What is the main conflict in Twilight in the Desert by Matthew Simmons?

Twilight in the Desert: The Coming Saudi Oil Shock and the World Economy was written by Matthew Simmons, an investment banker from Houston, Texas, who specializes in the energy industry. Simmons believes that Saudi Arabia, the world's single most important oil producing country, is running out of oil, and no one is prepared to deal with the impact. Saudi Arabia claims to have the situation under control and ensures the world that the country can provide the world with however much oil it will need for the next fifty years. Saudi Arabian oil production data has been concealed for more than twenty years now, and Simmons believes this is an attempt to hide the fact that Saudi Arabia's most important oilfields are declining. In the absence of this crucial data, Simmons uses more than 200 technical papers written for the Society of Petroleum Engineers over the past few decades to build a persuasive case.