Pore-Scale Network Modeling of Petrophysical Properties in Samples with Wide Pore Size Distributions
- Nijat Hakimov (University of Kansas) | Arsalan Zolfaghari (University of Kansas) | Amirmasoud Kalantari-Dahaghi (University of Kansas) | Shahin Negahban (University of Kansas) | Gary Gunter (Schlumberger-NExT)
- Document ID
- Society of Petroleum Engineers
- Abu Dhabi International Petroleum Exhibition & Conference, 12-15 November, Abu Dhabi, UAE
- Publication Date
- Document Type
- Conference Paper
- 2018. Society of Petroleum Engineers
- Pore-Network Modelling, Formation Factor, Low-Resistivity Pay, Microporosity, Archie's law
- 11 in the last 30 days
- 118 since 2007
- Show more detail
- View rights & permissions
|SPE Member Price:||USD 8.50|
|SPE Non-Member Price:||USD 25.00|
Archie's law is commonly used for the estimation of petrophysical properties of porous media linking electrical resistivity to water saturation. Therefore, low resistivity formation is expected to have high water saturation and hence, high water production. This, however, is not the case for many reservoirs around the world, for which low resistivity pay zones have been reported with very low or none water cut.
One of the main causes of Low Resistivity Pay (LRP) phenomena, especially in carbonates, is microporosity. Due to their small pore sizes, micro-pores have much higher threshold capillary pressures than macro-pores during drainage in the water-wet samples which resembles the original state of reservoirs before oil migrations. Because of that, we often find formations in which micro pores and macro pores are saturated with brine and oil, respectively. This indicates that there is a correlation between pore fluid occupancies and pore size distributions. The existence of connected pathways through micro-pores that are fully saturated with a conductive phase (i.e., brine) creates ‘shortcuts’ for the electrical current which causes short circuit and, ultimately, lowers rock resistivity measured from log analysis.
The purpose of this work is to investigate the impact of microporosity on the electrical properties of porous media through pore-scale network modeling techniques. To achieve this, a tortuous pore network is constructed on 2D rectangular regular lattice to represent macro pores and throats in the network. Next, the macro network is modified to include micro-pores. This has been done by adding a small rectangular lattice network of micro pores and throats. Radii and lengths of each element are chosen from the pre-specified ranges. This is done carefully to ensure that all networks of different scales fit geometrically within the lattice of a given size. We are specifically interested to investigate flow and electrical properties as a function of the locations, dimensions, and orientations of the micro-porosity regions. To achieve this goal, a comprehensive set of sensitivity analyses are done to assess the impact of various parameters including number of pores, tortuosity, geometry and location of microporosity (i.e., parallel or in series, continuous or non-continuous). The results are compared against Archie's equation, which is commonly used in the industry for log interpretation. This work helps to further expand the use of this equation for field applications, specifically, for formations containing rocks with wide pore size distribution.
|File Size||1 MB||Number of Pages||15|
Archie, G.E. 1942. "The Electrical Resistivity Log as an Aid in Determining Some Reservoir Characteristics." Transactions of the AIME 146 (01): 54–62. doi:10.2118/942054-G.
Boyd, A, H Darling, J Tabanou, B Davis, B Lyon, C Flaum, J Klein, Rm Sneider, a Sibbit, and J Singer. 1995. "The Lowdown on Low-Resistivity Pay." Oilfield Review, 4–18. https://www.oilfieldcentral.com/~/media/Files/resources/oilfield_review/ors95/aut95/composite.pdf
Bultreys, Tom, Luc Van Hoorebeke, and Veerle Cnudde. 2015. "Multi-Scale, Micro-Computed Tomography-Based Pore Network Models to Simulate Drainage in Heterogeneous Rocks." Advances in Water Resources, 78, (April). Elsevier Ltd: 36–49. doi:10.1016/j.advwatres.2015.02.003.
Bultreys, Tom, Wesley De Boever, and Veerle Cnudde. 2016. "Imaging and Image-Based Fluid Transport Modeling at the Pore Scale in Geological Materials: A Practical Introduction to the Current State-of-the-Art." Earth-Science Reviews. Elsevier. doi:10.1016/j.earscirev.2016.02.001.
Choquette, Philip W., and Lloyd C. Pray. 1970. "Geologic nomenclature and classification of porosity in sedimentary carbonates." American Association of Petroleum Geologists Bulletin, 54 (2): 207–50. doi:10.1306/5D25C98B-16C1-11D7-8645000102C1865D.AAPG bulletin 54, no. 2: 207-250.
Clennell, M. Ben. 1997. "Tortuosity: A Guide through the Maze." Geological Society, London, Special Publications 122 (1): 299–344. doi:10.1144/GSL.SP.1997.122.01.18.
Ehrenberg, Stephen N., and Olav Walderhaug. 2015. "Preferential Calcite Cementation of Macropores In Microporous Limestones." Journal of Sedimentary Research 85 (7): 780–93. doi:10.2110/jsr.2015.52.
Hamada, G. M., A. A. Almajed, T. M. Okasha, and A. A. Algathe. 2013. "Uncertainty Analysis of Archie's Parameters Determination Techniques in Carbonate Reservoirs." Journal of Petroleum Exploration and Production Technology. doi:10.1007/s13202-012-0042-x.
Xiong, Q., Baychev, T. G., & Jivkov, A. P. 2016. Review of pore network modelling of porous media: Experimental characterisations, network constructions and applications to reactive transport. Journal of Contaminant Hydrology. Elsevier B.V. https://doi.org/10.1016/j.jconhyd.2016.07.002
Zolfaghari, Arsalan, and Mohammad Piri. 2017. "Pore-Scale Network Modeling of Three-Phase Flow Based on Thermodynamically Consistent Threshold Capillary Pressures. I. Cusp Formation and Collapse." Transport in Porous Media 116 (3). Springer Netherlands: 1093–1137. doi:10.1007/s11242-016-0814-8.
Zolfaghari, Arsalan, and Mohammad Piri. 2017. "Pore-Scale Network Modeling of Three-Phase Flow Based on Thermodynamically Consistent Threshold Capillary Pressures. II. Results." Transport in Porous Media 116 (3): 1139–1165. doi:10.1007/s11242-016-0815-7.