Geoelectric investigations

GEOELECTRIC and CONDUCTOMETRY

Head: Włodzimierz Jerzy Mościcki (Geoelectical Part)

  1. DC-resistivity methods: Vertical Electrical Sounding (VES) and Electrical Resistivity Tomography (ERT); self-potential (SP) method; Induced Polarization (IP)
  2. Penetrometer Based Resistivity Profiling (PBRP) method
  3. Geothermal measurements and monitoring (contact temperature measurements)

 

Apparatus and type of measurements:

  1. SuperSting R8/IP/SP (manufactured by AGI, USA)

8-channel equipment.
Up to 112 electrodes can be connected at the same time.
A set of 8 cables with 14 electrode inputs, basic spacing of 2.25 m (allows measurements with a maximum spacing of 2 m and any smaller ones).
Set of 8 cables with 14 electrode inputs, basic spacing of 5.25 m (allows measurements with spacing in the 2-5 m range).
Specialist cable for performing underwater measurements – 56 graphite electrodes with a spacing of 2 m.

 

  1. MiniSting with Swift system (manufactured by AGI, USA)

1-channel equipment.
Up to 112 electrodes can be connected at the same time.
A set of 8 cables with 14 electrode inputs, basic spacing of 2.25 m (allows measurements with a maximum spacing of 2 m and any smaller ones).
Set of 8 cables with 14 electrode inputs, basic spacing of 5.25 m (allows measurements with spacing in the 2-5 m range).

GDRM-VAR (manufactured by ELMES-Warszawa, Eng. L. Mucha)

Apparatus for geoelectrical penetration measurements and for ERT method.
It is possible to perform electrical potential (DC) measurements and DC-resistivity measurements using three frequencies: 8 Hz, 33 Hz, 133 Hz. The current can be stabilized – 50 selectable values from 0.05 mA to 50 mA, which change in geometric progression.
The possibility of building any measurement pattern (performing specific measurements in a given time regime).
Additional equipment – set of probes and instrumentation for performing geoelectrical penetration measurements: up to a depth of 1.5 m the diameter of a probe is 10 mm, the depth measuring step is 1 – 2 cm; to a depth of 5 – 6 m, the diameter of a probe is approx. 22 mm, a typical depth measuring step of 5 cm.

 

  1. GDRM-ELMES (manufactured by ELMES-Warszawa, Eng. L. Mucha)

Apparatus for performing VES method (also electrical resistivity profiling method).
The possibility of simultaneous use of four MN dipoles and control of individual electrodes grounding resistance.
A set of current cables AB/2 = 1.39 – 139 m (7 points per log decimal) with the possibility of sounding to AB/2 = 260 m. Measuring dipoles MN/2 = 0.4, 2, 10 and 30 m.

 

Geoelectrical apparatus – physical quantities and phenomena measured: apparent resistivity, electrical resistivity, electrical resistance, self-potentials, electrode potentials, potential changes and resistivity dynamics.

 

Other equipment:

  1. Digital temperature recorders (electrical resistance of any sensor):

MicroEdge – 8-channel logger, selective measurement interval 1 s – 1 h;

ZetaTec – 4-channel logger;

16 temperature probes (NTC thermistors), probe length 1.8 m, diameter 0.5 cm

  1. Probe for measuring temperature and electrical conductivity of water in field conditions (e.g. in piezometers and water reservoirs up to a depth of 25 m)
  2. Microprobes for measuring the electrical properties of soil samples in situ.

 

Head: Wojciech Klityński (Conductometrical Part)

 

Equipment for conductometric measurements (GCM, Ground Conductivity Meters), GF Instruments, s.r.o. , Brno, Czech Republic : CMD-Mini Explorer oraz CMD-Explorer.The apparatus is used to measure the intensity of the secondary magnetic field in phase and in quadrature to the primary magnetic field.Measurement in the near-field EM field allows obtaining the so-called apparent conductivity reflecting the distribution of conductivity in the ground to a depth of about 7 m.  Each of these apparatus allows measurements at three different depth levels in the Vertical Dipol (VD) version (larger depth ranges, High version) and for three different levels in the Horizontal Dipol (HD) version (lower depth ranges, Low version). Both instruments consist of a system of three transmission coils and three receiver coils arranged in a tube-shaped frame (Fig. 2, 3), and the correct positioning of the ‘pipe’ (markers on the ‘pipe’ allow this) allows the use of two measurement variants HD-L-Low and VD-H-High).  The CMD Mini Explorer has a length of about 1.2 meters and effectively weighs about 2 kg.  The Mini Explorer also includes: Bluetooth adapter and Control Unit (Fig. 2). The CMD Explorer has a length of approx. 4.5 meters (consists of four combined modules) and an effective weight of approx. 8 kg. The Explorer also includes: Control Unit and Fix the control unit to the probe (Fig. 3).The measuring range for both instruments is characterized by a maximum measured apparent conductivity of 1000 mS/m with a sensitivity of 0.1 mS/m. The measurement accuracy is 4% with an apparent conductivity of 50 mS/m and the operating temperature range is from -10 to 50 oC.For the CMD Mini Explorer, the maximum depth ranges are: approximately 0.5 m, 1.0 m and 1.8 m in p.p.t. at 30000 Hz frequency and spacing S with values ​​of 0.32, 0.71 and 1.18 m.In fact, for the Low version (HD), the effective depth levels are about twice as small (the Low variant with spacing with the following symbols: 0.32L, 0.71L and 1.18Lm, depth ranges approx. 0.25, 0.5 and 0.9 m.p.p.). Maximum deep levels are obtained for the High version, i.e. around 0.5 m, 1.0 m and 1.8 m, p.t.t (High variant with distances: 0.32H, 0.71H and 1.18H m). For the CMD Explorer, the maximum depth ranges are approximately 2.2 m, 4.2 m and 6.7 m with the 10,000 Hz frequency.For the Low version, these are ranges of approx. 1.1, 2.1 and 3.5 m ppt (Low variant with 1.48L, 2.82L, 4.49L spacing) and for High version approx. 2.2 m, 4.2 m and 6.7 m (High variant with 1.48H spacing) , 2.82H, 4.49H.

 

a.       Geoelectric measurements using the GCM method        The GCM method is used to measure the apparent conductivity of geological medium in the depth range from about 0.25 to 6.7 meters (Fig. 2, 3). Quantitative interpretation using LMA and Occam methods of GCM profiling data from several depth levels allows obtaining depth sections or elevation sections of the conductivity distribution in the ground (Fig. 4).  Fig. 2  Measurements with CMD Mini Explorer. Fig. 3  Measurements with CMD Explorer.