CHANGE IN STANDARDIZED MEASURE

     Changes in the standardized measure of future net cash flows relating to proved oil and natural gas reserves are summarized below:

     Sales of oil and natural gas, net of oil and natural gas operating expenses, are based on historical pretax results. Sales of oil and natural gas properties, extentions and discoveries, purchases of minerals in place and the changes due to revisions in standardized variables are reported on a pretax discounted basis, while the accretion of discount is presented on an after-tax basis.