Method and device intended for permanent monitoring of an underground formation

摘要

The invention is a method and device for permanent seismic monitoring of an underground formation by means of one or more seismic emission-reception sets comprising a source (S) such as a vibrator and elastic wave receivers (R1, R2, . . . , Rn) such as geophones and/or hydrophones. A well (W) is drilled into the ground. Seismic receivers (R1 to Rn) are lowered therein and coupled with the surrounding formation. The section of the well is widened in the upper part thereof so as to form a cavity (P) against whose walls the seismic source (S) is pressed. Receivers (R) and source (S) are connected to an outside signal control and acquisition station (ST). The wells (W) can be exploration wells that are drilled for example around wells intended for production of reservoirs containing fluids, or mixed exploration and production wells. Each source can also be coupled with a cavity next to the well. The operations intended for setting of these equipments are relatively simple and the site coverage area of the various wells is reduced, which facilitates their integration in reservoir production sites. The method and device can be applied for monitoring of oil-bearing reservoirs or of gas storage reservoirs.