Geophysical Studies of Water Leakages From Reservoirs*

Abstract

Considerable water leakages from reservoirs make it difficult to attain the planned storage capacity. In some cases water leakages give rise to suffusion followed by catastrophes. Until recently methods for locating water leakages were extremely imperfect. Geophysical methods offer good prospects in this direction. For solving these problems, it is effective to use streaming potential measurements, water flow rate observations and thermometry. Laboratory experiments were carried out in connection with the fact that water leakages from reservoirs are characterized by negative anomalies of natural currents; the more filtration discharge, the higher these anomalies are. As a result, the relationship governing the intensity of streaming potential and sand granulometric composition, electrolyte concentrations and other factors were revealed. To determine the velocity of water flowing to leakage sites, a special device, based on the relationship between the temperature of a heated body and its resistance, is applied. This device simultaneously makes it possible to measure the water medium temperature. Observations at reservoir sites were effected by moving along the reservoir non‐polarizable potential electrodes and water velocity devices. Recordings were carried out automatically by the recording device of the logging apparatus. Under the conditions of ice cover on water surfaces, measurements were made through separate points by digging holes in the ice cover. Practical field observations were carried out at reservoir sites located in regions where fissured massive rocks as well as loose sediments predominate. In the first case field experiments were carried out in alpine reservoirs, in Armenia. The major water leakages were found to be concentrated on the right bank of the reservoir. In this connection it was not only possible to locate water leakage sites, but also to evaluate their relative intensity. These data were used for planning antifiltration measures. In the second case water leakages from a reservoir located in Uzbekistan in the submontane part of the Pamirs were studied. Streaming potential anomalies and high benthonic flow rates made it possible to discover high filtrations in the base and walls of the dam. Further perfection of these methods should not only permit the determination of water leakage sites and their relative intensity, but also filtration discharges in absolute units.

Streaming potential in porous media: 1. Theory of the zeta potential

“…Additionally, the self-potential method related to streaming potential anomalies constitutes a useful reconnaissance and mapping tool in studying water leakage in water reservoirs [Ogilvy et al, 1969]. Electro-osmosis can be used to control water flow through relatively impermeable soils [Casagrande, 1952] and to improve water migration in sandy soils [Socco et These approaches rely on finding the complete set of ionization, conservation, and thermodynamic equations to determine the mineral surface electrical potential and charge, which are then solved numerically, yet no comprehensive analytical model able to predict the surface electrical properties of silica as a function of pH and ionic strength is available.…”

O método do potencial espontâneo (SP): uma revisão sobre suas causas, seu uso histórico e suas aplicações atuais

“…Trata-se fundamentalmente do estudo do processo de eletrofiltração (potenciais de fluxo). Experimentos de laboratório (Ogilvy et al, 1969) demonstraram que existe uma relação entre a intensidade do potencial gerado, a porosidade do meio percolado, diferenças de pressão, concentrações de eletrólito (salinidade) e também a temperatura.…”

Hydrogeophysical Investigations at Hidden Dam, Raymond, California

“…These tasks are accomplished through the use of two complementary electrical geophysical methods, self-potentials (SP) and direct-current (DC) electrical resistivity, which have been commonly used in dam seepage and other integrated hydrogeologic studies (Berube, 2007;Ogilvy, 1970a, 1970b;Bolève et al, 2009;Corwin, 2007;Dahlin et al, 2008;Ogilvy et al, 1969;Panthulu et al, 2001;Sheffer, 2007;Sjö dahl et al, 2005Sjö dahl et al, , 2008Titov et al, 2005). SP is a passive method that is primarily sensitive to active subsurface groundwater flow and seepage, whereas DC resistivity is an activesource method that can provide information about changes in subsurface lithology and groundwater saturation.…”