Matrix-Fracture Interaction Dynamics in Carbonates and Tight Sandstones when Different Chemicals are Used as Fracturing Fluids and Oil Recovery Additives

We evaluated the influence of boundary conditions on matrix-fracture interaction dynamics and compared the effectiveness of various chemical agents under different reservoir environments. Chemical selection was investigated for different applications, i.e., hydraulic fracturing in gas and oil reservoirs and enhanced oil recovery (EOR) for the latter. Results showed significant differences in the performance of different chemicals when they were applied in carbonate and sandstone cores. Notably, the cationic surfactant CTAB, which was unsuitable for EOR in sandstone cores, exhibited high efficacy in carbonate cores. In contrast, the anionic surfactant O342, effective in sandstone cores, was found to be detrimental in carbonate cores. While most chemicals displayed consistent results between co- and counter-current imbibition, O342 showed notable discrepancies. This highlights the necessity of carefully considering boundary conditions when applying these chemicals in field applications. When comparing different rock types, the tight sandstone results showed a similar trend with those in the conventional sandstone cores in terms of the effectiveness of chemicals in enhancing the final oil recovery. On the contrary, tight sandstone and carbonate cores had similar time responses (the durations to reach certain oil recovery levels) due to their lower permeability compared to conventional sandstone cores.