MARNAUT meeting 22/01/2007 SUBTECH OBS TESTS Claude LEVEQUE IFREMER Underwater System Department Toulon

MARNAUT meeting 22/01/2007 Objectives of SUBTECH OBS Project Partners : CGG with IFREMER and Cybernetix Aims to develop oil reservoir monitoring by 4D ocean bottom seismic method Constraints: –OBS position, coupling and orientation must be as identical as possible by the time of successive seismic campaigns –Cost reduction is a main condition to develop the market

MARNAUT meeting 22/01/2007 Proposed solution (future offsh. oil applications) Matrix of seismic sensor tip sunk in the soil AUV deployed data recorder modules ( one recorder module on each tip for each campaign)

MARNAUT meeting 22/01/2007 Seismic monitoring Concepts : Sensors permanent on site Recording autonomous node installed and removed by an AUV for each operation Benefits Repetitive position of sensors Low cost of repetitive operations Recorded S-Waves

MARNAUT meeting 22/01/2007 Other concept for oil field exploration Matrix of autonomous nodes with self buried sensor head only deployed for an exploration campaign

MARNAUT meeting 22/01/2007 What are the benefits of deep sunk tip regards to the coupling quality ? –Better signal to noise ratio ? –Improve S Waves detection ? How deep to sink the tip? Compare 1 pole/tip node results1 sub bottom bulb node provider CGG 1 self buried sensor head node 3 standard OBS (bottom lay down 3 comp. geophone) provider Ifremer Concerns of MARNAUT tests

MARNAUT meeting 22/01/2007 Sub bottom Bulb Node Electronics Housing Bulb head Operational application Self Positioning Autonomous Node SPAN Functional mock up of SPAN OBS part to test during MARNAUT Bulb head: self buried by water jetting

MARNAUT meeting 22/01/2007 Self buried sensor head node SERCEL ARMSS Self buried by vibrating

MARNAUT meeting 22/01/2007 Standard IFREMER OBS

MARNAUT meeting 22/01/2007 WORK SCHEDULE MARNAUT first leg  OBS installation –Rod/tip node  cable deployment from Atalante –Bulb node & ARMSS  Nautile deployed –Standard OBS  from the ship During the time of the campaign –Some hours of air gun shots, during the 1 st half of campaign to provide some well identified seismic events ( Need MTA to help us and provide air gun &ship facilities) –Local seismic events recording

MARNAUT meeting 22/01/2007 WORK SCHEDULE MARNAUT last leg  OBS recovery –Standard OBS  self weight release –Bulb node & ARMSS  recovery by Nautile –Rod/tip node  recovery of recorder unit by Nautile Buoyancy lift module from Atalante, fit to the rode to extract and lift it After MARNAUT: data processing –IFR OBS  by IFREMERComparison –CGG OBS  by CGGof the results