The upper Bell Canyon reservoir sands of the North Delaware basin are very fine-grained, arkosic sands cemented with small amounts of carbonate. Their blanket distribution and sedimentary textures suggest a depositional medium such as density currents.

The geologic history at one stage seems to have involved a pre-depositional sorting of the sand prior to its final transportation across the North Delaware basin. The reservoir sands exhibit a uniformity in texture, and mineralogy that might allow them to be termed "blanket," even though they do not exist with uniform thickness throughout the basin. This thickness ranges from a trace to approximately 70 feet, having a cross-sectional shape characterized by a concave base and a flat top.

The location of these sand bodies seems to be determined by local subsidence or compaction of the pre-Ford sediments. The fact that some of these sand bodies are not continuous over the local adjacent highs gives rise to the trap mechanism of the reservoir. A favorable hydrodynamic condition may also be increasing the efficiency of the trap. Evaluation of the reservoir section is greatly enhanced by core analyses and the Gamma-Ray Sonic type log.

The two most prominent fields in the North Delaware basin are the North Mason and El Mar fields, the former producing since 1952 and the latter since early in 1959. Their average reservoir characteristics are very similar: porosity 24%, permeability 25-34 md., oil saturation 13%, and water saturation 44%.

Wells can be drilled for as little as $20,000 depending on the depth required in the location in the basin. Accumulative production to date is approximately 7,500,000 barrels for the entire Mason and North Mason fields over 8 years, and 950,000 barrels for the entire El Mar field over a 1-year period.

Deeper possibilities exist throughout the 4,000 feet of the Delaware Mountain group, as well as in the pre-Permian sediments. Future discoveries are imminent, for well density is increasing each month. This allows better evaluation of each new test, thereby giving rise to more realistic acreage appraisals.

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