Abstract: Coherency analysis, such as semblance scan or stacking amplitude, is used to locate diffractors. This is done utilizing traces of a recorded 3-D marine survey with one or more cables. Locations of each diffractor are determined by comparing the lateral coherency of the received amplitudes that each assumed diffractor position generates. Once the diffractors are located, noise energy originating from the diffractors is minimized.

Abstract: Method of processing seismic data corresponding to acquisitions carried out in a medium exhibiting azimuthal anisotropy, characterized in that for two sets of data corresponding, for one and the same seismic variable and for one and the same ground zone, to at least two different source/azimuth receiver pair sectors, an average between the data which correspond to the azimuth considered and data which correspond, for the same variable and the same ground zone, to a perpendicular azimuth sector is determined for each of the azimuths considered, and in that an estimate of the part common to the two sets thus obtained of averaged data is determined.

Abstract: The invention relates to a method for the acquisition of seismic data that uses sources operable to produce, when they are in a shooting station, seismic vibrations according to a sweep type shooting sequence, of predetermined duration and variable frequency. According to this method, the source and recording device clocks are synchronized, shooting is authorized for each of the sources at a series of predetermined shooting times tk,n, with k being an order number for a given source and n a source order number, between 1 and the number of sources Ns, and carried out on condition that the source is in a state to produce vibrations at such time tk,n, and the signals produced by the receivers are continuously recorded. The invention also relates to a system for seismic acquisition that implements this method.

Abstract: A method of seismic processing for obtaining information on the geophysics of the subsoil includes acquiring seismic traces at at least one point on the surface of the subsoil or in the subsoil, the seismic traces corresponding on each occasion to two perpendicular components of a shear wave emitted into the subsoil and reflected by different interfaces therein; applying a succession of transformations (?) at least to a temporal portion of the traces for each of these assumptions, determining the value of a parameter representative of the coherence/similarity between the result traces obtained in this way; and election as a function of the values obtained in this way that one of the hypotheses which is considered as being most representative of the subsoil, the two result traces obtained for said hypothesis being compensated traces of the subsoil birefringency.

Abstract: A device for seismic emission in an underground formation comprising one or more vibrators of any type and method for implementing same. According to a preferred embodiment, each vibrator comprises at least one pillar (1) of sensitive elements (of piezoelectric type for example) between two end plates or slabs (2, 3) and a signal generator for applying vibrational signals to the pillar. The pillar (1) is coated with a protective sheath (4) and the vibrator is positioned in a well or cavity (W) and embedded in a mass of a solid coupling material (7) in contact with protective sheath (4) and the two end plates (2, 3) over at least part of each of the respective faces thereof, which provides coupling of the vibrator with the surrounding formation. The vibrators can be buried at intervals in relation to one another in a well. Sequential triggering thereof with selected delays allows reinforcement of the waves emitted by the device in a preferred direction.

Abstract: The invention relates to an estimate of the seismic illumination fold (x, p) in the migrated 3D domain at an image point x, for a dip of vector p characterized in that the illumination fold I (z, p; s, r) is estimated for each (source s, receiver r) pair in the seismic survey, by applying the following steps:—determination of the reflection travel time tr(·xr(p);s·r) from the source s to the specular reflection point z, on the plane reflector passing through the image point x and perpendicular to the dip vector p, and then return to the reflector r; starting from the diffraction travel time td(·z;s·r) from the source to the said image point x and then return to the reflector r;—incrementing the said illumination fold I (X, p; s, r) related to the said (source s, receiver r) pair as a function of the difference between the diffraction travel time td(x;s,r) and the reflection travel time tr(xr(p)issr).

Abstract: This invention is a method of separating induced microseismicity signals from seismic signals acquired within active seismic monitoring operations carried out in underground zones under development which has application for monitoring of underground hydrocarbon or fluid storage reservoirs. Seismic records are formed from signals emitted by one or more seismic sources controlled by orthogonal signals. In this case, the signals are processed to separate the respective contributions of the at least one seismic source to the signals received and to reconstruct the seismograms equivalent to those that would be obtained by actuating the at least one seismic source separately.

Abstract: A method is provided for predicting a value of a designated rock or fluid property in a subterranean geologic volume. A first predicted value of the designated rock or fluid property is also assigned to a volume of a multi-dimensional, multi-scale model. A first predicted value of seismic response for the model volume is calculated from a response model using the first predicted value of the designated rock or fluid property, wherein the response model is responsive to changes in predicted values of the designated rock or fluid property. A synthetic trace is generated and iteratively compared to the corresponding trace obtained from one or more sets of actual seismic data to determine a difference while consistency is maintained between the types, scales and dimensions of values and data.

Abstract: The invention relates to a method of processing seismic data comprising a gather of seismic traces organised according to one or several acquisition parameters, each trace comprising a seismic signal defined by an amplitude as a function of time or depth, the method comprising the steps of: a) defining a base of elementary functions of the acquisition parameter(s), b) orthogonalising said elementary functions so as to define a base of orthogonal elementary functions c) for a given time or at a given depth, determining combination coefficients defining a combination of the orthogonal elementary functions, said combination being an estimator of a variation in the amplitude of the seismic signal as a function of the acquisition parameter(s).

Abstract: Method of processing a collection of seismic cubes corresponding to one and the same acquisition zone and to various moments of acquisition, characterized in that at least one seismic cube which is an estimate of the component common to at least two seismic cubes corresponding to different moments of acquisition is determined and this estimate of common component is subtracted from at least one of the two initial cubes.

Abstract: Seismic emission system for use in an underground formation, using at least one seismic source movable successively in a plurality of prepared activation locations and method for implementing same. The system comprises for example a plurality of coupling devices (1) including each for example two anchor elements (12, 9?) tightly coupled with the formation (by cementing for example). These anchor elements are secured to the seismic source (V) such as a vibrator of any type or an impulsive source by transmission elements (10, 13). The seismic source is coupled with coupling device (1) by fast locking means (18, 19). Coupling devices (1) can be preinstalled at a plurality of prepared activation locations above the formation to be monitored. Seismic monitoring operations can be carried out by moving at least one seismic source successively between the different locations where coupling devices (1) are installed.

Abstract: A method for deploying and retrieving seafloor equipment modules is disclosed. A conveyor has a fixed end and a free end. The conveyor is deployed into a body of water until the free end reaches, or is proximate to, the seafloor. The conveyor is dragged through the water. The equipment modules are slidably attached to the conveyor. The equipment modules slide along the conveyor to the seafloor, where the equipment modules engage the seafloor and are secured at a fixed position.

Abstract: Method and system intended for seismic monitoring of an underground zone (1), comprising simultaneously using several seismic vibrators. The system comprises for example several local units (LU) comprising each a vibrator (5), a seismic pickup antenna (2), a local acquisition and processing unit (6), and a central control and synchronization unit (8) for simultaneously controlling the various vibrators by means of orthogonal signals, local units (6) being suited, by means of particular; processing, to isolate and to reconstitute the seismograms corresponding to the contributions of the various vibrators. Applications: monitoring of a hydrocarbon reservoir during production or of a reservoir used for gas storage for example.

Abstract: A method of processing seismic traces corresponding to two modes of propagation in the subsoil, the method being characterized by the following steps: determining at least one pair of correlated events from the seismic traces corresponding to the two modes respectively; determining the ratio of the differences between the vertical travel times Ts and Tp in the S domain and in the P domain, corresponding to said correlated pairs of events; and determining the values of Ts and Tp over the time interval defined by the two pairs of correlated events so that throughout said time interval, the ratio rt=Ts/Tp is equal to the ratio Vp/Vs of the speeds in the P domain and in the S domain, and so that the mean value of said ratio r over said time interval corresponds to the ratio of the differences between the vertical travel times corresponding to the pairs of correlated events.

Abstract: The present invention comprises a non-iterative method of processing seismic traces. A constrained High Resolution Radon decomposition is performed at various frequencies in which the Radon decomposition at a given frequency is constrained as a function of the Radon decomposition at at least a lower frequency. It is emphasized that this abstract is provided to comply with the rules requiring an abstract which will allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope of meaning of the claims.

Abstract: The invention relates to a vibroseis analysis method in which frequency-sweep signals (10) are emitted into a subsurface, the signals reflected on the substrata of such a subsurface (10, 20) are logged and the logged signals are processed, a method in which the harmonics (20) of the fundamental signal (10) initially emitted are eliminated from the logged signals, by applying the steps consisting in: a) providing a time/frequency plot, showing the respective contributions of the fundamental (10) and of the harmonics (20) in the logged signal, b) providing a time/frequency plot also showing these contributions of the fundamental (10) and of the harmonics (20) in the logged signal, this plot having been stretched in the direction of the frequency axis such that the fundamental (10) of this plot is over the location of a harmonic (20) chosen from the plot; c) adapting the power amplitude of this stretched plot to make this amplitude correspond to that of the said chosen harmonic (20) of the plot; d) subtracti

Abstract: Seismic wave reception device comprising a hydrophone and/or a geophone and method for coupling it (or them) with a solid medium such as the subsoil. The device comprises at least one hydrophone (2) immersed in a closed flexible-walled sheath (7) filled with liquid (8) that is closed at one end by a sealed plug (9) provided with a sealed duct for a cable (10) connecting the hydrophone to a signal acquisition means (E). The sheath is arranged in a cavity (6) and tightly coupled with medium (5) substantially over the total surface thereof, preferably by means of a hardenable material such as cement. A geophone can be placed in the same coupling material in the vicinity of sheath (7) containing hydrophone (2). Application: seismic prospecting or monitoring operations in an underground formation, notably in order to discriminate the seismic upgoing and downgoing waves.

Abstract: A method of inverting events that have been picked from a depth-migrated seismic trace, wherein a collection of traces is determined by depth migration prior to addition, the traces reflecting vertically below, a given surface point, and processing is applied to said collection of traces in order to select a velocity field parameterization which optimizes the alignment of points which are migrated from said collection of traces.

Abstract: A seismic processing method to solve an eikonal equation to determine a travel time (t) of a sound wave between a seismic source at a first set of coordinates (x2,y2, z2) and a point underground at a second set of coordinates (x,y,z), comprising determining a distance between the seismic source and the point underground; obtaining a propagation time between the seismic source and the point underground; calculating a velocity variable (v) as a ration of the distance between the seismic source and the underground point divided by the propagation time between the seismic source and the point underground; and extrapolating on the velocity variable to obtain a travel time.

Abstract: Compact vibrator for emitting elastic waves in a material medium such as the subsoil. The vibrator comprises a baseplate (3) intended to be coupled in operation with a surface of this medium, an inertia mass (5) and at least a pair of electromechanical transducers (1, 2) comprising each one or more pillars (A, B) made for example of a piezoelectric or magnetostrictive material. Pillars (A) of first transducer (1) are interposed between baseplate (3) and a relay plate (4). Pillars (B) of the second transducer are interposed between relay plate (4) and inertia mass (5), on the same side of relay plate (4) as pillars (A) preferably, so that inertia mass (5) is positioned in the vicinity of baseplate (3), which contributes to the compactness and to the stability of the vibrator that can therefore be used on slightly sloping surfaces.