Method for improved identification of seismic events in a subsurface area under oilfield production conditions

摘要

Receivers (R) are placed in shaft(s) to collect elastic waves from underground and a reference detector (T) has a direct acoustic coupling to the exploitation equipment. The data from the receivers and reference detector are collected and compared, to divide them into sets indicating events which are independent of the exploitation, or directly or indirectly dependent. A catalogue of event types is established with a causal link between the exploitation, by correlating the signals. Recordings of events connected to hydraulic fracturing are selected and the fractures located by comparative analysis of the component signals from at least two receivers. Permanent receivers are installed in the shafts behind a lining tube or in the annular space between a lining tube and a shaft so it is left free for underground exploitation. The permanent receivers are installed in the same or different shafts. The reference detector is acoustically coupled to the exploitation equipment. The receivers are installed at different depths to allow the direction of propagation of events to be determined. System for applying this method, with receivers (R), detectors (T), means (27) of recording the signals, means (6) of transmitting and treating (7) the data.