3D porosity and mineralogy characterization in tight gas sandstones

Abstract

Tight gas reservoirs exhibit storage and flow characteristics that are intimately tied to depositional and diagenetic processes. As a result, exploitation of these resources requires a comprehensive reservoir description and characterization program to identify properties which control production. In particular, tight gas reservoirs have significant primary and secondary porosity and pore connectivity dominated by clays and slot-like pores. This makes them particularly susceptible to the effects of overburden stress and variable water saturation. This paper describes an integrated approach to describe a tight gas sandstone at the pore scale in 3D. In particular, the primary and secondary porosity of a tight gas sandstone are identified and quantified in three dimensions using 3D X-ray micro-CT imaging and visualization of core material at the pore scale. 3D images allow one to map in detail the pore and grain structure and interconnectivity of primary and secondary porosity. Once the tomographic images are combined with SEM images from a single plane within the cubic data set, the nature of the secondary porosity can be determined and quantified. In-situ mineral maps measured on the same polished plane are used to identify different microporous phases contributing to the secondary porosity. Once these data sets are combined, the contribution of individual clay minerals to the microporosity, pore connectivity, and petrophysical response can be determined. Insight into the producibility may also be gained. This illustrates the role 3D imaging technology can play in a comprehensive reservoir characterization program for tight gas.

3D characterisation of potential CO2 reservoir and seal rocks

“…mCT is an established and rapidly evolving technology of great value for a wide variety of materials at micron scales including petroleum geology, e.g. clastic (Golab et al 2010) and carbonate rocks (Arns et al 2005b), coal (Mazumder et al 2006), paper (Roberts et al 2003, biomaterials (Knackstedt et al 2006), bones (Zezabe et al 2005), volcanic ash (Ersoy et al 2010), paleontology (Long et al 2006), soil science, meteoritics, and geotechnics (Ketcham & Carlson 2001;Mees et al 2003;Sleutel et al 2008;Narsilio et al 2009). Considerable research is under way in the digital imaging of core material at the pore scale in 3D using mCT, which greatly enhances the ability to understand petrophysical response, multiphase flow properties and geological heterogeneity (Arns et al 2005a).…”

Diagenesis of Tight‐gas Sandstones in the Lower Cretaceous Denglouku Formation, Songliao Basin, Ne China: Implications for Reservoir Quality

“…Reservoir rocks in this unit display considerable variations in grain size, depositional facies and diagenetic infl uences that strongly affect reservoir quality. Tight-gas storage and fl ow characteristics are intimately linked to depositional and diagenetic processes (Rushing et al, 2008;Golab et al, 2010), but few studies of diagenesis and reservoir-quality evaluation of non-marine tight-gas sandstones have so far been carried out.…”

An Iterative CT Reconstruction Algorithm for Fast Fluid Flow Imaging

“…Recent advances in image acquisition speed are now permitting preliminary studies [1]- [3], but current temporal resolutions are insufficient to capture high speed behavior in low viscosity fluids. True high speed dynamic CT of multi-phase flow has potential applications across petroleum and geoscience research [4]- [6], in civil and environmental engineering [7]- [10], as well as for biomedical and materials science applications.…”