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Physical Oceanography/ Ocean Engineering

For over 20 years Woods Hole Group has been providing state-of-the-art services in the field of Physical Oceanography and Ocean Engineering using a variety of tools for a diverse clientele including oil and gas companies, engineering companies, rig providers, port and harbor authorities, and government agencies. As an applied science company, we have built our reputation on a solid scientific framework. Woods Hole Group designs, builds and installs multiple offshore observation systems, including real-time monitoring systems, collects high quality data, analyzes these data, and reports in the framework of numerous deepwater as well as coastal wave and current measurement programs worldwide. We specialize in the following:

Capabilities

  • Oceanographic Instrumentation Design & Evaluation
  • Data Acquisition, QAQC, Analysis, Interpretation & Reporting
  • Design Criteria Studies
  • Process-Oriented Modeling
  • Hydrographic/Geophysical Surveys

Snapshot:

Deepwater Furrows
Current Measurements


Woods Hole Group designed, deployed, and recovered six unique bottom frames in deep water in the Gulf of Mexico (~2800m depth) to investigate...[+]

Extremal Currents and
Fatigue Current Profiles


Our client required extremal and operational current profiles in support of oil production activities in the Makassar Strait offshore Borneo Indonesia ...[+]

ADCP
Intercomparison Study


The Eddy Joint Industry Project (EJIP) funded a study to assess the performance of the TRDI 75kHz Long Ranger ADCP (LR-75) in deepwater in ...[+]

Deepwater Furrows Current Measurements


Woods Hole Group designed, deployed, and recovered six unique bottom frames in deep water in the Gulf of Mexico (~2800m depth) to investigate special bottom features of interest. The bottom frames were custom designed for precision placement using ROVs. The one-year program had no interim instrument recovery but supported periodic, remote acoustic data access.

Two current profilers with different frequencies mounted on each frame were used to obtain detailed near bed profiles and less detailed longer profiles. Data were recovered at four-month intervals using acoustic modem technology from a surface vessel, thereby lowering costs. Recovering the data acoustically was a unique development successfully implemented by Woods Hole Group.

Further cost reduction was accomplished during final recovery of frames by using acoustic releases, so no costly ROV with vessel was necessary during this procedure as well. The instruments used were:

  • TRDI 300kHz Workhorse ADCPs for long profiles.
  • Nortek 2MHz Aquadopp profilers for short, near bed profiles in the furrows.
  • Linkquest UWM4000 modems used to recover data while deployed, working over ranges of up to 4000m.
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Extremal Currents and Fatigue Current Profiles


Our client required extremal and operational current profiles in support of oil production activities in the Makassar Strait offshore Borneo Indonesia. Woods Hole Group performed a study of oceanographic processes and extreme currents for this location, including extreme current profiles and profiles for fatigue analysis.

The methodology of the process-oriented analysis comprised spectral analysis, separation of the barotropic and baroclinic currents, empirical orthogonal functions, lag-correlogram, and tidal harmonic analyses.

The physical process analysis revealed a multi-layered kinematic structure of the flow with extremes confined to certain depth ranges. Four types of extreme current profiles were generated based on the finding that an extreme current speed of certain return period would occur in one of the layers characterized by a peak in the frequency of occurrence of current extremes.

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ADCP Intercomparison Study


The Eddy Joint Industry Project (EJIP) funded a study to assess the performance of the TRDI 75kHz Long Ranger ADCP (LR-75) in deepwater in the Gulf of Mexico. The LR-75 is widely used by the oil industry, but anecdotal evidence of poor performance of this instrument in low-scattering environments had been reported.

Woods Hole Group carried out a study over a three-month period at a site water depth of 2000m near a semi-submersible drill rig. The study involved three ROV-deployed ADCPs mounted in tripods on the sea floor - two LR-75s and one 300kHz Sentinel Workhorse ADCP (WHS-300) - oriented such that none of the beams pointed at the riser. In addition, five current sensors of various types were deployed on a short mooring that extended 500m above the sea bed, located 1km from the tripods with random beam orientation with respect to sub-sea structures.

Despite low backscatter conditions, the beam orientation controlled LR-75s provided apparently-valid data to 350m above the bottom. However, comparison with other current meters proved that side-lobe interference can cause a general low bias in the measured current speeds. The interference was proven to have been caused by structural components located beyond the previously considered valid range.

The extent of the low bias varied with distance from the LR-75, but was still in the range of 10-15% at the maximum attainable range (350m). Reflection or reverberation of side-lobe acoustic signals is responsible for these errors, and affects the acoustic measurement at a wider range than previously accepted.

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