ELECTROMAGNETIC ASSESSMENT OF OPEN POROSITY AT DEPTHS BELOW BOREHOLE

(Spichak V.V. Zakharova O.K. )

Feasibility study of the porosity forecast in depth and in the interwell space from electromagnetic sounding data in the borehole vicinity and electrical well logs is carried out. The porosity data are synthesized from the laboratory study of the samples’ properties for two boreholes drilled in the Bishkek testing site. The porosity forecast in depth is carried out using the 1D inversion of magnetotelluric sounding data in the vicinities of boreholes. Different variants of the forecast in depth are compared. It is shown that taking into account both electromagnetic sounding resistivity and resistivity well logs enables increasing the forecast accuracy several times (the appropriate relative errors are, in average, around 2%).......

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  • 2020  № 2, pp. 45-50

GEOPHYSICAL RESEARCHES OF THE SETTLEMENTS OF THE BRONZE CENTURY KONOPLYANKA-1 AND KONOPLYANKA-2 (SOUTH URAL)

(Noskevich V.V. Fedorova N.V. )

Geophysical studies were conducted on the territory of the Bronze Age settlements: the fortified settlement Konoplyanka-1 and the un fortified settlement Konoplyanka-2. A micromagnetic survey was performed and magnetic maps of the settlements were constructed. Using GPR, a study of fortifications and wells was carried out. The obtained magnetic maps became the basis for choosing the place of archaeological excavations on the monuments. A comparison of geophysical and archaeological results showed that magnetic maps were able to accurately reconstruct the plan of ancient settlements, and the use of GPR makes it possible to restore the shape of underground objects and determine their depth.......

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  • 2020  № 2, pp. 51-57

GEOPHYSICAL EXPRESSION OF THE SUBSURFACE STRUCTURE IN THE SVETLINSKAYA HYDROELECTRIC POWER STATION AREA ON THE VILYUY RIVER

(Velikin S.A. Spektor V.B. )

This article discusses characteristic features of the geological and geophysical structure of the foundation and left-bank abutment of the Svetlinskaya Hydroelectric Power Station. It is shown that the geological environment in the station area remains highly active at present. A dynamic model of the subsurface is proposed which differs from those developed during the design and construction stages. To prevent dangerous situations in a timely manner, it is proposed to strengthen the monitoring system by expanding the scope of existing observation programs.......

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  • 2020  № 2, pp. 58-65

ERRORS OF GEO-LOCATION IN DETERMINING THE DEPTH OF SOIL BOUNDARIES IN THE AREA OF THE CITY OF YAKUTSK

(Neradovskii L.G. )

A statistical analysis of errors in geo-location in determining the depth of soil boundaries in the area of Yakutsk is done. It is established that the probable distribution of errors taking into account of their sign obeys the normal law. The average error value calculated from a sample of 1499 wells is 0.44 m, and differs from the general average error by ±0.01 m. This accuracy allows us generally to consider georadiolocation as a high-precision method of detailed study of the structure of frozen soils, which is comparable in order of errors with the errors of core drilling.......

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  • 2020  № 2, pp. 66-72

COMPLEXING OF AREAL MAGNETIC DATA AND PALEOMAGNETIC STUDIES IN CRIMEA TO CLARIFY A GEOLOGICAL STRUCTURE OF BODRAK FORMATION INTRUSIONS OF THE MIDDLE JURASSIC

(Zolotaya L.A. Kosnyreva M.V. Palenov A.Yu. Philippovich A.V. )

Magmatic formations in Crimea have been studied by geologists for over a hundred years. These studies are carried out mainly by the method of field observations, which cannot answer many important questions about the structure and genesis of these formations. Magmatic bodies have high magnetization values in comparison with containing rocks, which is the physical prerequisite for use of magnetic prospecting. This article focuses on the analysis of new high-precision areal magnetic survey data at a scale of 1:10000, performed on peripheral part of the Kachinsky anticlinorium in Crimea, near to the Bodrak river and Trudolubovka village, in a complex with paleomagnetic studies of the Middle Jurassic J bd intrusions. The authors, using magnetic data, show a variant of areal mapping of a complexly deployed intrusive complex and supplement their studies with magnetic modeling of a geological section. Magnetic modeling was carried out taking into account a remanent magnetization data, which values were obtained from data of selected paleomagnetic collection. The results allow us to re-examine the spatiotemporal relationships between intrusions of the Bodrak formation and rocks enclosing them in the study area.......

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  • 2020  № 2, pp. 73-81
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