Abstract
For liquids-rich shale plays, surfactants have proven to be a critical component inhydraulic fracturing fluid systems for enabling enhanced oil and gas recovery. The industry's most commonly used surfactant of choice is a non-emulsifying surfactant (NES), but it has been demonstrated previously that a weakly emulsifying surfactant (WES) appears to be more efficient in mobilizing oil through tight pore throats. In this study, fundamental differences between those two surfactant types are further
demonstrated by using a Reservoir-on-a-Chip (ROC) approach, which allows direct visualization of oil recovery with the various surfactant fluids; allowing for the testing of both homogenous and heterogeneous pore structures with various
geometries. The lab testing showed that in comparison to a non-surfactant bearing control fluid, both surfactant types appear to yield much higher oil recovery efficiency; but the WES appears to be able to yield a higher oil recovery efficiency than the NES at equal pore volumes. As a result of the lab testing indications, a multiple well trial program has been conducted in two separate areas of the Eagle Ford Shale. Production data from the wells that are stimulated with a WES-bearing fracturing fluid are normalized in terms of lateral lengths, frac stages, and proppant volumes, and compared to the offset wells stimulated with a NES-bearing fracturing fluid. Early production results suggest that wells treated with the WES exhibited
enhanced productivity in comparison to those treated with the NES. Oil and core samples have been collected from the selected area wells and analyzed to correlate well performance to specific surfactant chemistry needs exhibited by the rock and reservoir fluid.