【作者】 刘刚；

【导师】 达拉拉伊·帕维尔；

【作者基本信息】 吉林大学 ， 地质工程， 2019， 博士

【摘要】 作为目前世界范围内钻进速度最快的冰层钻进方法之一,热水钻被广泛用于冰架下部冻融过程的观测、冰下沉积物取样、冰层物理结构研究、温度测量、冰层蠕变研究、冰下基底滑移速度测量、冰下湖连接通道的获取、宇宙中微子的捕捉以及一些其它的科学目的。本文的主要目的是进行热水钻进系统的理论研究,建立主要钻进参数(热水流量、输送压力和温度)、可控结果变量(钻孔直径、钻进速度、油耗和钻孔冻结速度)和独立变量(目标钻进深度和冰层温度)之间的关系。本文对目前国内外热水钻进技术的研究意义和现状进行了归纳总结,详细介绍了现今在高山冰川和极地冰层钻探中应用最为广泛的冰层钻探方法——热水钻,并认识到我国在热水钻技术的应用和理论研究上的严重匮乏,尝试解决热水钻融冰过程理论研究不足的问题,对热水钻进过程进行数值模拟,并研发了一套浅层热水钻进系统。论文研究得到的主要结论如下:(1)本文通过建立热水钻融冰过程理论模型,发现:较高的流量和温度能够在钻进时实现更大的钻进速度和钻孔直径。对于中深层热水钻系统来说,沿程压力损失在热水输送压力中占决定性作用,而沿程压力损失由软管长度、软管内径和流量决定;相对来说,为了实现热水对孔底冰层的充分接触,局部压力损失在浅层热水钻系统中往往更加重要。钻孔的冻结时间取决于冰层温度和初始钻孔直径。(2)本文使用显热容法对热水钻融冰过程进行数值模拟。通过数值模拟发现,在短时间的钻进融冰过程中,流量和温度对钻进速度的影响显著,而对钻孔直径影响较小。钻孔重新冻结的模拟结果与融冰过程理论计算结果相似。对0.3米的钻孔来说,若冰层温度为-30℃时,12 h后钻孔就几乎完全冻结;而当冰层温度仅为-10℃时,钻孔在72 h后依然没有完全冻结。(3)设计研发了一套浅层热水钻进系统,在极地冰盖或高山冰川进行浅层观测孔快速钻进中具有巨大的应用价值。浅层热水钻系统由四个子系统构成:水体加热系统,主体是高压热水清洗机,可以产生温度范围为80-155℃、流量范围为4–10 L/min的热水,并以不超过14 MPa的最大压力输出;水体输送系统,包括卷扬、高压软管和地面管路及阀门等;钻具系统,包括钻塔、配重和喷嘴;测控系统,包括测控箱及编码器、温度传感器、压力传感器、水压表、流量计、内径百分表等传感器或仪表。(4)浅层热水钻进系统整体工作良好。系统在使用1.8 mm、2 mm和2.5 mm单孔喷嘴时,钻进比较顺利,而大孔径喷嘴(3 mm喷嘴)产生了较大直径的钻孔但钻进速度非常小。在使用10 L/min流量和60℃热水喷射温度时,使用1.8mm和2 mm喷嘴以34-37 m/h的最大钻进速度进行钻进,能够产生98-114 mm的钻孔;而使用2.5 mm喷嘴则在25 m/h的钻进速度下产生146-156 mm的钻孔。系统的最高热效率为83%,这是由于该钻孔的钻进速度达到29.5 m/h,同时钻孔深度仅为3 m。但在大多数钻孔中,热效率一般在67-76%的范围内。热量损失主要是热量导入周围冰层和空气中,以及加热器内燃料的不充分燃烧。(5)实验结果与热水钻融冰理论进行了对比分析。实验数据与参数理论预测的偏移基本都不超过7%(事实上,大多数实验数据要稍小于理论曲线),个别实验点与参数理论预测的偏移达到了21%,误差的产生是由于实验中的观测误差和系统故障。但就总体而言,热水钻融冰理论模型能够准确预测热水钻系统的主要参数。更多还原

【Abstract】 Hot-water drilling is one of the fastest methods to drill boreholes in glaciers and nowadays it is actively used for the observation of ocean cavities under ice shelves,the retrieval of sub-ice seabed samples,the study of internal ice structures,video imaging,temperature logging,measurements of deformation within ice,the determination of basal sliding velocity,clean accessing to subglacial lakes,and many other scientific objectives.The main aim of the research is to develop theoretical basis of the hot-water ice drilling systems and establish relationship between the key drilling parameters(flow rate,delivery pressure and temperature of the delivered water),controlled outcome variables(diameter of the drilled borehole,rate of penetration,power and oil consumption for ice melting and refreezing rate of the borehole)and independent variables(current/target depth and temperature of ice).The paper summarized the research significance and current development of hot water drilling technology at home and abroad in high-mountain glaciers and polar ice drilling,recognized the serious lack of theoretical research of hot water drilling technology in China,and tried to solve the problems of insufficient theoretical research on hot water drilling and ice melting process.Numerical modeling of hot-water drill was made and a shallow hot-water drilling system was developed.The main conclusions of the paper are:(1)Theoretical estimations of hot-water drilling parameters showed that higher flowrate and water temperature could achieve bigger rate of penetration(ROP)and borehole diameter.In most cases of intermediate or deep hot-water drilling,the friction pressure losses play critical roles in the required delivery pressure of hot water flow,and mostly depend on the length of the hose,hose diameter,and flow rate,while the local pressure losses may be much more important for shallow drills to provide a strong contact upon bottom ice.The length of time that a borehole remains sufficiently open depends on the surrounding ice temperatures and initial borehole radius.(2)The author used effective heat capacity method to make simulation modeling of hot-water ice-melting process.For short-time simulation,flowrate and water temperature have obvious effect on ROP but fewer influence on borehole diameter.The results of modeling simulation of refreezing rate are similar with the calculation results.For 0.3 m borehole diameter,if ice temperature was-30℃,the borehole would totally get frozen after 12 h;if ice temperature was-10℃,the borehole would keep open even after 72 h.(3)A portable shallow hot-water drill system has been designed and tested in an ice drilling test facility that allows the testing of numerous ice drills throughout the year.The shallow hot-water drill system is composed of 4 sub-systems: water heating system,consists of a high pressure washer,that could deliver water at a temperature in the range of 80–155?C,a flow of 4–10 L/min and a pressure as high as 14 MPa;water delivery system,mainly consists of winch and high-pressure hose,valves;drilling system,consists of mast,dead weight and nozzle;control and measuring system,consists of control box,encoder,temperature sensors,water pressure gauge,flow meter,inner dimeter gauge etc..(4)In general,the shallow hot water ice drilling system worked adequately.The nozzles with a 1.8-mm,2-mm,and 2.5-mm orifice diameter fit best with the system,and a large orifice diameter(3 mm)created a large-diameter borehole with a proportionate decrease in the ROP.Under the hot water flowrate of 10 L/min with a temperature of 60 °C,the 1.8-mm and 2-mm nozzles created 98–114 mm diameter boreholes at a penetration rate of 34–37 m/h,while the 2.5-mm nozzle produced a 146–156 mm borehole at a rate of approximately 25 m/h.The highest efficiency(relation of power used for ice melting to input power from fuel energy)of 83% was achieved in the Run 17 because ROP was as high as 29.5 m/h and drilling depth was quite shallow(only 3 m)resulting rather small heat losses in surrounding ice.While in the other runs the efficiency was smaller in the range of 67-76%.The heat losses were attributed mainly due to the unproductive heat conducted into ice or air and energy loss in burner.(5)Results of the theoretical estimations were evaluated through comparison with the main drilling parameters obtained through laboratory tests.Most of the deviation between the experiments and theoretical estimations did not exceed 7%(in most cases the experiment data were smaller than the theoretical lines).However,several experimental points had a deviation as high as 21%,which could be explained by the observational errors and system malfunctions during the tests.In general,the theoretical data and model seems to be accurate and can be used for estimations of the main parameters of hot-water drilling systems.更多还原