polymerase chain reaction

In order to detect circulating cells of hepatocellular carcinoma(HCC) in the peripheral blood with reverse transcripition polymerase chain reaction (RT-PCR ), alpha-fetoprotein (AFP ) mRNA was tested in the blood samples of 113 cases of HCC and 69 controls (including 30 cases of liver cirrhosis, 9 cases of metastatic liver cancer and 30 normal subjects). 20/43 (46. 5% ) cases of HCC and 2/30 (6. 7% ) cases of liver cirrhosis are positive and the cases of nletastatic liver cancer and normal controls were negative for human AFP(hAFP) rnRNA. The presence of hAFP mRNA in the peripheral blood seems to be correlated with intrahepatic and distant nletastasls of HCC and portal vein thrombosis. It is concluded that the presence of hAFP mRNA in the peripheral hloocl is an indicator of circulating HCC cells and can be used to diagnose the rnetastasisof HCC through henlatogenous route and RT-PCR amplification of hAFP mRNA is a sensitive and specificprocedure for detecting circulating cells of HCC.

Synoptic-scale reversal of dipole surface temperature anomalies over East Asia and Central Siberia in November 2021

2021年11月,东亚与中西伯利亚经历了相反的冷暖异常转换,表现为“中西伯利亚偏冷,东亚偏暖”与“中西伯利亚偏暖,东亚偏冷”的交替出现.该偶极型气温异常的天气尺度反转伴随着大尺度大气环流异常的反转.进一步分析表明,东亚与中西伯利亚的偶极型气温异常反转是1979-2021年期间11月欧亚气温日变化的主导模态之一(发生概率超过56%).

数字经济背景下商贸流通企业的新零售转型路径研究

为了解决商贸流通企业在数字经济时代的发展困境并探析有效的新零售转型路径,从新零售的商业本质与技术特质入手,综合运用马克思主义政治经济学和西方经济学的相关理论进行逻辑分析,从数字经济对新零售的赋能和新零售对数字经济的反哺两个方面阐述了新零售与数字经济的耦合性关系,解析新零售转型的制约因素与困难,探索数字经济背景下商贸流通企业的新零售转型路径。研究发现,基于数字经济与新零售的高度耦合性,数字经济背景下的新零售商业借助数字技术介入商品内分工,通过根本改变供需对接模式而实现供需全链路的实时匹配,即能解决当前传统商贸流通企业的经营难题,又为提高商品流通效率、提振国民消费经济、建设现代流通系统提供了有力支撑。研究表明,身处数字经济时代的商贸流通企业应尽快转变旧有认知和商业逻辑,促成数字技术与商业信息的正循环,从以“货”为核心向以“人”为主轴转变;实际运营层面关注新零售的人才培育与梯队建设,革新组织架构,形成整套的数字化管理模式;同时注重自我职能开发与角色转变,在国内国际双循环相互促进的新发展格局中发挥更大的经济与社会价值,在更高层次实现新零售的全面转型升级。

内循环脱氮反应器处理炼化反渗透浓水的工程应用

在内循环(Internal circulation,IC)厌氧反应器结构基础上,设计了IC脱氮反应器,并研究了其在炼化反渗透浓水处理中的工程应用。结果表明,IC脱氮反应器启动快、运行稳定。在进水TN为18.7~39.0 mg/L,平均26.6 mg/L条件下,经IC脱氮反应器处理后出水TN为1.89~14.0 mg/L,平均4.65 mg/L,显著低于《陕西省黄河流域污水综合排放标准》(DB 61/224—2018)表1中B标准对于TN≤15 mg/L的排放要求;出水悬浮物质量浓度低,平均为18.6 mg/L;后续内循环曝气生物滤池出水COD平均为35.4 mg/L,可稳定控制在50 mg/L以下,综合处理效果好。同时,该设备占地面积小,工艺简单,水处理直接成本为1.36元/m3,具有显著的经济效益。

反循环气动潜孔锤进气端分流引射接头设计及结构参数分析

为解决反循环气动潜孔锤在钻进过程中岩石重复破碎及排渣效率低下的问题,笔者基于NGQ-320反循环气动潜孔锤设计了进气端分流引射接头。该接头可实现潜孔锤供气量的动态调节,其引射结构可以将部分压缩气体引入中心通道,对井底流场产生泵吸作用的同时改善冲击机构的动力供给;同时采用CFD技术研究了分流引射接头局部流场,分析了喷射孔夹角、喷射孔开口深度、喷射孔直径和喷射孔偏转角度等参数对中心通道抽吸性能的影响,确定了各项结构参数的较优取值。结果表明,分流引射接头在喷射孔开口深度320~330 mm、喷射孔夹角30°~35°、喷射孔直径12 mm、喷射孔偏转角11°~13°的情况下具有较好的抽吸性能。

基于力-构-能模型的钻井法凿井钻进参数设计思路与方法

竖井钻机钻井法是实现井筒机械化、无人化和智能化建设的重要技术之一。西部弱胶结地层钻井法凿井基岩破碎难、刀具损坏率高、糊齿和吸渣口堵塞等现象突出,高钻压、排渣不及时、泥包钻头易导致钻头憋死,而大扭矩钻进又发生了钻杆断裂、钻具掉落等事故,进尺缓慢和反复提钻维修、钻具打捞导致钻井工效极低,主要原因是钻头结构及其刀具布置不合理、钻进参数与岩石条件不匹配、破岩与排渣效率不协调。为解决弱胶结地层钻井法凿井“破不掉、排不出、进尺慢、能耗高”的现实难题,梳理了竖井钻机钻头破岩钻进技术现状及存在的问题,以“系统”和“过程”为基本观点,提出了基于力-构-能协调模型的钻进参数设计思路与方法,应重点围绕弱胶结地层钻井法凿井钻头结构设计及其力学特征、基于钻头滚刀运动轨迹的滚刀布置、基于气-液-固耦合流场的排渣效率优化以及基于能量转化机制的钻进参数优化4个主要方面开展研究,进而形成融合钻头结构、滚刀布置、洗井排渣和能量消耗等多因素的钻头高效钻进参数设计方法,为西部弱胶结地层钻井法凿井低能耗破岩、高效率排渣和破-排效率协调作业提供支撑,推动竖井钻机钻井法在西部弱胶结地层凿井中的应用。

市域线地铁车站超深围护结构施工关键技术研究

上海软土地区地下车站基坑越来越深,对超深围护地下连续墙的施工质量控制提出了新的挑战。在试成槽基础上,通过采取在深厚砂层成槽泥浆中加入改良泥浆,对超深槽段刷壁设备进行改进,超长钢筋笼双螺纹套筒连接以及气举反循环设备改进等施工措施,有效控制了地下连续墙在深厚砂土层中成槽的墙底沉渣厚度及整个地下连续墙的施工质量。优良的墙体完整性在基坑开挖阶段得到了有效的验证,积累的经验可为今后类似上海深厚砂层深基坑地下连续墙工程施工提供借鉴。

大直径竖井钻机压气反循环洗井效率模型试验研究

针对我国西部侏罗系地层钻井法凿井钻进与洗井效率低下问题,以西部可可盖煤矿中央回风立井钻井法凿井为研究背景,基于自主研发的压气反循环洗井试验装置,开展压气反循环洗井的相似模型试验研究,并采用正交试验和极差分析相结合的方法,探究钻头转速、风压和风管埋入系数等因素对压气反循环洗井效率的影响规律,最后提出了高效洗井的参数组合。研究结果表明:①通过正交试验和极差分析结果,得出洗井效率主要影响因素的敏感性排序为:钻头转速>风压>风管埋入系数;②基于模型试验结果,提出了洗井效率的评判指标清屑率和携岩率,二者均随钻头转速、风压的增大呈先大幅增长后小幅降低的趋势,且与风管埋入系数呈正相关关系;③洗井液排量与钻头转速呈负相关关系,钻屑排量随着钻头转速、风压的增大均呈现先增长后降低的趋势;④基于模型试验结果,提出了高效洗井参数:钻头转速为8.6 r/min;风压为1.44 MPa;风管埋入系数为0.837。研究结果可为提高西部侏罗系地层钻进与洗井效率低下问题提供有益参考。