Advanced characterisation of tight unconventional rocks
M. Knackstedt A and A. Golab ADigitalcore.
The APPEA Journal 52(2) 665-665 https://doi.org/10.1071/AJ11079
Published: 2012
Abstract
Tight unconventional rocks have become an increasingly common target for hydrocarbon production. Exploiting these resources requires a comprehensive reservoir description and characterisation program to accurately estimate reserves and identify properties that control production. In particular, this requires mapping the porosity at multiple scales and understanding the coupled contributions of fractures, variable pore types, microporosity and mineral heterogeneity to flow, petrophysical response, reserves assessment and recovery processes.
This extended abstract describes a formation characterisation study based on the integrated analysis of data in 2D and 3D at multiple scales on sets of plugs from three unconventional tight gas plays: coal, tight gas, and shale. Heterogeneity and geological rock typing is considered at the core scale by classical 3D imaging techniques. Mineralogy and secondary microporosity characterisation is mapped at the plug scale with different modes of 3D X-ray micro-CT analysis coupled with SEM and SEM-EDS analysis.
In particular, the pore connectivity and production potential is probed. SEM and FIBSEM imaging is then used to reveal the porous microstructure of the key phases at the nano-scale in 2D and 3D. This information, collected at multiple scales, is integrated to provide an understanding and quantification of the pore structure and connectivity of these complex rocks. Petrophysical properties that impact the storage capacity and production characteristics are then computed for each key phase and data up-scaled to the plug scale using standard procedures. Results compare favourably with core analysis data, where available.
The presentation slides for this speech have not been made available to APPEA at this stage.
Mark Knackstedt is a professor at the Department of Applied Mathematics at ANU and CTO of Digitalcore. He had led a research team at ANU that has pioneered the development of the new image-based core analysis. This technology presents a paradigm shift in the petroleum industry’s approach to core acquisition and analysis. He was an SPWLA distinguished speaker in 2007–08 and 2009–10 and received the George Matson medal from the AAPG in 2009 and the ENI award for New Frontiers in Hydrocarbon Research in 2010. |
Alexandra Golab is a senior geologist with Digitalcore. She holds a BSc (Adv) (honours, class one) in geology and chemistry, and a PhD (geochemistry) (graduated 2003). She has worked as a geoscientist in several sectors including a university, a national research organisation, and an environmental consulting company. She has published one book about CO2 geosequestration opportunities in NSW and numerous journal articles, conference papers, and technical reports about coal, carbonate mineralogy, aqueous geochemistry, soil remediation, and unconventional reservoir porosity characterisation. She is guest editor of a special issue of the Australian Journal of Earth Sciences (AJES) about CO2 sequestration. Member: SPE, FESA. |
References
Golab, A.N., Knackstedt, M.A., Averdunk, H., Senden, T., Butcher, A.R., and Jaime, P. (2010). 3D porosity and mineralogy characterization in tight gas sandstones. The Leading Edge 29, 1476–89.Gottlieb, P., Wilkie, G., Sutherland, D., Ho-Tun, E., Suthers, S., Perera, K., Jenkins, B., Spenser, S., Butcher, A., and Rayner, J. (2000). Using quantitative electron microscopy for process mineralogy applications. Journal of the Minerals, Metals and Materials Society 52, 24–25.
Knackstedt, M., Jaime, P., Butcher, A.R., Botha, P.W., Middleton, J., and Sok, R., 2010—Integrating reservoir characterization: 3D dynamic, petrophysical and geological description of reservoir facies. SPE Asia Pacific Oil and Gas Conference and Exhibition, Brisbane, Australia, 18–20 October, SPE 133981.
Latham, S., Varslot, T., and Sheppard, A.P. (2008). Image registration: enhancing and calibrating X-ray micro-CT imaging. Society of Core Analysts 35, 1–12.
