Presentation on theme: "Geometrics, Inc. 45 years experience in making geophysical instruments San Jose, California USA Douglas Groom, Director of Geoelectrical Products."— Presentation transcript:
Geometrics, Inc. 45 years experience in making geophysical instruments San Jose, California USA Douglas Groom, Director of Geoelectrical Products
Geode EM3D New geophysical instrument for High-resolution CSAMT surveys (controlled source audio magnetotellurics) Minex Central Asia, April 2014 Astana, Kazakhstan
Geode EM3D Features What is it? Distributed network of up to forty EM receivers each have six channels for total 240 EM channels Each receiver configurable for up to six telluric (E-field) channels and up to three magnetic (H-field) channels Durable metal enclosure. Low noise front end as low as 10 nV/rtHz Low distortion front end Automatic calibration in the field Automatic contact resistance measurement in the field Much more
Highlights Synchronized electric and magnetic field measurements for CSAMT, AMT, and more Synchronized by GPS to CSAMT transmitter Rugged instrumentation Reliable network architecture Backed by 45 years of experience in geophysical instrument manufacture
Geode EM3D 24-Channel Network 20 E – 4 H Channels
Benefits Why use it? High-density 3-D data sets for complete characterization of your mining prospect Rapid data collection with all channels GPS- synchronized to a single transmitter Flexible spacing of H-field sensors to maximize resolution yet minimize cost Scalable network from 6 channels up to 240 channels Full tensor CSAMT using two transmitter polarizations Automatic contact resistance measurement for better data quality In-field calibration for more accurate measurement Future AMT, IP, Resistivity modules available
Geode EM3D Single Receiver
High-resolution, high-density EM data with many sounding stations at the same time (simultaneous data acquisition ). Traditional CSAMT uses a separate setup for each sounding. For example, for 50 traditional CSAMT stations (soundings) the transmitter must be run fifty times and the station moved 50 times. Typically 30 minutes to one hour transmitter run time for each station meaning 50 hours of transmitter time for the survey, not including setup time. Geode EM3D allows a single setup of all stations and one transmitter run for acquisition of all 50 sounding at the same time (simultaneous acquisition). That is only 30 to 60 minutes in total for all 50 stations.
Orienting and leveling magnetic coils can be the most time consuming process in setting up a station
Geode EM3D offers flexibility in the use of H-field magnetic sensor coils Saves time: Traditional CSAMT requires burying coils for every sounding. Each time the station is moved the coils are reburied. Geode EM3D network allows using magnetic coils on one receiver to be used for multiple soundings on other receivers so fewer coils need to be buried. Improves efficiency: Operator can choose the optimal number of magnetic coils for the survey needs. For example H-field measurements can be used for every two E-field measurements, or maybe only every six, ten, or more E-field measurements, depending on the complexity of the geology and the requirements of the survey. Improves data quality: Using multiple Hy and Hx on different receivers, at different locations simultaneously, allows local referencing to improve data quality.
Easily scalable system from single- receiver 6-channel system to 40- receiver, 240-channel system Maximum flexibility in survey setup. Each receiver can be any combination of E and H up to six channels, such as: 3E/3H 4E/2H 5E/1H 6E
Field setup and channel parameters Note automatic contact resistance for every E-field dipole
GeodEM2010 Acquisition Menu Note “Measure Contact Resistance” and “Measure AC & DC Level” Contact resistance measured on automatically on all electrode channels. AC and DC noise level measured automatically.
China GeoTech Beijing Introduction of multi-node Geode EM3D to Chinese
120-Channel, 20-Receiver setup on bench
In-field screen display of test signal into 120 channel Geode EM3D
Better results with full tensor CSAMT Traditional CSAMT only does scalar (Ex/HY) impedance calculations. The Geode EM3D can easily do full-tensor measurements (Ex/Hy and Ey/Hx) using multiple polarizations from the controlled-source transmitter.
Geode EM3D field test approximately 100 km north of Beijing Four receiver network consisting of 20 channels used. Four magnetic (H-field) channels Sixteen electric (E-field) channels Four channels not deployed
Grounding transmitter dipole with metal plates and stakes
Chinese made 30 kW transmitter + controller + power supplies + junction boxes + monitoring gear
Two 15 kW generators for 30 kW Chinese transmitter
Set up frequency scheduler
CSAMT field data 16 channels at 8 Hz with 1.5 kW transmitter at 12.5 km distance
CSAMT field data 16 channels at 8 Hz with transmitter at 12.5 km distance
Real-time CSAMT impedance curves for six soundings in field
CSAMT and AMT now with future, IP, resistivity and other methods in future The first Geode EM3D product is controlled source audio magnetotellurics (CSAMT). Future products plans include AMT (natural- field audio magnetotellurics), induced polarization (IP) resistivity and other geoelectrical techniques.
Setting parameters for AMT acquisition Note that seven channels defines tensor site Ex, Ey, Hx, Hy, Hz, Hx2 and Hy2 for local reference
AMT real-time times series field display (natural field with no transmitter)
System Configurations 1. Single Node – One GeodeEM box used for AMT/CSAMT/IP with various configurations 6E, 5E1H, 4E2H, 3E3H 2. “Typical” Small Networked System – Four Geode EM3D receivers is the base network, with various configurations possible 3. “Maximum” Networked System – 40 GeodeEM boxes, i.e. 240 channels. – 20 Geode EM networ of 110 on display in Laurel Geophysical booth in exhibition hall.