Pgs Geophysical As

Scania Cv Ab

Peter Lindqvist

Robert Andras Juhasz

Mattias Südow

Frederick James Barr

Johan Mattsson

Philip Heelan

Joel Skogman

Erik Björnemo

Erik Bjornemo

James Mackay

Panagiotis Verras

A method and apparatus for a streamer having a total field magnetometer ('TFM'). A streamer includes a plurality of TFMs in proximity with one another and distributed symmetrically about an axis of the streamer. A streamer includes a first subset of TFMs in a streamer section and in proximity with one another; a second subset in the streamer section and in proximity with one another; wherein the first subset is not in proximity with the second subset. A method includes towing a streamer through a body of water, the streamer comprising first and second TFMs; acquiring magnetic data with the first and the second TFMs; and reducing noise in the data based on at least one of: averaging data from the first and the second TFMs; filtering data from the first and the second TFMs; estimating motion of the first TFM; and estimating rotation of the first TFM.

Noise reduction for total field magnetometer measurements

A method and system for estimation of electromagnetic earth responses in a marine electromagnetic survey. A method may comprise estimating initial values of the electromagnetic earth responses and ambient noise applicable to the marine electromagnetic survey; and processing electromagnetic data based on the initial values of the electromagnetic earth responses and the ambient noise to obtain a joint estimation of updated values of the electromagnetic earth responses and the ambient noise, wherein the electromagnetic data was acquired with one or more electromagnetic sensors, wherein the electromagnetic data contains measurements of an electromagnetic field.

Joint estimation of electromagnetic earth responses and ambient noise

Embodiments described herein provide an EM source cable assembly with a buoyant member having first and second ends, and a longitudinal axis connecting the first end to the second end, and a plurality of indentations disposed along a surface of the buoyant member between the first end and the second end, wherein the indentations are operable to receive corresponding cables. The indentations extend along the longitudinal axis, and may be arranged helically about the longitudinal axis. The buoyant member may have a low density core material and a dense outer material, each of which may be a polymeric material. The low density material may be a foam, and the buoyant member may be formed by coextruding the low density material and the dense outer material.

Buoyant marine electromagnetic cable assembly

Disclosed are methods and apparatus for electromagnetic surveying using dynamically-selected source waveforms. In accordance with an embodiment of the invention, a source waveform is adapted by dynamically selecting a source waveform from the set of pre-calculated waveform sequences. The dynamic selection of the source waveform may depend on a measured background noise level. Other embodiments, aspects, and features are also disclosed.

Methods and apparatus for electromagnetic surveying using dynamically-selected source waveforms

Methods and systems for determining and removing swell noise from electric field data collected from streamers towed at different are disclosed. In one aspect, a first set of streamers called upper streamers is towed at a shallow depth, and the second set of streamers called lower streamers is towed below the upper streamers. Receivers located along the streamers measure surrounding electric fields and produce electric field signals. A proportionality parameter is calculated as a function of the electric field signals generated by vertically aligned receivers. The proportionality parameter can be used to calculate an approximate swell noise that is used to remove swell noise from electric field data measured by the receivers.

Systems and methods for removal of swell noise in marine electromagnetic surveys

The current application is directed to methods and systems for processing EM-survey data in order to extract accurate earth-response curves from the raw EM-survey data. The more accurate earth-response curves are obtained as a result of a generally non-linear decimation, or parameterization, of the earth-response curves, the non-linear parameterization generally applied to extraction of earth responses from raw EM-survey data collected by multiple EM sensors. Parameterization of the earth-response curves and data allows for greater accuracy in estimating the earth-response curves from raw EM-survey data due to use of estimation methods based on processing over-determined raw EM-survey data. In addition, parameterization of earth-response curves may lead to a decrease in computational complexity and an increase in computational efficiency in subsequent intermediate-stage and final-stage processing operations.

Method and system for processing data acquired in an electromagnetic survey

The present disclosure describes various geophysical survey systems and methods for mapping an electric potential field. At least one illustrative embodiment includes an electromagnetic (EM) source and geophysical survey cables that each includes multiple electrodes spaced apart along each geophysical survey cable's length, and multiple data acquisition units that each obtains measurements indicative of an electric potential between two the electrodes. A modeling module is included and configured to calculate a reference potential at a selected electrode for each of the plurality of geophysical survey cables, as well as a calculation module to combine signals representative of the measurements to produce signals indicative of the electric potential of each electrode relative to the reference potential.

Electromagnetic geophysical survey systems and methods employing electric potential mapping

The present disclosure describes various geophysical survey systems and methods for mapping an electric potential field. At least one illustrative embodiment includes an electromagnetic (EM) source and geophysical survey cables that each includes multiple electrodes spaced apart along each geophysical survey cable's length, and multiple data acquisition units that each obtains measurements indicative of an electric potential between two the electrodes. A calculation module is included and configured to combine signals representative of the measurements to produce signals indicative of the electric potential of each electrode relative to a reference potential assumed to be present at a selected electrode for each of the plurality of geophysical survey cables. Each reference potential is assumed to be of a magnitude that is within a tolerance range of a common reference potential.

A disclosed geophysical survey cable includes a signal amplifier coupled between two electrodes spaced apart along the length of the geophysical survey cable (the electrodes being coupled to the signal amplifier by a first conductor pair), and a noise amplifier coupled to a second conductor pair positioned substantially parallel to the first conductor pair. The geophysical survey cable further includes a combiner that combines a noise signal provided by the noise amplifier with a sensor signal provided by the signal amplifier to provide a sensor signal with a reduced noise component.

Growing community of inventors

Segeltorp, Sweden

Peter Lindqvist