Surface geophysics

Reflection Seismic 2D/3D

The reflection seismic acquisition consists of generating acoustic waves on surface and registering the amplitude variations for the waves train reflected from subsoil. These wave amplitude variations are caused for acoustic impedance (density x velocity) changes between different subsoil layers.
Acoustic waves can be generated using mechanical punchers and/or explosive (located source) or Vibroseis (controlled source). The amplitude variations are measured using several geophones (2D profiles or 3D mesh) and registered by a centralized acquisition system (seismograph) or by decentralized nodes.
In both 2D and 3D cases, the horizontal dimension is space and the vertical one is time which with processing is converted to depth, after estimation of subsoil velocities.

Microseimic Acquisicion and processing

Monitoring of induced microseismic events is key to hydraulic fractures evaluation and optimization. Its main objective is to characterize the induced fractures structure and the density distribution for a specific formation.
The microseismic activity is measured using geophones located to map a sector related to the studied induced fracture, leading to its geometry estimation.

Downhole / Crosshole

Dowhole and Crosshole are seismic techniques to measure wave’s propagation velocity in wells, with higher precision and resolution compared to surface recordings.
The Downhole registry consists in a tri-axial geophone lowered into a well while seismic waves are generated on surface. At specific depths, the geophone records directly the waves transmission times.
The Crosshole utilizes two wells, one to generate the seismic waves and the other to register the wave’s transmission times from one to the other.

Multifrequency EM

In situ thermal resistivity test

Ground Probing Radar - Georadar (GPR)

Groud Probing Radar - Georadar (GPR)

The Ground Probing Radar (GPR) is a high-resolution tool recording high frequency subsurface EM waves reflection, allowing a precise estimation of depth for the detected objects, as well as of their nature and origin. It is a non-invasive method which permits investigations without excavations and that is normally required for environmental, engineering, archeology and other shallow studies.

Gravity

3D Inversion/modeling (MT, IP, Mag, Grav)

3D Inversion and Modeling of Magnetoteluric (MT), Induced Polarization (IP) and potential methods (Gravity – Magnetometry) data.
Wellfield counts on important data processing centers in Santiago, Chile and Buenos Aires, Argentina, equipped with legally licensed specific software and with 500 parallel processing cores to handle large datasets with short timing.

Magnetometry

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.

MASW/REMI

MASW / REMI

Both MASW (Multichannel Acquisition Surface Waves) and REMI (Refraction Microtremor Arrays) consist in the characterization of surface seismic waves and specifically for Vs (shear wave velocity). MASW uses an active seismic source and registers high frequencies signal while REMI uses passive sources and registers medium-low frequencies. Together they allow obtaining the total velocity dispersion over the complete frequency range to obtain Vs.

Environmental Monitoring using ERT (Electrical Resistivity and Humidity content, natural and intervened subsoils, leach heaps and Pads)

Monitoring of subsoil humidity content and its resistivity variations through periodical measurements using the Electrical Tomography technique (ERT). The regular follow up in time allow to check the status for known risk situations as well to detect any new potential threat.

Induced Polarization (IP) - classic and deep (Telluric Correction), VIP; 2D and 3D

IP studies are used to investigate mineralization of interest, especially disseminated Sulphur, based on formation chargeability and resistivity measurements. Also, it allows estimation of permeability in groundwater studies.

Reflection seismic processing 2D/3D

Reflection Seismic

The reflection seismic acquisition consists of generating seismic waves on surface and registering the amplitude variations for the waves train reflected from subsoil. These wave amplitude variations are caused for impedance (density x velocity) changes between different subsoil layers. The seismic wave travels between 2 medias with different impedances and part of its energy is reflected at the interphase while another part is refracted through the interphase. Reflection seismic consists in measuring the waves travel time from the seismic source to surface geophones, being reflected at the interphase. Knowing times and seismic waves speed allow to calculate the wave trajectory to obtain images of geometry and location of interphases (subsoil lithologies contacts).
Seismic waves can be generated using mechanical punchers and/or explosive (located source) or Vibroseis (controlled source). The amplitude variations are measured using several geophones (2D profiles or 3D mesh) and registered by a centralized acquisition system (seismograph) or by decentralized nodes.

Refraction seismic

Seismic Tomography is a geophysical method for subsoil exploration through waves transmission. It consists in generating seismic waves by hitting the ground (manually or using mechanical systems such as portable Propelled Energy Generators and Accelerated Weight Drop Systems or thumper trucks) and detecting them in different locations through geophones equally spaced along a profile. This technique allows recording the subsoil compressional velocity Vp.

Vertical Electrical Sounding (VES)

The Vertical Electrical Sounding (VES) allows to measure a subsoil resistivity vertical profile (1D), using a four electrodes array. Two current electrodes are installed with a specific spacing on the ground and are used to transmit the electrical current to the subsoil. The other two electrodes, also installed on the ground, are used to measure the voltage difference. The investigation depth is directly related to the current electrodes spacing.

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

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.

Surface geophysics

Surface geophysics services