Scientific research in the area close to the Russian Antarctic station Vostok has been carried out since its founding on December 16, 1957. The relevance of work to study the region is steadily increasing, which is confirmed by the Strategy for the Development of Activities of the Russian Federation in the Antarctica until 2030. As part of the Strategy implementation, Saint Petersburg Mining University solves the comprehensive study issues of the Vostok station area, including the subglacial Lake Vostok, related to the development of modern technologies and technical means for drilling glaciers and underlying rocks, opening subglacial reservoirs, sampling water and bottom sediments, as well as carrying out comprehensive geological and geophysical research. For the successful implementation of the Strategy, at each stage of the work it is necessary to identify and develop interdisciplinary connections while complying with the requirements for minimizing the impact on the environment. During the season of the 68th Russian Antarctic Expedition, the staff of the Mining University, along with the current research works , began research of the dynamic interactions between the forces of the Earth, from the deepest depths to the surface glacier. Drilling and research programs have been completed. The drilling program was implemented jointly with colleagues from the Arctic and Antarctic Research Institute at the drilling complex of the 5G well. The research program included: shallow seismic studies, core drilling of snow-firn strata, study of the snow-firn strata petrostructural features, studies of cuttings collection filters effectiveness when drilling snow-firn strata and the process of ice destruction in a reciprocating rotational method, bench testing of an acoustic scanner. As a result of drilling in 5G well at the depth range of 3453.37-3534.43 m, an ice core more than 1 million years old was obtained.
During the seasonal work of the 64th Russian Antarctic Expedition in 2018-2019 at the “Vostok” drilling facility named after B.B.Kudryashov (“Vostok” station, Antarctic) specialists of Saint Petersburg Mining University conducted experimental investigations on the process of drilling by melting with simultaneous expansion of wells in the ice mass. A test bench and a full-scale model of a thermohydraulic reamer-drilling tool were developed, manufactured and tested for the research. The first bench tests of the full-scale model proved its efficiency and suitability for experimental drilling with simultaneous expansion of wells in ice mass; its operational capabilities were determined and the drawbacks that will be taken into account in future were found out. The article substantiates the choice of constructive elements for thermohydraulic reamer-drilling tool. It is determined that the technology of full diameter drilling with simultaneous expansion of the well in ice mass can be implemented by combining contact drilling by melting and convective expansion with creation of forced near-bottomhole annular circulation of the heated heat carrier. Dependencies of expansion rate on main technological parameters were determined: active heat power of heating elements in penetrator and circulation system, mechanical drilling rate, pump flow rate. According to the results of investigations, the experimental model of thermohydraulic reamer-drilling tool will be designed and manufactured for testing in conditions of well 5G.
We produce an information about results and features of the 5G borehole drilling in Antarctic layer at Russian station Vostok. Main regularities of the change structured and physical properties by Antarctic ice layer depth, which determine mechanical and reological properties if ice, which influence to sinking of a borehole and to the maintaining of it in a working condition, the safe and competitive technologies creation for drilling of strong ice layers and the environmentally safe technology of the subglacial reservoirs unsealing. We also produce results of the ice cores researching and the paleoclimatic raws construction, which are reconstructed by the ice cores researching from Vostok station, which is compared with isotopic graph. This graph describes changes of World ocean level.
Directional drilling technology can be used in glacier boreholes to obtain additional ice cores and to pass over sticking drills. Experimental sidetracking of 5G-2 hole in the deep borehole at Vostok station, Antarctica, showed the high efficiency of the directional drilling without using of special whip-stocks to deviate the hole.
Ecologically safe penetration into the subglacial Lake Vostok discovered in the depth of 3,700 m in East Antarctica (more than 10,000 km2 , hypothetically freshwater and containing relict life forms) requires development of new methods, technologies and technical means of drilling.
The primary results of the research and engineering work of the Department of Technology and Technique of Well Drilling, carried out and completed in 2000, are presented. The main result of drilling long wells in the ice of Antarctica is the development of the project of environmentally safe opening of the subglacial Lake Vostok, a unique natural phenomenon, the complex study of which is of the greatest interest to the world scientific community. A 505 m long well with full core recovery was drilled on the Academy of Sciences glacier (Severnaya Zemlya archipelago) in the framework of the international environmental program PEGAIS. Geophysical measurements were carried out in the well. A new method of tubeless casing and sealing of anomalous intervals using a fusible binding material and a thermal plugging penetrator was developed. Basic theoretical and technological principles of liquidation plugging of hydrogeological wells with the use of economical and environmentally safe cementing mortar based on cheap mineral waste were developed. Effectively conducted research and experimental developments on the combined heat and hydrodynamic effects on low-productive sands to increase oil and gas production wells, clarified the laws of the hydro and foam core. New applied programs for PC were formed, allowing to increase adequacy of data and to expand the field of application in evaluation of regulation and stabilization of circulation and heat exchange processes during well sinking and development.
