The activity of oil and gas exploitation in Brazil demands a significant infrastructure for provision of goods and services in order to support these activities. Most of Brazilian gas and oil reservoirs are concentrated in offshore sedimentary basins, mainly in ultra-deep waters, which increases the degree of risks involved in the drilling operations, necessitating the use of drilling fluids in order to maintain the integrity of the formation drilled, thus minimizing these related operational risks.
Drilling fluids are products formulated of a combination of different chemical compounds using water or oil as the main dispersant media or a synthetic specific dispersant media. The final fluid composition will depend on the characteristics and behavior of the reservoir to be drilled. The main purpose of the drilling fluids is transportation of the cuttings to the surface, sub surface pressure control and well stabilization. After use the drilling fluids and cuttings are treated on the offshore facility in order to evaluate the disposal possibilities, whether they can be discharged at sea or should be sent onshore to receive the appropriate treatment. In the environmental sphere the aspects due to the drilling fluids use, treatment and disposal are regulated by IBAMA (Brazilian Institute of Environment and Renewable Natural Resources), which defines standards for discharge to the sea, parameters to be evaluated, tests to be carried out before and after use, and criteria for their disposal (overboard or onshore) depending on analysis results.
This study aims to describe the process adopted for treatment of drilling fluids in offshore drilling units, the requirements for discharging them to the sea, the onshore logistics for treatment and disposal, the forms of treatment currently available in Brazil, and additionally suggesting the adoption of new technologies that enable the recovery of the constituents of the drilling fluids with the aim of reusing them in further industrial processes.