Abstract The increasing demand for lithium (Li), driven by the transition to sustainable energy solutions, necessitates a deeper understanding of the sources and mechanisms of Li enrichment in unconventional reservoirs, such as oilfield brines. This study presents a conceptual model that integrates geological, hydrogeological, and geochemical processes to explain the formation of Li-rich oilfield brines. Our model identifies primary Li sources, including Li-bearing igneous rocks and sedimentary deposits, and highlights the critical role of tectonic activity, fault systems, and hydrothermal fluid migration in transporting Li from deep-seated origins into oilfield brines. We also emphasize the importance of hydrologically closed basins, arid climates, and evaporative processes in concentrating Li and other dissolved solids. The model provides a framework for understanding the complex interplay of geological and hydrogeological factors that control Li enrichment in oilfield brines, and have implications for the global exploration of Li resources. By applying this conceptual model, explorers and researchers can identify prospective areas for Li discovery and development, ultimately contributing to a more sustainable and secure Li supply chain.