Salt Steerability and Hard Rock Drilling Performance in Santos Basin

摘要

The drilling operation in the pre-salt Santos basin faced great challenges from the beginning, so efforts were concentratedrnto obtain a better drilling performance as a consequence of the high daily rates of drilling rigs. In this way, we look for arncombination of drill bits and drilling systems to increase the drilling performance, both in drilling and path control in saltrnformations, also looking for solutions to increase the rates of penetration in the reservoir, once these rocks have extremelyrnlow rates of penetration. To overcome these challenges some aspects were prioritized, such as control of verticality in salt andrnin the case of directional wells, the path control, vibration monitoring and continuous improvements in drill bits selection.rnThe low penetration rate in the reservoir can be considered the most important problem, the main constraint in a challengingrnscenario composed by ultra deep water, very large layers of halite with anhydrite on the top and at the bottom, the greatestrndepth of the wells and particularly the low rates of penetration in the carbonate rocks in the reservoir.rnThis paper presents the strategy of bottom hole assembly selection used to control the well verticality, the work developedrnto make a good selection of a more efficient drilling system in such scenario. It presents the evolution of drilling performancernin the reservoir and salt formations, and complement with the work applied to mitigate the deleterious effects of vibration thatrnaffect the rates of penetration and tool reliability. Finally, the paper offers some suggestions for speeding up performance atrnthose points that remain as an opportunity for improvements.