PERMEABILITY OF PHU PHAN AND SAO KHUA SANDSTONES UNDER HIGH CONFINING PRESSURES (10-50 MPa)

Abstract

Constant head flow test has been performed on twenty-four cylindrical rock specimens obtained from Phu Phan and Sao Khua formations, representing ones of the aquifers in northeast of Thailand. The specimens are prepared with nominal diameters of 54 mm and length-to-diameter ratio of 1.5. The flow direction is normal and parallel to bedding planes. The test procedure is in accordance with the ASTM standard practice. The permeability of Sao Khua sandstone is lower than that of Phu Phan sandstone. It decreases with increasing confining pressures. The flow rates in the direction normal to the bedding planes are lower than those parallel to the bedding planes. The permeability anisotropy tends to be independent of the confining pressure. It is about 10 for Phu Phan sandstone, and 12 for Sao Khua sandstone. The effective porosity of Phu Phan sandstone is higher than that of Sao Khua sandstone, particularly under high confining pressures. They range from 4.5% to 7.3% for Phu Phan sandstone and 1.9% to 4.3% for Sao Khua sandstone.