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Vol. 10 (2007 year), No. 3

Baranov N.A.
Freedom as an element of political development of Russia

Data of fifteen months of fluid level variations in the world’s deepest borehole, the 12.26 km deep Kola Superdeep, Northwest Russia, have been recorded and analyzed. The borehole is uncased from 8.28 km to 8.56 km depth and is locked further down. The obtained series were mostly sampled at 5 minutes intervals but are not free of gaps due to occasional technical problems. Analysis of the data has revealed that (1) the fluid level in the borehole is steadily falling, so is not in hydraulic equilibrium with the pore pressure in the rocks at depth. The equilibrium level is not known because the borehole is repeatedly refilled with fresh water. (2) Although the hydraulic transmissivity appears to be rather low, the rocks at depth have the capacity to absorb and transport significant amounts of fluids that enter via the borehole. (3) Due to the low transmissivity of the rocks alongside the open hole section, tidal and barometric efficiencies are small and do not allow to deduce significant poroelastic parameters that would hold for quasi-static conditions. It is not clear whether the low transmissivity reflects the natural situation or is artificial, e.g. due to remains from the drilling mud. (4) We noticed an increasing number of rising gas bubbles, which has shown that the borehole is not under static conditions. Composition and origin of the gases are still unknown. (5) A very unusual, 200 sec long free oscillation period of a 16.7 km long water column inside the borehole can easily be initiated by pouring water into the borehole. Fluid levels of two more shallow boreholes in the vicinity of the superdeep one were monitored for about two months. Although both boreholes are uncased for their major parts, signatures of the fluid level curves are quite different. One well-aquifer system is highly sensitive to tidal and barometric forcings, the other is not. The unequal behaviour could indicate that the hydraulic regimes change over rather small distances in this crystalline environment.

(in Russian, стр.8, fig. 0, tables. 0, ref 37, Adobe PDF, Adobe PDF 0 Kb)