This project addresses the performance of wells in hydrocarbon reservoirs. The productivity of an oil or gas well determines the efficiency of extracting fluids from the subsurface formations, and hence the well performance has a direct and immediate impact on economic returns from a reservoir asset. Hydrocarbon delivery, or drive fluid injection, can be reduced to far below its potential by loss of effective permeability in a near-wellbore zone (termed formation damage) or by obstructions to flow in the well completion assembly. This reduction can be provoked by inappropriate decisions or activities related to the selection of well fluids or completion solutions, the implementation of the same, or unpreparedness for incompatibilities between system components. WP-2002 aims to deliver petroleum engineering development strategies and products to drill, complete and maintain wellbores in such a manner that the optimum delivery potential of a hydrocarbon reservoir is protected and maintained throughout its entire economic life. To reach this goal, a strategy with four major elements was been defined: - Developing cost-effective laboratory and field diagnostic methods to characterise and quantify the undamaged and potentially impaired production potential of a reservoir. - Conducting systematic applied research on well fluid design with special consideration given to the formation damaging effects of well fluids, and the underlying mechanisms. - Developing cost-effective field practices for maximising well deliverability. - Creating a simulation tool to support well planner¿s decisions. These are the main results from the project: - A unified test protocol for laboratory formation damage assessment has been proposed. The protocol consists of functional procedures that attempt to standardise formation damage service projects. - Through well designed experiments, improved knowledge about formation damage mechanisms for: -- Polymer containing water-based fluids and --Emulsion based fluids has been generated. This knowledge will be of importance in designing of well fluids, and as input to the simulation models. -To support the well planners with mud design software have been developed (BestMud and Maximize). - In order to clarify and improve the clean-up procedures, tailored to the type of fluid and completions, an examination of 230 case histories has been carried out. To facilitate data storage and analysis a database has been constructed which assesses the success criteria of the key element of the drilling and completion process. It was found that there is a clear distinction between the different options available.