seismic imaging of seneca and cayuga lakes: christopher a. scholz syracuse university...
TRANSCRIPT
Seismic Imaging of Seneca and Cayuga Lakes:
Christopher A. ScholzSyracuse University [email protected]://rifts.syr.edu
New York State Museum
Financial support from New York State Energy Research
Development Authority
In-kind processing support fromSterling Seismic Services, Ltd.
Collaborators:
Syracuse Univ.Chris ScholzMike McGluePeter CattaneoKiram LezzarNick PetersBob LyonsRJ HartwellPhil Arnold
Hobart-WilliamSmith CollegesJohn NicholsJohn AbbottJohn Halfman
New YorkState MuseumRich NyahayJustin DemingCourtney LugertRose SchulzeBrian Slater
Cruise participants:
Earth Satellite Corp.,1997, Remote Sensing and Fracture Analysis for Petroleum Exploration of Ordovician to Devonian Fracture Reservoirs of New York
Outline• Small Lake Seismics: Acquisition issues
and parameters: Practical experiences from the Finger Lakes
• Data processing efforts
• Preliminary interpretations and key geologic features
• The October ’02 Survey – what worked and what didn’t
Acquisition Parameters
• Approach: Simpler is better!!!
• 24-bit recording
• 12-fold data
• 12.5 m groups; ~625 m total offset
• 5 m streamer depth; 2 m gun depth
• Differential GPS acquisition (sub-meter accuracy)
• Streamer leveling: Digicourse Birds
Acquisition Equipment• OYO DAS-1 48-channel, Digital Seismic
Acquisition System
• ELICS Delph2 high-resolution seismic acquisition system (for real-time QC)
• 2 x 40 c.i. I-O Sleeve Gun airgun array
• Portable diesel-powered seismic air compressors (58 SCFM total)
• Single channel streamer (for real-time QC)• 48 Ch. 600 m (active) ITI Stealth array seismic
streamer w/ 150 m lead-in (Primary Streamer)
Acquisition Challenges
• Small vessel
• Short (but solid!) streamer
• Crooked line navigation
• Limited compressor capability….
• Streamer levelers marginal at slow shooting speeds
• Limited daylight
• Recreational boaters
• Environmentally sensitive setting
Hobart William Smith CollegesR/V William Scandling, Seneca Lake
I-O Sleeve Gun Array
(2 X 40 c.i. guns)
I-O Sleeve Gun Array
(2 X 40 c.i. guns)
I-O Sleeve Gun Array
(2 X 40 c.i. guns)
~95 km total acquisition:Cayuga, Seneca – two axial lines each
The October ‘02 Survey
Data Processing
• Initial processing by SU, subsequent intensive processing by Sterling Seismic Services, Ltd.
• Significant changes between
Brute stack
Enhanced stack
Kirckhoff Migration
Kirckhoff Migration + FK-filtering
Data Processing• Crooked line geometry• High-resolution radon demultiple routine• Kirckoff migration• FK filter
Brute stack
Enhanced stack
Kirckhoff Migration
Kirckhoff Migration + F-K Filter
Lineaments
Faults
Tracklines
InferredFault
Enhanced stack – full line
Initial Observations• Up to 200 m of Quaternary fill• Bedrock surface follows regional dip• Rugged bedrock topography – tracklines not uniformly on
top of bedrock thalweg• Considerable relief on high-amplitude events below
Quaternary fill !?!• Offsets on Paleozoic reflections – 20 ms or more
Enhanced stack – full line
Exposed bedrock
ApparentOffsets
Survey Challenges – Post-mortem• Seismic source constraints – not a limiting factor
• High velocity section – perhaps the major issue; longer streamer preferable
• Thick Quaternary fill and narrow bedrock valley – side echo effects not a major problem, but complex bedrock surface morphology had major impact
• Limited budget and cruise window – processing budget; cruise window limiting factor = amount of daylight available
• Limited number of nearby wells, with full log suites