Exxon made waves in the energy M&A markets by announcing its acquisition of Denbury, Inc. In total, the headline value was around $4.9 billion. However, while Denbury is an energy company on the whole, it is made up of two main segments that have very different economics, and neither of their business segments appears to be worth the $4.9 billion price tag. So what did Exxon buy exactly, and how might one value it?