Wellfield Services Ltda.
About us
Wellfield Services Ltda. is a company specialized in providing geophysical services for mining, oil and energy industries as well as for groundwater, environmental and geotechnical studies. For 25 years has forged a trajectory of excellence, joining technical competence and capability, innovation, qual...MORE +
Organization
Wellfield Services Ltda. is organized in 5 divisions each one related to a specific service.
The company workforce of over 200 people is diverse and includes professionals like geophysicists, geologists, engineers and technicians. MORE +
History
Founded in 1993 to perform exploration and assessment for groundwater, Wellfield Services was pioneer in offering services related to hydrological resources for the northern Chile mining industry.
Between 1995 and 1997 the company went through a process of expansion as well as professionalization, which paved the road for the continuous innovation politics that characterizes Wellfield. MORE +
Nakamura-HVSR (Horizontal Vertical Spectral Ratio)
The HVSR method (H/V Spectral Ratio or Nakamura) is a non-intrusive assay based on environment micro-vibrations recording (on ground surface according to the vertical and to N-S and E-W perpendicular directions). The horizontal and vertical components relation results in a composite signal which process and analysis lead to the Soil Fundamental Period. This parameter is critical to prevent that a man-made structure’s period matches the soil period resulting in seismic amplification for resonance with the consequent structural damage.
Passive seismic - SPAC (Spatial Autocorrelation Method)
It is a passive seismic method where micro-tremors are recorded through a set of equidistant stations, generally arranged in triangular arrangements, forming pairs of stations with variable azimuths. The data processing is carried out through spatial autocorrelations where it is possible to estimate the surface waves phase velocity, regardless of their propagation direction with more robust results than ReMi. These seismic data can be processed with the F-K technique (“Frequency-Wavenumber Domain”) that allows transforming these records to the Frequency-Wave Number domain to filter the noise in the signal more quickly.
Passive seismic - CEOS - Nakamura HVSR
The indirect CEOS surface wave spectral ratio method can quickly estimate the basement depth. It is also known as Nakamura-HVSR Method (Horizontal Vertical Spectral Ratio or H / V Spectral Ratio). It is a non-intrusive test, based on the collection, at defined time intervals and by means of a triaxial seismometer (N-S, E-W and Z), and subsequent analysis, of environmental micro-vibrations on the ground surface. By relating the horizontal and vertical components or spectra, a composite signal is obtained that is processed and analyzed to obtain the Resonance Frequency or Soil Fundamental Period. This parameter is of vital help to prevent the period of some structures from coinciding with the period of the ground, avoiding seismic amplifications due to resonance effect and, therefore, the consequent damage to the structure. It is used for seismic microzone studies, evaluating site effects. Additionally, from this relationship, through regression, it is possible to estimate the thickness of the sedimentary fill and, therefore, the basement depth. The method consists of recording over a prolonged period (~ 20 min), using a triaxial seismograph, on the earth's surface, the vertical and horizontal components of the environmental vibrations or micro-tremors.
Passive seismic - Monitoring using environmental seismic noise
It is a technique that allows to monitor over time the development of Vs and Vp velocities in a distributed array for geotechnical purposes (fluid content variations and generation of ruptures in the subsoil). This temporal monitoring makes it possible to detect microvariations not observable with classical seismic methods.
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.