Training on RES2DINV and SibER-48
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Presentation, embedded below was developed to bring users up to speed in interpretation of their resistivity data. Class for end users was conducted in Indonesia and included training on field data collection with SibER-48 using ~ 900 m long profile in Wenner-Schlumberger and pole-dipole (remote electrode) 2D tomography. On the second day users received hands-on instructions on data import into RES2DINV software, quality assurance of the data based on visual approach as well as through RMS of the interpretation model. General discussion about non-uniqueness of the subsurface interpretation model for 1D, 2D, and 3D representations has followed this class.
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Training on RES2DINV and SibER-48
- 1. Training on RES2DINV/RES3DINV software (Geotomo software, Malaysia) LARISA GOLOVKO, PH D LANDVISER LLC HOUSTON, TX
- 2. Materials need Each participant need to bring laptop! Copy folder 1RES2DINV to each laptop: Two .d2d files with data from yesterday Software installs Manuals for SibER-48, RES2DINV, RES2DMOD Off-line instruction pages from www.landviser.net Dr. Loke’s Course Notes on Theory of 2D&3D resistivity surveys Install software: SibER Tools RES2DINV, etc. RIPPP
- 3. VES (1D-2D-3D) ER/SP/IP equipment SibER-48 ( <2A) & LandMapper ( 7 mA) Stationary DC equipment usually measures three electrical parameters – resistivity (ER), induced polarization (IP), self- potential (SP) “Unlimited” depths and resolutions through electrode spacing/combination Usually automatic multiplexing of 4-electrode arrays Max depth ~½-1/3 of surface wire spread, also somewhat limited by output current/instrument sensitivity: environmental applications need between 2 mA to 500 mA (EPA http://www.epa.gov/esd/cmb/GeophysicsWebsite In most conditions in Indonesia the input voltage of <60 V is recommended
- 4. SibER-48 SibER roll along layout 48-electrodes single channel Resistivity and Induced Polarisation imaging instrument SibER-48 Developed in 2012 Produced 50 pcs, distributed in Russia, Ukraine, Armenia, Indonesia. Fastest single channel ERT instrument in the World. Technologies and innovations
- 5. V Receiver Transmitting electrodes Grounded electrode Every one of 48 electrode is connected to transmitter or receiver. The automatic switchboard is switching the electrodes, making the ρ measurement at various depth and on line position. The data inversion process inverts the data into 2D cross-section. The set of 2D cross-sections can be processed by 3D inversion procedure. Electric Resistivity Tomography and Induced Polarization method and SibER device for shallow (up to 300 m) subsurface survey Siber-48
- 6. SibER 48 electrodes, one channel, up to 2 A Different arrays can be used to improve resolution / increase depth of penetration (see SibER example pdf)
- 7. 2D and 3D resistivity studies - multiplexing of different arrays
- 9. First field day Use SibER Tools to create electrode layouts and load into instrument.
- 10. First field day Use SibER Tools to create electrode layouts and load into instrument. 2 profiles: mtl01slb.d2d – Schlumberger mtl01wna.d2d – Wenner Alpha Use RiPPP to view profiles and pseudosections, clean data and export in RES2DINV format .dat
- 11. Arrays Possible Layout # Elec. Nane RES2DINV code Example file 4 Wenner- Schlumberger 7 PIPESCHL.DAT 3 Pole-Dipole 6 PDIPREV.DAT 2-4 General Array 11 RATCMIX.DAT http://landviser.net/content/formatting-array-input-data-file-res2dinv- surface-electrodes-any-geometry
- 12. General electrode format Ax[m] Bx[m] Mx[m] Nx[m] Center[m] Depth[m] Tx.I[mA] Tx.U[V] Rx.U[mV] Rx.SP[mV] ?[Ohm*m] M[mV/V] Q[%] 0 60 20 40 30 10.38 315.194 0 151.446 0 60.3795 0 0 20 80 40 60 50 10.38 368.972 0 146.133 0 49.7697 0 0.437 40 100 60 80 70 10.38 269.278 0 101.485 0 47.3599 0 0.264 60 120 80 100 90 10.38 321.36 0 105.864 0 41.3968 0 0.294 RiPPP raw data table
- 13. Schlumberger - RiPPP Schlumberger (20 m, 8 cables = 980 m length, 160 m depth) Schlumberger (5 m, 8 cables= 245 m length, ~40 m depth)
- 15. Schlumberger - RiPPP The pseudosection gives a very approximate picture of the true subsurface resistivity distribution. However the pseudosection gives a distorted picture of the subsurface because the shapes of the contours depend on the type of array used as well as the true subsurface resistivity. The pseudosection is useful as a means to present the measured apparent resistivity values in a pictorial form, and as an initial guide for further quantitative interpretation. One common mistake made is to try to use the pseudosection as a final picture of the true subsurface resistivity.
- 17. General electrode format Ax[m] Bx[m] Mx[m] Nx[m] Center[m] Depth[m] Tx.I[mA] Tx.U[V] Rx.U[mV] Rx.SP[mV] ?[Ohm*m] M[mV/V] Q[%] 0 60 20 40 30 10.38 315.194 0 151.446 0 60.3795 0 0 20 80 40 60 50 10.38 368.972 0 146.133 0 49.7697 0 0.437 40 100 60 80 70 10.38 269.278 0 101.485 0 47.3599 0 0.264 60 120 80 100 90 10.38 321.36 0 105.864 0 41.3968 0 0.294 RiPPP raw data table Exported in RES2DINV Íîâûé ïðîåêò.dat 20 11 0 Type of measur ement (0=app. resistivity,1=resistance) 1 497 2 0 4 0 0 60 0 20 0 40 0 0.480485 4 20 0 80 0 40 0 60 0 0.396054 4 40 0 100 0 60 0 80 0 0.376878 4 60 0 120 0 80 0 100 0 0.329425 4 80 0 140 0 100 0 120 0 0.388033
- 19. Loading data file .dat into RES2DINV
- 21. Running inversion – options for Quality Control Manually removing bad data Changing damping factors Inversion model file .inv
- 22. Presenting data profiles Changing depth to linear Bedrock detection Removing bad data with RMS after initial inversion and re-running inversion.
- 23. Schlumberger – kiriar01 Schlumberger (20 m, 8 cables = 980 m length, 160 m depth)
- 24. Schlumberger – kiriar01 Schlumberger (20 m, 8 cables = 980 m length, 160 m depth) 5 data points manually removed in RES2DINV
- 25. Pole-dipole – kiriar02 Bad electrode connection troubleshooting in the field (re-run profile => kiriar03) Cleaning in RES2DINV - 15 data points removed
- 28. Pole-dipole – kiriar03 changing damping factor
- 29. Pole-dipole corrected (>60% RMS removed) – kiriar03-60.dat
- 30. Pole-dipole corrected >60% RMS removed
- 31. Pole-dipole corrected >60% RMS removed
- 35. Measuring EC of saturated soil paste in standard four-electrode cells
- 36. LandMapper – measuring ER in deep soil pit, Philippines (2004)
- 37. Also available: New Hand-held resistivity/self-potential meters – LandMapper ERM-03 and ERM-04 - available NOW Multi-frequency electromagnetic scanner AEMP-14 – available NOW SibER-64 18-channel resistivity/IP system ( available Now) Free Agricultural Geophysics webinar series www.ag-geophysics.org 1st and 2nd recordings already on contact Larisa Golovko, Ph.D: info@landviser.net +1-609-412-0555
- 38. Vertical Electrical Sounding (1D) Simple and fast Provide profile distribution of ER from soil surface to any depth Easily customized sounding depths through different electrode arrays Many freeware available for 1D data interpretation: f.e. RES1DINV
- 39. Manual soil VES MN= 2m - constant for the whole VES profile (1D) All measurements done at K0=1 (or K1=10, K2=100 to boost the signal) Manual VES procedure – spread AB electrodes completely and then move AB electrodes inward to pre-set distances. – www.landviser.net
Notas del editor
- For IP surveys using the dipole-dipole array, one common method is to place the plotting point at the intersection of two lines starting from the mid-point of the C1-C2 and P1-P2 dipole pairs with a 45-degree angle to the horizontal. It is important to emphasize that this is merely a plotting convention, and it does not imply that the depth of investigation is given by the point of intersection of the two 45 angle lines (it certainly does not imply the current flow or iso-potential lines have a 45 angle with the surface). Surprisingly, this is still a common misconception, particularly in North America!