Whiting Petroleum Corporation is engaged in oil & natural gas exploitation, acquisition & exploration activities, primarily in the Gulf Coast/Permian Basin, Rocky Mountains, Michigan & Mid-Continent regions of the US. The Company's focus is on maintaining a balanced portfolio of lower-risk,long-lived oil & natural gas properties that provide stable cash flows to fund projects. Whiting has a balanced portfolio of oil & natural gas reserves, with approximately 51.5% of its proved reserves consisting of natural gas & approximately 48.5% consisting of oil. As of Apr 1, 2003, approximately 65.3% of the 439.2 billion cubic feet equivalent (Bcfe) of proved reserves have been classified as proved developed producing (PDP). Proved developed non-producing (PDNP) & proved undeveloped (PUD) reserves constitute 5.7% & 29%, respectively, of the proved reserves as of Apr 1, 2003.