Over the last three years, Shell's McAllen Ranch Field in Hidalgo County, Texas, has increased daily production rates by nearly 300%. This dramatic increase in production is due to a combined program of recompletions, commingling and an aggressive development drilling campaign, touched off by a field study and supported by a 3-D seismic survey. This recent development program has been very successful. The first eighteen wells have booked over 100 BCF and additional drilling locations are being evaluated.

This paper highlights the development program which concentrated on optimizing well locations through a better understanding of structure and stratigraphy. A detailed study of the "S" sand in North McAllen has shown this reservoir to be a stratigraphic trap with structurally related porosity development and capillarity-controlled downdip limits. Updip production limits have been identified by the event amplitude on the 3-D seismic survey and are supported by well control. Structural mapping from the 3-D survey indicates that, in addition to a number of major faults, the "S" sand is broken by a series of radial faults that exhibit small amounts of throw (<100 feet). They do not act as seals but do influence well locations.

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