Offshore Geotechnical Engineering

Christian Olsen

Geotechnical Discipline Manager

Subsea 7
Stavanger
Norway
Phone (NO): + 47 95992412
E-mail: christian.olsen@subsea7.com
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Offshore Geotechnical Engineer

Updated 11.04.14 ** New tab: reviews**

What is Geotechnical Engineering?

This homepage sets out to present what is geotechnical engineering for anyone interested. The page mainly focus on my personal interest in offshore geotechnical engineering, but will also provide the visiter with a good introduction to the subject: what is geotechnical engineering?

A friend and I have created the worlds first I-phone APP which assess bearing capacity on clay. The APP is currently very simple, but we have a plan to make it more advanced. See more here.

Under the tab UNI, you will find some info on the Subsea 7 Stavanger office geotechnical collaboration with universities. We currently collaborate with NTNU and DTU, but we may want to collaborate with other universities.


Geotechnical Engineering at Subsea 7

At Subsea 7, I work as a Geotechnical Discipline Manger in the Stavanger office. The geotechnical team currently consists of seven engineers, providing geotechnial support to both tenders and projects. Typical work tasks in the geotechnical team include:

  • Use of limit analysis for estimation of collapse load for foundations subject to complex loading

  • Use of Plaxis (2D and 3D) to design complex soil-structure interaction problems

  • Geotechnical design of pipe soil interaction for inplace design of flexible flowlines and pipelines

  • Rock foundation design on soft clay

  • Perform geotechnical design basis and identify potential needs for additional site investigation

  • Evaluation of ploughing and trenching solutions

  • Client representative on board third party vessels

  • Supervision of junior geotechnial engineers

  • Technically responsible for subcontracts with engineering houses and rock dumpers


Geotechnical Design in Subsea 7 Stavanger - Examples

One of the geotechnical teams lastest acheviements is the foundation design of the Asta Hansteen spar anchors. These have been designed inhouse with use of amongst other PLAXIS 3-D. It is believed that these may be the largest suction anchors ever installed in Norway. This LINK is to a Statoil hopepage where you can read more about the Aasta Hansteen spar anchors.


The Geotechnical Team have prepared a paper for the OTC in Houston. The paper is a lesson learned paper on the counteract design for pipeline installation complete in collaboration with COWI for the Shell Ormen Lange project. The geotechnical design is based on limit equilibrium design to determine the horizontal capacity due to the contact force from the pipeline during pipelay.




Further, COWI used both Abaqus and Flac to perform the design. The most difficult aspect of the design was the strength variation in the soil. We managed to complete a design which optimized the allowable seastate for installation and avoided a rock dump campaign. I presented the paper during OTC in session 32, Lateral Buckling and Walking and Pipe Soil Interaction. The paper can be downloaded from the onepetro homepage: Lessons Learned - Counter-acts Used To Install Pipelines Offshore In Very Soft Clay


University lecturer in Geotechnical Engineering

Since 2012, I have been lecturing Geotechnical Engineering (5 ECTS) at Stavanger University. The course in geotechnical engineering is for first year civil engineering students. There are approx 70 students. I have structured the course as Chalk and talk, and prefer use of practical experience from work. I strive to bring items for each session such as torevane, sedimentary roks, geotechnical reports, geotechnical soil sample tubes etc. I teach in my spare time since I am full time employed at Subsea 7.


Engineering Education

Graduated from Aalborg University with a Ms.C in civil engineering in 2007. During my studies, I spent one semester at Griffith University in Australia where I completed a detailed analysis and examination of coastal structures and design of pile foundations which is a branch of offshore geotechnical engineering.



Offshore Geotechnical Engineering in Subsea 7

Engineering at Subsea 7

Subsea 7 engineer and deliver complex projects in the offshore industry. Each project is engineered in a project team consisting of engineers for various disciplines. Subsea 7 has adopted the matrix structure for the projects and disciplines work together. I work as Manager of the Geotechnical Team in Stavanger and we deliver support to the Projects.


Tasks as a geotechnical Engineer

As Subsea 7 mainly engineer and install risers, umbilicals, flexibles and pipelines offshore, most of my work as a geotechnical engineer is connected with these activities. I engineer initiations systems, provide geotechnical engineering assessment of soil conditions, design pipeline protection structures and subsea rock structures.

I deliver geotechnical support to the projects which covers but is not limited to preparation of geotechnical design basis, design of gravity structrures, pipe - soil interaction and FEM analysis in PLAXIS. When standard solutions are no longer applicable I use the FEM programs PLAXIS 2D and 3D supported with limit equilibrium calculations.

Lately, I have delivered geotechnical engineering to tenders and projects. Some of the main projects are Skarv, Norne, Alve, Ormen Lange, Gja and Volund. Further, I have prepared a two-day internal course on Geotechnics for engineers in collaboration with principal engineer.


Geotechnical Engineer Offshore

After completion of all rock design and coordination of the rock dump campaigns on the Dong Trym project, I was offshore on the Van Oords Nordnes in May 2010. As the only Acergy client rep on board, I was responsible for all communication between Nordnes and Acergy, approval of the work and I managed changes in scope.

Noverber 2008, I went offshore on the Maersk Advancer as client rep for Acergy. We trenched for the Volund project with CTC equipment on the vessel. No geotechnical engineering was required, howeever, it was a good experience for me as an offshore geotechnical engineer.

In connection with two procedures I completed, I went offshore on the Acergy Petrel in June 2008. It was my first trip offshore as an engineer and I worked as project engineer. I worked with the offhsore manager and the deck foreman.


Secondment as Geotechnical Engineer at NGI

Summer of 2008, I was invited to the Norwegian Geotechnical Institute (NGI) for a two weeks secondment. The Secondment was a mutural agreement between Acergy in Stavanger and The Norwegian Geotechnical Institute. At the Norwegian Geotechnical Institute I had mentoring sessions with some of the world leading offshore geotechnical engineers and practical geotehcnical work in the NGI laboratory. For those who do not know, NGI is a/the world leading consulting house for offshore geotechnical engineering... and they know better than most what is geotechnical engineering.