RE: NAVI've put together a spreadsheet on the junior O&G sector.
According to YE 2007 proven reserves (not including probable) Diaz had 234k bbl and 10,535 MMcf.
Using the somewhat outdated ratio of 6:1 crude:NG gives them 11,939 MMcfe.
At $8.00 NG that gives a NAV of $1.06/share
At $11 NG that gives us a NAV of $1.53/share
Using the rather conservative 'standardized measure', which factors out recovery and retirement costs along with taxes, and uses an NPV-10 calculation, their reserves have an NPV of $41MM. When I factor out debt and cash on hand, the company has an NPV of $0.36/share. I believe this NPV-10 was calculated using $7.50 NG and $85 crude, but you'd have to go and look at the filing to be sure.
Under $.25 share, this stock appears to be at least 50% undervalued even by the most conservative accounting you'll find.
I owned DZR in 2005 and had decent timing getting in and out. Have been buying shares again recently.