Nano-emulsions as Cement Spacer Improve the Cleaning of Casing Bore During Cementing Operations

Abstract

Abstract Nano-emulsions are emulsions where the droplet size of internal phase is less than 500 nm. Due to their small dimensions they have a high surface area and show very peculiar properties. Solvent in water nano-emulsions combine the high efficiency of the small dimensions of solvent to a low interfacial tension, due to the presence of the surfactant mixture used to prepare nanoemulsions. Solvent in water nano-emulsions used as cement spacer formulation could allow optimizing the cleaning of the casing during the cement job with a high improvement of the performances of the spacers currently in use. This methodology, based on high efficiency system with reduced chemical dosage, could also result in a considerable optimization of product cost of cement operation. The objective of this study has been the formulation of direct nano-emulsions (o/w), with a selected solvent as internal phase, in order to improve the casing - open hole cleaning and reverse the surfaces wettabitlity to allow better adhesion of slurry between casing and hole. Specific laboratory tests have been carried out to compare commercial spacers currently used in common drilling practice with nano-emulsions formulated in Eni Laboratories. Different nano-emulsions were performed in function of solvent content. The nano-emulsion efficiency was evaluated throughout different methods: Metallic Grid Test, Wettability Test, Contact Angle, Shear bond test. All tests highlight good cleaning properties of nano-emulsions and their better efficiency compared with common spacers.