ABSTRACT

A new geologic evaluation of Swan Lake field led to the discovery of twenty-four new reservoirs. The field was originally found in March, 1950; and initial development drilling ended in 1957. Sun Oil Company took over operations in 1970. A new Lower Frio structural interpretation indicated the crest of the deep closure had not been penetrated. The Sun Oil Company No. 27 G. T. Brooking, drilled in December, 1972, found new deep production. New reservoirs were also discovered in the previously drilled upper part of the Frio section.

The improved logging techniques used in the wells alowed a more quantitative look at all the sands. Combination logging tools providing a simultaneous recording of induction resistivity, acoustic velocity, and computed Rwa curve were used exclusively. Using the Rwa curve as a hydrocarbon indicator, low resistivity sands that appeared wet from casual examination were tested and found productive. Other sands which appeared to have no vertical separation from overlying water sands were tested and found productive.

Twelve new wells were drilled from 1972 through 1974. The drilling program resulted in a significant increase in the daily gas and oil production rate. Multiple recompletion opportunities which will minimize the production decline rate in the near future were also created.