New Approach for Completion Applications With Higher Internal Phase Inverts Utilizing Innovative Surfactants

Abstract

A new surfactant capable of providing stable emulsions to as low as a 20/80 oil/water ratio while still maintaining a continuous oil phase is now possible. The new surfactant works in a variety of brines allowing flexibility in formulations and applications. The high internal phase emulsion allows formulations of higher density with less total solids. These high internal phase emulsions are stable at high temperatures and provide manageable (adequate) low-end rheological properties suitable for drilling and completion applications. This system demonstrates relatively less syneresis than a conventional invert. Using a higher internal phase requires less oil and subsequently lowers costs both from initial base fluid cost and final disposal of the base fluid. This new surfactant can also be used to formulate systems for conventional alpha-beta gravel packing, whereby the rheology profile approaches Newtonian properties. This paper will detail the chemistry behind the new surfactant, initial laboratory assessments and the potential applications for this new technology.

Intelligent Completions and Un-Cemented Liners Combine to Provide a Fully Completed Solution with Zonal Isolation in Norway

“…horizontal lateral in the Ekofisk and Tor chalk reservoirs would be performed using an 11 ppg oilbased ("oil-based" indicates inverted phase) emulsion containing 60 lbs/bbl calcium carbonate. This system is unique in that it lays down an oil-wet calcium carbonate filter cake, but can be converted to a water-wet filter cake once acid is applied and the pH is lowered (Lim et al 2011). The water-wet filter cake, consisting almost entirely of calcium carbonate, can be dissolved with HCl acid allowing for effective stimulation of the entire completion length.…”

“…Although the chalk is highly acid soluble, there were concerns that the oil based mud (OBM) occupying the annulus and the OBM filter cake on the borehole wall could impede acid/chalk contact stimulation treatment. To minimize the potential of the OBM impeding the access of the acid to the chalk reservoir, an acid-reversible OBM (Lim et al 2011) was used to drill the reservoir section. This oil-external mud system was designed to be reversed to a water-external state on contact with acid to allow ready access of the acid treatment stage to the filter cake and chalk reservoir.…”