RAS-24 Exploration Seismograph

The RAS-24 is a modular 24-channel, high resolution, signal enhancement seismograph designed for shallow refraction and reflection surveys, and general geophysical exploration. Based on a "distributed" approach, like larger seismic systems used for oil and gas surveys, the RAS-24 is the first refraction/reflection seismograph to combine state-of-the-art 24-bit conversion with a flexible, expandable architecture that provides the ease of use of a conventional system with the advantages of a distributed system.

APPLICATIONS

Oil & gas exploration Mineral exploration Geotechnical surveys Engineering geology Groundwater surveys VSP and tomography

Depth-to-rock Fault location Site remediation Surface wave analysis Rippability surveys Teaching and research

EASY TO USE 

Operating under Windows 95/98/2000/XP, the RAS-24 system software has a familiar point and click interface which is easy to learn and operate. With buttons, scroll bars and single key commands for commonly used functions, the RAS-24 user interface is designed to allow direct access to important system functions.
And setting up the RAS-24 couldn’t be easier. Select the type of survey you want to perform -- refraction, 2D reflection with roll, or 3D -- and the RAS-24 configures itself. And once you’re back in the office, you can review the observer's log and view pick and print records on your office system using the same software that you ran in the field.

EXPANDABLE 

Because the RAS-24 is a distributed system, it provides a unique flexibility not found in any other engineering seismograph. Connect one RAS-24 to a laptop and you have a very portable 24-channel (or optionally 12 channels) refraction seismograph. Connect 10 units together in a line and you have a 240-channel, 2D reflection seismograph complete with roll. Rearrange those same 10 units and you have a 10 line, 24 channel/line 3D system. And no special hardware is required for any of these configurations. The system software manages the roll for 2D and the active portion of the spread for 3D operation so no roll switches or CDP cables are required. The ability to add channels to fit the job at hand ensures that the RAS-24 will be able to handle all your future exploration requirements.

Below is a typical setup for a 24-channel refraction survey.

The 48-channel setup below could be used for either a refraction or reflection survey. Recording can be from all 48 channels or from a smaller number of channels situated anywhere within the spread. Channels may be rolled manually or automatically one or more stations between shots.

48-Channel Single-Line Layout

The 72-channel spread below was shot in a 3D arrangement with 24 channels per line on each of three lines. All or part of a line may be recorded depending on the survey requirements.

3D 72-Channel Three-Line Layout

CONSISTENT DATA QUALITY 

The RAS-24 provides an extensive array of tests to ensure that the system is functioning properly and that your data is being accurately recorded. And the tests are easy to perform, requiring no external equipment or connections. Select an individual test to verify the performance of a particular specification or choose System Test and the RAS-24 will automatically step through all available tests. Results are graphically displayed and logged to disk. Tests include geophone pulse, geophone resistance, geophone similarity, leakage, amplifier noise, dynamic range, A/D offsets, amplifier pulse, CMR, system timing accuracy, channel to channel crosstalk, sine wave, phase similarity, and gain similarity.

REDUCED FIELD TIME SETUP 

ADVANCED SYSTEM SOFTWARE 

The RAS-24 provides advanced features such as an integrated observer's log recorded with each record, and a time stamped shot log which provides a continuous log of recording activity allowing you to retrace events that happened in the field.

The system provides two adjustable filters which may be independently configured as low-cut, high-cut, bandpass or bandstop. For surveys using weight-drop or hammer energy sources, the signal enhancement feature may be used to add (stack) successive shots together to improve the signal-to-noise ratio. Individual shots may be stacked and unstacked as desired and the polarity of each stack may be changed to facilitate shear wave studies.

For 2D reflection shooting, the RAS-24 offers integrated line management with autoroll and a graphical line geometry display showing the shot point, roll direction, total number of channels on line, and active channel positions.

The RAS-24 provides a broad range of intuitive display options which allows you to view the data the way you prefer. With a single click, you may expand or contract the display in the time or channel direction, display all the even or all the odd traces, or zoom in on an individual channel.

RAS-24 ADVANTAGES OVER CONVENTIONAL SEISMIC INSTRUMENTS

For surveys with 48 channels or more, the distributed approach used in the RAS-24 provides significant advantages over conventional seismographs:

• Expandable in inexpensive 24-channel units. Just add
  another RAS-24 and the system automatically recognizes it.
• No roll switch for reflection shooting. Roll is controlled
  by the system software.
• No heavy, expensive CDP cables. Uses 12-channel
  spread cables for all configurations.
• Integrated 3D operation. The RAS-24 system software manages
  each line as an independent entity.
• All testing functions are built in and controlled by the operator from the
  laptop using the RAS-24 system software. The performance of the entire
  system may be verified in the field with just two clicks of the mouse.
• Since the RAS-24 acquisition unit is separate from the
  controller (the laptop), the controller may be easily upgraded
  to faster, more capable models as they become available.

Whether you’re looking for a 12-channel refraction seismograph or a 240-channel reflection system for 3D, the RAS-24 has the data quality, features and performance you need for the most demanding jobs.

To download a fully functional version of the RAS-24 system software or to receive a free evaluation copy by mail, please send a request to sales@seistronix.com.