MARNAUT meeting 22/01/2007
SUBTECH OBS TESTS
Claude LEVEQUE
IFREMER
Underwater System Department
Toulon
MARNAUT meeting 22/01/2007
Objectives of SUBTECH OBS ProjectPartners : CGG with IFREMER and Cybernetix
• Aims to develop oil reservoir monitoringby 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
results 1 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 1st 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 IFREMER Comparison– CGG OBS by CGG of the results
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