Recent evolution of drill bits for hard and abrasive formations

The paper analyzes the recent technological developments of bits utilized to drill hard and abrasive formations. Longer time on bottom and faster penetration rate are an increasingly demanding issue for drilling bits. To this purpose, the technology of drilling bits has evolved, and continues to advance to meet the challenging needs of today’s drilling industry. Hard and abrasive formations normally pose many problems for PDC and roller cone bits drilling. The new technology of impregnated bits, however, seems more suitable because offers the latest technology in bits designed for drilling hard and abrasive formations. Normally the impregnated bits use a state-of-the-art combination of specific features and materials to withstand the most rigorous drilling conditions. After a review of recent technologies, the paper describes an application in recently drilled wells of Southern Italy. Here, hard rock drilling is particularly significant for the complexity of drilled formations, making bit selection a crucial point of both well planning and drilling operation. Moreover, the paper illustrates a new method of bit performances evaluation, called Bit Index, which, together with other evaluation indexes, has been used to evaluate the performances of new technology bits.