The use of a high quality mud is an essential requirement to guarantee a successful drilling operation. The drilling industry aims to build wells at low costs and as fast as possible. Among other drilling problems, an adequately formulated drilling fluid will prevent wellbore instability while contributing to generate an in gauge borehole. Usually, one of the desired properties of a drilling mud is the least as possible interaction with the drilled formation. On the other hand, the idea of a chemically active fluid that would react with the rock to help improving drilling performance is very welcome. This kind of fluid should not only mitigate drilling problems but also contribute for the improvement of the overall process. The work presents the advances in drilling fluid technology to overcome the challenges that have arisen with the discovery of Pre Salt offshore Brazil, specially the drilling of long salt section containing highly soluble salt layers and the low penetration rates in hard carbonate rocks. An extensive theoretical and experimental work was carried out to assist drilling fluid design in this drilling scenario. A special fluid formulation developed to interact with carbonate rocks and increase penetration rate is presented. Although some important issues have yet to be addressed, the preliminary results show a good potential for the new technology.

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