Currently the prospecting and exploration for hydrocarbons continues to be one of the most promising directions in geological exploration. The use of pulsed electrical exploration technique for prospecting of hydrocarbon reservoirs in combination with seismic prospecting makes it possible to significantly increase the probability of discovering the deposit, thereby lowering the likelihood of drilling an exploratory well that will not give an inflow. Also with the help of seismic exploration it is quite difficult to identify non-structural deposits. One of the reasons for the occurrence of anomalies caused by induced polarization (IP) is the epigenetic pyrite formed above the deposit as a result of the formation of a geochemical barrier at the boundary of the penetration of atmospheric oxygen. The presence of abnormally high values of induced polarization in the upper part of the section that differed from the background value within one of the deposits located at the southern part of Yakutia was manifested in the results of a one-dimensional inversion of the data from the electromagnetic sounding and induced polarization (EMS-IP) technology, performed within the polarizing horizontally layered model of the medium, in which the frequency dependence of the resistivity is described by the Cole-Cole formula. The idea of EMS-IP is to maximize the full use of information from transient processes induced by rectangular polarity pulses that are used in traditional DC methods. For the EMS-IP method, a high resolution and depth of study were obtained using the mean gradient setup. The investigated anomaly of the induced polarization is present at a depth of about 150 m and is confined to the pyritized interval of intensely fractured rocks of the Jurassic deposits, which is confirmed by a core sample data selected from the exploration hydrogeological wells. The one-dimensional mass inversion of the data showed sensitivity to the layer with an abnormally high value of the IP. The discrepancy in the model containing the pyrite layer is much higher than in the model not containing the pyrite layer.
In 2014 in the south of Yakutia in the course of groundwater exploration works a complex of geophysical methods was tested: aeromagnetic and electrical prospecting was carried out using near-field transient sounding and electromagnetic sounding with induced polarization. Prospective structures for hydrogeological drilling are zones of discontinuous tectonic faults. In order to identify them, data from aeromagnetic and electrical prospecting were used. Results of drilling confirmed the presence of watered areas; however, analysis of obtained information allowed to come to the conclusion that the amount of water in the faults has no direct connection to electrical conductivity.
For diatremes searching on Anabar crystalline shield classical scheme with measuring in both in frequency and time domain has been used. Using original algorithms in combination with robust statistical methods allow to significantly increase efficiency information quality of the field material and detect transient during switch on current pulse. The robust regression procedure was used for removing curves dependence from transmitter-receiving setup. Sediments covered diatreme was discovered in the vicinity of etalon object. The diatreme, which was verified more recently by a borehole, was non manifested in the resistivity map. Inversion of areal data of transients was performed within five-layers one dimensional induced polarization model and sensitivity is observed up to 1200 m depth.
Intensive offshore exploration is being conducted at the present time. Due to areal alterations over the hydrocarbon deposits high pyrite concentration is accumulated. This effect results in induced polarization anomalies which can be discovered with differentially normalized electrical method. The survey is being carried out in the process of a vessel movement by six channels. dU(t) fields are obtained per one current pulse. These data are highly-correlated. Transformation of these data into orthogonal high dimension space as well as robust multivariate regression procedure application allow to distinguish the geological heterogeneities response. This investigation is developing the anomalies recognition technique.
