In 1979, Nolte1  pioneered an analysis of pressure decline after fracturing to gain information on fluid loss characteristics, fracture dimensions, fluid efficiency and fracture closure time. Since then, this method has received ever increasing attention in the petroleum industry. In the Nolte method, a fracturing job of short duration is performed on a formation, and pressure decline data are collected after shut-in before attempting a large-scale treatment. The information gained from the pressure decline analysis is utilized to design large-scale treatments to help achievebetter performance. This treatment of short duration is conventionally called a 'MINI-FRAC' job. This analysis by Nolte was initially limited to the Perkins and Kern model for fracture geometry. In Nolte's original work, two type curves were developed for analysis, one being used for treatments in which fluid efficiencies are low and the other for treatments in which fluid efficiencies are high.

In the present paper, Nolte's analysis has been extended to two other standard models, i.e. Christianovich-Zheltov and the Penny or radial model. An additional type curve has been developed which can be used for all three models. This type curve should replace one of the Nolte type curves used for high fluid efficiency.

The results of this analysis indicate that for minifrac treatments of short duration, it is advisable to first run a penny model analysis and compare results obtained from the Christianovich-Zheltov model and Perkins and Kern model because at earlier stages of growth the fracture may be penny-shaped. This model also indicates that Christianovich-Zheltov model is less sensitive to the estimate of gross fracture height than the Perkins and Kern model. The estimate of gross fracture height is rather difficult.

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