Application of multiscale technology to oil and gas field development: A review of the state of the art in chemical modification of rock wettability

With the gradual depletion of global petroleum resources, an in-depth understanding and precise control of reservoir wettability has become key to enhancing oil recovery. This review systematically examines the research progress and application prospects of various chemical agents—including surfactants, chelating agents, nanomaterials, modified brines and alkali solutions, and polymers—in controlling reservoir wettability. Current studies are primarily based on crude oil characteristics and natural core samples, and are constrained by the complexity of mineral composition and crude oil chemistry. Future experiments should systematically investigate the interactions between active crude oil components and rock minerals, and employ advanced characterization techniques to deepen understanding of wettability-control mechanisms. Although most surfactants are cost-effective, their stability in complex reservoir environments is poor, which limits their application. Emerging gemini and composite surfactants have demonstrated good potential for wettability alteration; future research should develop highly adaptable surfactants through multi-ion synergistic effects. The selection of chelating agents and operational parameters requires further optimization, and their wettability-control mechanisms and synergistic effects with surfactants should be elucidated. The application of nanomaterials in wettability modification is still in its early stage, with issues such as colloidal stability and adsorption kinetics requiring further investigation. Despite the risk of pore-throat blockage in high-salinity, low-permeability reservoirs, optimizing nanomaterial formulations remains an effective solution. Low-mineralization water injection shows application potential, but its water-source compatibility and production-enhancement mechanisms remain controversial. Future efforts should focus on developing efficient, alkali-free composite flooding systems to overcome current technological bottlenecks. Field deployment still faces multiple challenges, including adsorption loss, precipitation plugging, formation damage, and cost-environmental concerns; it is recommended to optimize formulations and injection strategies through refined pilot tests, while developing green, biodegradable multi-component chemicals to achieve large-scale application of chemical EOR. This study also explores multiscale techniques for chemical-induced wettability alteration, providing novel insights and integrated strategies for advancing wettability-control research, ultimately aiming to bridge theoretical knowledge and field application in oil and gas extraction.