改善海底大位移水平井钻头综合性能的新途径

New way to improving comprehensive performance of bit in offshore high angle deviated holes.

在研制大斜度定向井、水平井专用钻头时，一个关键问题就是如何较精确地确定实钻状态下这种钻头在井底的各项受力参数。利用非线性有限元力学方法，编制了一套井下钻头非线性力学分析计算机软件，运用高速度、大容量计算机对井眼内全管柱做了力学分析，较准确地得出钻头部位的各项力学参数，并预测了其后的钻头走向。预测计算结果在一口海上水平井的钻进中得到验证。采用这种计算方法，可为研制新型定向井和水平井专用钻头提供不可缺少的重要参数，也为加快新型钻头的研制开辟了一个新途径。

In designing bits for using in high angle deviated holes and horizontal holes, one of the important things is to determine precisely all the forces on the bit under the actual drilling conditions. By using the nonlinear finite element method, a computer software for nonlinear mechanical analysis of downhole bits is developed, and a mechanical analysis of the whole string in the hole is conducted by means of computer, thereby the mechanical parameters of the bit are obtained, and the advancing direction of the bit in the future is predicted. The results of prediction and calculation are verified in drilling an offshore horizontal hole. Important parameters for bits used in directional holes and horizontal holes can be obtained by using the abovementioned method.