【作者】 范黎明；

【导师】 殷琨；

【作者基本信息】 吉林大学 ， 地质工程， 2011， 博士

【摘要】 前几十年,人们对易进入地区和浅表层资源勘探开发的程度较高,资源已近枯竭；而对边远、高原、复杂条件及深部地层资源勘探不足,有待于更大的投入和开发。现今世界高度重视资源的勘探与开发,投资矿业,加速勘探和开发,已成为世界(包括中国)的经济热点。先进的钻孔设备,领先的钻孔技术,应是当前较长时期内急需研究和发展的对象。贯通式潜孔锤反循环连续取心钻探技术集潜孔锤高效碎岩、流体介质全孔反循环、不停钻连续获取岩矿心三种先进钻探工艺于一体,效率达到常规钻探方法的6-10倍,全孔反循环对孔壁无冲刷,不停钻连续地排出岩矿心,不用水,不受季节寒冷、地层破碎或冻结、岩石坚硬、缺水等因素的影响。我国在该技术研究中已处国际领先地位,并利用该技术解决了一批钻探难题。但是实践发现,正常钻进时,在极破碎、漏失严重地层和大风量条件下反循环排渣效果不理想,仍有小部分气体携带细颗粒岩粉从外环间隙逸出,出现孔口返尘现象,导致部分岩矿样丢失。反循环形成是否彻底是这项钻进技术能否广泛而顺利推广的关键问题。反循环形成的好坏,最重要的因素就是反循环钻头。反循环钻头结构类型、结构参数、喷孔设置等等是钻头形成反循环的关键因素,因此,深入研究更利于反循环的反循环钻头结构以完善反循环中心取样工艺是极其必要的。为了进一步提高贯通式潜孔锤反循环钻进的反循环排渣能力,完善并推广潜孔锤反循环钻进工艺技术,本文结合国内外反循环钻头研究现状,创新设计引射器式反循环结构、环喷式反循环结构、内喷式反循环结构等更有利于提高反循环效果的钻头形式,并对它们各自的关键结构参数进行了数值与试验研究。研究结果不仅表明了新设计的反循环钻头结构形式较传统的反循环钻头具有更强的反循环排渣能力,同时还为设计高性能反循环钻头提供了技术支持。具体研究内容与结论如下：1、引射器式、环喷式、内喷式等反循环结构的数值与试验研究采用EFD数值模拟技术,对引射器式、环喷式、内喷式等新型反循环结构形式的各关键结构参数进行数值模拟。利用正交设计中的数学试验原理对仿真结果进行数据处理。通过讨论各结构参数对反循环效果的影响规律,寻找最有利于反循环的最优结构参数组合,并分析各结构参数之间的主次关系。同时以EFD数值模拟结果为参考,设计反循环试验台,对这两类结构反循环效果进行试验。研究表明,试验结果与仿真结果吻合较好。(1)影响引射器式、环喷式反循环结构反循环效果的主要结构参数有：喷嘴直径、内喷孔直径、内喷孔高度、内喷孔层数、喷嘴距离、底喷孔直径、环空间隙大小等。其中,喷嘴参数和内喷孔参数对反循环效果影响显著。引射器式、环喷式反循环结构的结构参数对反循环的影响规律基本一致：喷嘴直径越小越好；内喷孔层数和内喷孔直径取较大值则会更有利于反循环,而内喷孔高度不能设得太高；较大的喷嘴距离和底喷孔直径均有利于提高反循环效果；收缩角θC对反循环的影响完全可以忽略；扩压槽深度、扩压槽仰角对反循环的影响相对喷嘴直径、内喷孔其他结构参数来说比较小；(2)内喷孔式反循环结构的关键结构参数就是内喷孔直径、内喷孔层数、内喷孔高度。在内喷孔式反循环结构中,内喷孔直径和内喷孔层数是越小越好,与前两类钻头相应变化规律相反；而内喷孔高度在引射器式、环喷式、内喷式三种结构中都有一样的规律,即越小抽吸越强烈；(3)数值与试验研究结果表明,内喷式反循环结构反循环能力最强,其次是环喷式反循环结构、引射器式反循环结构,传统反循环结构反循环效果最差。试验过程中,创新设计的引射器式、环喷式、内喷式反循环结构均能顺利地将环空中的砂粒、岩屑抽吸进中心孔,充分说明了这三种反循环结构的强力反循环性能。2、边界条件对反循环效果影响规律的数值与试验研究影响反循环效果的另一关键因素就是边界条件：系统供风量Qv和中心孔背压PCEN。风量有两类(共三个)关键值,一是“拐点”风量,即该风量下,反循环效果达到最佳；二是临界风量Qvo(左临界风量QV01和右临界风量Qv02),当风量QV<Qvo时,环空发生泄漏；当Qv01<QV<Qv02时,Qv环>0,环空气体被抽吸至钻头中心孔中,反循环效果最好；当Qv>Qv02时,环空发生漏失,反循环效果变差。因此,要想形成良好反循环,必须将风量控制在一定范围。中心孔背压的升高会降低反循环效果,增加环空漏失的几率。当中心孔背压升高时,风量的关键值也会增大,因此可以适当增加系统供风量以避免因中心孔背压升高而造成反循环形成不良的现象。本文的主要创新点包括：(1)本文在前人研究的基础上,对反循环钻头反循环机理和反循环结构进行了继承和创新,提出了三种新式的反循环钻头结构设计方案。试验证明,三种反循环结构均能对反循环效果带来进一步的提升,且内喷孔式反循环结构对环空的抽吸能力最强；(2)提出了系统风量的两类关键值(即“拐点”风量和临界风量)是影响特定结构反循环效果的关键。且这两类关键值随着结构参数和中心孔背压变化而变化。对于具体的情况,找到特定的关键风量范围是保证钻进过程中反循环形成良好的关键；(3)试验器设计时,吸取了以往试验器的设计经验。新设计的反循环试验器可测试的结构参数更多,可替换性也有所提高；(4)首次利用EFD技术对反循环钻头结构进行大量而系统的优化设计分析,同时也是首次将正交设计和回归分析全面贯穿于反循环钻头流场分析和室内试验设计中。数值模拟和试验表明,采用EFD分析技术在钻头结构优化设计中具有良好的可操作性和可靠性,且正交试验设计和正交回归设计的应用,不仅极大地减少分析和试验时间,更提高了试验的科学性和有效性。更多还原

【Abstract】 Several decades before, resources existing in the area that is easy to reach or in superficial stratum were terribly developed, and they become nearly exhausted. But the resources existing in some outlying areas, plateau, complex condition and deep stratum are waiting for more inputs and development. Investing mining industryand speeding up resource exploration and development turns to be a worldwide (including China) hot economic topic. Advanced drilling equipment and technology should have been researched and developed for a long period.The hollow-through DTH hammer reverse circulation(RC) continuous coring drilling technology has three advantages including high efficiency, reverse circulation and capturing cores continuouslywhile drilling. Its drilling efficiency can be 6-10 times as traditional drilling methods. Reverse circulation will never damage the wall, and it will never be restricted by water, frigid weather, fragmenting stratum, frozen stratum and hard rocks due to its unique drilling mechanism. Research on this drilling technology in our country has already been in the lead of entire world and lots of drilling problems have been solved with it. However, it is found that the RC performanceis not satisfactory enough when drilling in extremely cracked stratum or under heavy air input working condition. There is still a little bit air with small cuttings escape into the annulus under that circumstance. As a result, a small scale of dust appears on the ground and this causes a partial loss of samples. Whether the reverse circulation runs good or not is an essential problem to its promotion. And the key factor which influences RC performance most is the RC bit. The structure types, geometry parameters, nozzle, and etc. are all the important factors of reverse circulation. Therefore, it is absolutely necessary to do more and further research on RC bit structure in order to perfect this RC drilling technology. For the sake of improving slag discharge performance of hollow-through DTH hammer RC drilling system, perfecting and promoting this advanced drilling technology, the author gave three types of innovative designs of high performance RC bit including ejector-based RC bit, annulus-injecting RC bit, and interior-injecting RC bit based on research status at home and abroad. Then, numerical investigation and experiment were carried out to study the relationship between geometry variation and RC performance. It is resulted that the performance of new-designed RC bit works much better than traditional ones, and also the technique support is supplied to design high performance RC bit. More details about research and conclusions as follows:1、Numerical investigation and experiment of ejector-based, annulus-injecting, and interior-injecting RC bitNumerical simulation was carried out to investigate the geometry parameters of ejector-based, annulus-injecting, and interior-injecting RC bit with the method of EFD numerical solution. And mathematic experiment principle belonging to orthogonal design was used to process the data obtained from simulation. The regularity about how those geometry parameter variations influence the RC performance was discussed to find out the most effective parameter combination and the primary and secondary relationship among those parameters. Then, RC experiment rig was designed on the basis of EFD simulation, and it is found that the results from EFD mostly coincide with those from experiment.(1) Main geometry parameters that influence the RC performance of ejector-based and annulus-injecting RC bit include nozzle diameter, interior injector diameter, interior injector height, number of interior injector layers, nozzle position, bottom injector diameter, annulus size, etc. And geometry parameters of nozzle and interior injector have the greatest effect on RC performance among all of those above.Both of the two types of bits have the same regularityhow the RC performance is affected by those parameters. That is, the smaller nozzle diameter is the better RC performance comes; More interior injector layers and larger interior injector diameter bring better RC performance too, while interior injector height acts in an opposite manner; And further distance between nozzle and bottom injector and bigger bottom injector diameter are good for promoting RC performance; However, converge angleθC can be neglected, and, diffuser depth and diffuser angle give little effect on RC performance either.(2) Key geometry parameters of interior-injecting RC bit are interior injector diameter, numbers of interior injector layers and interior injector height, separately. According to its research, smaller interior injector diameter and fewer layers are usually good for RC performance and this regularity is totally contrary to ejector-based and annulus-injecting RC bit, although interior injector height has the same influence to RC performance among those three types of RC bits---the smaller the greater.(3) Results from numerical investigation and experiment show that, interior-injecting RC bit has the most powerful RC capability, then annulus-injecting and ejector-based RC bit are separately ranked second and third, and traditional RC bit comes to the last place. Cuttings and sand grains existing in the annulus can be easilysucked up, and this gives a sufficient proof that these three new-designed bits have extremely high RC performance.2、Numerical investigation and experiment of how the boundary condition affects RC performanceBoundary condition is another critical factor including system air input (QV) and central exhausting tube back pressure (PCEN),and these two boundary condition parameters affect RC performance as well。There are two kinds of key QV. One is called "inflection point" air input, namely, the RC performance will come to the best when QV equals to it. The other is critical air input (QV0)including left critical air input (QV01) and right critical air input(QV02).When QV<QV0, air leakiness happens in the annulus, and reverse circulation is formed incompletely. When QV01<QV<QV02, air in the annulus is easily sucked into the bit, and reverse circulation runs strongly efficiently. When QV>QV02, air leakiness happens in the annulus again, worsening RC performance greatly. Consequently, system air input must be controlled within an appropriate range for the sake of satisfying RC performance. As to PCEN, increasing it is disadvantageous to reverse circulation, and the chance of air leakiness in annulus rises too. However, poor RC efficiency caused by largePcEN can be avoided by augmenting QV.Main innovative aspects in this dissertation include:(1) Three new types of RC bits were designed based on inheritance and innovation of RC mechanism and RC bit structure researched before by other researchers. Experiment shows that, the three of them can obviously promote RC performance, and interior-injecting bit is proved to be the best of them.(2) Innovative reverse circulation mechanism was put forward that two kinds of key system air input ("inflecting point" air input and critical air input) are extremely essential to RC performance, and both of them change while central exhausting tube back pressure changes. As to some specified issues, finding out key system air input is the guarantee of satisfactory RC performance during drillings.(3) Based on the experience of other experiment rig design before, new-designed experiment rig can test more geometry parameters, and it is also much more replaceable.(4) The EFD simulation was firstly employed to research RC bit geometry parameters and structure optimization systemically. And, orthogonal design and regression design were utilized to study RC bit flow field and conduct experimental design for the first time too.According to the results from simulation and experiment, there is reliability and accuracy using EFD technique to deal with RC bit structure optimization. And, orthogonal design and regression design can save lots of time in numerical investigation and experiment, andmake the experiment much more scientific and efficient.更多还原