Statoil Petroleum As

Equinor Energy As

Westerngeco L.l.p.

Statoil Asa

Electromagnetic Geoservices As

Schlumberger Technology Corporation

Statoilhydro Asa

Services Petroliers Schlumberger

Westerngeco Seismic Holdings Limited

Lasse Amundsen

Harald Westerdahl

Mark Thompson

Lars Ole Løseth

Julian Edward Kragh

Johan O A Robertsson

Tage Rosten

Johan Olof Anders Robertsson

Tage Røsten

Arne Johannes Kaaijk Jenssen

Johan Robertsson

Luc Thomas Ikelle

Frank Agnar Maaø

Egil Holvik

Ørjan Pedersen

Johan Olof Robertsson

Lars Ole Loseth

Johan OA c/o Schlumberger Cambridge Robertsson

Ed c/o Schlumberger Cambridge Res Ltd Kragh

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.

P/S wave measurement and compensation

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.

Method and system for generating geophysical data

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.

Seismic modeling

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 () and receiver () 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.

Method of and apparatus for processing CSEM data, program, storage medium, computer and use of method

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.

CSEM survey method

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.

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.

Apparatus for marine seismic survey

A method of providing seismic data (such as marine seismic data). A seismic source is actuated at a plurality of source locations (S, S). For each source location, a multicomponent seismic measurement is performed at least one receiver location (S). 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 (S). The additional data are output and/or used (S).

Method of providing seismic data

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.

Method of processing marine CSEM data

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.

Method of and apparatus for analyzing data from an electromagnetic survey

A method of determining a vertical component of particle velocity from seismic data acquired using at least one receiver disposed within a water column includes determining the vertical component of particle velocity from the pressure at a first location and a second location. The first location is the location of a first receiver, and is vertically beneath the second location. The method uses an operator accurate for seismic data acquired at a vertical separation between the first and second locations of up to at least 0.4 times the minimum wavelength of seismic energy used to acquire the seismic data. The second location may be at or above the surface of the water column. Alternatively, the method may be applied to a twin streamer seismic surveying arrangement in which the second location is below the surface of the water column and is the location of a second receiver.

Processing seismic data

A method of analyzing an electromagnetic wavefield includes the steps of measuring the electric and magnetic fields at at least one receiver, formulating a respective spatial domain filter in respect of each of mutually orthogonal components of each of the electric and magnetic fields, and applying the filters to the measured acquired data to decompose the wavefield into upgoing and downgoing components.

Electromagnetic wavefield analysis

A method of deriving a calibration filter for electromagnetic data is provided. The method comprises providing a source () of electromagnetic radiation and subsequently measuring components of the source electromagnetic field () at a receiver when the source is sufficiently close to the receiver that the down-going signal dominates over the up-going signal reflected from features below the receiver. Such a measurement can be used in frequency domain analysis () to extract the down-going signal component and derive a calibration filter for the receiver. The method is repeated () for each receiver used in an electromagnetic sounding survey.

Method and apparatus for deriving a calibration filter for electromagnetic data

A method processing an electromagnetic wavefield response in a seabed logging operation. The wavefield is resolved into upgoing- and downgoing components. The downgoing component represents reflections from the sea surface while the upgoing component represents reflections and refractions from subterranean strata. The upgoing component is then subjected to analysis.

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Trondheim, Norway

Lasse Amundsen