Thermal Methods Implementation in Porosity Determination of Shale Rocks

Determining the pore space in microporous rocks is a great analytical challenge, due to their very low effective porosity and permeability. The aim of the study was to examine the possibility of determining porosity parameters in shale rocks using a set of methods: differential thermal analysis, retort distillation, and Dean-Stark. These methods are used for low-permeability rock containing hydrocarbons, such as: shale gas, shale oil and tight gas. These methods enables specification of the amount of water contained in the sample and, consequently, determination the different levels of saturation and porosity.

The study showed varied shale porosity values ranging from 0 to more than 5%. It was found that the samples with the highest porosities in the combustion process evolve relatively large amounts of carbon dioxide, which indicates that the porosity is related to the presence of organic matter.

There was no complete correlation of the various methods test results. It seems that for determining the porosity of tight shale rocks, the most efficient would be the use of several complementary methods.