Geomechanics assessment of shale under interaction with thermally conditioned crosslinked fracturing fluid

Abstract

Slickwater and linear gel applications in hydraulic fracturing of shale gas reservoirs are faced with challenges. Proppants are poorly transported, produced fractures are narrow, and fluid leak-off potential is high with slickwater usage. Linear gel requires a large concentration of gelling agent for proppant suspensibility. Crosslinked fracturing fluid provides better clean-up properties, requires lower polymer concentration, and is associated with minimal fluid loss. Shale geomechanical behaviour under interaction with crosslinked fracturing fluid remains poorly understood. Crosslinked fracturing fluid was formulated and used in the saturation of Eagle Ford shales under temperature conditions. Mineralogical characterization and elemental composition analysis were carried out using FESEM, EDX, and XRD technologies. Samples’ geomechanical properties were evaluated through the application of a uniaxial compression system and afterward subjected to failure pattern analysis. Eagle Ford shale-crosslinked fracturing fluid interaction under reservoir temperature conditions demonstrated the potential of promoting shale mechanical integrity. Unconfined compressive strength (UCS) varied from 67.26 to 133.79 MPa, and static Young’s modulus (E_sta) from 5.49 to 7.63 GPa. These were higher than ambient sample UCS and E_sta at 61.39 MPa and 4.78 GPa respectively. The developed fit-driven correlations (R-squares: 0.71223 and 0.622) can support the assessment of UCS response with known E_sta or PIM for Eagle Ford shale under uniaxial compression and fluid saturation at temperature conditions. Uniaxial compression of samples to failure indicated the dominant occurrence of multiple axial splitting among Eagle Ford shales. This research can be of relevance in engineering design of crosslinked fracturing fluid towards optimized hydraulic fracturing of shale.