Validating Predicted Fracture Corridors by Statistical Comparison With Well Data
- Sait I. Ozkaya (Consultant)
- Document ID
- Society of Petroleum Engineers
- SPE Reservoir Evaluation & Engineering
- Publication Date
- April 2019
- Document Type
- Journal Paper
- 2019.Society of Petroleum Engineers
- geomechanical or seismic models, fracture corridors, validation, conditional probability, contingency tables
- 7 in the last 30 days
- 59 since 2007
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A challenge in oil-reservoir studies is evaluating the ability of geomechanical, statistical, and geophysical methods to predict discrete geological features. This problem arises frequently with fracture corridors, which are discrete, tabular subvertical fracture clusters. Fracture corridors can be inferred from well data such as horizontal-borehole-image logs. Unfortunately, well data, and especially borehole image logs, are sparse, and predictive methods are needed to fill in the gap between wells. One way to evaluate such methods is to compare predicted and inferred fracture corridors statistically, using chi-squared and contingency tables.
In this article, we propose a modified contingency table to validate fracture-corridor-prediction techniques. We introduce two important modifications to capture special aspects of fracture corridors. The first modification is the incorporation of exclusion zones where no fracture corridors can exist, and the second modification is taking into consideration the fuzzy nature of fracture-corridor indicators from wells such as circulation losses. An indicator is fuzzy when it has more than one possible interpretation. The reliability of an indicator is the probability that it correctly suggests a fracture corridor. The indicators with reliability of unity are hard indicators, and “soft” and “fuzzy” indicators are those with reliability that is less than unity.
A structural grid is overlaid on the reservoir top in an oil field. Each cell of the grid is examined for the presence and reliability of inferred fracture corridors and exclusion zones and the confidence level of predicted fracture corridors. The results are summarized in a contingency table and are used to calculate chi-squared and conditional probability of having an actual fracture corridor given a predicted fracture corridor.
Three actual case studies are included to demonstrate how single or joint predictive methods can be statistically evaluated and how conditional probabilities are calculated using the modified contingency tables. The first example tests seismic faults as indicators of fracture corridors. The other examples test fracture corridors predicted by a simple geomechanical method.
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Al-Omair, A. A., Elrafie, E. A., Agil, M. F. et al. 2010. Natural Fracture Detection, Characterization and Modeling Using the Event Solution Synergy Approach. Presented at the SPE Abu Dhabi International Petroleum Exhibition and Conference, Abu Dhabi, 1–4 November. SPE-137276-MS. https://doi.org/10.2118/137276-MS.
Barton, C. A. and Zoback, M. D. 1994. Stress Perturbations Associated With Active Faults Penetrated by Boreholes: Possible Evidence for Near-Complete Stress Drop and a New Technique for Stress Magnitude Measurement. J Geophys Res 99 (B5): 9373–9390. https://doi.org/10.1029/93JB03359.
Beekman, F., Badsi, M., and van Wees, J-D. 2000. Faulting, Fracturing and In Situ Stress Prediction in the Ahnet Basin, Algeria—A Finite Element Approach. Tectonophysics 320 (3–4): 311–329. https://doi.org/10.1016/S0040-1951(00)00037-8.
Biryukov, D. and Kuchuk, F. J. 2012. Transient Pressure Behavior of Reservoirs With Discrete Conductive Faults and Fractures. Transp Porous Media 95 (1): 239–268. https://doi.org/10.1007/s11242-012-0041-x.
Bourbiaux, B., Basquet, R., Cacas, M.-C. et al. 2002. An Integrated Workflow To Account for Multi-Scale Fractures in Reservoir Simulation Models: Implementation and Benefits. Presented at the Abu Dhabi International Petroleum Exhibition and Conference, Abu Dhabi, 13–16 October. SPE-78489-MS. https://doi.org/10.2118/78489-MS.
Bourne, S. J., Brauckmann, F., Rijkels, R. et al. 2000. Predictive Modelling of Naturally Fractured Reservoirs Using Geomechanics and Flow Simulation. Presented at the Abu Dhabi International Petroleum Exhibition and Conference, Abu Dhabi, 13–15 October. SPE-87253-MS. https://doi.org/10.2118/87253-MS.
Cacas, M. C., Daniel, J. M., and Letouzey, J. 2001. Nested Geological Modelling of Naturally Fractured Reservoirs. Petrol Geosci 7 (S): 543–552. https://doi.org/10.1144/petgeo.7.S.S43.
Chatterjee, R. 2008. Effect of Normal Faulting on In-Situ Stress: A Case Study From Mandapeta Field, Krishna-Godavari Basin, India. Earth Planet. Sci. Lett. 269 (3–4): 458–467. https://doi.org/10.1016/j.epsl.2008.02.040.
Chopra, S. 2002. Coherence Cube and Beyond. First Break 20 (1): 27–33. https://doi.org/10.1046/j.1365-2397.2002.00225.x.
Cosentino, L., Coury, Y., Daniel, J. M. et al. 2002. Integrated Study of a Fractured Middle East Reservoir With Stratiform Super-K Intervals—Part 2: Upscaling and Dual-Media Simulation. SPE Res Eval & Eng 5 (1): 24–33. SPE-76642-PA. https://doi.org/10.2118/76642-PA.
Deng, B.-W., Lee, C.-H., and Chang, J.-L. 1995. Characterization and Interpretation of Variability of Fracture Pattern in Jointed Andesites. J Chin Inst Eng 18 (6): 787–799. https://doi.org/10.1080/02533839.1995.9677747.
Dershowitz, B., LaPointe, P., Eiben, T. et al. 2000. Integration of Discrete Feature Network Methods With Conventional Simulator Approaches. SPE Res Eval & Eng 3 (2): 165–171. SPE-62498-PA. https://doi.org/10.2118/62498-PA.
Duriez, J., Scholtès, L., and Donzé, F.-V. 2016. Micromechanics of Wing Crack Propagation for Different Flaw Properties. Eng Fract Mech 153 (March): 378–398. https://doi.org/10.1016/j.engfracmech.2015.12.034.
Elfeel, M. A., Couples, G., Geiger, S. et al. 2010. Upscaled Multi-Phase Flow Properties of Fracture Corridor. Presented at the SPE Caspian Carbonates Technology Conference, Atyrau, Kazakhstan, 6–8 November. SPE-139463-MS. https://doi.org/10.2118/139463-MS.
Excel is a registered trademark of Microsoft Corporation, One Microsoft Way, Redmond, Washington, 98052.
Fisher, R. A. 1934. Statistical Methods for Research Workers, fifth edition. London: Oliver and Boyd.
Gao, D. 2013. Integrating 2D Seismic Curvature and Curvature Gradient Attributes for Fracture Characterization: Methodologies and Interpretational Implications. Geophysics 78: O21–O31. https://doi.org/10.1190/geo2012-0190.1.
Guerriero, V., Vitale, S., Ciarcia, S. et al. 2011. Improved Statistical Multi-Scale Analysis of Fractured Reservoir Analogues. Tectonophysics 504 (1–4): 14–24. https://doi.org/10.1016/j.tecto.2011.01.003.
Guo, G., George, S. A., Rhonda, P. et al. 1999. Statistical Analysis of Surface Lineaments and Fractures for Characterizing Naturally Fractured Reservoirs. In AAPG Memoir 71: Reservoir Characterization—Recent Advances, ed. R. A. Schatzinger and J. F. Jordan. Tulsa, Oklahoma: American Association of Petroleum Geologists.
Guo, P., Yao, L., and Ren, D. 2016. Simulation of Three-Dimensional Tectonic Stress Fields and Quantitative Prediction of Tectonic Fracture Within the Damintun Depression, Liaohe Basin, Northeast China. J Struct Geol 86 (May): 211–223. https://doi.org/10.1016/j.jsg.2016.03.007.
Haddad, J., Ramos, J., and Aldana, M. 2014. In-Situ Stress Constrain: A Geomechanics Study To Evaluate the Influence of the Structural Geology. Presented at the SPE Latin America and Caribbean Petroleum Engineering Conference, Maracaibo, Venezuela, 21–23 May. SPE-169364-MS. https://doi.org/10.2118/169364-MS.
Hoek, E. and Brown, E. T. 1988. The Hoek-Brown Failure Criterion—A 1988 Update. In Proc., 15th Canadian Rock Mechanics Symposium, ed. J. Curran, 31–38. Toronto: University of Toronto.
Horne, R. N. 1995. Modern Well Test Analysis: A Computer-Aided Approach, second edition. Palo Alto, California: Petroway.
Lange, A., Basquet, R., and Bourbiaux, B. 2004. Hydraulic Characterization of Faults and Fractures Using a Dual Medium Discrete Fracture Network Simulator. Presented at the Abu Dhabi International Petroleum Exhibition and Conference, Abu Dhabi, 10–13 October. SPE-88675-MS. https://doi.org/10.2118/88675-MS.
Laubach, S. E., Eichhubl, P., Hargrove, P. et al. 2014. Fault Core and Damage Zone Fracture Attributes Vary Along Strike Owing to Interaction of Fracture Growth, Quartz Accumulation, and Differing Sandstone Composition. J Struct Geol 68A (November): 207–226. https://doi.org/10.1016/j.jsg.2014.08.007.
Lefranc, M., Hussein, A. M., Tan, C. P. et al. 2014. 3D Structural Restoration and Geomechanical Forward Modeling in a Visco-Plastic Medium to Natural Fracture Prediction in a Malay Producing Field, Offshore Malaysia. Presented at the Offshore Technology Conference–Asia, Kuala Lumpur, 25–28 March. OTC-24753-MS. https://doi.org/10.4043/24753-MS.
Li, J. Z., Laubach, S. E., Gale, J. F. W. et al. 2017. Quantifying Opening-Mode Fracture Spatial Organization in Horizontal Wellbore Image Logs, Core and Outcrop: Application to Upper Cretaceous Frontier Formation Tight Gas Sandstones, USA. J Struct Geol 108 (March): 137–156. https://doi.org/10.1016/j.jsg.2017.07.005.
Liu, J., Ding, W., Yang, H. et al. 2017. Quantitative Prediction of Fractures Using the Finite Element Method: A Case Study of the Lower Silurian Longmaxi Formation in Northern Guizhou, South China. J Asian Earth Sci 154 (1 April): 397–418. https://doi.org/10.1016/j.jseaes.2017.12.038.
Lorenz, J. C., Sterling, J. L., Schechter, D. S. et al. 2002. Natural Fractures in the Spraberry Formation, Midland Basin, Texas: The Effects of Mechanical Stratigraphy on Fracture Variability, and Reservoir Behavior. AAPG Bull. 86 (3): 505–524. https://doi.org/10.1306/61EEDB20-173E-11D7-8645000102C1865D.
Macaulay, E., Reilly, C., Anderson, H. et al. 2016. Predicting Realistic Natural Fracture Distributions Using Structural Modelling—Best Practice Work-flows for Evaluating Prospects and Targeting Sweet Spots in Unconventional Reservoirs. Presented at the SPE/AAPG/SEG Unconventional Resources Technology Conference, San Antonio, Texas, 1–3 August. URTEC-2461243-MS. https://doi.org/10.15530/urtec-2016-2461243.
Maerten, L., Gillespie, P., and Polard, D. D. 2002. Effects of Local Stress Perturbation on Secondary Fault Development. J Struct Geol 24 (1): 145–153. https://doi.org/10.1016/S0191-8141(01)00054-2.
Massonnat, G., Viszkok, J., and Vrignon, M. 2002. Hierarchical Organization of Flow Network in Fractured Carbonate Reservoirs: Identification and Characterization of Key Parameters. Presented at the SPE Annual Technical Conference and Exhibition, San Antonio, Texas, 29 September–2 October. SPE-77488-MS. https://doi.org/10.2118/77488-MS.
McDonald, J. H. 2014. G-Test of Goodness-of-Fit—Handbook of Biological Statistics, third edition, pp. 53–58. Baltimore, Maryland: Sparky House Publishing.
Narr, W., Schechter, D. S., and Thompson, L. B. 2006. Naturally Fractured Reservoir Characterization, first edition. Richardson, Texas: Society of Petroleum Engineers.
Nelson, R. 2001. Geological Analysis of Naturally Fractured Reservoirs, second edition. Oxford, UK: Elsevier Technology and Engineering Series, Elsevier.
Neves, F. A., Zahrani, M. S., and Bremkamp, S. W. 2004. Detection of Potential Fractures and Small Faults Using Seismic Attributes. The Leading Edge 23 (9): 903–906. https://doi.org/10.1190/1.1803500.
Olson, J. E., Hennings, P., and Laubach, S. E. 1998. Integrating Wellbore Data and Geomechanical Modeling for Effective Characterization of Naturally Fractured Reservoirs. Presented at the SPE/ISRM Rock Mechanics in Petroleum Engineering, Trondheim, Norway, 8–10 July. SPE-47352-MS. https://doi.org/10.2118/47352-MS.
Ozkaya, S. I. 2008. Using Probabilistic Decision Trees To Detect Fracture Corridors From Dynamic Data in Mature Oil Fields. SPE Res Eval & Eng 11 (6): 1061–1070. SPE-105015-PA. https://doi.org/10.2118/105015-PA.
Ozkaya, S. I. 2010. Use of Exclusion Zones in Mapping and Modeling Fracture Corridors. SPE Res Eval & Eng 13 (4): 679–687. SPE-120136-PA. https://doi.org/10.2118/120136-PA.
Ozkaya, S. I. 2014. SUPERPOSE—An Excel Visual Basic Program for Fracture Modeling Based on the Stress Superposition Method. Comput Geosci 64 (March): 41–51. https://doi.org/10.1016/j.cageo.2013.11.011.
Ozkaya, S. I. 2017. Modeling Finite-Fracture Networks in a Partially Fractured Reservoir in the Middle East. SPE Res Eval & Eng 20 (4): 839–853. SPE-185171-PA. https://doi.org/10.2118/185171-PA.
Ozkaya, S. I. 2018. FRACOR—Software Toolbox for Deterministic Mapping of Fracture Corridors in Oil Fields on AutoCAD Platform. Comput Geosci 112 (March): 9–22. https://doi.org/10.1016/j.cageo.2017.11.016.
Ozkaya, S. I. and Richard, P. D. 2006. Fractured Reservoir Characterization Using Dynamic Data in a Carbonate Field, Oman. SPE Res Eval & Eng 9 (3): 227–238. SPE-93312-PA. https://doi.org/10.2118/93312-PA.
Rotevatn, A. and Bastesen, E. 2014. Fault Linkage and Damage Zone Architecture in Tight Carbonate Rocks in the Suez Rift Egypt: Implications for Permeability Structure Along Segmented Normal Faults. In Advances in Study of Fractured Reservoirs, ed. G. H. Spence, J. Redfern, R. Aguilera, et al. Vol. 374, 79–95. London: Geological Society of London Special Publication.
Sanders, C., Bonora, M., Richards, D. et al. 2004. Kinematic Structural Restorations and Discrete Fracture Modeling of a Thrust Trap: A Case Study From the Tarija Basin, Argentina. Mar Pet Geol 21 (7): 845–855. https://doi.org/10.1016/j.marpetgeo.2003.09.006.
Sheskin, D. J. 1997. Handbook of Parametric and Nonparametric Statistical Procedures. Boca Raton, Florida: CRC Press.
Smart, K. J., Ferrill, D. A., Morris, A. P. et al. 2012. Geomechanical Modeling of Stress and Strain Evolution During Contractional Fault-Related Folding. Tectonophysics 576–577 (5 November): 171–196. https://doi.org/10.1016/j.tecto.2012.05.024.
Su, H., Lei, Z., Zhang, D. et al. 2017. Dynamic and Static Comprehensive Prediction Method of Natural Fractures in Fractured Oil Reservoirs: A Case Study of Triassic Chang 63 Reservoirs in Huaqing Oilfield, Ordos Basin, NW China. Petrol Explor Develop 44 (6): 972–982. https://doi.org/10.1016/S1876-380417.30109-X.
Zhang, X. and Koursabeloulis, N. C. 2010. Estimate of Permeability of Fracture Corridors/Networks: From Data Acquisition to Reservoir Simulations. Presented at the International Oil and Gas Conference and Exhibition in China, Beijing, 8–10 June. SPE-131218-MS. https://doi.org/10.2118/ 131218-MS.