Drilling costs are significantly influenced by bit performance when drilling in off-shore formations. Retrieving and replacing damaged downhole tools is an extraordinarily expensive and time-intensive process, easily costing several hundred thousand dollars of off-shore rig time plus the cost of damaged components. Dynamic behavior of the drillstring can be particularly problematic when drilling high strength rock where the risk of bit failure increases dramatically. Many of these dysfunctions arise due to the interaction between the forces developed at the bit-rock interface and the modes of vibration of the drillstring. Although existing testing facilities are adequate for characterizing bit performance in various formations and operating conditions, they lack the necessary drillstring attributes to characterize the interaction between the bit and the bottom hole assembly (BHA). A facility that includes drillstring compliance and yet allows real rock/bit interaction would provide an advanced, practical understanding of the influence of drillstring dynamics on bit life and performance. Such a facility can be used to develop new bit designs and cutter materials, qualify downhole component reliability, and thus mitigate the harmful effects of vibration. It can also serve as a platform for investigating process-related parameters which influence drilling performance and bit-induced vibration to develop improved practices for drilling operators. Sandia National Laboratories is pursuing the development of an advanced laboratory simulation capability which allows the dynamic properties of a BHA to be reproduced in the laboratory. This simulated BHA is used to support an actual drill bit while conducting drilling tests in representative rocks in the laboratory. The advanced system can be used to model the response of more complex representations of a drillstring with multiple modes of vibration. Application of the system to field drilling data is also addressed.

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