Abstract: A method for use in surveying a subsurface region beneath a body of water by detecting compressional, P, waves propagating through the body of water includes locating one or more sensor systems in the water at or close to the subsurface region, using the or each sensor system to detect P waves in the water, and translating all or a portion of the data representing the detected P waves to a higher level above the subsurface region. In the method, the effects of S waves, propagating in the subsurface and converted at the water/subsurface interface into P waves propagating in the water or along the seabed interface, in the translated data is reduced.

Abstract: A method of generating geophysical data using at least one source. The method may include the steps of generating a geophysical wavefield with a varying signature using at least one source, wherein the signature is varied in a periodic pattern.

Abstract: A method of seismic modeling using an elastic model, the elastic model including a grid having a grid spacing sized such that, when synthetic seismic data is generated using the elastic model, synthetic shear wave data exhibits numerical dispersion, the method including: generating generated synthetic seismic data using the elastic model, wherein the generated synthetic seismic data includes synthetic compression wave data and synthetic shear wave data, and modifying the generated synthetic seismic data to produce modified synthetic seismic data by attenuating at least some of the synthetic shear wave data in order to attenuate at least some of the numerically dispersive data.

Abstract: A method of generating geophysical data using at least one source. The method may include the steps of generating a geophysical wavefield with a varying signature using at least one source, wherein the signature is varied in a periodic pattern.

Abstract: A method of generating geophysical data using at least one source. The method may include the steps of generating a geophysical wavefield with a varying signature using at least one source, wherein the signature is varied in a periodic pattern.

Abstract: A method of processing controlled source electromagnetic (CSEM) data is provided for reducing the airwave contribution. CSEM data are acquired, for example using a conventional towed source (4) and receiver (5) arrangement. The recorded data are weighted in accordance with the geometrical spreading of the airwave component. The differences between pairs of weighted data records are then formed.

Abstract: A method of seismic modeling using an elastic model, the elastic model including a grid having a grid spacing sized such that, when synthetic seismic data is generated using the elastic model, synthetic shear wave data exhibits numerical dispersion, the method including: generating generated synthetic seismic data using the elastic model, wherein the generated synthetic seismic data includes synthetic compression wave data and synthetic shear wave data, and modifying the generated synthetic seismic data to produce modified synthetic seismic data by attenuating at least some of the synthetic shear wave data in order to attenuate at least some of the numerically dispersive data.

Abstract: There is disclosed a method of performing a controlled source electromagnetic survey, which includes in one embodiment deploying a receiver and an electric dipole source. The source defines a dipole axis. An electromagnetic field is transmitted from the electric dipole source. First and second horizontal components of an electromagnetic field response are detected using the receiver. A vertical component of the electromagnetic field response is then estimated using the detected first and second horizontal components of the electromagnetic field response.

Abstract: A method for use in surveying a subsurface region beneath a body of water by detecting compressional, P, waves propagating through the body of water includes locating one or more sensor systems in the water at or close to the subsurface region, using the or each sensor system to detect P waves in the water, and translating all or a portion of the data representing the detected P waves to a higher level above the subsurface region. In the method, the effects of S waves, propagating in the subsurface and converted at the water/subsurface interface into P waves propagating in the water or along the seabed interface, in the translated data is reduced.

Abstract: A method for use in surveying a subsurface region beneath a body of water by detecting S waves propagating through the subsurface region. The method comprises using a first sensor configuration to detect mixed S and P waves on or in the subsurface region, using a second sensor configuration located on or in relatively close proximity to the subsurface region to detect P waves in the water, and using the P waves detected in the water to compensate the detected mixed S and P waves, and thereby attenuate the effects of P waves in the mixed S and P waves.

Abstract: A method of generating geophysical data using at least one source. The method may include the steps of generating a geophysical wavefield with a varying signature using at least one source, wherein the signature is varied in a periodic pattern.

Abstract: A method for use in surveying a subsurface region beneath a body of water by detecting S waves propagating through the subsurface region. The method comprises using a first sensor configuration to detect mixed S and P waves on or in the subsurface region, using a second sensor configuration located on or in relatively close proximity to the subsurface region to detect P waves in the water, and using the P waves detected in the water to compensate the detected mixed S and P waves, and thereby attenuate the effects of P waves in the mixed S and P waves.

Abstract: An apparatus for conducting a marine seismic survey is disclosed. The apparatus includes a plurality of sensors configured to measure water pressure, a horizontal derivative of the pressure in two orthogonal directions, vertical particle velocity or acceleration of the water, and a horizontal derivative of the vertical particle velocity or acceleration in two orthogonal directions.

Abstract: A method of providing seismic data (such as marine seismic data). A seismic source is actuated at a plurality of source locations (S2, S4). For each source location, a multicomponent seismic measurement is performed at least one receiver location (S3). A reconstructing method is applied to each multicomponent measurement to obtain additional data corresponding to source locations additional to the source locations at which the source was actuated (S5). The additional data are output and/or used (S6).

Abstract: A method is provided for processing marine controlled source electromagnetic data. Inline and broadside marine controlled source electromagnetic data are provided, for example by means of one or more horizontal electric dipoles and one or more receivers disposed in a water column above a subsurface to be surveyed. A linear combination of the inline and broadside data is formed so as to reduce the airwave content.

Abstract: An apparatus for conducting a marine seismic survey is disclosed. The apparatus includes a plurality of sensors configured to measure water pressure, a horizontal derivative of the pressure in two orthogonal directions, vertical particle velocity or acceleration of the water, and a horizontal derivative of the vertical particle velocity or acceleration in two orthogonal directions.

Abstract: A method is provided for analyzing data from an electromagnetic survey of a region so as to indicate the presence of a hydrocarbon reservoir. The survey provides vertical magnetic dipole data and electric dipole data, or provides measurement data from which these dipole data may be determined. The amplitude of the vertical magnetic dipole data is determined, optionally after normalising the data with reference date relating to the same region. Similarly, the amplitude of the electric dipole data is determined, optionally after similarly being normalised. The amplitudes are then compared to provide an indication of the likelihood of the presence of hydrocarbons in the region.

Abstract: There is disclosed a method of performing a controlled source electromagnetic survey, which includes in one embodiment deploying a receiver and an electric dipole source. The source defines a dipole axis. An electromagnetic field is transmitted from the electric dipole source. First and second horizontal components of an electromagnetic field response are detected using the receiver. A vertical component of the electromagnetic field response is then estimated using the detected first and second horizontal components of the electromagnetic field response.

Abstract: A method of processing controlled source electromagnetic (CSEM) data is provided for reducing the airwave contribution. CSEM data are acquired, for example using a conventional towed source (4) and receiver (5) arrangement. The recorded data are weighted in accordance with the geometrical spreading of the airwave component. The differences between pairs of weighted data records are then formed.

Abstract: A method of providing seismic data (such as marine seismic data). A seismic source is actuated at a plurality of source locations (S2, S4). For each source location, a multicomponent seismic measurement is performed at least one receiver location (S3). A reconstructing method is applied to each multicomponent measurement to obtain additional data corresponding to source locations additional to the source locations at which the source was actuated (S5). The additional data are output and/or used (S6).