Structure and permeability: geologic controls on induced seismicity at Nurek reservoir, Tadjikistan, USSR

Journal Article · Thu Oct 01 00:00:00 EDT 1981 · Geology; (United States)

DOI:https://doi.org/10.1130/0091-7613(1981)9<440:SAPGCO>2.0.CO;2· OSTI ID:5915988

Leith, W ^[1]; Simpson, D W; Alvarez, W

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1. Lamont-Doherty Geological Observatory, Palisades, NY

Induced seismicity at Nurek, Tadjik S.S.R., is occurring within the upper plate of the Ionakhsh thrust, which passes at depth directly beneath the reservoir. Within the immediate vicinity of the reservoir one can contrast two distinct areas, one seismic and the aseismic. Both consist of rocks that can be shown to have a highly anisotropic permeability due to alternating permeable and impermeable strata. Water flow is favored along bedding while essentially prohibited across bedding. However, because the two areas differ in structure, they also differ in their vertical component of permeability, as a direct result of the different attitudes of the bedding. In the aseismic area, vertical fluid flow is blocked by a syncline that cups the base of the reservoir. In the seismic area, a plunging anticline that crops out beneath the reservoir allows water to flow to depth in the high-permeability direction-along bedding. Because effective stress changes at depth are dependent on permeability characteristics, knowledge of subsurface permeability or permeability anisotropy can serve as a means by which to predict the distribution of induced seismic activity. Thus, while regional geologic studies may indicate the presence of lithologies that are conducive to the transmission of pore-water pressure, access of water to these units depends on the structural arrangement beneath the reservoir, on a very local scale.

• OSTI ID: 5915988
• Journal Information: Geology; (United States), Vol. 9:10
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
54 ENVIRONMENTAL SCIENCES
USSR
WATER RESERVOIRS
PERMEABILITY
SEISMICITY
GEOLOGIC FAULTS
GEOLOGY
LITHOLOGY
POROSITY
RESERVOIR ENGINEERING
SEDIMENTARY ROCKS
STRESSES
ASIA
EASTERN EUROPE
ENGINEERING
EUROPE
GEOLOGIC STRUCTURES
ROCKS
SURFACE WATERS
580200* - Geophysics- (-1989)
520100 - Environment
Aquatic- Basic Studies- (-1989)