1
Migration Aperture
I confirm that the migration aperture was not taken into account by Greenfields, the
reason why the limits of the 3D have been extended outside the limits of Bahar Block,
increasing the 3D surface to be acquired, then increasing the cost of the 3D.
I also confirm that the migration aperture was not included in Socar 3D acquisition. So
the width of the useful 3D cube will be 3 km and not 6 km.
To avoid any misunderstanding on this technical subject may I recommend you to provide
Greenfields geophysicists with the following references for 3D seismic survey designs.
Planning Land 3D seismic surveys by Andreas Cordsen, Mike Galbraith and John
Pierce
Geophysical Developments No 9 published by the SEG (including the CD)
In addition, Andreas is giving this course on call in 3 days and he has a planning soft
equivalent to MESA, so you can plan your 3D yourself (Andreas gave this course to Total in
2003 and to SRAK a JV between Total, Shell and Saudi Aramco in 2006).
Migration aperture is treated in chapter 3
3D Seismic Survey Design by Gijs J.O. Vermeer: SEG Geophysical references series
No 12
Gijs is very good geophysicist retired from Shell now and has his own consulting Company
called 3DSymSam. Chapter 5 of this book talks about OBC acquisition.
2
Planning
Below is the planning provided during Paris meeting:
20012/2013 OBC seismic
Acquisition
2012
Nov
2013
Dec
Jan
Feb
Mar
Apr
May
June
Bid Preparation by Company
Bid preparation by Contractor
Bid analysis & award
Contract finalisation & Signature
Mobilisation
Start Recording
To avoid what is happening on Bahar 2 OBC 3D (in 328 operations days, only 48 km2 have
been recorded to date i.e. 0.15 km2 per day), we are planning the new 3D OBC according
to the Accepted Standards this means the Procedures and State of the Art techniques, as
used and applied within the Geophysical Industry. It takes time to prepare the CFT including
a Standard Contract for the acquisition including detailed legal and technical parts and not
only be limited to a Scope of Work with just the recording parameters. For your information,
the already finalized CFT documents represent 180 pages.
3
ACQUISITION AREAS
Taking into account the migration aperture, 2 options are considered with and without Area
IA as per the following maps. The estimated cost of the 2 options is attached
Option A without Area IA
Option B with Area IA
FINANCIAL SUMMARY FOR OPTIONS A (290 km2) & B (385 km2)
Contractor Cost
Contractor Cost
T O T AL CO ST
Option A
$500 000,00
$250 000,00
$125 000,00
$6 000,00
$9 000,00
Option B
$500 000,00
$250 000,00
$125 000,00
$6 000,00
$9 000,00
OP T ION A
Option B
$80 000,00
$75 000,00
$23 200 000,00
$28 875 000,00
Option A
$500,00
Option B
$500,00
$145 000
$192 500,00
Option A
$1 000,00
Option B
$1 000,00
$290 000
$385 000,00
Option A
Option B
$90 000,00
$90 000,00
Option A
Option B
$24 475 000,00
$30 292 500,00
Option A
Option B
$1 500,00
$1 500,00
$348 000,00
$462 000,00
Option A
Option B
$2 000,00
$2 000,00
$14 000,00
$14 000,00
Option A
Option B
$24 837 000,00 $30 768 500,00