Severe fluid losses experienced during drilling in ultra deep waters have brought the attention to the need for non-invasive fluids to guarantee a successful operation. Also, the low mud weights usually required to pass through low fracture gradient formations and the increasing number of depleted reservoirs demand the availability of aqueous and/or non-aqueous light weighted drilling fluids as an alternative to aerated muds. The present paper shows the results from lab tests aiming mainly:
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The development of a filtration model to calculate filtration flow rates and depth of penetration accounting for non-newtonian rheology and type of bridging agent on filtration mechanism;
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The evaluation of filtration characteristics of different fluid formulations;
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The effect of different polymers and bridging agents on filtration properties of fluids;
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The development of non-invasive fluid formulations.