The Jones sand reservoir in the Schuler field, came under unitized operation on February 15, 1941. Gas injection commenced on July 1, 1941. Under unitized injection of 90 per cent of the produced gas volume, it is estimated that the ultimate recovery will be 20,000,000 barrels of oil more than would have been recovered under a continuation of ordinary primary methods.

The effectiveness of the pressure maintenance operations is controlled by the reservoir characteristics. Some of the most important of these characteristics have been accurately recorded from laboratory analyses of cores, which were taken in nearly all wells, and the study of these data has provided a sound basis for these operations.

"Core graphs" include core-analysis data, electric-log diagrams, and drilling time. These graphs bring out whatever correlations exist between core data and electric logs. Gas-oil contact is clearly indicated and permeability variation is one of the most prominent features.

Cross sections made up of core-permeability profiles bring out the absence of continuity of shaly or silty zones of low permeability or of zones of high permeability; this absence of continuity represents very favorable conditions for the gas-cap type of pressure maintenance.