Mining
Mining
Surface geophysics
Gravity
Gravity
The gravity geophysical method detects the gravity field variations on the earth surface related with the subsoil density distribution. From these results is possible to locate formations, reservoirs, basement and other structures with density contrast.
3D Inversion/modeling (MT, IP, Mag, Grav)
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
Magnetometry
The magnetic prospection investigates the earth magnetic field variations recording both the total magnetic value as well as its gradient. The anomalies are caused by rock physical properties variations such as magnetic susceptibility and/or remaining magnetization.
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.
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)
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
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.
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.
Well Logging
Structures confirmation
Structures confirmation
Acoustic and optical televiewers records offer a precise confirmation of wells orientation with respect to geological mapping, identifying structure in cores and comparing this information with the televiewer data, discriminating faults type and shear zones allover along the well depth.
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.
North seeking Gyroscope
North seeking Gyroscope
This tool records the well orientation with no need for a surface azimuth reference. Knowing the tool depth and the azimuth and inclination registries, it is possible to determine the well´s North and East deviations as well as the altitude with respect to its surface well collar.
Wellfield Services performs these measurements with both single stations and continuous methods, applying a plan of quality assurance to guarantee the registry precision.
Mechanic Gyroscope
Mechanic Gyroscope
Since 1994, Wellfield Services performs mechanic gyroscope registries of wells trajectory. This technique is not affected by magnetic effects and allows high precision recording of azimuth and inclination in both open wells and inside bars.
Maxibor
Maxibor
Maxibor tools allow measuring the well deviation, functioning in memory mode without needing acquisition system and winch. It is particularly useful for the pipeline assisted ascending logs because does not require a cable and is not affected by the drill rods rotation. Anyway, it needs the azimuth as a start reference which must be measured using another tool.
Ascending well profiling
Ascending well profiling
Wellfield Services counts on a wide experience in positive (ascending) well logs, such as in underground mining tunnels toward the surface, which require special installation and additional well tools.
Induced Polarization (IP) - classic and deep (Telluric Correction), VIP; 2D and 3D
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.
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.
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.
Magnetic Susceptibility
Magnetic Susceptibility
Magnetic susceptibility (MS) measurements provide a fast assessment for rock magnetic minerals content. This useful information is used for geological and hydrothermal alteration interpretations as well as to evaluate deposits with highly magnetic minerals such as some kinds of iron minerals.
High resolution acoustic Televiewer
High resolution acoustic Televiewer
Wellfield Services introduced the Borehole Televiewer technique in Chile in 1996, developing a wide experience in its application.
The high resolution acoustic Televiewer provides well wall pseudo-images to investigate the subsoil structure features through computer assisted images reconnaissance. It consists of a transductor operating at high frequency in pulse-eco mode. The important amount of obtained information, combined with a classification scheme for structural features and with the lithological, geological, chronology and tectonic information, all together, are ideal for structural statistical analysis. The technique is applicable to large scale structure, up to various meters size, as well as to microstructures.
High resolution optical Televiewer
High resolution optical Televiewer
If the well is dry or filled with clean transparent fluid, it is possible to obtain a well wall high resolution true colors optical image. This also provides information about the fractures infilling material, besides of all the other information. The best performance is for diamond drilled smooth and even well walls, intercepting colored rocks.