VICO's tighter gas sands in the 12000- to 13000-ft. depths have proven to be very difficult to produce efficiently. During the past two decades, hydraulic fracturing and acid stimulation of these zones has proven to be economically, mechanically, and logistically impractical. Recent evaluations of the damage mechanisms in these formations have indicated that crushed zone effects after perforating might be playing a larger role in some zones than previously thought. Thus, new techniques to increase production efficiency have been sought. Two perforating techniques are showing particular promise.

Extreme overbalance perforating, incorporating proppant with some of the highest pressures used to date (nearly 15,000 psi surface and 19,000 psi at depth), have been successfully executed and the results using this method have been encouraging.

The other new perforating method is the extreme underbalance technique, This method employs a specially designed modular gun system. and has been used in monobore completions. Underbalance as high as 4700 psi was achieved. The jobs have resulted in some of the most prolific wells in these reservoirs.

For the first time in the industry, new equipment technology that allows a true comparison between underbalance and extreme overbalance techniques has also been employed.

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