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

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．

Key words:rock mechanical properties; mechanical specific energy theory; bit evaluation and optimization; acceleration potential analysis