Water
Water Services
Surface geophysics
2D and 3D Magnetotellurics (AMT/MT)
2D and 3D Magnetotellurics (AMT/MT)
Magnetotellurics is a geophysical passive technique which permits to map the subsoil electrical resistivity distribution, from shallow up to several thousand meters depth. It is applied to the Earth crust and mantle investigation as well as to oil & gas, geothermal, groundwater and mining explorations. This method records both the Earth electric and magnetic fields in stations located on the ground surface. The relation among these 2 fields, in the frequency domain, is named as “impedance tensor” and is directly related to the underneath subsoil electrical resistivity distribution.
Time Domain Electromagnetics (TDEM) and nano TDEM
Time Domain Electromagnetics (TDEM) and nano TDEM
Time Domain Electromagnetics (TDEM) is a geophysical exploration technique to assess the subsoil electrical resistivity, especially for stratified geology. TDEM measurements are widely applied in hydrogeology and especially in groundwater detection. This technique uses a transmitter Tx and a receptor Rx connected to conductive cable loops. The Tx is connected to the external loop and cause a current pulse at specific frequency and for a determined time interval, inducing an electromagnetic field propagating through the stratified subsoil. The Rx is connected to the internal loop and is configured to record the subsoil electromagnetic behavior when the current pulse in the external loop is suddenly shut off. This behavior provides information about the subsoil electrical resistivity distribution. The loops can also be concentric and coincident.
The differences between normal TDEM and nano TDEM are basically loop size, current frequency and timing, resulting in different investigation depth (DOI): the TDEM presents higher DOI but less resolution at shallow depth, (and starting from about 30-40 m depth), while the nano TDEM investigates a minor DOI but with much higher shallow resolution, starting from a few meters depth.
Electrical Resistivity Tomography (ERT) 2D and 3D
Electrical Resistivity Tomography (ERT) 2D and 3D
The Electrical Resistivity Tomography (ERT) allows obtaining 2D sections and 3D models for the subsoil resistivity distribution. The difference with the related and simpler VES technique is the much higher measurements density and the 2D/3D algorithms to model and interpret data.
ERT is a contact method which uses a set of several electrodes installed on the surface along a profile (2D) or according a regular mesh (3D). Direct current injection into subsoil through pairs of electrodes allows voltage measurements between other electrodes pairs. A switching device, configured according specific protocols, automatically performs all the possible combination, of injection and voltage electrodes pairs, resulting in high density data laterally as well as with depth. This data set allows a detailed reconnaissance of the subsoil electrical resistivity distribution.
Well Logging
Mineral incrustations and bacteria analysis (WSE USA)
Mineral incrustations and bacteria analysis (WSE USA)
Mineral and bacteria incrustations in pipes and well walls can plug and collapse water wells. Preventive detection and analysis allow early diagnosis and specific treatment to inhibit this development. There are several ways (mechanic and chemical) to remove and/or inhibit incrustation, which choice depends on source and sediment nature, so analysis are critical issues to efficiently solve each specific case.
Water quality: pH, temperature, conductivity, Redox
Water quality: pH, temperature, conductivity, Redox
Wellfield Services offers trustable Temperature, Salinity, pH, Eh and Pressure registries in water wells, using sensors that are periodically calibrated using patron solutions, verified by USA laboratories measurements.
Density
Density
Well wall in-situ density continuous recording is performed with a formation-density sensor, which provides data to identify low density as well as high density stratus related, for instance, to coal presence and basic metal mineralogy, respectively.
Wells diameter (Caliper)
Wells diameter (Caliper)
The mechanic caliper well profiling represents the average well diameter, as detected by the tool mobile fingers that are adjusted through springs.
The caliper anomalies could represent fractures, stratification plans, fluid transmission cavities and, usually, show the distance between the fractures that cross with wells.
Lefranc test
Lefranc test
Test to measure permeability in permeable or semi-permeable soils. The test measures the flow needed to maintain a constant water level in a well (static load) or, alternatively, the water level decay velocity (variable load).
Lugeon test
Lugeon test
Test to estimate the permeability in rocky soils, measuring the water flow that can be injected at constant pressure in different well sections.
Flowmeter, spinner
Flowmeter, spinner
A rotating instrument is utilized to measure the fluid flow inside a well. An helicoidal-shaped (blade) rotor gains a certain rotation speed which is related to the effective flow velocity.
High Pressure (P) and Temperature (T) well logs
High pressure P and temperature T well logs
Wireline logs in geothermal high P and T wells with memory tools.
Neutron porosity
Neutron porosity
Porosity well log based on slowing down and capture of neutrons by the hydrogen contained in the subsoil formations. This technique allows registering the correct porosity for specific formations, (limestone, sandstone, dolomite), assuming that formation pores are fluid-filled and in units related to formation type (vol/vol or u.p.). The measurement is statistical and based on thermal neutron detection, so precisions is higher for high counting speed, i.e. low porosity.
Hydraulics test
Hydraulics test
The test consists of a pressured water injection into an isolated sounding portion, closed on one or both sides by one or two packers, to measure the amount of water that can be absorbed by the ground. It is applied on rock or consolidated ground with medium to low permeability.
Gamma Ray
Gamma Ray
Gamma Ray log is used to discriminate different lithologies through their specific natural radioactivity, and for Uranium exploration. Gamma ray count increments can be related to lithological changes, alterations and radioactive mineralizations.