Generally, water saturations in the Devonian Shale are low. Production records indicate minimal, if any, water in the areas producing gas or gas and oil. This low water saturation appears to be the key to stimulating the shale, especially in the oil-producing areas.

The introduction of water in the stimulation fluid appears to reduce the permeability to oil, which is reflected in poorer production. The relative permeability reduction seems to be more of a problem than particle migration or clay swelling and could explain the good initial results from straight nitrogen treatments. However, the lack of a proppant, even with low closure stress, leads to very rapid declines.

Water-base stimulation fluids appear to increase water saturation in the Devonian Shale. Use of 90+ quality foam with sand should provide a method of minimizing saturation changes while creating a propped fracture. Initial results indicate this technique provides better sustained production increases in the Devonian Shale.

This paper defines areas of production, describes the geology and presents physical data of the Devonian Shale. It also compares results of several types of treatments that have been used in the Devonian Shale. These results indicate 90+ quality foam with sand should provide an improved stimulation technique for this formation.

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