Microemulsions as Flowback Aids for Enhanced Oil and Gas Recovery after Fracturing, Myth or Reality: A Turnkey Study to Determine the Features and Benefits

Abstract

Flowback aids have been long reported in the literature as being beneficial to enhance clean-up after stimulation treatments, and in particular hydraulic fracturing. The goal is for the flowback aids to allow the piston like flowback and return of fluids from the reservoir resulting in minimal losses to the formation and no memory effect that hampers back production. Microemulsions have also been reported in the literature and a review (including patent landscape) creates somewhat of a myth around their exact mechanism of performance and benefit to the application.The present work was concerned with the development of flowback aids based on micro-/nanoemulsion technology for enhanced gas and oil recovery after fracturing application. The goal was to formulate microemulsion concentrates which form nanoemulsions when diluted into fracturing fluids and provide strong surface and interfacial tension reduction to minimize reservoir damage.Microemulsions have been formulated with various possible surfactants and oil systems. The performance of the different formulations has been evaluated with different test methods, adopted from literature and industry best practice in order to screen for most promising microemulsion systems and compared to their aqueous equivalents to determine the performance benefits offered by emulsified packages. High throughput experimentation and robotic formulation was utilized to screen several thousand formulations from nearly 50 different surfactant packages. This allowed for incredible synergistic properties to be discovered very quickly and efficiently. The development of a new class of microemulsion package that is made up of almost 100% renewable and environmentally friendly components has made a large step change towards the state of the art of this class of flowback aids.Regain permeability and core flow testing was performed on the best performing microemulsion formulations to determine the effect of field application. The result of this work was that microemulsions do offer some benefits over individual surfactants, not so much in surface tension modification but very much on the non-emulsification of crude oil and water and multiphase flow in porous media -so often seen as the primary damage mechanism in oil well fracturing.

A Literature Review of CO2, Natural Gas, and Water-Based Fluids for Enhanced Oil Recovery in Unconventional Reservoirs

“…These chemical EOR techniques have resulted in favorable laboratory-scale EOR in ULR results. The injected fluids can be formulated for specific formations via the changes in the number, type, and concentration of surfactants, selection of brine salinity, and introduction of other additives . Anionic surfactants appear to be most effective, ,,,,, but some researchers recommend the use of nonionic or cationic surfactants.…”

Microemulsion-enhanced displacement of oil in porous media containing carbonate cements

“…Recent studies suggest that putting surfactants into microemulsified state prior to injection may improve their performance. Because MEs exhibit lower adsorption propensity on mineral rocks, 6 better demulsification capacity, 7 and higher stability at elevated temperature and brine pH/salinity compared to surfactant solutions, 8 they are considered as good carrier systems that can deliver surfactants deeper into the formation, 9 and maintain the surfactant concentration in the displacement front. 10 Microemulsions are dynamic systems in which the interface is continuously and spontaneously fluctuating.…”

Nowe rodzaje cieczy przemywających osady z płuczki inwersyjnej przed zabiegiem cementowania otworów wiertniczych

“…Poprzez dobór odpowiednich środków powierzchniowo czynnych możliwe jest także zmniejszenie objętości zatłaczanych cieczy i skrócenie czasów płukania otworu, zmniejszając przy tym ilość powstałych odpadów wiertniczych [2,6,9,14,15].…”