Downscaled Capillary Pressure and Relative Permeability of Small Cores for Network Model Validation

Abstract:

This paper presents the results of drainage capillary pressure and relative permeability measurements made on cores having different bulk volumes ranging from 0.5 to 12 cm3. The aim of the experiments was to provide reliable experimental data which can be used to validate the predictive value of micro-CT based network models for capillary pressure and relative permeability. The micro-CT based network models use realistic networks constructed from the X-ray images of the rock samples having a typical bulk volume of 0.3 cm3. Experimental data for drainage capillary pressure were obtained using the centrifuge technique. The results of the largest cores were verified by the data obtained on the same sample using the porous plate technique. Relative permeability data were obtained by history matching the unsteady state displacement data. Homogeneous model sandstones (Berea and Bentheim) and carbonate (Mt. Gambier) were used in the experiments. Air-brine and oil-brine fluid-systems were used for drainage capillary pressure and relative permeability measurements, respectively. The relative permeability data were compared with those predicted from empirical and geometry based models using capillary pressure data. Good agreement was obtained for the drainage capillary pressure measured on all samples used. The residual saturations obtained from the cores used in the displacement experiments were also in good agreement. The models were found to predict relative permeability of oil and water with varying degrees of success. For water relative permeability, the Pirson model predicts the experimental data successfully while the Corey, Corey-Brooks/Burdine and van Genuchten/Burdine models predict the data of oil relative permeability better than the others. The results demonstrate for the first time that reliable drainage capillary pressure and relative permeability measurements can be made on small model sandstone and carbonate cores of representative scales used in micro-CT-imaging.

• Periodical: International Journal of Engineering Research in Africa (Volume 4)
• Pages: 15-26
• DOI: https://doi.org/10.4028/www.scientific.net/JERA.4.15
• Online since: May 2011
• Authors: O.A. Olafuyi, Y. Cinar, M.A. Knackstedt, W.V. Pinczewski
• Keywords: Capillary Pressure, CT-Imaging, Downscaling, Network Model, Relative Permeability

References

[1] L.P. Dake, Fundamentals of Reservoir Engineering, Elsevier Science B.V., New York, (2001).

[2] P.E. Øren, S. Bakke and O.J. Arntzen, Extending predictive capabilities of network models, SPE Journal 3 (1998) 324-336.

DOI: 10.2118/52052-pa

[3] A.P. Sheppard, R.M. Sok and H. Averdunk, Techniques for image enhancement and segmentation of tomographic images of porous materials, Physica A 339(1-2) (2004) 166-172.

DOI: 10.1016/j.physa.2004.03.057

[4] A.W. Talash, Experimental and calculated relative permeability data for systems containing low tension additives. SPE 5810, presented at SPE IOR Symp, Tulsa, OK (1976).

DOI: 10.2118/5810-ms

[5] S.J. Salter and K.K. Mohanty, Multiphase flow in porous media: I. Macroscopic observation and modeling. SPE 11017, presented at the SPE Ann. Fall Tech. Conf. & Exhib, New Orleans (1982).

DOI: 10.2118/11017-ms

[6] M.J. Oak, L.E. Baker and D.C. Thomas, Three-phase relative permeability of Berea sandstone. JPT (August 1990): 1054-1061.

DOI: 10.2118/17370-pa

[7] M.J. Blunt, M.D. Jackson, M. Piri and P.H. Valvatne, Detailed physics, predictive capabilities and macroscopic consequences for pore network models of multiphase flow, Adv. In Water Res 25, (2002) 1069-1089.

DOI: 10.1016/s0309-1708(02)00049-0

[8] V.H. Nguyen, A.P. Sheppard, M.A. Knackstedt and W.V. Pinczewski, The effect of displacement rate on imbibition relative permeability and residual Saturation. Journal of Petroleum Sci. & Eng. 52(1-4) (2006) 54-70.

DOI: 10.1016/j.petrol.2006.03.020

[9] O.A. Olafuyi, Y. Cinar, M.A. Knackstedt and W.V. Pinczewski, Spontaneous imbibition in small cores, SPE 109724, presented at the SPE Asia Pacific Oil & Gas Conf., Jakarta, Indonesia (2007).

DOI: 10.2118/109724-ms

[10] M. Honarpour, L. Koederitz and A.H. Harvey, Relative Permeability of Petroleum Reservoirs. CRC Press Inc, Boca Raton, FL (1986).

DOI: 10.1201/9781351076326

[11] W.R. Purcell, Capillary pressures – Their measurement using mercury and the calculation of permeability therefrom, " Trans. AIME 186 (1949) 39-46.

DOI: 10.2118/949039-g

[12] N.T. Burdine, Relative permeability calculations from pore size distribution data. Trans. AIME 198 (1953) 71-78.

DOI: 10.2118/225-g

[13] R.H. Brooks and A.T. Corey, Properties of porous media affecting fluid flow. Journal of Irrig. Grain. Div. 6 (1966) 61.

DOI: 10.1061/jrcea4.0000425

[14] M.T. van Genuchten, A closed form equation for predicting the hydraulic conductivity of unsaturated soils. Soil Science, (1980).

DOI: 10.2136/sssaj1980.03615995004400050002x

[15] Y. Mualem, A new model for predicting the hydraulic conductivity of unsaturated porous media. Water Resour. Res. 12(3) (1976) 513-522.

DOI: 10.1029/wr012i003p00513

[16] A.T. Corey, The interrelation between gas and oil relative permeabilities. Producers Monthly (November 1954): 38-41.

[17] S.J. Pirson, Oil Reservoir Engineering. McGraw-Hill, New York, (1958).

[18] S. Bakke and P.E. Øren, 3-D pore scale modeling of sandstones and flow simulations in the pore networks. SPE Journal 2, (1997) 136-149.

DOI: 10.2118/35479-pa

[19] P. Forbes, Quantitative evaluation and correction of gravity effects on centrifuge capillary pressure curves. SCA 9734, presented at the Society of Core Analysts Symp. (1997).

[20] Y. Cinar and F.M. Orr Jr., Measurement of three-phase relative permeability with IFT variation. SPE Res. Eval. & Eng. (Feb. ), 33-43 Soc. Am. Journal 44 (2005) 892-898.

DOI: 10.2118/89419-pa