The article analyses the results of geophysical studies of rift structures in East Antarctic, direct geological surveying of which is impossible due to a thick ice sheet. A model is proposed for the formation of Lake Vostok depression suggesting its emplacement within the regional transtensional zone. The Lake basin includes the southern longitudinal graben forming along the main shear and the northwestern basin, which is estimated as a pull-apart structure. Based on results of the gravity and magnetic field interpretation proposed in the article, the identification and parameters of the interblock suture zone in the basement of the coastal part of the subglacial Lake Vostok are substantiated. Similarities in the structure of the Earth’s crust of regional and local structures containing Lakes Vostok and Baikal have been recorded for a large number of features: spatial correlation with position of regional shear zones; geniculate morphology of lake basins composed of linear longitudinal depressions parallel to direction of the shear zone and depressions controlled by diagonal fault displacements; relief of adjacent structures; steepness of coasts; high seismicity with earthquakes localized along the main axes of fault displacements as well as the Earth’s crust structure of geostructures controlling these basins. The formation model of rift structures of East Antarctic localized along subparallel shear zones is presented. To explain the geodynamic nature of rift systems, the model of the upper mantle convective cell is used. The Vostok, Scott, Aurora, Concordia, Adventure, Wilkes, and Astrolabe depressions form an extensive tectonic zone approximately 2,000 km long and 1,500 km wide. Tectonic schemes showing localization of the East Antarctic rift system as well as depressions of the Mesozoic West Transbaikal rift area and the Cenozoic Baikal-Stanovoi rift zone are presented.
Scientific and technological progress over the last century has led to an enormous increase in the consumption of minerals, including energy resources. Most of the exploited oil and gas fields are already considerably depleted, so it is necessary to search for new hydrocarbon resources, particularly at great depths. Deep drilling plays a special role in solving this problem. The article considers the world and Russian experience of ultra-deep wells drilling. The methods and technologies used in the construction of wells, as well as complications and accidents occurring during their drilling were analyzed. The analysis revealed that the existing limitations for drilling parameters of deep and ultra-deep wells are caused by the technical characteristics of surface and bottomhole drilling equipment, which do not meet the extreme drilling conditions. The directions for development of deep and ultra-deep well drilling machinery and technologies are suggested. The notion of extreme rock and geological drilling conditions is introduced, which describes drilling in conditions of hydrostatic pressure of flushing fluid column and high bottomhole temperature both at stable and unstable wellbore conditions, coming close to the upper limit of operating technical characteristics of bottomhole assembly, the drill string and flushing fluid.
Comprehensive interpretation of the results for regional seismic operations and reinterpretation of archived seismic data, their correlation with the drilling data of more than 30 deep wells, including Severo-Novoborsk parametric well, made it possible to clarify the structural maps and thickness maps of all seismic facies structures developed in the territory and water area in the junction of the north of Izhma-Pechora depression and Malozemelsko-Kolguevsk monocline of Timan-Pechora oil and gas province. Data obtained were used at basin modeling in TemisFlow software in order to reconstruct the conditions of submersion and transformation of organic substance in potential oil and gas bearing formations. Modeling made it possible to get an idea of the time and conditions for the formation of large zones of possible hydrocarbons accumulation, to establish space-time connections with possible sources of generation, to identify the directions of migration and on the basis of comparison with periods of intense generation, both from directly located within the operation area and outside them (taking into account possible migration), to identify zones of paleoaccumulation of oil and gas. Work performed made it possible to outline promising oil and gas accumulation zones and identify target objects for further exploration within the site with an ambiguous forecast and lack of industrial oil and gas potential.
