Offshore Site Investigation
Considerations
There are many considerations when planning an offshore site investigation (S.I), many more than are mentioned herein.
The size of the project, the location of the project, the water depth and phase of the project would all be a large factor in defining an offshore S.I scope of work. Have you performed a desktop study to define what information already exists? Have you performed a risk assessment to define the main requirements of the S.I (where is your soils risk)? Is the subsea infrastructure likely to change location regardless of the S.I results?
If the schedule allows, the Geophysical S.I should be performed first as this will give an immediate indication of major issues (slopes, geohazards, rock outcrops, shallow gas etc...) within the corridor of proposed subsea architecture installation. Geotechnical sampling can then also be planned/targeted in areas of interest as identified from the preliminary geophysical interpretation. Are specifc cores required to allow a geohazard assessment to be performed?
When both geophysical and geotechnical data has been acquired it is vital that the data is integrated such that interpretation of geophysics is aided by the geotechnical ground truthing. This may take the form of a ground model and / or a fully integrated GIS suite of data.
Laboratory testing on Geotechnical samples should be planned in accordance with design requirements, thus it is key to identify the expected foundation solutions early in the project. Laboratory testing type or specification should be determined with specific foundation types in mind.
Undertaking the correct S.I for the project is critical for the mitigation of future risk for all parties involved and can lead to significant cost savings in design and thus fabrication / installation.
There are many considerations when planning an offshore site investigation (S.I), many more than are mentioned herein.
The size of the project, the location of the project, the water depth and phase of the project would all be a large factor in defining an offshore S.I scope of work. Have you performed a desktop study to define what information already exists? Have you performed a risk assessment to define the main requirements of the S.I (where is your soils risk)? Is the subsea infrastructure likely to change location regardless of the S.I results?
If the schedule allows, the Geophysical S.I should be performed first as this will give an immediate indication of major issues (slopes, geohazards, rock outcrops, shallow gas etc...) within the corridor of proposed subsea architecture installation. Geotechnical sampling can then also be planned/targeted in areas of interest as identified from the preliminary geophysical interpretation. Are specifc cores required to allow a geohazard assessment to be performed?
When both geophysical and geotechnical data has been acquired it is vital that the data is integrated such that interpretation of geophysics is aided by the geotechnical ground truthing. This may take the form of a ground model and / or a fully integrated GIS suite of data.
Laboratory testing on Geotechnical samples should be planned in accordance with design requirements, thus it is key to identify the expected foundation solutions early in the project. Laboratory testing type or specification should be determined with specific foundation types in mind.
Undertaking the correct S.I for the project is critical for the mitigation of future risk for all parties involved and can lead to significant cost savings in design and thus fabrication / installation.
Resources
As stated in the introduction, there are few free online resources for Subsea Geotechnical Engineering, however the OSIG (Offshore Site Investigation and Geotechnics) website is perhaps the best (link below). Guidance documents for S.I for renewables, offshore pipelines and offshore structures are provided.
In the north sea the BGS maps provide a good basis for a desk top study and a general understanding of the geology across the UKCS.
The website of Professor Robertson also provides same fantastic downloads on site investigation and cone penetration testing.
As stated in the introduction, there are few free online resources for Subsea Geotechnical Engineering, however the OSIG (Offshore Site Investigation and Geotechnics) website is perhaps the best (link below). Guidance documents for S.I for renewables, offshore pipelines and offshore structures are provided.
In the north sea the BGS maps provide a good basis for a desk top study and a general understanding of the geology across the UKCS.
The website of Professor Robertson also provides same fantastic downloads on site investigation and cone penetration testing.
S.I Contractors
In addition, links below can be found some offshore S.I contractors offering a wide range of services (we're happy to add more if we've missed someone out).
In addition, links below can be found some offshore S.I contractors offering a wide range of services (we're happy to add more if we've missed someone out).