Pore-Scale Characterization of Carbonates Using X-Ray Microtomography

Abstract

A reservoir carbonate core plug has been imaged in 3D across a range of length scales using high resolution X-ray microtomography (µ-CT). Data from the original 40-mm diameter plug was obtained at the vug scale (42 µm resolution) and allows the size, shape and spatial distribution of the disconnected vuggy porosity, φ vug = 3.5% to be measured. Within the imaged volume over 32,000 separate vugs are identified and a broad vug size distribution is measured. Higher resolution images, down to 1.1 µm resolution, on subsets of the plug exhibit interconnected porosity and allow one to measure characteristic, intergranular pore size. Pore scale structure and petrophysical properties (permeability, drainage capillary pressure, formation factor, and NMR response) are derived directly on the highest resolution tomographic dataset. We show that data over a range of porosity can be computed from a single plug fragment. Data for the carbonate core is compared to results derived from 3D images of clastic cores and strong differences noted. Computations of permeability are compared to conventional laboratory measurements on the same core material with good agreement. This demonstrates the feasibility of combining digitized images with numerical calculations to predict properties and derive cross-correlations for carbonate lithologies.

Study on microheterogeneity and seepage law of reservoir after long-term water flooding

“…Moreover, after long-term flooding in reservoir of the Jidong Oilfield, the separation of pore and throat becomes better, and microheterogeneity of reservoir gradually becomes weaker. The rule has not been reported before (Elliott and Dover 1982;Sorbie et al 1989;Lymberopoulos and Payatakes 1992;Xu et al 1999;Fredrich et al 1995;Fredrich 1999;Delerue et al 1999;Lindquist and Venkatarangan 1999;Liang et al 2000;Blunt (2001); Radlinski et al 2002;Siddiqui and Khamees 2004;Coenen et al 2004;Arns et al 2004Arns et al , 2005Knackstedt et al 2006;Al-Kharusi and Blunt 2007;Tomutsa et al 2007;Hou et al 2007;Youssef et al 2008;Dong and Blunt 2009;Mustafa et al 2009;Xu et al 2010;Peng et al 2012;Saurabh et al 2013;Theis et al 2014). …”

“…Elliott and Dover (1982), Sorbie et al (1989), Lymberopoulos and Payatakes (1992), Xu et al (1999), Fredrich et al (1995), Fredrich (1999, Delerue et al (1999), Lindquist and Venkatarangan (1999), Liang et al (2000), Blunt (2001), Radlinski et al (2002), Siddiqui and Khamees (2004), Coenen et al (2004), Knackstedt et al (2006), Al-Kharusi and Blunt (2007), Tomutsa et al (2007), Blunt (2009), Peng et al (2012), Saurabh et al (2013), Theis et al (2014), have researched the technologies and algorithms of constructing the digital core and 3D pore network model, and the 3D pore network model has been rapidly developed and widely applied. Among those technologies, the method of constructing 3D pore network model with digital core reconstructed by high-precision X-ray CT scanning is dominant, and it is future direction of researching microstructure of reservoir pore (Hou et al 2007;Arns et al 2004Arns et al , 2005Youssef et al 2008;Mustafa et al 2009). However, limited by equipment and technological conditions, China has not achieved much fruits in the field of reconstructing 3D pore network model.…”

High-resolution X-ray computed tomography in geosciences: A review of the current technology and applications

“…Pirlet et al (2010; studied diagenetic formation of gypsum and dolomite and the mineral assemblages in cold-water coral mounds by means of micro-CT (Van Rooij et al, 2011). Arns et al (2005a;2005b) performed petrophysical analysis from reservoir core fragments and pore-scale characterization of carbonates by micro-CT. Uchida et al (2000) examined the occurrences of natural gas hydrates beneath the permafrost in the Mackenzie Delta. Synchrotron experiments for studying core samples has previously been shown to provide excellent two-and threedimensional high resolution descriptions of pore structure and mineral distributions of core material (Coenen et al, 2004;Coles et al, 1998).…”

Technical Note. The Concept of a Computer System for Interpretation of Tight Rocks Using X-Ray Computed Tomography Results

“…Information on porosity, spatial distribution of pores, as well as information about pore channels tortuosity can be obtained by applying image processing methods on the CT results, in order to segment images. It is crucial regarding evaluation of capacity of the rock for media flow (Arns et al 2005). X-ray computed tomography measurement begins when X radiation beam is emitted by X-ray tube.…”