The selection of the drilling fluid is an essential part of a drilling operation. Drilling fluids vary from simple WBM to complex NADF. In this comparison the differences of the various muds are analysed by calculating the life cycle costs of mud for two wells. With effective solids control equipment it is possible to use and reuse these muds for a long time. When using NADF it is common to rent the mud system. Applying this option the customer can avoid purchase and storage costs. The dominating criteria for the selection of the most suitable drilling fluids are technical requirements and quality considerations. But these are not the only important criteria, also environmental aspects are essential factors. The strategy is a reduction of the environmental impacts to as low as reasonably practicable by applying best available technology. This implicates the use of drilling fluids with the lowest toxicity, which fulfil the technical requirements. It also includes the minimization of the amount and the toxicity of the residual waste. Public environmental awareness demands the application of environmental friendly methods, irrespective of costs. Therefore the application of diesel based mud is unacceptable for western type stock noted companies. Public environmental awareness demands the application of environmental friendly methods, irrespective of costs. Therefore the application of diesel based mud is unacceptable for western type stock noted companies.