High-rate acid fracturing treatments

Foamed acids can be effective in improving contact with longer treatment intervals. As in fracture acidizing, most foams are 60-75 quality. The lightness of foam makes it an effective stimulation fluid for damaged gas wells. As with emulsions, the pumping of foam at high rates is not always possible. 

Overflush. The purpose of the overflush is to displace add from the wellbore and push the acid volume forward, thereby increasing the penetration distance. When viscous acid is used, a large overflush can effectively increase the etched fracture length. The overflush is a critical step in the treatment design. A high rate is beneficial. 

This technique calls for the pumping of acid treatment stages at as high a rate as possible, but below fracturing pressvne. 

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