VE464 ASSURING HIGH PRODUCTIVITY AND QUALITY FOR VIBROSEIS OPERATIONS. Ahead of the Curve SM

Transcription

1 VE464 ASSURING HIGH PRODUCTIVITY AND QUALITY FOR VIBROSEIS OPERATIONS Ahead of the Curve SM

2 VE464 For decades the VE416, followed by the VE432, have been the most advanced Vibrator Digital Control Systems in the industry; well known for the precision of their generated signals and the diversity of Vibroseis techniques they have managed. The VE464, successor of this tradition of advanced vibrator electronics, benefits from the latest developments in integration, radio transmission and servocontrol. With these major improvements, the VE464 delivers and controls signals with higher accuracy and speed, allowing its users to implement vibroseis seismic easier than ever, aiming for ever increasing productivity and fl exibility. The VE464 is a powerful Vibrator Digital Control System, using a fully auto-adaptive servomechanism. It enables the use of advanced Vibroseis techniques such as: - pseudo-random sweeps - multiple simultaneous sources in fl ip-fl op or slip-modes (1) - coded sweeps - cascaded (2) sweeps The VE464 has reached an even higher level of fl exibility, offering dedicated sweeps, by programming a different sweep per vibrator in a given fl eet. One of the major advancement of the VE464 is the use of TDMA Radio (Time Division Multiple Access) instead of the standard VHF transmissions (still an option of the VE464). TDMA Radio, due to its full duplex protocol, increases the capacities of the system allowing: - no interference when using more than 2 fl eets in navigation mode, - the use of an increased number of fl eets (32 fl eets max.) In addition, TDMA Radio has its own integrated GPS system used for both synchronizing the sweeps and tracking the vibrators with differential corrections for guidance options. External satellite DGPS and Glonass receivers can still be used with VE464 for integrated tracking of source positions. Digital Pilot Generator (DPG) The DPG is connected to the data acquisition system through an Ethernet link and acts as a master control unit for the VE464 system. The DPG can be: - either fully integrated with the 428XL Sercel acquisition system, - or connected to any other type of acquisition system, using its own graphic user interface. The VE464 DPG is a rackable unit, the same size as an LCI-428, offering 60% less volume compared to the VE432. There is one single electronic board in the DPG which is also used in the DSD.

3 VE464 Digital Servo Drive (DSD) Installed in each vibrator, the DSD performs real time control of the vibrator ground force, as well as computes and transmits complete attribute sets for the QC database. The VE464 DSD is a more compact unit than the DSD of the VE432 (35% less volume). It has an improved design made up of only two easy accessible boards requiring less time in maintenance. The DSD benefi ts from new accelerometers equiped with a new bolting plug. The VE464 DSDs can be equipped with an external Tablet PC acting as a QC terminal and a monitor for the GPS guidance option. With its large screen, the Tablet PC provides effortless programming of the DSD and allows effi cient comparison of servocontrol parameters from one DSD to an other. Furthermore, the Tablet PC allows Wi-Fi connection between DSDs to make sure they all benefi t from the same consistent set-up. The VE464 DSD cabling (lift circuit, power supply, vibrator control with accelerometers) is compatible with the VE432 cabling, simplifying the upgrade from one system to the other. A DSD can be used in standalone mode (without DPG) when using a single vibrator, for example in cases of VSP seismic acquisition. VE464 Main features Signal generation With 428XL acquisition system, up to 32 different simultaneous digital pilot signals and 2 analog signals can be generated by the DPG. The 24-bit digital pilots allow for better quality and lower noise signal generation. A pilot or a sweep signal is generated from an operator-defi ned library of 32 basic signals combined with high-line parameters. Basic signals are defi ned by their frequency range, frequency vs. time law, sweep length, initial phase value, tapers and amplitude vs. time law, or any custom law. A single DPG can handle a maximum of 32 vibrators whether used independently or in some combination of multiple vibrator fl eets. Digital vibrator control By an automatic identifi cation procedure, the VE464 digital model is adapted to any type of vibrator without the need for manual adjustment. The fully digital auto-adaptive servomechanism performs with optimal control minimizing the phase and distortion while maximizing the fundamental output. The integrated GPS allows a high level of precision in signal synchronization and in particular a T 0 accuracy of ± 10 μs. Optimal digital control allows: - fast sweep rate, - combination of sweep segments with no dead time, used in cascaded (2) sweeps or multiple source applications, - pseudo-random sweeps, for environmentally friendly vibration. Enhanced real-time Quality Control The DSD integrates a complete set of functions for automatic sensor tests. The check for coherence between measurements contributes to quality assurance, ensuring that the vibrator generates the proper sweep, without any risk of polarity inversion.

4 A complete QC data base is generated for real-time or post-processing analysis including: - phase - distortion - fundamental ground force In addition, the digital control identifi es the ground viscosity and stiffness, which regularly provides information on the ground absorption model and can be used to enhance seismic data. Other QC measurements can be sent to the acquisition system in real time or stored on a local hard disk or a USB memory stick for further analysis and treatment requested by some particular acquisition methods (i.e. HFVS (3) ). These measurements include: - fundamental ground force - reference signal - mass acceleration - baseplate acceleration Bar-graph QC display All the QC information is displayed within color bar-graphs with automatic threshold detection. For each vibrator, current values and average values over the last 50 vibrations are shown. Complete graphic display In addition to the QC database information, the VE464 has the capability to graphically display the Phase, Distortion and Force results vs. Time or Frequency for each vibrator in real time. QC Statistics On request, statistics on the QC database can be generated, for daily or longer time period analysis, to detect any drift in vibrator performance or to be used as a preventive maintenance tool. GPS Vibrators Guidance Each vibrator can be guided by its Sercel acquisition systems from one pre-planned VP to the next one by using the GPS guidance option of the VE464. Time or Frequency curves Bar Graph QC Display

5 Specifications SIGNAL LENGTH up to 64 s in 1-s steps FREQUENCY VS. TIME LAW linear, logarithmic, pseudo-random, user defi ned FREQUENCY RANGE 1 to 300 Hz in 1-Hz steps AMPLITUDE VS TIME LAW linear interpolation TAPERS up to 1/2 signal length, Blackman Law MAX. NUMBER OF VIBRATORS 32 T 0 ACCURACY ±10 μs (GPS pps) CLOCK ACCURACY no drift. GPS accuracy QC DATA BASE FORMAT Positioning data QC attributes PHYSICAL Size : W x D x H SPS fi le APS fi le DPG : 440 x 385 x 88 mm DSD : 168 x 427 x 283 mm Weight including mounting parts DPG : 3.6 kg DSD : 11 kg TEMPERATURE RANGE Operating 0 C to 45 C Storage -40 C to 70 C POWER SUPPLY DPG DSD 110 V or 220 V / 30 W 12 V / 80 W (1) i.e. : slip-sweep invented by P.D.O. (2) Exxon pattent (3) Mobil pattent

6 Sercel - France 16 rue de Bel-Air B.P CARQUEFOU Cedex Telephone: (33) Fax: (33) sales.nantes@sercel.com S.A. au capital de Siège Social: 16 rue de Bel-Air Carquefou R.C.S. Nantes. Code APE 2651B Sercel Inc. - USA Park Row Houston, Texas Telephone: (1) Fax: (1) sales.houston@sercel.com Printed in France. Sercel 10/08 Ahead of the Curve SM