Geophysics and Geohazards – Defining Subsea Engineering Risk

 

24 February 2011 Joint SUT and ASEG International Seminar, Subsea Australasia Conference 2011,

Perth, Australia

 

Report

‘Geophysics and Geohazards – Defining Subsea Engineering Risk’, a joint SUT and ASEG one-day seminar, was held in Perth on the 24th February 2011 as part of the Australasian Oil and Gas (AOG) Exhibition and Conference. An almost full house ensured this second conference, which first took place in March 2010, was truly successful.

After the usual formalities including the thanks to Fugro as the principal sponsor, Dan McConnell, VP Marine Consulting, AOA Geophysics, gave the keynote presentation, ‘On Marine Seep Hunting for Oil and Gas Exploration’. The use of a combination of multibeam echo sounder bathymetry and backscatter data with accurately placed piston cores at the seep sites to directly sample a petroleum system was described. An astounding 46% of the targets showed unambiguous thermogenic gas and 13% showed evidence of migrated liquid petroleum.

Stephen Wardlaw, Business Development Consultant, Fugro Geoconsulting Pte Ltd, then described how autonomous underwater vehicles (AUVs) are now routinely utilised in deepwater site investigations for oilfield developments. Drawing on examples, Stephen’s paper reviewed the contribution from the various AUV instruments, and discussed techniques currently used in AUV data integration in the assessment of engineering geohazards.

The use of marine resistivity surveys on dredging projects, and cable and pipe route surveys to assist in port design and alluvial mining projects was described by Dr Ir Peteralv Brabers, General Manager, Demco NV (Belgium). Dr Ir Brabers provided an insight into the theory of resistivity principles and a brief comparison between acoustic methods and marine geo-electric methods.

After the morning tea and coffee break, Dr Ouzani Bachir, Geoscientist, Offshore Geo-Survey Sdn Bhd, discussed deepwater geohazards characterisation. Unlike the continental shelf where geohazards are well documented and site investigation methods are established, deepwater environments are unfamiliar and lack well logs and borehole data. The use of seismic inversion and amplitude versus offset (AVO) analysis for shallow water flows and gas hydrates assessments was discussed.

Dan McConnell returned to the podium to describe his involvement in the DOE-Chevron Joint Industry Gas Hydrate Project in the Gulf of Mexico, 2009 (Leg II). The three-week, $11.5m expedition drilled seven logging-while-drilling (LWD) holes at three sites that tested a variety of geologic/geophysical models for the occurrence of gas hydrate in sand reservoirs in the deepwater Gulf of Mexico.

The lunch break and an opportunity to visit the exhibition was followed by a description by Bachir Ouzani on how the iCUBE 3D volumes converted from 2D seismic lines shot at 50–500m spacing provide increased data density and allowed improved lateral geological continuity and definition of geological structures.

Dr Steve Tyler, Principal Geophysicist, Fugro Survey Pty Ltd, then described how data from a geohazard and environmental baseline survey within the Bonaparte Basin confirmed a barrier reef complex extended from the Sahul Platform through to the Ashmore reef area approximately 18 000 years ago. The geophysical data highlighted the structural complexity of this area with a significant number of pockmarks identified around the flanks of these outcropping palaeo-reefs.

A system of faults extending along the west coast and up to the North West Shelf was described by James Hengesh, Research Fellow, University of Western Australia (UWA). A magnitude 7.3 earthquake, the largest in Australia’s history, occurred along one of these faults, and other faults have the potential to produce similar large magnitude events. Work is underway at UWA to better understand the hazard posed by these faults and to incorporate them in future seismic hazard assessments for major infrastructure projects in Western Australia.

Dr Douglas Bergersen, CEO/Geophysicist, Acoustic Imaging, described the oil and gas industry desire to standardise the presentation of baseline marine survey data for better long- term management of information across offshore development areas. One such template for the storage of information is the Seabed Survey Data Model (SSDM) based around the ArcGIS geodatabase structure. Dr Bergersen’s paper presented an overview of the integration to date and discussed how software tools may be used to assist and optimise the identification, characterisation and quantification of marine geohazards. The seamless transfer of information to the SSDM was illustrated with a case example from the North West Shelf of Australia.

 

Developments in Marine Renewable Energy

 

16 June 2011 London Evening Meeting

Chairman Dr Bob Allwood, Chief Executive, SUT

 

Report

 

Flyer

 

Presentations

Design, Engineering and Construction of the Wave Hub Project

Wave Hub is a grid-connected offshore facility in South West England for the large scale testing of technologies that generate electricity from the power of the waves. It leases space to wave energy device developers and exists to support the development of marine renewable energy around the world. This talk covered its design, construction and its installation.

 

Chas Spradbery – Renewables Business Manager – J P Kenny

Chas Spradbery is the Renewables Business Manager for J P Kenny. Chas is a Mechanical Engineer by training with a Ph.D. in Materials Science. He has spent the majority of his career working as a subsea engineer in the oil and gas sector where he achieved a number of world firsts including the worlds deepest trunkline which was designed for depths of just over 3000m. For the past four years he has worked exclusively in the Offshore Renewable Energy sector where amongst other things he was responsible for the design and development of Wave Hub. He is a Fellow of the Institute of Marine Engineers.

 

Dan Pearson – MeyGen Ltd

Dan Pearson CEO of MeyGen has extensive specialised experience in project development, financing and overall delivery of renewable energy projects. He has been intimately involved in the successful development and commercial delivery of a number of renewable energy projects over the past 13 years. Dan presented on The MeyGen project. The MeyGen project is located in the Inner Sound of the Pentland Firth, the body of water that separates the north Scottish mainland from Stroma Island. Approximately four years ago, an initial site selection process was conducted on the whole of the Pentland Firth using a tidal flow model which was created in order to highlight areas of suitable resource for tidal stream energy projects.

 

Subsea Hot Taps

 

8 June 2011 Aberdeen Branch Evening Meeting

Chairman James Woods, Subsea Execution Team Lead, Shell UK

Sponsored by Subsea 7

 

Flyer

 

Overview

Since the start of the modern subsea offshore oil industry the requirement to join, modify and extend pipelines underwater has been an operational requirement. As a consequence ‘Hyperbaric’ habitat welding evolved and once the technique reached an acceptable level of reliability it was extended to enable ‘Hot Taps’ to be performed. Hot tapping is a method of making a connection to a pipeline whilst the pipe remains pressurised and without interruption to the normal flow or operating regime of the pipeline, and has been carried out extensively subsea since the mid to late 70’s.

Hot tapping has traditionally been carried out manually by divers, although some automatic systems have been used in the past. However, now we have entered an era of ever deeper water depths outside the range of divers, and necessity, being the mother of invention, has promoted new remote and innovative systems.

The evening’s speakers covered traditional hot tapping, remote hot tapping and a non- welded system of hot tapping, and aimed to bring the audience up to date with current hot tap developments. In addition, a Tech Byte covered some of the available inspection techniques for the processes.

 

Presentations

Subsea Hot Tap Experiences by Technip Norge AS 2007–2010

Geir Leden, Principal Engineer – Technip Norge AS

Technip Norge AS has in the period 2007–2010 completed three projects with subsea hot tap operations. Hot tapping has been carried out by use of both diver operated and remotely operated drilling machines in water depths ranging from 95 to 845 meters. A total of six hot taps have been performed, three hot taps through welded tees and three hot taps through pre-installed flanges. This presentation showed the basic concept of Hot Tapping as well as a description of some of the specific challenges that have occurred during the three projects.

 

World’s First Deep Water Remote Hot Tap

Keith Evans, MD  – Clear Well Subsea Limited

Aberdeen based Clear Well Subsea have provided a unique hot tapping solution to Norwegian state oil company Statoil. As part of the Ormen Lange South Development, located in almost 1000m of water, Statoil required two new connections to the existing 30” gas export pipelines. The two hot taps constitute the first successful use of the remote hot tapping system in deep water and were performed at pressures and temperatures well beyond the capability of existing designs enabling the team to claim a number of world firsts. This presentation explained the evolution and implementation of the unique technology developed by Clear Well Subsea.

 

Tech Byte – Subsea Automated Ultrasonic NDT Inspection of Hot Tap Welds

Craig Emslie, Integrity Services Manager – Sonomatic Aberdeen

Sonomatic is a specialised inspection company who has been involved in a number of subsea hot tap campaigns. Their involvement has been focused on conducting specialised inspection, from measuring the profile of the pipeline prior to securing the hot tap, to inspection of field welds prior to connecting to the pipeline. This short presentation presented an overview of the inspections that Sonomatic has conducted and recent developments in ROV deployed inspection tools.

 

Subsea 7 Grouted Tee Hot Tap Technology

Dan Vu, Engineering Manager – Life of Field Services

Grouted Tee technology was developed for hot tapping onto cross country transmission pipelines in the late 1990s. It is now a proven and accepted method for carrying out live intervention on gas and oil pipelines. In 2009, Subsea Grouted Tee™ (SSGT) was successfully developed for subsea pipelines at diver depths. This presentation described the mechanics of Grouted Tee hot tap technology on subsea pipelines and provided high level technical, safety and time comparisons over the traditional welded and mechanical options. It also outlined a further design consideration enabling diverless hot tap operations in deep and ultra deep water environments.