基于岩石力学特性和机械比能理论的钻头评价和优选

Bit evaluation and optimization based on rock mechanics and mechanical specific energy theory

摘要:

针对川西某构造的地质构造和地层特征，本文以井史资料和测井数据为基础，建立了地层强度参数和岩石力学参数剖面，得出了分布规律，即岩石强度和可钻性级值普遍较高，且变化趋势同弹性模量、粘聚力、内摩擦角等力学参数一致，在2500～2700 m地层达到峰值，而泊松比则相反，达到最低值。提出了基于岩石力学特性和机械比能理论的钻头评价和优选方法，得出了每段地层钻头的机械比能值，对已使用钻头的使用效果进行系统评价，发现采用的PDC钻头效果不理想，形成了牙轮钻头、孕镶钻头为主的钻头推荐方案，为工区钻井提速设计提供指导。

Abstract:

In reference to the geological structure and formation characteristics of Western Sichuan， the paper establishes the profile of the formation strength and rock mechanics parameters according to the well history data and logging data， and derives the distribution rule which shows general high rock strength and drillability and consistency of the change trend with the elastic modulus， cohesion， and internal friction angle. The mechanical parameters reach the maximum at 2500 to 2700m deep formation， while the poissons ratio decreases to the minimum. The bit evaluation and optimization method based on the theory of rock mechanics properties and the mechanical specific energy theory is proposed with the mechanical specific energy of the bit concluded for each section of formation. The performance of the bit which has been used is also evaluated， and it is found the PDC bit performance is not satisfactory. As a result， a bit recommendation which puts priority to the rock bit and the impregnated bit is presented to provide guidance for drilling speed design for the work area．