The Horseshoe Canyon-Gallup field, T. 30-31 N., R. 16-17 W., San Juan County, New Mexico, was discovered in September, 1956. It now contains approximately 90 wells.

The field produces from the Gallup formation of the Mesaverde group. The oil accumulations are stratigraphic and occur in highly localized sandstone lenses. The thickness of these lenses ranges from a feather-edge to more than 20 feet. Although numerous lenses are present, they are usually referred to as belonging to one of the two "sands." The "upper sand," which consists of several interbedded sandstones and shales, is the most widespread. It produces throughout the field. The "lower sand" is long and narrow. It generally consists of not more than two main sand bodies with thin lenses, in places found above and below. It is found throughout the northwest-southeast extent of the field.

Structural information to date is adequate to indicate that it bears only a minor relation to accumulation.

Shallow depths and substantial reserves make this field possibly the best oil investment in the Four Corners area. Average depth is 1,400 feet with over-all cost of approximately $20 per foot for a completed well.

Producible oil reserves per well vary due to the lenticular nature of the reservoirs; however, 3,000 barrels per acre is average. Pay-out period is approximately 7 months with a 4:1 ratio of investment to return.

Future exploration for this stratigraphic type of Gallup accumulation should be limited to the

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band of deposition between the area of continuous beach sands and the seaward pinch-out of the Gallup tongue. In addition, fractured reservoirs with poorly developed sands could be expected throughout this band and for a short distance seaward.

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