Abstract
Identification, quantification, and mobility assessment of shale pore fluids are crucial for shale oil development. Conventional coring often leads to fluid loss. This study used cryogenically preserved, sealed core samples, combined with core exposure, centrifugation, drying, and solvent extraction, applying a dual-cutoff T2 relaxation approach (T2c1 = 0.28 ms, T2c2 = 0.61 ms) and a Gaussian mixture model to quantify fluid states and corresponding pore sizes. Results show significant fluid loss during core exposure, while solvent extraction cannot fully remove trapped fluids. Pore fluids are classified as immobile (17.09%), borderline mobile (21.99%), and mobile (60.92%). Medium-to-large pores (25–1000 nm) mainly host free oil and mobile water, whereas small pores (<25 nm) contain adsorbed oil and bound water, with ∼25 nm as the lower threshold for mobile fluid. This framework provides a quantitative basis for evaluating shale fluid mobility and producibility, aiding sweet spot identification and hydraulic fracturing optimization.
Paper Information:
Zhao, X., Wang, M., Li, X., Wang, M., Xiao, D., Li, J., Tang, Y., Jiang, J., Qin, P. Revisiting fluid mobility in shale: Dual-cutoff NMR evidence from cryogenically preserved cores. International Journal of Hydrogen Energy, 2026, 235: 155194. https://doi.org/10.1016/j.ijhydene.2026.155194.
