Due to an increased understanding of the effects of formation damage, it has become commonplace to test the damage potential of drilling fluids with reservoir core, prior to drilling. This preventive approach has shown to be more effective than neglecting pre-drilling laboratory testing. However, the current approaches are lacking in many areas.

Through research, as part of an E.U. funded project, well productivity 2002, a standard procedure for testing the formation damage of drilling fluids has been developed. The research provides a number of explanations as to why previous "round robin" studies display large variations in results between laboratories. False ranking of drilling fluids and formations were subsequently produced due to the varied procedures currently used. Explanations and solutions are specified in order to allow future testing to be repeatable in any laboratory and most importantly, representative of the wellbore situation.

The result of the research is a cost-effective procedure, which can be scaled to the reservoir after testing. Although the laboratory equipment used is not greatly different from that used in many laboratories, there are procedural changes. These changes allow accurate testing and ranking of formation damage potential. The results detail representative fluid application, basic fluid ranking procedures and a more advanced investigative procedure, which determines type and extent of damage expected from the formation and fluids. Additions to these procedures allow for the testing of solid and chemical completions, to provide a strong tool for well planning.

The research was part of Work Package 1 of the E.U. project "Well Productivity 2002" and the recommended methods are already being used in a number of reservoir studies. It is intended to present future work using these methods, in parallel with well data.

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