高温地热井三牙轮钻头的研制与应用

Development and application of tri-cone bit suitable for the drilling of high-temperature geothermal wells

由于深部地层温度高、井下环境十分恶劣,高温地热井钻井施工过程中所使用的三牙轮钻头普遍存在着掉齿的现象,给钻头的寿命和单趟进尺都带来了非常不利的影响,因而亟待开展适应高温地热井钻井的钻头固齿力学和钻头延寿方面的研究。为了解决高温地热井钻井过程中的三牙轮钻头掉齿问题,基于实验分析和数值模拟,开展了三牙轮钻头固齿强度研究,研制了个性化的三牙轮钻头新产品并进行了现场应用。研究结果表明:(1)在同等齿型直径及固齿过盈量参数条件下,180℃高温环境下固齿强度下降幅度介于14.7%~83.3%;(2)切削齿直径和镶齿过盈量对于三牙轮钻头固齿强度的影响十分显著,增加齿孔间接触面积及优化镶齿过盈量能够有效提高齿孔对切削齿的固紧力;(3)新产品在东非大裂谷OLKARIA区块地热资源钻探现场应用的效果表明,该新钻头能够有效地防止高温地热钻井钻头掉齿、提高综合破岩效率、降低钻井成本。结论认为,该研究成果对于我国青海、西藏及海南等省区高温地热井钻井用钻头设计与应用具有重要的参考价值。

Due to high temperature and bad downhole environment in deep strata,tri-cone bits frequently suffer tooth loss in the drilling and construction process of high-temperature geothermal wells,which has extremely adverse influence on their service life and one-trip drilling footage.Therefore,it is in urgent need to study the tooth fixation mechanics and life prolonging means of the bits suitable for the drilling of high-temperature geothermal wells.In order to solve the tooth loss problem of tri-cone bits in the drilling process of high-temperature geothermal wells,this paper studies the tooth fixation strength of tri-cone bits based on experimental analysis and numerical simulation.In addition,a new product of personalized tri-cone bit is developed and applied on site.And the following research results are obtained.First,at the same tooth type,tooth diameter and tooth fixation interference,the tooth fixation strength decreases by 14.7%to 83.3%in the environment of high temperature(180℃).Second,the influence of cutter diameter and insert interference on the tooth fixation strength is very significant.The fastening force of a tooth hole to a cutter can be increased effectively by increasing cutter-hole contact area and optimizing insert interference.Third,the field application effect of the newly developed tri-cone bit in the OLKARIA Block of the East African Rift Valley indicates that this product can effectively avoid tooth loss in the drilling process of high-temperature geothermal wells,improve composite rock breaking efficiency and reduce drilling cost.In conclusion,the research results are of great reference significance to the design and application of bits used for the drilling of high-temperature geothermal wells in Qinghai,Tibet and Hainan.