The subglacial Lake Vostok in Antarctic is a unique natural phenomenon, its comprehensive study involves sampling of water and bottom surface rocks. For further study of the lake, it is necessary to drill a new access well and develop environmentally safe technologies for its exploration. This article discusses existing and potential technologies for sampling bottom surface rocks of subglacial lakes. All these technologies meet environmental safety requirements and are conducive for sampling. The authors have proposed an alternative technology, using a walking device, which, due to its mobility, enables selective sampling of rocks across a large area from a single access well. The principal issues, related to the implementation of the proposed technology, are investigated within this article. This report is prepared by a team of specialists with many years of experience in drilling at the Vostok Station in Antarctic and in experimental work on the design of equipment and non-standard means of mechanization for complicated mining, geological and climatic conditions.
The paper proves the timeliness of obtaining and examining bottom sediments from subglacial Lake Vostok. Predictive geological section of Lake Vostok and information value of bottom sediments have been examined. Severe requirements towards environmental security of lake examinations and sampling of bottom sediments rule out the use of conventional drilling technologies, as they would pollute the lake with injection liquid from the borehole. In order to carry out sampling of bottom sediments from the subglacial lake, it is proposed to use a dynamically balanced tool string, which enables rotary drilling without any external support on borehole walls to transmit counter torque. A theoretical analysis has been carried out to assess the operation of the tool string, which is a two-mass oscillatory electromechanical system of reciprocating and rotating motion (RRM) with two degrees of freedom.
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.
In this paper results of experimental studies of ice cutting process with using cutter type bits are presented. The bit operation, ranges of rational value of bit taper and rate of penetration are analysed. Reasons causing complications during drilling well in ice deeper then 3000m are determined on the basis well drilling in Vostok station and Dom C and possible ways to overcome them.
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.
One of the main factors of environment contamination on the gas industry ventures is waste water. To improve the ecological situation at gas fields the joint purification, treatment and flooding of associated liquid, industrial and domestic waste water into lost circulation horizons is proposed.
In spite of the certain success in ice drilling technology, there are enough accident examples of the deep coring in so-called warm ice, which is characterized by the increasing of ice crystals and has temperatures closed to the pressure melting point. The generally accepted recommendations for choosing of rational drilling parameters in such ice don’t exist. The low reliability of the drilling process as often as not resulted to the one of the most severe accident in the hole – sticking of the core drills. The effective accident elimination is possible due to the ice dissolving in the sticking zone by the delivery in this zone of the solvent active to ice, for example, ethylene glycol or its aqueous solution.
The peculiarities of design of technical means intended for drilling wells in glaciers are considered. Polar and high-mountain regions of the Earth are characterized by a unique combination of unfavorable conditions for practical activity, therefore, besides general requirements for design of technical means, special requirements for weight and dimensions, power consumption and operational characteristics of used materials are made. Specific technical solutions of drilling room constructions, means of lowering and lifting and auxiliary operations, as well as measures aimed at reduction of material and energy intensity of drilling operations on glaciers are presented.
In order to drill "dry" wells in snow-firn and ice strata, the SPbSMI (TU) Department of Drilling Technology and Technology is developing a technology of mechanical drilling with bottom-hole air circulation to remove cuttings. The electromechanical drilling tool for drilling with bottom-hole air blowout is similar to the previously developed KEMS-112* drilling tool for drilling deep wells filled with filling fluid.
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.
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В большинстве современных машин зубчатые передачи являются основными узлами, влияющими на работоспособность, надежность и стоимость машин. В проектировании зубчатых передач важное значение имеют расчеты их на прочность ...