This paper illustrates how the use of a Multifunctional Surfactant (MFS) can improve initial production and sustain production in underpressurized, liquids-rich, tight sandstone (SS) reservoirs such as the Glauconite formation in West-Central Alberta. Surfactants are commonly used in hydraulic fracturing fluids for multiple purposes and surface-tension reducing additives (flowback aids), demulsifiers and/or foamers are among the most widely used. When using surfactants, the goal is to mitigate the damaging effects of the fracturing fluid by enhancing fluid and polymer cleanup to improve oil and gas recovery during production.
Glauconite field trials were conducted, and the MFS was used in one of two ways, as a foamer, or as a flowback aid. Additionally, field trials were presented comparing flowback fluid properties in neighboring horizontal wells from another tight SS formation in Western Alberta, the Notikewin, a mostly dry-gas reservoir with some liquids production. One Notikewin well was stimulated using a MFS and another using a Conventional Foamer (CF). Laboratory and field test showed superior performance by the MFS over Conventional Surfactants (CS) or CF.
Foamed or energized fracturing fluids are dispersions of gas in a liquid, typically water, that are often used to stimulate low-pressure or water-sensitive reservoirs. A foamed fracturing fluid also uses a surfactant or foamer to aid in foam generation and stability. Foam quality is the volumetric gas content of the fracturing fluid or the volume of gas divided by the total volume of foam. In petroleum literature, when the gas-volume fraction is too low to provide a significant increase in apparent viscosity, it is considered an energized fluid. Energized fluids usually vary from 10 to 30% gas. If the volume percentage of gas is greater than 52% it is considered a foam (Bing Kong et. al., 2016). Most foams used in fracturing fluids range from 65 to 85% quality (Q) (Blauer & Kohlhass 1974). The gas-phase typically uses nitrogen (N2), although other products such as carbon dioxide, natural gas or propane may be used. N2 is the gas-phase used in energized or foamed-water-based hydraulic fracturing fluids referenced in this paper.
