Stephen Franks has more than 40 years in the petroleum industry. He has worked as a research scientist with Atlantic Richfield's (ARCO) Exploration and Production Technology Company in Plano, Texas, and with Saudi Aramco's Advanced Research Center in Dhahran, Saudi Arabia. He also has worked in petroleum exploration and production (ARCO Oil and Gas Company, ARCO Alaska, Inc.) and as Manager of Geological Headquarters Staff for ARCO in Dallas, Texas. More recently he has been involved in exploration for subsurface lithium-rich brines and other critical minerals. His primary interests and expertise are pore-level reservoir characterization, reservoir quality prediction, clay mineralogy, and the application of formation water chemistry in evaluating well tests and assessing basin and reservoir-scale compartmentalization. He consults for a number of major national and international oil companies and national research centers and for independent oil and gas companies in the USA.