A Novel Approach to Stimulating Tight Reservoirs Using Cyclic Thermochemical Fluids

The oil and gas industry has consistently demonstrated advancements in technology since its inception in 1847, with an increasing focus on unconventional hydrocarbon reservoirs. Given the complexity inherent in extracting oil and gas from such reservoirs, researchers continue to explore innovative technologies that are more cost-effective, environmentally friendly, and capable of improving the recovery rate of trapped oil within these reservoirs to optimize the process. In this context, a novel technology, centered on using cyclic thermochemical fluids to stimulate unconventional formations and thereby reduce breakdown pressure, which has an impact on reducing cost in hydraulic fracturing, is proposed in this research. By the sequential application of these fluids, the objective is to induce thermal shock within the rock, thereby altering its mechanical characteristics and potentially generating hydrocarbons from the total organic carbon content (TOC). These fluids serve a dual role, both releasing and absorbing heat from the rock matrix. To evaluate the efficacy of this method, shale core samples with various organic contents are used. The study aims to investigate how varying the sequence of cyclic thermochemical fluid treatments impacts changes in TOC, mechanical properties, and breakdown pressure. Results showed that breakdown pressure was reduced by 79.3% and 82.6% in shale and organic-rich carbonate mudrock samples, respectively, when the cyclic endothermic–exothermic thermochemical treatment method was applied. A reduction in Young’s modulus in all thermochemically treated samples and changes in Poisson’s ratio showcase the effectiveness of the thermochemical application. Additionally, TOC reduction by 0.94% and 0.78% in the respective samples was noticed, which might qualify the method as having the potential to support TOC maturation. The findings of this research, when applied on a field scale, can improve the efficiency of hydraulic fracturing operations by minimizing costs through the reduction of breakdown pressure, enhancing hydrocarbon recovery efficiency through the formation of microfractures, and mitigating the impact of high pressures during hydraulic fracturing jobs.