Development of a New Technique for Emulsifiers Optimization

Summary The primary and secondary emulsifiers of the oil-based muds (OBMs), which are the main expensive chemicals, need to be added to control the emulsion stability and the mud properties. Invasion of the filtrate introduces excess emulsifiers in the reservoir and leads to formation damage in forms of wettability alteration and permeability reduction, hence resulting in a decrease of the well productivity. This is recognized as one of the major mechanisms of the formation damage during overbalanced drilling, having significant economic impact on the petroleum industry, particularly for high-pressure and high-temperature wells. In the present work, experimental study has been carried out to assess the performance and the influence of the emulsifier’s concentration on the emulsion stability and the formation damage. A new technique has been developed based on the particle size analyzer (PSA), which can be used for optimizing emulsifier’s concentration and assessing the quality performance of various emulsifiers. The optimization and the emulsion stability results have been validated by standard American Petroleum Institute (API) testing procedure and return permeability tests. The key parameters which are useful and relevant to optimum emulsifier’s selection are to prevent the barite sag and to minimize the formation damage to increase the well productivity.