Perm Journal of Petroleum and Mining Engineering (Sep 2017)
Biphase multi-pole compensated asynchronous motor for oil industry
Abstract
Results of geomechanical modelling of a stress-strain state of salt rocks in conditions of layer mining at mines of Belaruskali JSC are reviewed. There are sudden powerful gas dynamic phenomena (GDP) occur from the bedrock of mines such as salt and gas emission, bedrock destruction followed by gas release. Moreover, there are areas that are potentially dangerous due to gas dynamic phenomena acting from the bedrocks. For the conditions of the Starobinsk deposit of potassium salts gas accumulations in bedrocks of mines are usually confined to clayish interlayers and layers in salt rocks. Therefore, it is assumed that disclosure of clay contacts is a geomechanical prerequisite for GDP. That leads to formation of channels for migration of free gases and formation of artificial gas-saturated zones under the influence of mining operations. Task statement includes setting of parameters for collapse of the roof rocks of the Third potash formation being under the mining, localization of plastic deformations in the enclosing rocks and opening of clay contacts in a salt thickness. It is taken into account that collapsed rocks of a long face roof fill the goaf and form technogenic geo-environment with respect to their decompaction. The geo-environment is also included in the calculation scheme of mathematical modeling. In order to determine a stress-strain state of rocks, a model of an ideal elastic plastic medium with internal friction is used. In this case, clay interbedding are described by Goodman's contact elements. Based on results of solution of a number of model problems in a two-dimensional statement, there is a conclusion made on the significant influence of clay interbedding in the bedrocks of a formation under the mining on the possibility of occurrence of gas dynamic phenomena. It is established, that in presence of three and more clay contacts in the layer of underlying halite there are conditions created for formation of a multi-stage focus of GDP, formed when gas-saturated clay contacts are exposed. Periodic character of formation of GDP focuses is noted during the movement of the front of cleaning works.
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