The invention notably relates to a method for controlling depth of a seismic cable having ballasts spaced apart along its length and providing a neutral buoyancy to the seismic cable, the seismic cable being adapted for midwater data acquisition, each end of the seismic cable being connected to a respective surface autonomous vessel exerting tension on the cable through a respective lead-in cable having a negative buoyancy, the method comprising, with respect to a target depth, varying the deployed length of each lead-in cable and/or the tension exerted on the cable by each respective surface autonomous vessel. This provides an improved solution for seismic prospecting in aquatic mediums.

Embodiments herein use an acquisition vessel towing a plurality of receivers and a seismic source and a source vessel towing a seismic source to acquire seismic data corresponding to a subsurface below a bottom surface of a body of water. When activating the seismic source on the acquisition vessel, the plurality of receivers acquire survey data for a central coverage area underneath a swath defined by the plurality of receivers. However, when activating the seismic source on the source vessel, the plurality of receivers acquires survey data for a side coverage area. The embodiments herein control a separation distance between the acquisition and source vessels so that there is a gap between the central and side coverage areas resulting from activating the seismic sources towed by those vessels. This gap can reduce the cost and time required to perform the seismic survey.

The present invention relates to a seismic sensor node and corresponding measuring device for point measurements in seismic surveys of geological subsurface formations, where the sensor node includes a sensor housing with at least one movement sensor, the sensor node comprising a plate structure being adapted to be positioned into the sea bed, the sensor housing having a predetermined outer shape and the plate structure being adapted to receive and essentially enclose the sensor housing for providing acoustic coupling between the plate structure and the sensor housing, and the plate structure having a rotational symmetric structure with a vertical axis. The plate structure comprises a number of radially oriented plates secured together and being adapted to penetrate the sea bed with minimal displacement of the sea bed materials.

A low-vibration collar system for vibration mitigation in a device towed in water. The low-vibration collar system includes a clamp attached to a streamer towed underwater by a seismic vessel, the streamer comprising a plurality of sensors to record seismic data; a collar configured to be attached to the clamp; a connecting mechanism located on the collar and configured to attach an ancillary device to the collar; and a vibration mitigation system configured to attenuate an amplitude of a vibration produced by the ancillary device. The vibration interferes with seismic data recorded by seismic sensors located on the streamer.

In some examples, an unmanned marine surface vessel connected to a three-dimensional array of sensors positioned are deployed in proximity with an obstruction area of a survey environment. The three-dimensional array of sensors positioned in proximity with the obstruction area of the survey environment records signals that are affected by a target structure.

Embodiments included herein are directed towards a marine seismic streamer. The seismic streamer may include an outer skin formed in a longitudinally extending tubular shape, an inner surface of the outer skin defining an internal volume containing a gel substance. The seismic streamer may also include a plurality of micro-electro-mechanical (MEMS) sensors and a plurality of hydrophones associated with the outer skin, wherein the plurality of MEMS sensors are spaced non-uniformly in the seismic streamer along an axial direction of the streamer, such that not more than 100 MEMS sensors are located in the seismic streamer over a continuous 100 meter axial length of seismic streamer. The seismic streamer may further include an electronics system extending axially through an inside portion of the outer skin and a strength member core extending axially through an inside portion of the outer skin.

A method for acquisition of seismic data in a marine environment.

An autonomous underwater base for handling an autonomous underwater vehicle (AUV) equipped with seismic sensors for recording seismic signals during a marine seismic survey. The autonomous underwater base includes a storing module configured to store the AUV; an inlet/outlet module configured to control access of the AUV to the storing module; and a control module having a positioning system configured to adjust a position of the base in water. The positioning system autonomously drives the storing module from a first position to a second position underwater.

A method for designing 4-D seismic acquisition source and receiver repeatability specifications, the method including: locating, with a computer subsurface anomalies above a target reservoir zone from analysis of high-resolution reflectivity images for the target reservoir zone; determining, with a computer, how the anomalies above the target reservoir zone modify target illumination for variations in the 4-D seismic acquisition source and receiver positions; and determining, with a computer, repeatability specifications for a monitor seismic survey, wherein tolerances for the source or receiver positions varies across an acquisition area based on how the anomalies modify the target illumination.

Various implementations described herein are directed to a method of acquiring seismic data. The method may include towing an array of marine seismic streamers coupled to a vessel. The array comprises a plurality of lead-in cables and streamers, and the plurality of lead-in cables comprises an innermost lead-in cable and an outermost lead-in cable with respect to a center line of the vessel. The method may also include towing a plurality of source cables and one or more seismic sources such that the one or more seismic sources are positioned between the innermost lead-in cable and the outermost lead-in cable.