Institut Francais Du Pe'trole

Compagnie Generale De Geophysique

Companie General De Geophysique

Yves R Ollivier

Jean Laurent

Charles Naville

Guy Pignard

Pascal Dedole

A VSP or reversed VSP type seismic prospecting method according to the invention allows disturbances contained in seismic recordings produced by tube waves propagating along wells and refracted in zones close to the surface to be minimized. The method disperses a gas under pressure, having preferably a high compressibility, capable of absorbing these tube waves. The gas may be generated by an explosive chemical reaction set off in situ, at a certain depth of the well (which may constitute the seismic wave source). The method has an application for seismic prospecting or drilling noise monitoring.

Seismic prospecting method and device in wells allowing guided waves filtering

The invention concerns an apparatus for the acquisition of a seismic signal transmitted by a drill bit, placed at the end of a drill pipe rotating about an axis of rotation. According to the invention, the acquisition apparatus consists of a coupling connector (110) intended to be fixed to the said drill pipe (10), an insulating rotor (120), designed to be fixed to the said connector, and fitted with parallel strip conductors (121,122) connected respectively to the outputs of at least one vibration transducer (111) integral with the connector/rotor combination, means (151) for fixing the rotor (120) to the connector (110) and means (152) for centering placed on the said coupling connector, designed to maintain the said strip conductors (121,122) centered on the axis of rotation (21), and a stator (160) forming a retaining ring on the said insulating rotor (120) and containing contacts (161,162) provided to cooperate respectively with the strip conductors of the rotor, and the relative motion of the stator (160) and the rotor is ensured by at least support bearings (163,164). Application to the geophysical survey or the subsoil.

Apparatus for the acquisition of a seismic signal transmitted by a

Device for generating seismic impulses for, for example, seismic prospecting, inside a hole or drilling well by impact of a weight or mass falling onto a target element coupled with a wall of the hole or drilling well. The target element is bound up with a variable volume anchorage element capable of being expanded so that it strikes against the wall of the hole or drilling well and is surmounted by a guiding column along which slides a hammer or weight forming the mass. A cable lifting system and magnetic devices enable the hammer or weight to be hoisted to a particular height above the target element.

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Lardy, France

Yves R Ollivier