2. www.asiangeos.com
SUB BOTTOM PROFILE
History
Types
How They Work
Frequency/Resolution
Use For Interpretation
Boomer Plate Sparker System: 50 Hz to 4KHz
Pinger System: 10 to 24 kHz Pinger 4 X 4 Transducer
Boomer System: 0.2 to 3KHz
Pinger Chirp System: 0.5 to 24KHz
Air Gun System
5. www.asiangeos.com
How They Work
Some of the
sound will
reflects off and
some will
penetrates the
seafloor
The sound pulse
from the source
travels down to
the seafloor
The reflected
sounds travel
back to
surface
Received by
transceiver or
hydrophones
D=V t/2
D is the depth in meter , ‘V’ is the velocity, ‘t’ is the two way time (TWT)
6. www.asiangeos.com
How They Work
The sub bottom profiler data recorded in millisecond (ms) two
way time (TWT)
Two way time = time travel to seafloor/layer + time travel to
receiver
Velocity assume value of 1600m/s-consider of solid velocity is
higher than water velocity. The water velocity range in Malaysia
is around 1540m/s
7. www.asiangeos.com
FREQUENCY AND RESOLUTION
HIGER
FREQUENCY
SYSTEM
HIGER FREQUENCY
SIGNALS HAVE
SHORTER WAVE
LENGTHS AND ARE
ABLE TO
DISCRIMINATE
BETWEEN LAYERS
THAT ARE CLOSE
TOGETHER
PINGER
AND CHIRP
LOW
PENETRATION
HIGH
RESOLUTION
LOWER
FREQUENCY
SYSTEMS
LONGER SOUND
PULSE LENGTHS
TRANSMIT MORE
ENERGY AND
YIELDS DEEPER
PENETRATION
BOOMER,
SPARKER
AND MINI
AIR GUN
HIGH
PENETRATION
LOW
RESOLUTION
29. www.asiangeos.com
2DHR SEISMIC DATA INTERPRETATION
Seismic Section Equalized Data-EQL Seismic Section Real amplitude pulse-RAP Anomalies and Faults Chart
30. www.asiangeos.com
GEOHAZARD
Definition:
a geological state that may lead to widespread damage or risk.
These can be long term or short term geological and/or
environmental conditions that are associated with normal
geological processes. Geohazard investigation involve using
specialized equipment to determine the severity of this state/risk.
32. www.asiangeos.com
GEOPHYSICAL SITE SURVEY
Geophysical site survey:
Survey to support dredging and reclamation projects; determine
filling/dredging quantities; outline seabed train & sub seabed
profile.
Survey to locate underwater objects, ensure under-keel clearance
of fairways
Survey for shallow and deeper geologic study and hazard
definition.
40. www.asiangeos.com
TYPES OF GEOPHYSICAL SURVEYS FOR
GEOHAZARD STUDY
• Analogue Debris Survey
• Pipeline Route Survey
a) Proposed pipeline route survey
b) Pre-lay pipeline route survey
c) Post-lay pipeline route survey
d) Pipeline surveillance survey
• Analogue and Digital Site Survey
41. www.asiangeos.com
THE IMPORTANCE OF SITE SURVEY FOR
GEOHAZARD STUDY
It provide high definition data and images of the specific areas for
development and set down of subsea facilities
It provides detailed seabed and sub seabed image and profiles
within the first 50 metres below seabed for seabed and shallow
foundation & design.
It provides (2DHR) high resolution and detailed sub seabed images
and profiles within the first 1 seconds TWT in the attempt to map
delineate shallow gas hazards that may pose a constraint to
drilling- improving/enhancing 3D data interpretation.
43. www.asiangeos.com
EXAMPLE OF GEOHAZARD
SHALLOW PALEO CHANNEL-Potential to jack-up rig punch through
Seismic Section Equalized Data-EQL
Sub Bottom Profile- Sparker Data
Channel Pattern in Drawing Chart
44. www.asiangeos.com
EXAMPLE OF GEOHAZARD
SHALLOW PALEO CHANNEL-Potential to jack-up rig punch through
Seismic Section Equalized Data-EQL
Sub Botom Profile- Sparker Data
Channel Pattern in Drawing Chart
