The history of oilmen and the energy bankers who loan them capital is inextricably bound together. Energy bankers have reacted, adjusted and evolved alongside the same business cycles, regulatory changes and commodity-price gyrations that have challenged the generations of oilmen they banked. In many respects, however, it is remarkable how little has changed during the past 100 years in the fundamentals of lending against collateral that has been hidden underground for millions of years. Nor has there been much change in the relationship between the early wildcatters willing to risk...