It is an important part in scientific drilling to predict the drilling speed and make out drilling plans according to the rock drillability grades. Then the precise prediction of rock drillability is one of the key fundamentals especially for high-quality and high-efficiency ultradeep well drilling, thus to improve the ROP and reduce costs. Therefore, by use of the mathematical statistical method, based on the drilling, logging and mud data obtained from wells already completed at the thrust structure at the Kuqa depression and the statistical analysis of experiment data on micro-bit drillability, we established the rock drillability profiles in both vertical and horizontal direction for ultra-deep drilling at the thrust structure at the Kuqa depression. Thus, the rock drillability can be predicted rather accurately, which can meet the needs of drilling on site. Meanwhile, a software is then developed for design calculation. The application of the drillability profiles and this software proves that the error between the calculated value and the actual drilling data is 5 -8％, so they can be widely used. To achieve the most technical and economical benefits,the rock drillability profiles can be adjusted according to different areas and structures.%根据地层岩石可钻性级值预测钻井速度、制订钻井计划是科学钻井的一项重要内容.精确地预测地层可钻性是实现超深井优质高效钻井的重要基础之一,对提高钻井速度、降低钻井成本具有十分重要的意义.应用数理统计的方法,依据库车坳陷山前构造已完钻井的钻井、录井、测井资料,以及室内微钻头可钻性实验数据统计分析,建立了库车坳陷山前构造超深井横向、纵向地层岩石可钻性剖面,较精确地预测了地层可钻性级值,满足了现场钻井工作的需要.并编制了设计计算软件,现场应用表明预测值与实测值误差为5%～8%,具有广泛的推广应用价值,对于不同地区、不同构造,应对地层岩石可钻性剖面进行修正,以获得最佳的技术经济效益.
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