Ministry of Natural Resources and the Environment of the Russian Federation  
 
 
The Federal Subsoil Resources Management Agency  
 
 
«Rusgeology» JSC
 

Marine seismic research of 2D CDP

Methodology and technique of 2D CDP Seismic Acquisition with towed streamer

Seismic data acquisition will be carried out with the use of ION DigiStreamer system, which includes onboard recording system and seismic streamer. Length of seismic streamer active part will be 7000m (max. 8000m), which will provide for fold coverage of 140 (max. 80) with channel spacing 12.5 meters and shotpoint interval 25 meters. Nominal streamer depth is from 6 to 15 m. Streamer control, depth and position control will be implemented using depth controllers installed along the streamers with interval 300 m.

Seismic data arriving to the onboard system in digitized form are recorded on IBM 3590/3592 magnetic medium (or HD) in SEG-D format.

Air guns array will be used as a source of elastic vibrations. Source array is composed of 2 sub-arrays 9 guns each, on 15m base. Source firing time is initiated by navigation system, and shot pulses are formed by LongShot controller providing automatic timing correction for each gun, their time characteristics analysis, and identification of spontaneous and skipped shot points with printout of statistics of the whole emitting system.

Prior to survey commencement and further on, a full set of tests as provided by equipment manufacturer will be carried out on a monthly basis, at intervals not more than 35 days. The tests will be recorded on magnetic tape and analyzed onboard. During the entire period of survey, the status of recording equipment will be controlled by daily tests prescribed by the manufacturer.

Background noise will be recorded prior to the start and upon completion of each line, followed by analysis in order to define root-mean square noise level for each record. In the course of line acquisition, control gathers with all channels and time marks will be produced at intervals of 100 shotpoints. Single trace display for the near channel will be produced for each line.

In the course of field works, seismic data pre-processing will be performed by onboard processing system PROMax for operative quality control of acquired data.

Average planned speed of line acquisition - 4.5 knots - provide for good performance and acceptable noise level for the towed equipment.

Positioning of the vessel and towed equipment will be performed by two independent navigation systems with the use of GPS and GLONASS satellites.



Recording system DigiSTREAMER

2DType

Manufacturer

Recording form

Sampling interval

HF filter Analogue

LF filter

Recording devices

Storage media

Display system plotter

DigiSTREAMER 2D

ION USA

SEG-D (rev.2) 8058 32-bit IEEE

0.5,1, 2, 4 ms

2 Hz , 6 dB/octave

103-824 Hz , 256 dB/octave

RAID-system,24 Tbyte; IBM 3592 data storage

IBM 3592 cartridges

OYO GS-624-24”



Streamer DigiSTREAMER

Type

Manufacturer

Length of the streamer active part

Length of cable (Lead-In)

Number of channels

Length of active section

Diameter of active section

Type of filler

Operational depth (export section type)

Survival depth

Streamer working temperature

Streamer storage temperature

Hydrophone group interval

Type of hydrophones Teledyne

Number of hydrophones in group

Groups of hydrophones

Group sensitivity

Seismic winch Maximum capacity

DigiSTREAMER

ION (USA)

7000 m (max 8 000 m)

350 m

560 (max 640 at length 8 000 m) v

99.7 m

53 mm +/- 3 mm (5,3 cm)

Solid state (patent, unliquid gel)

30 m max (98 ft)

300 m (984 ft)

from -5 to +30°C (from 23 to 86°F)

from -20 to +60°C (from -4 to 140°F)

12,5 m (8 groups per section)

T-2BXE

8

In-line layout with distribution for noise control

19 V/bar

to 8 000 m(ODIM A/S, Norway)



Devices of the streamer’s depth and positioning

Type of depth control devices:

- Without course indicator

- With course indicator

Manufacturer

Interface of data exchange with

the seismic streamer

Fixed direction indicator

- Accuracy

Depth sensors accuracy

DigiBird 5010/5010-2

Exportable Compass Bird 5011E/5011E-2

ION (USA)


Serial FSK, 26 kHz, 2 400 bit/sec

DigiCOURSE Model 321 Magnetic Compass

+-0,5 °

+-0,15 meters



Energy source system

Type of source points

Manufacturer

Number of pressure lines

Number of sources in each line

Length of the lines

Distance between the Lines

Conducting wire length

Total volume of cameras

Controller type

Temporary permit

Winches

High pressure compressors

Type


Sleeve Gun SG-IIB

ION, USA

2

9

15 m

7 – 10 m

600 ft

2 860 cubic inch

LongShot (Real Time Systems Inc., USA)

0,1 msec

2 basic and 4 auxiliary (ODIM A/S, Norway)

3 pcs.

Sauer WP-6442 (209 bar (2000 psi), 500 cu m/h)

(Germany)



Navigation seismic complex (at the additional request)

Type

Manufacturer

ORCA-2D

ION Concept Systems Limited (USA)



 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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