Investigation of Pore Structure of Coal Measure Rocks

Abstract

The fundamental information on the pore structure of coal measure rocks contributes not only to study of physics of fluid flow through the rocks, but also to that of the mechanical properties such as water effect upon the strength of the rocks. From this point of view, investigation were made on measurement of the pore size distribution of coal measure rocks by mercury penetration and correlation it with the several physical characteristics of these rocks.
The results are summarized as follows;
1) Each coal measure rocks, that is, sandstone, sandy shale, shale and coaly shale, shows its characteristic pattern of pore size distribution. These characteristics can be represented numerically by using the pore volumes corresponding to the specifically defind ranges of pore radius.
2) It is possible to determine approximately the internal specific surface area of a rock from the pore size distribution.
3) There is a correlation between the pore volume corresponding to the range of radius 37.5 Å≤r<10³ Å and the equivalent montmorillonite content determined by methylene-blue adsorption method, which significantly affects the mechanical properties of coal measure rocks.
4) The Young's modulus of the solid part of rock, which is calculated from the mercury penetration curve, shows that this modulus is fairly greater than that of the rock, which consists of pore and solid parts.