Abstract: Method for inverting, in the frequency domain (42), controlled source electromagnetic survey data (41) acquired using a time-division compound waveform made up of sub-sequences of different base waveforms, for example square waves of different frequencies. A windowed Fourier decomposition method is used, with the window size and shape designed in consideration of the sub-sequences. The window length may be twice the length of the compound waveform, or more. Alternatively the window length may be comparable to the sub-sequence length, or slightly less. Window shapes include cos2, rectangular, and triangular. The method addresses the problem of unknown arrival times for each sub-sequence, and also transition transients that occur between sub-sequences.

Abstract: A method for detecting hydrocarbons is described. The method includes obtaining seismic data associated with a body of water in a survey region, analyzing the seismic data to identify at least one noise indicator to produce a noise indicator image; and determining seepage locations by comparing the at least one noise indicator image to the seismic data.

Abstract: A method for detecting hydrocarbons is described. The method includes obtaining seismic data associated with a body of water in a survey region. Then, a filter is applied to at least a portion of the seismic data to enhance diffraction anomaly signals with respect to horizontal or nearly horizontal signals associated with the water-column to form filtered seismic data. Once filtered, seepage locations are identified from the filtered seismic data.

Abstract: Method and system is described for marine surveying. The method involves operations for exploring and developing hydrocarbons with one or more unmanned vehicles. The unmanned vehicles are used to perform marine surveying and to obtain one or more samples that may be used to identify chemical, hydrocarbon and/or biologic information, which may be used for environmental monitoring of bodies of water.

Abstract: Method and system is described for hydrocarbon exploration and development. The method and system include one or more remote devices, such as buoys, which are utilized to identify and collect samples of target materials. The buoys include measurement components, sampling components and storage components to manage the obtained samples.

Abstract: Method and system is described for hydrocarbon exploration and development. The method and system include one or more remote devices, such as buoys, which are utilized to identify and collect samples of target materials. The buoys include measurement components, sampling components and storage components to manage the obtained samples.

Abstract: Method and system is described for marine surveying. The method involves operations for exploring and developing hydrocarbons with one or more unmanned vehicles. The unmanned vehicles are used to perform marine surveying and to obtain one or more samples that may be used to identify chemical, hydrocarbon and/or biologic information, which may be used for environmental monitoring of bodies of water.

Abstract: A method for detecting hydrocarbons is described. The method includes obtaining seismic data associated with a body of water in a survey region. Then, a filter is applied to at least a portion of the seismic data to enhance diffraction anomaly signals with respect to horizontal or nearly horizontal signals associated with the water-column to form filtered seismic data.

Abstract: Method for inverting, in the frequency domain (42), controlled source electromagnetic survey data (41) acquired using a time-division compound waveform made up of sub-sequences of different base waveforms, for example square waves of different frequencies. A windowed Fourier decomposition method is used, with the window size and shape designed in consideration of the sub-sequences. The window length may be twice the length of the compound waveform, or more. Alternatively the window length may be comparable to the sub-sequence length, or slightly less. Window shapes include cos2, rectangular, and triangular. The method addresses the problem of unknown arrival times for each sub-sequence, and also transition transients that occur between sub-sequences.

Abstract: There is provided a system and method for creating a physical property model representative of a physical property of a region. An exemplary method comprises transforming information from a model domain that represents the physical property model into simulated data in a data domain, the data domain comprising simulated data and measured data representative of a plurality of observations of the region. The exemplary method also comprises determining an areal misfit between the simulated data and the measured data representative of the plurality of observations of the region. The exemplary method additionally comprises performing an evaluation of the areal misfit based on known criteria. The exemplary method comprises adjusting data in the data domain or information in the model domain corresponding to a region in the model domain based on the evaluation of the areal misfit.

Abstract: A method and apparatus of constructing a signal for a controlled source electromagnetic survey is described. In one embodiment, a method is described that includes determining a first waveform and a second waveform, the first waveform and second waveform related to a combined frequency spectrum and bandwidth associated with a geophysical survey line. Then, a signal is constructed by sequencing the first waveform with the second waveform. This signal may be utilized in a transmitter, which may be pulled by a vessel along the geophysical survey line.

Abstract: A method and apparatus for evaluating submarine formations, such as geological formations located generally under a body of water. Multiple hydrofoils (130), responding to moving water, hydrodynamic, or Bernoulli forces, provide controllable orientation and separation for multiple receivers (135) as they are towed (125) through water (110) in the course of a geophysical survey such as a controlled source electromagnetic survey. The inventive method can be used to provide mutual orthogonality for three antennas in a multiple component electromagnetic receiver.

Abstract: A waveform design method is presented for controlled source electromagnetic surveying. A desired source spectrum (82) is specified based on a desired resistivity depth image resolution (81) with spectral amplitudes determined by expected noise levels (83). Techniques are disclosed for designing a source waveform to match the desired source spectrum. When better resolution is desired at a target zone, this leads to a required clustering of frequency components. A modulated waveform can be used to provide this clustering of frequency components.

Abstract: A method for designing a controlled-source electromagnetic survey that will discriminate between a defined deep marginal-interest reservoir (2) and specified false positive resistivity structures of concern (3, 4, 5). A reservoir model and a false positive model are constructed for each false positive scenario. The resistivity of the false positive model may be tuned to give electromagnetic data similar enough to the reservoir model when forward modeled that any differences fall in the model null space. A null-space discriminating ratio (“NSDR”) is defined, for example as the peak normalized difference of the two related modeled electromagnetic field data sets. An area coverage display of NSDR values (6) allows determination of such additional data as may be needed to distinguish the false positive body, and a survey design is developed accordingly (7). Reduction of the number of variables affecting the area coverage displays is a key feature of the method.

Abstract: Method for reducing air wave and/or magnetotelluric noise in controlled source electromagnetic surveying by either shielding the source (61) from the air interface, shielding the receivers from downward traveling electromagnetic energy, or by employing a second source (62) to preferentially cancel the air wave (and MT) part of the signal, or a combination of the preceding.

Abstract: A method and apparatus of constructing a signal for a controlled source electromagnetic survey is described. In one embodiment, a method is described that includes determining a first waveform and a second waveform, the first waveform and second waveform related to a combined frequency spectrum and bandwidth associated with a geophysical survey line. Then, a signal is constructed by sequencing the first waveform with the second waveform. This signal may be utilized in a transmitter, which may be pulled by a vessel along the geophysical survey line.

Abstract: A method and apparatus of constructing a signal for a controlled source electromagnetic survey is described. In one embodiment, a method is described that includes determining a first waveform and a second waveform, the first waveform and second waveform related to a combined frequency spectrum and bandwidth associated with a geophysical survey line. Then, a signal is constructed by sequencing the first waveform with the second waveform. This signal may be utilized in a transmitter, which may be pulled by a vessel along the geophysical survey line.

Abstract: There is provided a system and method for creating a physical property model representative of a physical property of a region. An exemplary method comprises transforming information from a model domain that represents the physical property model into simulated data in a data domain, the data domain comprising simulated data and measured data representative of a plurality of observations of the region. The exemplary method also comprises determining an areal misfit between the simulated data and the measured data representative of the plurality of observations of the region. The exemplary method additionally comprises performing an evaluation of the areal misfit based on known criteria. The exemplary method comprises adjusting data in the data domain or information in the model domain corresponding to a region in the model domain based on the evaluation of the areal misfit.

Abstract: A waveform design method is presented for controlled source electromagnetic surveying. A desired source spectrum (82) is specified based on a desired resistivity depth image resolution (81) with spectral amplitudes determined by expected noise levels (83). Techniques are disclosed for designing a source waveform to match the desired source spectrum. When better resolution is desired at a target zone, this leads to a required clustering of frequency components. A modulated waveform can be used to provide this clustering of frequency components.

Abstract: A method for seismic exploration using nonlinear conversions between electromagnetic and seismic energy, with particular attention to the electromagnetic source waveform used. According to the invention, seismic returns from a source waveform are correlated with a reference waveform, with both waveforms custom designed to minimize both correlation side lobes and interference from linear electroseismic effects. A waveform element is selected which may be sequenced by a binary or similar digital code embodying the desired custom design to generate an input sweep with the needed depth penetration and noise suppression. Correlation of the seismic response with the reference waveform in a data processing step mathematically aggregates the seismic response from the input sweep into a single wavelet. Preferred binary digital codes include prescribed variations of maximal length shift-register sequences. Also, an apparatus for generating the desired waveforms.