Nowadays, AMT is definitely an inalienable part of subsurface imaging technology and one can hardly imagine geophysical exploration of ore minerals without using this method. Audio magneto-telluric is used in great variety of applications at different stages of prospecting and exploration process: deep resistivity structure studies; mapping the faults; imaging of the intrusive bodies; direct search of the ore bodies; imaging of the metasomatites and more. So far, Nord-West has collected over 15 thousand AMT stations. These observations have been carried out in numerous surveys assessing the various type ore deposits
Spectral IP with phase measurement was proposed by the Soviet scientists back in 1960-1980. In contrast with the conventional time domain induced polarization, this technique provides better accuracy of the data and productivity in the field.
IP anomalies nature anlysis
Both sulfides, being the main targets in IP prospecting, and widely spread coal or graphite rocks, display high chargeability values, which make the distinguishing between them quite challenging. In order to solve this problem and efficiently recognize the nature of IP anomaly we analyze the shape of the IP decay response.
Since 1998 we've been developing and manufacturing our own geophysical portable instruments and signal processing software. Our advantage, compared with other geophysical service companies, is that we have the possibility to constantly improve both hardware and software and implement innovative designs, keeping our technology at the highest level of industrial and research standards.
Deep resistivity Tomography
Implementation of multi-electrode acquisition arrays for DC resistivity imaging of essentially inhomogeneous media (tomography) has become a general trend in recent years. By the use of standard resistivity tomography instruments one can study the resistivity structure up to the depth of 100-120 m, which is normally not enough for ore prospecting. Nord-West has developed improved tomography techniques based on our hardware designs, allowing inferring the resistivity structure up to 300-400 m in depth.
In recent years, we've begun doing petrophysical measurements (mostly focusing on measuring IP responses) which are of great importance for recognition of the anomaly origin and help to significantly increase the accuracy and reliability of the interpretation.
Nord-West's RND department has been developing an interwell resistivity tomography technique for imaging the rich sulfide ore. Acquiring multi-electrode interwell data and their subsequent 2D-inversion allows taking the informational content of the resistivity/IP imaging to a whole new level if a target object displays enough contrast with the background rocks in terms of electrical properties.
Nord-West owns lots of software tools for geophysical data interpretation, analysis and integration of the results into generalized projects. We have developed and are currently using up-to-date software with capabilities for signal processing and data inversion, which can be used for interpretation of DC Resistivity, Induced Polarization and Controlled Source EM Frequency Domain data. A number of software packages are available for Resistivity Tomography data inversion (RES2DINV, ZOND2DRES, ZONDCHT), as well as gravity and magnetic data analysis and inversion (Geosoft Oasis Montaj, Coscad 3D, TM-2D, TG-2D).
Cooperation with Universities
Nord-West is constantly in touch with the leading Russian scientific institutions, including universities and research centers. We organize conferences, workshops and educational courses for students. Some 20 students from different universities attend our field training courses each year.