Abstract: A method for geophysical source steering including towing a first geophysical source through a body of water; and adjusting a first steering parameter of the first geophysical source while towing the first geophysical source. An apparatus for geophysical source steering including a first marine vibrator source having a first housing structure; a first vibrational surface functionally coupled to the first housing structure such that at least a portion of the first vibrational surface can vibrate relative to the first housing structure; and first steering control equipment.

Abstract: Techniques are disclosed relating to wide towing of marine survey signal sources. In one embodiment, an apparatus includes a signal source and a wing coupled to the signal source. In this embodiment, the wing is configured to impart a force to the signal source when towed through a body of water by a survey vessel. In this embodiment, the force includes a lateral component and a vertical component. The wing may be configured to impart the force based on a shape of the wing and an orientation of the wing. The wing may extend over at least a third of a length of a keel of the apparatus. At least a majority of a top surface of the wing may be oriented within 20 degrees of parallel to a surface of the body of water. The wing may include a plurality of wing sections.

Abstract: Geophysical sensor cables. At least some of the example embodiments are sensor cable sections including hydrophone groups defined along a geophysical sensor cable section, the hydrophone group may include: a substrate of flexible material having electrical traces thereon, the substrate within the internal volume or embedded within the outer jacket, and the substrate having has a length measured parallel to the longitudinal axis; and a plurality of hydrophones mechanically coupled to the substrate. The substrate may have a variety of shapes, including one or more strips, helix, double helix, and cylindrical.

Abstract: Techniques are disclosed relating to geophysical surveying. In some embodiments, a marine survey vessel tows multiple sensor streamers including a group of four innermost streamers in a cross-line direction relative to a centerline of tow. In some embodiments, the vessel tows two or more vibratory sources between two outermost streamers in the first group, in a cross-line direction. In some embodiments, the two or more sources are simultaneously operated using different codes that are uncorrelated to at least a threshold degree. Various disclosed narrow-tow techniques may allow increased streamer separation without reducing cross-line bin size and/or reduce cross-line bin size for a given streamer separation, relative to conventional techniques.

Abstract: A method for geophysical source steering including towing a first geophysical source through a body of water; and adjusting a first steering parameter of the first geophysical source while towing the first geophysical source. An apparatus for geophysical source steering including a first marine vibrator source having a first housing structure; a first vibrational surface functionally coupled to the first housing structure such that at least a portion of the first vibrational surface can vibrate relative to the first housing structure; and first steering control equipment.

Abstract: Techniques are disclosed relating to wide towing of marine survey signal sources. In one embodiment, an apparatus includes a signal source and a wing coupled to the signal source. In this embodiment, the wing is configured to impart a force to the signal source when towed through a body of water by a survey vessel. In this embodiment, the force includes a lateral component and a vertical component. The wing may be configured to impart the force based on a shape of the wing and an orientation of the wing. The wing may extend over at least a third of a length of a keel of the apparatus. At least a majority of a top surface of the wing may be oriented within 20 degrees of parallel to a surface of the body of water. The wing may include a plurality of wing sections.

Abstract: Techniques are disclosed relating to wide towing of marine survey signal sources. In one embodiment, an apparatus includes a signal source and a wing coupled to the signal source. In this embodiment, the wing is configured to impart a force to the signal source when towed through a body of water by a survey vessel. In this embodiment, the force includes a lateral component and a vertical component. The wing may be configured to impart the force based on a shape of the wing and an orientation of the wing. The wing may extend over at least a third of a length of a keel of the apparatus. At least a majority of a top surface of the wing may be oriented within 20 degrees of parallel to a surface of the body of water. The wing may include a plurality of wing sections.

Abstract: Techniques are disclosed relating to reducing drag on cables towed behind a vessel in a body of water. In one embodiment, an apparatus includes a signal source coupled to a survey vessel via a source cable, and the source cable includes a plurality of floats along its length. The floats may in some embodiments allow the source cable to be lifted partially, substantially, or entirely above the surface of the water. Lifting the cable above the surface of the water may in turn decrease the amount of hydrodynamic drag on the cable, reducing the force necessary (e.g., from lateral deflectors on the cable or at the signal source) to tow the source and/or the force necessary to attain a desired lateral position for the signal source. The disclosed techniques may in some embodiments be used to tow such sources at relatively wide lateral separations.

Abstract: Techniques are disclosed relating to wide towing of marine survey signal sources. In one embodiment, an apparatus includes a signal source and a wing coupled to the signal source. In this embodiment, the wing is configured to impart a force to the signal source when towed through a body of water by a survey vessel. In this embodiment, the force includes a lateral component and a vertical component. The wing may be configured to impart the force based on a shape of the wing and an orientation of the wing. The wing may extend over at least a third of a length of a keel of the apparatus. At least a majority of a top surface of the wing may be oriented within 20 degrees of parallel to a surface of the body of water. The wing may include a plurality of wing sections.

Abstract: Techniques are disclosed relating to reducing drag on cables towed behind a vessel in a body of water. In one embodiment, an apparatus includes a signal source coupled to a survey vessel via a source cable, and the source cable includes a plurality of floats along its length. The floats may in some embodiments allow the source cable to be lifted partially, substantially, or entirely above the surface of the water. Lifting the cable above the surface of the water may in turn decrease the amount of hydrodynamic drag on the cable, reducing the force necessary (e.g., from lateral deflectors on the cable or at the signal source) to tow the source and/or the force necessary to attain a desired lateral position for the signal source. The disclosed techniques may in some embodiments be used to tow such sources at relatively wide lateral separations.

Abstract: A survey method includes towing one or more sources and one or more streamers behind a vessel to acquire geophysical survey data. Steering signals are determined for at least one of: the one or more sources, the one or more streamers, and the vessel. The steering signals minimize an error function having parameters that include a measure of a cross-line position error and a measure of data quality. The cross-line position error may be measured as an offset of the sources or the receivers from their desired paths, or in some embodiments as an offset between midpoints for base survey traces and subsequent survey traces. Some embodiments may employ a maximum spatial cross-correlation coefficient between a newly acquired trace and one or more base survey traces as a data quality measure, while others may employ a time shift, a phase rotation, or a normalized root mean square error. Data quality may indicate sensor noise levels.

Abstract: A disclosed pressure-responsive sensor includes a flexible element contained within an enclosure and a membrane configured to exert an electrostatic force on the flexible element to cause the flexible element to respond to pressure variations on the membrane. A disclosed pressure-sensing method includes electrostatically coupling a membrane to a flexible element contained within an enclosure to transfer a pressure response of the membrane to the flexible element. Motion of the flexible element is converted into a pressure signal.

Abstract: A survey method includes towing one or more sources and one or more streamers behind a vessel to acquire geophysical survey data. Steering signals are determined for at least one of: the one or more sources, the one or more streamers, and the vessel. The steering signals minimize an error function having parameters that include a measure of a cross-line position error and a measure of data quality. The cross-line position error may be measured as an offset of the sources or the receivers from their desired paths, or in some embodiments as an offset between midpoints for base survey traces and subsequent survey traces. Some embodiments may employ a maximum spatial cross-correlation coefficient between a newly acquired trace and one or more base survey traces as a data quality measure, while others may employ a time shift, a phase rotation, or a normalized root mean square error. Data quality may indicate sensor noise levels.

Abstract: A disclosed pressure-responsive sensor includes a flexible element contained within an enclosure and a membrane configured to exert an electrostatic force on the flexible element to cause the flexible element to respond to pressure variations on the membrane. A disclosed pressure-sensing method includes electrostatically coupling a membrane to a flexible element contained within an enclosure to transfer a pressure response of the membrane to the flexible element. Motion of the flexible element is converted into a pressure signal.

Abstract: A disclosed digital sensor includes a pair of piezoelectric sensors that respond to acceleration and pressure in opposite ways, a pair of digital transducer circuits each employing a quantized feedback path to obtain digital sensor signals for the piezoelectric sensors, and a combiner circuit that combines the digital sensor signals to produce a compensated digital output signal. The compensated digital output signal may be a pressure compensated acceleration signal, an acceleration compensated pressure signal, or both. Also disclosed is a signal detection method that includes configuring a pair of piezoelectric membranes in a piezoelectric sensor to respond to acceleration and pressure in opposite ways, and based on their responses, producing at least one of a digital pressure compensated acceleration signal and a digital acceleration compensated pressure signal. The digital signals may be produced in part by applying a quantized feedback signal to at least one of the piezoelectric membranes.

Abstract: A receiver streamer system for marine electromagnetic surveying includes a first streamer, and a second streamer disposed substantially parallel to and spaced apart from the first streamer. A first pair of electrodes is associated with the first streamer and a second pair of electrodes is associated with the second streamer. Each of the first and second pairs of electrodes is functionally associated with a voltage measuring circuit configured to measure voltage along an inline direction. At least one electrode on each of the first and second streamers is configured and associated with a voltage measuring circuit to make voltage measurements in a cross-line direction.

Abstract: A receiver streamer system for marine electromagnetic surveying includes a first streamer, and a second streamer disposed substantially parallel to and spaced apart from the first streamer. A first pair of electrodes is associated with the first streamer and a second pair of electrodes is associated with the second streamer. Each of the first and second pairs of electrodes is functionally associated with a voltage measuring circuit configured to measure voltage along an inline direction. At least one electrode on each of the first and second streamers is configured and associated with a voltage measuring circuit to make voltage measurements in a cross-line direction.