SERCEL  SEAL  System

Sercel expertise in the field of seismic acquisition systems and geophysical streamers is well recognized. The Seal System is the result of 30 years of streamer manufacturing and 40 years of development of acquisition systems, gaining improvements through flexibility in their architecture, higher integration of electronics, lower power consumption and higher reliability.

With modern intuitive front-end software, the Seal System brings to the World of Marine seismic acquisition two major break-throughs:

- Advanced flexible architecture for an optimal productivity;
- Small diameter arrays (Fluid or Solid).

Thanks to its flexible architecture the Seal System fulfills the requirements of today and probably tomorrow. On board, the Central Unit of the Seal System can be interfaced with any of the external systems used in the instrument room (source synchronizer, positioning and navigation systems, processing systems) and the auxiliary channels acquisition unit can be easily placed in the most convenient location.

Out-board, taking advantage of the power of fully distributed electronics, the length of the streamer section overlap, the number of hydrophones per channel and their location can be tailored to better fit the changing demands of sophisticated and complex marine surveys.
Furthermore, data transmission and power supply benefit from a highly reliable redundant architecture for an optimal productivity.

With a diameter no bigger than 50mm (Fluid or Solid), the Seal streamers open door to either smaller vessels or more streamers per vessel for higher productivity.

The Solid Seal cable design offers increased noise attenuation over fluid, filled sections during periods of marginal weather conditions which cause the fluid within the section to slosh back and forth, creating pressure on the hydrophones. The absence of streamer fluid, even in the flexible end terminations, enables seismic operations in the World's environmentally sensitive areas. Built to withstand the forces of nature endured during marine seismic operations Solid Seal are the strongest marine streamers available today.

The key characteristics of the Seal Systems are :

- Multiroute Telemetry - entirely fault tolerant to transmission breakdown;
- Power Management - entirely tolerant to power supply failure;
- Multi vessel flexible architecture;
- 20,000 channels recording capacity;
- 960 channels @ 2ms per streamer;
- 50mm only streamer diameter (Fluid or Solid);
- Streamlined canisters;
- Distributed waterproof electronics with few connectors;
- 150m sections with 12 channels per section;
- 12km streamer length;
- Permanent instrument test.

Control Modules

Central Unit (CMXL)
The CMXL is the new Central Unit of the Seal System that increases its maximum channels capacity. Designed with a modular configuration, the CMXL can control up to 10,000 Ch (20,000 when using 2 CMXLs in parallel). It manages the flow of acquired data between the streamers and the various recording and peripheral equipment (Tape drives, plotters, positioning, navigation, QC) via SCSI and Ethernet links.

Graphic User Interface (GUI)
The GUI is a bank of screens to graphically and intuitively set-up, control and troubleshot the system.

Power Module (PWM2)
With one PWM for each streamer, the current provided is a ± 175 V DC one under a power of 500 W. A PWM2 assures also the current limitation, the remote and manual ON/OFF, the leakage measurement and the cutoff and the measurement of the streamer consumption voltage.

Connecting Line Acquisition Unit (LAUXM)
The LAUXM assures the connection between the streamers and the ACM.

Auxiliary Channels Unit (AXCU)
Integrated in a rack or located near to the sources, the AXCU connects to the ACM the auxiliary channels (Time Break, near field sensors, TB volume).

Deck Cable Crossing Unit (DCXU)
The DCXU assures the connection between the streamers and the CMXL. It also linksthe streamers to the necessary control modules (NSU, PWM2) and eventually dispatches the various control information to the deck.

Peripheral Equipment

Tape Drives
Single or Dual Tape drives using 3490E type 1/2'' cartridges can be provided. The CD 490E tape drive allows a data transfer rate of 20MB/s with a storage capacity of 2.4GB.

CD590 Tape Drive
Single or Dual Tape drives using 3590 type 1/2'' cartridges. The CD590 tape drive allows a data transfer rate of 40MB/s with a storage capacity of 30GB.

Several other peripherals including workstation, plotters, CD drives, printers, cartridge tape drives complete the configuration of the Seal System.

Fluid or Solid Sections

The key characteristics of the Seal streamer technology are:

- the smallest streamer diameter in the industry and streamlined canisters (50mm),
- the fewest canisters and connectors of the industry,
- 150m sections, 12.5m typical channel spacing (12Ch/section), designed for 12Km streamer length,
- 960 channels @ 2ms per streamer, 20000 channels (250Km) recording capacity;
- oil blocked sections and waterproof distributed electronics, the fluid sections are fault tolerant to skin damage;
- the solid sections offer the same benefits than the fluid ones in terms of reliability and flexibility, plus a mechanical design that has incorporated a breaking strength to working load ratio of 4:1; which extends the working life of the cable.

The Seal System In-Sea Equipment represents the state-of-the-art of todays streamer technology.
Occupying at least 40% less volume in-sea, the Seal System allows operations either with more equipment or on smaller vessels. With 1 canister and only 6 connectors per 750m section, the Seal System smaller volume in-sea also implies at least 30% less drag force for the vessel. The Seal presents the advantages of an easy handling and storage and an increased reliability for a consequent operating cost reduction.

Lead-In
The Lead-In is composed of a Short Head Section (SHS), a Head Elastic Section Extension (HESE), a Head Elastic Section (HES) and a Tail Elastic Section (TES).
These are dedicated sections allowing mechanical links at the head and the tail of the streamer.

Head Auxiliary and Power Unit (HAPU)
The HAPU assures the following functions :
TLFOI power supply; first Acquisition Line Sections power supply; 48V, 30W power supply for the head buoy and consumption monitoring; measurement of the tensile stresses.

Acquisition Line Section (ALS)
With a length of 150m, an ALS acquires data from 12 channels with a 12,5m typical spacing.
Overlap of acquisition between two sections can be defined. Each ALS can be easily tracked with a RF identifier and location of each compass bird fixed on it is detected while winding the streamer to automatically stop the winch.

Line Acquisition Unit Marine (LAUM)
LAUMs assure data compression, data routing and power supply of the ALSs. 5 ALSs can be inserted between two LAUMs, meaning for example that a 960 Ch streamer is made up of 16 x 5 sections and 16 LAUMs.

Tail Auxiliary and Power Unit (TAPU)
The TAPU assures the following functions :
complete of the transmission lines; 48V, 30W power supply for the tail buoy and consumption monitoring.

Streamer to Tail Interface Cable (STIC)
The STIC is mainly made of a swivel to allow rotating freedom between the streamer and the tail buoy.

Control Software

The Seal Control Software offers control, power and flexibility. It is a key to evolution. The Seal Control Software presents user-friendly control and fast troubleshooting advantages :
- Quick instrument tests;
- Efficient on-line and continuous streamer tests (capacitance, frequency, response, noise);
- Seismonitor.
The Seal Control Unit Software also allows to detect and overcome troubles such as :
- Fault tolerance to transmission breakdown with multiroute telemetry;
- Fault tolerance to power supply failure with multiroute power supply.

QC Software

SeaPro QC
The SeaPro QC Software is an On-line Real-Time Seismic QC tool for Marine Seismic Data. SeaPro QC can be implemented on-line with standard marine acquisition systems to offer a powerful tool for real-time QC of seismic data, without the need for any tape manipulation. All QC functions are performed in parallel with the seismic data acquisition without slowing down marine operations.

SeaPro Bin Software
The SeaPero Bin Software is a Management & Coverage Analysis tool of Seismic Marine Surveys. SeaPro Bin provides within a very comprehensive and user friendly environment all the necessary information to efficiently define and analyse the seismic parameters involved in the management of a 3D seismic marine survey. Multi-surveys and multi-users package, SeaPro Bin offers facilities to easily give access to the computed data acting as a binning data base manager. The calculation flexibility and power of SeaPro Bin make feasible the exploration of different assumptions and the adjustment of different parameters with instantaneous display and replay of calculation results without overloading needlessly the memory or the disk-space of computer.