SPE Lecture-July: Characterization of Pore Network and Matrix Permeability in Gas Shale Reservoirs: Considerations for Reservoir Modelling

Natural gas currently offers one of the most viable alternatives to swiftly reduce greenhouse gas emissions from power generation and eventually move towards a lower-carbon energy grid. Although they are still largely in the exploration phase, gas shale reservoirs could be crucial for meeting Australia’s growing energy demand in a more sustainable way. However, the complexity of their pore network, as well as the specific gas storage and flow transport properties present, makes reservoir characterization particularly challenging. Shales do not fall under any particular lithological classification and may be composed of a wide range of minerals, so a combination of at least two core analysis methods is usually recommended for a better understanding of their pore network and gas storage potential. Matrix permeability is another critical parameter when the viability of gas shale reservoirs is assessed, yet its determination is not an easy task and even the validity of Darcy’s law itself needs to be analyzed. While hydraulic fractures are always necessary to stimulate the initial gas production in shales, the long-term gas production potential will be mostly controlled by the matrix flow properties. Thus, the evaluation of prospective shale plays requires a holistic and pragmatic approach that can ultimately lead to more realistic subsurface models.

This lecture primarily aims to shed some light on the porosity, pore size distribution and matrix permeability concepts in shale reservoirs, and also introduce the methodologies typically followed to obtain the data from core samples. Additionally, real laboratory results will be presented and the limitations of each technique -including gas adsorption, mercury injection, nuclear magnetic resonance and quasi steady-state permeability- will be briefly discussed. Finally, the effect of certain variables on the experimental determination of petrophysical parameters from shale cores will be addressed, along with its significance for the reduction of uncertainties in subsurface description and prediction.

Speaker: M. Nadia Testamanti, Department of Petroleum Engineering, Curtin University

Nadia Testamanti is an advanced PhD Candidate and Sessional Academic in the Department of Petroleum Engineering at Curtin University. Her research is focused on the petrophysical characterisation of gas shale reservoirs, particularly the study of their pore network and gas flow properties. She holds a degree specialized in Petroleum Engineering from ITBA University, Argentina, and has over 5 years’ experience in the oil and gas industry. Before beginning her doctoral studies, she worked as a reservoir engineer for Pan American Energy (2011-2014) in Argentina.