It is useful to map hydraulic fractures in order to improve the rate of success of such operations and to optimize the pattern of stimulated wells. The proposed method can be used during a minifracturing or prefracturing operation and necessitates a downhole 3D acoustic detector clamped in the well. A few to a few dozen cubic meters of gel being injected during fracturing phases, the acoustic activity is recorded after every injection, then signals containing apparent P and S waves are analyzed to determine the directions and distances of the emitting sources. A number of arrivals cannot be easily interpreted, in particular those corresponding to refractions along the casing. Two field examples corresponding to a vertical and an inclined fracture are given. Knowing the P and S wave velocities in the different layers and a careful choice of the tool position are essential to the success of the method.

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