Laboratory simulation experiment on dissolution of limestone under hydrodynamic pressure

Abstract

To study the dissolution mechanisms of limestone driven by hydrodynamic reservoir pressure during different storage periods, a simulation experiment on the limestone in a hydropower station of Wujiang River in China was performed. Using a set of specially designed pressure corrosion equipment in an open system, the experiment simulated the dissolution process of limestone under hydrodynamic pressure (0–2.0 MPa) and temperature (15–85 °C). Results show that the amount of dissolution and its rate increase with hydrodynamic pressure and rising temperature, as a result the curve of dissolution rate is obviously changed. In addition, dissolution of carbonate rocks includes both chemical dissolution and physical damage. Differing from the situation under atmospheric pressure, with hydrodynamic pressure rise chemical dissolution, and physical damage increased synchronously ratios tending to be one-to-one. Results show that there is a coupling relationship between chemical dissolution and physical damage leading to a degree of more aggressive dissolution. Microscopic research based on scanning electron microscopy and a mercury injection test shows that the dissolution not only affects the surface of the rock, secondary pore, and mineral form, but also the inner pore structure, decreasing the permeability and connection among the structural planes of the rock.