The present disclosure is directed to a system to locate seismic data acquisition units in a marine environment. The system can include a first seismic data acquisition unit. The first seismic data acquisition unit can include a case having a wall defining an internal compartment, a power source, a clock, a seismic data recorder, and at least one geophone disposed within the case. The system can include a flexible connector and a telltale component, wherein the flexible connector and the telltale component can be stored adjacent to the first seismic data acquisition unit, wherein a second seismic data acquisition unit is coupled with the first seismic data acquisition unit.

An example system can comprise autonomous submarines and an auxiliary station including a power supply. Each autonomous submarine can include a respective power supply and a respective marine survey node coupled thereto. The auxiliary station can be configured to dock the autonomous submarines in a body of water and recharge the respective power supply of each of the autonomous submarines via the power supply of the auxiliary station. Each autonomous submarine can be configured to autonomously navigate from and return to the auxiliary station and position the respective marine survey node on an underwater surface.

The present disclosure is directed to delivering nodes to an ocean bottom. A system can include a tether management system (TMS) towed by a vessel that moves on the surface of the ocean in a first direction. An underwater vehicle (UV) can be connected to the TMS and can move in a second direction that is different from the first direction. A thruster can be coupled to the TMS can cause the TMS to move in a third direction that is different from the first direction. A control unit can control the thruster to move the TMS in the third direction based on a cross-line location policy, and cause the UV to deploy nodes to target locations on the ocean bottom.

A system can include a source and a front float coupled to the source. The front float can include a winch configured to adjust a position of the source. The front float can include a control unit configured to control functions associated with the front float. Lead-ins can be coupled to the front float and the source and configured to accommodate transfer of electrical energy between the front float and the source.

The disclosure discloses a trajectory optimization method and device for accurately deploying marine sensors under water. The method includes the following steps. 1. Randomly select N sets of initial control variables within a range. 2. Input all of N sets of x.sub.i to the sensor's underwater glide kinematics and dynamics models, and calculate the smallest distance between N actual deployment positions and target deployment positions. 3. Determine whether the number of iterative operations is less than the preset value, if yes, perform global random walk and local random walk on N sets of x.sub.i, obtain N sets of x.sub.i again, and return to step 2; otherwise, go to step 4. 4. Output the control variable x.sub.i corresponding to Δs(x).sub.nminmin and the corresponding trajectory as the optimal control variable and optimal trajectory. The disclosure can improve the accuracy of prediction on the underwater three-dimensional trajectory of the marine sensor.

Systems and methods for surveying a seafloor utilize two or more of seismic data, acoustic data and electrical potential or resistivity data to identify the locations of objects on or beneath the seafloor. The methods involve moving survey equipment over a geographic area of the seafloor and conducting a plurality of sensing or detecting operations while moving the survey equipment over the geographic area. The plurality of operations include two or more of: (1) a seismic operation that emits seismic energy toward the seafloor and collects seismic data based on seismic energy that returns from the seafloor, (2) an acoustic operation that emits acoustic energy toward the seafloor and collects acoustic data based on acoustic energy that returns from the seafloor, and/or (3) an electrical operation that supplies electrical power into seawater and that collects electric potential data indicative of electric potential that is induced into the seawater.

Methods, systems, and apparatuses are disclosed for sensing acoustic waves in a medium. One example system includes a first elongated member, a first motion sensor sensitive to vibrations of the first elongated member, a second motion sensor spaced apart from the first motion sensor and also sensitive to vibrations of the first elongated member, and a first vibration source operably coupled to the first elongated member and configured to vibrate the first elongated member.

A seismic survey system for recording seismic data underwater in the presence of underwater currents. The system includes first plural buoys configured to descend in water at a predetermined depth (H1) and each having a seismic receiver for recording the seismic data; a first vessel configured to launch the first plural buoys along a first line; and a second vessel configured to recover the first plural buoys at a second line, wherein there is a predetermined distance between the first and second lines. The first plural buoys are configured to travel underwater, at substantially the first predetermined depth (H1), from the first line to the second line, due exclusively to the underwater currents.

Presented are methods and systems for collecting marine seismic data. The collected seismic data can be low frequency (e.g., less than 10 Hz) or it can be a full seismic bandwidth (1-200 Hz) depending on if the low frequency tuned sources and tuned receivers are combined with conventional sources and receivers. The low frequency sources can be towed or they can be autonomous and positioned in the survey area by tether, drifting or self-propelled. The tuned low frequency receivers are towed at a depth greater than conventional receivers and the sources can be fired independently or simultaneously.

Apparatus and techniques are disclosed relating to a two-axis sensing element. In various embodiments, a two-axis sensing element includes a mounting plate that includes a first pair of mounting slots oriented in a first direction and a second pair of mounting slots oriented in a second, different direction. Further, in various embodiments, the two-axis sensing element may include a first pair of bender elements and a second pair of bender elements. The first pair of bender elements may be mounted through the first pair of mounting slots such that the first pair of bender elements is oriented in the first direction and the second pair of bender elements may be mounted through the second pair of mounting slots such that the second pair of bender elements is oriented in the second, different direction. In various embodiments, the mounting plate may transect each of the bender elements into two cantilever portions.