Resistivity Imaging Systems

Resistivity imaging systems allowing automated electrode sampling for 3D surveys, marine surveys, and borehole ERT. Systems from 24 to more than 4,000 electrodes.

Syscal Kid Switch 24, for depths to 25m

Syscal Kid Switch 24 resistivity imaging system for depths to 25m. Designed for shallow ground water surveys, archaeological surveys, and geologic mapping.

Heritage GeoPhysics is pleased to announce the new multinode resistivity imaging option of its subcompact resistivity meter, the Syscal Kid. Specially designed for shallow resistivity imaging the Switch 24 features an internal switching board supporting 24 electrodes. Two cable strings with 12 electrode take outs each are connected to the back of the meter. Software is provided to automatically perform roll along surveys.

The all new user interface is quickly absorbed so that a wide range of users from archaeologists, to civil engineers, to geologists, can easily take advantage of the Switch 24's capabilities. Select the type of array, enter your electrode spacing, and tell the instrument to start. When sampling is complete move the cables down the line and start again. During data upload chose the profiles to be merged, create a final data file, and send it to Surfer for pseudo section display, or to your imaging software for modeling. Surveys are quickly completed, even with a single operator.

Resistivity anomaly over an ancient Roman Tomb (2D inversion of Wenner Data). Electrodes were spaced at 0.5m intervals. Total time to set up equipment, collect data, invert data, and print results was just over an hour.

The electrode string is made of heavy duty cable, as typically is used in the seismic industry. Each cable has 12 take outs, spaced at 1, 2, or 3m intervals. A cable with 3m spacing is 40m long and weighs about 2.5Kg. Thus, with two 3m cables a profile would be 72m, or roughly 236 feet. Depending on the type of array used this would yield survey depths in the 200 foot range, or 70m.

General Specifications

The Syscal Kid features what is called auto ranging. This means that the instrument automatically sets the correct output voltage based on the level of the measured signal. No more fussing with output voltage selections to get the best measured signal. The Kid also features automatic SP compensation, but does it better than most. What is unique to all of the Syscal meters though, is that during stacking, with every third stack, SP is again measured and reapplied, so that any drift during the stacking process is corrected. The result is a very accurate measurement, even in the presence of significant noise.

• Output Voltage: 200V (400 Peak to Peak)
• Output Current: 500mA
• Rechargeable Battery or External: 12 V
• Memory: 1,400 Readings
• Input Voltage: ± 2.5V, Protected to 200V
• Input Impedance: 22MOhm
• Resistivity Range: 0.001 to 10,000 Ohm meter
• Accuracy: 1%
• Weight/Size: 3.0Kg, 23 x 18 x 23cm

Syscal Kid console, instruction manual, data transfer cable and software, 2 cable strings with 12 take outs each, 24 metallic electrodes and connectors.

Syscal Junior Switch Imaging System, to 70m

Syscal Junior Resistivity Imaging system for mid range ground water studies, archaeology studies, and geologic mapping. The Junior Switch system may be equipped with 24, 48, or 72 internal switches for ERT surveys using cables with 5-10m spacing.

Resistivity Imaging For Environmental Applications

• Compact yet powerful
• 400 V - 100 W - 1.2 A
• Automatic ranging
• Automatic switching

Compact, easy-to-use and field proof, the Syscal Junior Switch measures both resistivity and chargeability (IP). It is ideal for environmental and civil engineering applications such as pollution monitoring and mapping, salinity control, depth-to-rock determination and weathered bedrock mapping. It can also be used for shallow groundwater exploration (depth and thickness of aquifers).

With the Syscal Junior Switch resistivity surveys can be performed very efficiently with one operator only.

RESISTIVITY IMAGING

• Aim: imaging the underground geological structures through surface electrical measurements
• Principle: use multi conductor seismic cables to lay out up to 72 electrodes per profile, with additional parallel lines of up to 72 electrodes to permit 3D acquisition. Automated sampling of any desired array of up to 1,000 electrodes.
• Apparent resistivity: p = K*V/I, K depending on the electrode separation
• Resistivity pseudo-section: contoured plot of the apparent resistivity data, using the electrode distance as a pseudo-depth parameter
• True resistivity section: contoured plot of the resistivity distribution obtained through the inversion of the measured data (using a non linear parameter fitting scheme)
• Applications: environmental studies, groundwater investigation, civil engineering, archaeology...

Preset arrays (Wenner, dipole,…) or customized arrays are uploaded through the user-friendly ELECTRE (version 2) PC software. The roll-along capability is implemented.

ACCURACY

• Automatic SP compensation including linear drift
• Digital stacking for noise reduction
• Standard deviation computation
• Noise may be monitored before injection

• RES2DINV for pseudo-section inversion to true resistivity (and IP) 2D section.
• RES3DINV (PC), for inversion to true resistivity (and IP) 3D data

• Automatic ranging (microprocessor controlled)
• Intensity: up to 1200 mA
• Voltage: up to 400V (800V peak to peak)
• Power: up to 100 W
• Selectable cycle time of 0.5 , 1 or 2 s, programmable from 0.25 to 10 sec.
• Current measurement precision: 0.5% typical.

• Measuring process: automatic ranging and calibration
• Input impedance : 20 MW minimum.
• Input voltage protection up to 1000V, range from –10 V to +10 V.
• Power line rejection
• Voltage measurement precision: 0.5% typical
• Noise reduction: continuous stacking selectable from 1 to 255 stacks.
• SP compensation through automatic linear drift correction.
• Resistivity accuracy: 0.5% typical
• Induced polarization (chargeability) measured over four predefined windows.
• Chargeability accuracy: 1% of measured value for input voltage higher than 10 mV.

• Weather proof
• Shock resistant fiber-glass case
• Operating temperature: -20 to +70 °C
• Dimensions: 31 x 23 x 35 cm. Weight: 11 kg
• Internal memory for 2700 readings
• Power supply: two internal rechargeable 12V, 7 Ah battery ; optional external 12V backup car battery for transmitter power
• Autonomy with internal battery: several thousands of readings
• Standard string weight: 15 kg each for 5m spacing

Syscal R1+ Switch Imaging System, to 150m

Syscal R1 Plus Switch Imaging System may be used for mapping groundwater and geologic targets. Supports up to 72 electrodes at electrodes spacings up to 10m. May be used with Switch Plus boxes to expand sytem to as many as four parallel lines of 72 electrodes for 3D acquisition, or up to 1,000 electrodes for ERT applications.

• Compact yet powerful
• 600 V - 200 W - 2.5 A
• Automatic ranging
• Automatic switching

Compact, easy-to-use and field proof, the SYSCAL R1 PLUS Switch measures both resistivity and chargeability (IP). It is ideal for environmental and civil engineering applications such as pollution monitoring and mapping, salinity control, depth-to-rock determination and weathered bedrock mapping. It can also be used for shallow groundwater exploration (depth and thickness of aquifers).

With the SYSCAL R1 Plus Switch resistivity surveys can be performed very efficiently with one operator only.

RESISTIVITY IMAGING

• Aim: imaging the underground geological structures through surface electrical measurements
• Principle: use multi conductor seismic type cables to lay out up to 72 electrodes per profile, with additional parallel lines of up to 72 electrodes to permit 3D acquisition. Automated sampling of any desired array of up to 1,000 electrodes.
• Apparent resistivity: p = K*V/I, K depending on the electrode separation
• Resistivity pseudo-section: contoured plot of the apparent resistivity data, using the electrode distance as a pseudo-depth parameter
• True resistivity section: contoured plot of the resistivity distribution obtained through the inversion of the measured data (using a non linear parameter fitting scheme)
• Applications: environmental studies, groundwater investigation, civil engineering, archaeology...

Preset arrays (Wenner, dipole,…) or customized arrays are uploaded through the user-friendly ELECTRE (version 2) PC software. The roll-along capability is implemented.

ACCURACY

• Automatic SP compensation including linear drift
• Digital stacking for noise reduction
• Standard deviation computation
• Noise may be monitored before injection

• RES2DINV, RES3DINV, for pseudo-section inversion to true resistivity 2D section.

• Automatic ranging (microprocessor controlled)
• Intensity: up to 2500 mA
• Voltage: up to 600V (1200V peak to peak)
• Power: up to 200 W
• Selectable cycle time of 0.5,1 or 2s, programmable from 0.25 to 10 sec.
• Current measurement precision: 0.5% typical.

• Measuring process: automatic ranging and calibration
• Input impedance : 10 MW minimum.
• Input voltage protection up to 1000V, range from –10 V to +10 V.
• Power line rejection
• Voltage measurement precision: 0.5% typical
• Noise reduction: continuous stacking selectable from 1 to 255 stacks.
• SP compensation through automatic linear drift correction.
• Resistivity accuracy: 0.5% typical
• Induced polarization (chargeability) measured over four predefined windows.
• Chargeability accuracy: 1% of measured value for input voltage higher than 10 mV.

• Weather proof
• Shock resistant fiber-glass case
• Operating temperature: -20 to +70°C
• Dimensions: 31 x 23 x 35 cm. Weight: 11 kg
• Internal memory for 2700 readings
• Power supply: two internal rechargeable 12V, 7 Ah battery ; optional external 12V backup car battery for transmitter power
• Autonomy with internal battery: several thousands of readings
• Standard cable string weight: 15 kg each for 5m spacing

Syscal Pro Multi Channel Resistivity System, our Top of the Line Model

Multi Channel, Multi Electrode, Multi Capable
Ten Channel, 3D, Marine, ERT Monitoring System Ready for your project.

Ideal For:

• Contractors Needing High Speed/3D Acquisition.
• Deep Groundwater, Geologic Surveys.
• Marine Surveys in Fresh or Salt Water.
• Borehole ERT type Monitoring Projects.

Need more Power? Order the Pro with the Receive only mode and use any external time domain IP transmitter(such as one of our VIP series IP transmitters) for kilowatts of power and larger dipole spacings to reach depths unmatched by lesser resistivity systems.

The Pro has pulse durations as short as 150 milliseconds. Initial results from first users have indicated good results at this rate, improving survey speed further. A multi channel instrument's primary advantage over single channel designs is the improvement in survey speed. With ten channels the Syscal Pro offers more channels than the competition, a 25% improvement over systems with only eight channels.

As a multi electrode imaging system the Syscal Pro will support up to 120 electrodes on a single line at 10m spacing. Other systems may do this, but only the Pro has the power to carry it through. For 3D surveys up to 3 additional lines of 120 electrodes may be supported using the optional Switch Pro switching boxes(at right), creating up to a 4 by 120 electrode 3D array.

The standard Pro system offers GPS input and a continuous data acquisition mode, so it is ready to go for marine surveys.

By adding the optional Sysmar Marine Acquisition software an operator can acquire and display a pseudosection with depth and location on a PC in real time. Stainless steel and graphite electrodes are offered for use in fresh or salt water respectively. For those users needing only a system for deep marine, salt water environments, please go to our Syscal Pro Deep Marine system.

For cross hole ERT, and other monitoring applications, the standard Pro system includes two alarms that may be set to trigger the instrument to collect an array at 2 different times during a 24 hour period. For this type of application a Syscal Pro may also be fitted with up to 192 internal electrode switches, creating a very compact and economical system. With addition of the ComSys Remote software a local PC may be used for data storage, which also allows for any stored array to be run at any time scheduled by the user.

For the research geophysicist a Syscal Pro Switch system may be used to monitor lab experiments with the alarm function. In this mode an optional adapter box is used so that bare wire connections may be easily made. Standard are 20 programmable IP windows, and input voltage of 15V on the first channel, and up to an additional 15V total on channels 2-10. The standard system also offers a low current option that extends the A/D low range for accurate low current measurements.

Typical Configurations

Standard Syscal Pro System includes console, with internal transmitting and receiving batteries, external 12V power cable, 2 battery chargers, data transfer cable, ProSys software for data transfer, data management, filtering, and output to third party formats for modeling, and Electre Pro software for array design, including 3D.

Syscal Pro Switch systems offer internal electrode switches in groups of 24 to support 24, 48, 72, 96, or 120 electrodes. Standard cable spacing is available at 5 or 10m, or may be optionally ordered at user defined spacings up to 10m. Switch Pro boxes are available in groups of 24 to include 24, 48, 72, 96, or 120 switches per box for surface surveys, or up to 192 switches per box for monitoring systems. Adapter Boxes are available for all switch designs to allow connection of standard bare wire to any Syscal Pro or Switch Pro.

Surface cables may be ordered at any spacing from 1-10m. Marine cables are available with stainless steel or graphite electrodes with user defined lead in and spacing. Borehole cables may also be ordered with any combination of lead in, number of electrodes, and spacing. Adapter cables are made as needed to support connection of borehole cables. An external power booster is available consisting of a 1,200W converter with AC/DC motor generator.

Output Specifications:

• Automatic injection ranging, microprocessor controlled.
• Current, up to 2.5A.
• Voltage, up to 1,000V(2,000V peak to peak), or up to 1,500V(3,000V peak to peak) with external converter.
• Power, up to 250W, or 1,200W with external converter.
• Pulse duration, 0.15, 0.25, 0.5, 1, 2, 4, and 8 sec.
• Current Precision, 0.2% typical.

• Input Impedance, 100MŮ.
• Input voltage, Channel 1 is 15V, Channels 2-10 are additional 15V, input protection 1,000V.
• Notch Filters, 50 and 60Hz.
• Voltage Measurement, 0.2% typical, 1µV resolution.
• Automatic Stacking and Averaging.
• Automatic SP correction with linear drift correction on every third stack with real time digital filtering.
• Induced Polarization, total chargeability plus 20 automatic or user defined slices.
• Simultaneous measurement of voltage and current during stacking.

• Memory for 21,000 readings
• Serial RS232 data transfer
• Serial port for GPS input.
• Operating Temperature, -20°C to +70°C.
• Weight, 10Kg
• Size, 31 x 23 x 23cm.
• Power supply, 2 internal 12V 7.2Ah batteries, or external 12V.

Switch Plus - 3D Resistivity Imaging

Switch Plus boxes are used with the Syscal Resistivity Imaging systems to expand the number of electrodes. The boxes may be placed on lines up to 20m distant, to allow parallel lines of data to be collected for true 3D arrays.

Conventional resistivity systems require the operator to lay out a profile in an “S”, or snake, shape, in order to collect 3D resistivity data. With the new Switch Plus concept this is now much more efficient, with easy roll along capability. At the heart of the system is the Syscal Junior Switch 48 resistivity meter. This unit incorporates a 100W resistivity meter with 48 nodes (switches) built into the console. By adding up to three additional Switch Plus Boxes of 48 nodes each we can create a system with 192 nodes, and possible line layouts as shown below.

The 100 W power delivered by the SYSCAL Jr Switch-48 allow to obtain good signal-to-noise ratios for dipole-dipole measurements even in suburban areas.

Application

Two types of line layouts are possible, as shown below. At the left are shown eight lines of 24 electrodes each, with the system set to roll to additional lines. Standard seismic type cable is used, with a typical spacing of up to 5m between nodes, and up to 50m between lines.

Here we show the ability of the system to roll along the line, running 4 sets of 48 nodes per line. For practical ease the recommended array is a combination of in-line colinear dipole-dipole, and broadside equatorial dipole-dipole, the latter having a greater depth of investigation.

Specifications:

• Two Bendix plugs for 24 take-out electrode string each. Other configurations on request (such as four plugs for 12 take-out electrode string each, or 48 single binding posts).
• Link cable length: 10 m standard (other length on request)
• Dimensions: 23 x 18 x 23 cm for the standard configuration
• Weight: 4,5 kg
• Power supply: internal rechargeable 12 V & 6.5 Ah battery or external 12 V car battery
• Operating temperature: -20 to + 70°C

CORIM Continuous Profiling Resistivity System

A contunuous resistivity profiling system for depths to 5m.

Features:

• Continuous Profile Resistivity Measurement
• Real Time Data Display
• Investigation Depth of 3 Meters
• Rapid Data Collection

The CORIM System consists of a trolley that supports the system controller and power supply, along with distance measuring device and notebook PC, attached to up to seven capacitive electrodes, and a final transmitting electrode, each with their electronics. The system may be pulled by hand, or by a vehicle, at speeds up to a few kilometers per hour.

With it's continuous data collection capability the CORIM system may find applications for measurement of earth resistivity in cases where other geophysical techniques may not be appropriate, such as areas of high clay content, or excessive cultural noise. The CORIM system can be expected to make measurements with a 3-4 meter depth limit, with a resolution of about 0.3 meter.

The electrode carpets consist of one meter spaced capacitive plate electrodes with a receiver unit mounted on each. Each receiver then connects to the system controller in the trolley. One of the electrode carpets functions as the transmitter and contains an independent transmitter with its own battery pack. A spare transmitter battery pack may be kept on the trolley and recharged from the main system, so that it is ready when needed.

Mounted on one of the trolley wheels is an optical pulse encoder to measure distance and trigger readings every 0.2 to 10 meters. The acquisition software displays vehicle speed and warning messages when the speed is too fast. Control of the system is from the PC via a serial port connection. System status, including battery voltages, are displayed on the PC.

During system setup the Compensation routine may be run. This measurement calculates the local SP effect and zeros this for data analysis. The Compensation measurement may be made several times on a profile in order to correct for changes in surface conditions.

As data acquisition begins the apparent resistivity values calculated for each electrode carpet, or channel, are continuously displayed, either digitally, or as a series of profiles. A marker function allows the operator to mark fiducial points for later reference.

The CORIM View software is used to filter and display the final data. Data may be displayed and printed as either a series of line profiles or as a pseudosection. Data may be displayed as either raw data, or as Compenstation(SP) corrected data.

Standard Components:

6 Receiver dipole carpets, 1 transmitter dipole carpet, 6 receiver electronics, 1 transmitter electronics, transmitter battery, receiver controller, main rechargeable battery, battery chargers for main, and transmitter batteries, distance encoder, trolley, spare parts kit, software and manual.

Syscal Pro Marine Resistivity System

Multi Channel, Multi Electrode, Multi Capable

Fresh Water/Salt Water Surveys
Graphite or Stainless Steel Electrodes

The Syscal Pro is a ten channel resistivity meter offering superior transmitting power, up to 2.5A, a feature of considerable importance for marine surveys.

Interest in marine resistivity surveys has contributed to the offering of a software package enabling integration of GPS and echo sounder data for real time display of pseudo sections.

The standard Syscal Pro offers a continuous acquisition mode and connection for GPS receivers. In this mode readings are taken and stored at a frequency of once every two seconds.

An optional marine acquisition package called Sysmar is offered to allow a local PC to be used to display the real time pseudo section with GPS and echo sounder data, and to store data to the hard drive. This permits acquisition of long profiles that may exceed the instrument’s memory.

For fresh water surveys the cable is floated. Dipole separation is dictated by the depth of interest.

System Components

A standard system will include the Syscal Pro resistivity meter, a cable of graphite or stainless steel electrodes, with 13 electrodes at a spacing defined by the client, optional Sysmar data acquisition software, and optional GPS/Echo Sounder.

Cable specification should include electrode spacing and material, lead in length, and tail length. The cable is a multi conductor type with Kevlar reinforcement. Client should supply tow rope to take strain from electrode cable, and floats to support cable.

Spacings of 5m would lead to a profile length of 65m, and a survey depth of approximately 13m. 2D inversion software is now available to support a floating cable geometry.

A reasonable survey speed may be something in the 5Km/hr. range. A cable with 5m spacing and ten dipoles, running at one sample every two seconds, would yield readings at about 3m intervals.

In salt water the conductivity is very high, so only surveys in shallow water can be done with a floating cable. In deeper salt water the electrode cable must be dragged along the bottom. This is a challenging type of deployment, but has been carried out in many areas.

SYSCAL Pro "deep marine"

10 CHANNELS MARINE RESISTIVITY SYSTEM 40 A OUTPUT CURRENT

• 10 simultaneous reception channels
• 40 A – 2000 W – 56 V
• GPS input
• Internal or external (computer) storage

This version has been specifically designed for marine survey in high conductive medium (like salt water) thanks to the high output current capability.

Marine survey with GPS:

A GPS/Sounder can be directly connected to the unit by a serial link for a continuous recording of the location of the 10 channels and of the water bottom all along the profile. In that mode, using the 10 reception channels, a set of 10 resistivities is measured and stored approximately every 2 seconds.

Graphite electrodes:

Specific cables with graphite electrodes can be supplied to fit to that environment ; this allows to get low resistance values and to avoid corrosion due to water contact.

Sysmar software:

A specific remote PC software (SYSMAR) can be used for setup and data storage (no memory limitation) and for a graphical picturing in real time of the resistivity pseudo-section.

Inversed Resistivity section (3000 data points acquired in 10 minutes)

SYSCAL PRO "deep marine" CONFIGURATION

The marine cable made of 13 takeouts (2 for the current injection and 11 for the voltage reception) is connected to the SYSCAL Pro unit by the front panel plugs.

In thick water layer conditions, a specific cable can be submerged and dragged on the bottom. The standard spacing between takeout is 4 meters; cable with other spacing can be supplied to match your requirements.

Graphite electrodes floating cable connected to SYSCAL Pro 10 channels

Data are continuously transferred into the computer and can then be processed by the PROSYS software (data managing software for SYSCAL unit). From this software, one has the opportunity to visualize graphically the apparent resistivity section and process the data (filter, add data files…). Then, one can export the data to .txt. file or to interpretation software like RES2DINV software for pseudo-section inversion to true resistivity 2D section.

TECHNICAL FEATURES

OUTPUT SPECIFICATIONS

• Current: up to 40 A
• Voltage: up to 56 V (4 DC 12V batteries connected in serie)
• Power: up to 2000 W
• Pulse duration: from 150 ms to 8 s
• Current measurement precision: 2 % typical

• Measuring process: automatic ranging and calibration
• Input impedance: 100 M.
• Input voltage:
• Max. channel 1: 15 V
• Max. channel 2 to channel 10: 15 V
• Protection up to 1000V
• 50 to 60 Hz power line rejection
• Voltage measurement:
• Precision: 0.2 % typical
• Resolution: 1 µV
• Noise reduction: automatic stacking number in relation with a given standard deviation value
• SP compensation through automatic linear drift correction

• Data flash internal memory: more than 21 000 readings
• Serial link RS-232 communication
• Power supply: 1 internal rechargeable 12V, 7.2 Ah battery for electronics power supply ; 1 to 4 external 12V standard car batteries for transmitter part
• Protection against polarity inversion
• Internal fan cooling system
• Shock resistant fiber-glass case
• Operating temperature: -20 to +70 °C
• Dimensions: 31 x 23 x 28 cm
• Weight: 10 kg