Abstract
The hydraulic fracturing technique is based on pumping a given fluid at a high pressure greater than the rupture pressure of the reservoir rock, which causes the creation of high permeability channels inside the rock. This process also makes the fluid contained in the formation flow preferentially through the newly cracked channels. After stabilizing the pressure inside the rock formation, the fracturing fluid may settle inside the fracture or even infiltrate into the formation. The next step, known as flowback, consists of removing all fracturing fluid so the well can start producing. Under certain conditions, significant amounts of hydrocarbons can remain inaccessible, and problems such as water blockage, fluid trapping, and flowback efficiency reduction can occur, which can cause loss of fluid in the formation and a low production of hydrocarbons. The present work aims to present the effect of flowback aids, composed of combinations of surfactants, in brines and fracturing gels. Flowback aids act mainly on the surface of fracturing fluids and at their interface with the reservoir hydrocarbons. They reduce the deformation resistance of fluid droplets allowing them to cross narrow formation channels. They also reduce the resistance of the fracturing fluid to return to the surface, helping it avoid blocked channels. Consequently, these additives reduce the formation damage and improve the production of reservoir fluids. Experiments were carried out to measure rheology, stability, surface, and interfacial properties, and a physical simulator of flow in porous media was used. The rheology results showed that the flowback aids did not change the consistency of the fracturing gel. The experiments with the physical simulator showed that the presence of the flowback aids made the brines flow through a porous medium faster compared to the brines without the flowback aids. The results of the surface and interfacial properties measurements showed that a small amount of flowback aids can efficiently change the surface properties of brines and their interfacial properties with the crude oil. These changes improve the malleability of the injected fracturing fluid and reduce the crude oil's resistance to push the fluid back to the surface, allowing a more efficient production of hydrocarbons.
