An Improved Triple-Porosity Model for Evaluation of Naturally Fractured Reservoirs
- Ali Al-Ghamdi (University of Calgary) | Bo Chen (Yangtze University) | Hamish Behmanesh (Petroleum University of Technology) | Farhad Qanbari (Petroleum University of Technology) | Roberto Aguilera (University of Calgary)
- Document ID
- Society of Petroleum Engineers
- SPE Reservoir Evaluation & Engineering
- Publication Date
- August 2011
- Document Type
- Journal Paper
- 377 - 384
- 2011. Society of Petroleum Engineers
- 5.7.5 Economic Evaluations, 1.14 Casing and Cementing, 5.7 Reserves Evaluation, 5.6.1 Open hole/cased hole log analysis, 4.3.4 Scale, 5.8.6 Naturally Fractured Reservoir
- Vugs, Petrophysics, Carbonates, Natural fractures, Triple porosity
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Many naturally fractured reservoirs are composed of matrix, fractures, and nontouching vugs (there can also be any other type of nonconnected porosity that can occur; for example, in intragranular, moldic, and/or fenestral porosity). An improved triple-porosity model is presented that takes these different types of porosities into account. The model can be used continuously throughout a reservoir with segments composed of solely matrix porosity, solely matrix/fractures, solely fractures/vugs, or the complete triple-porosity system.
The model improves a previous triple-porosity algorithm by handling rigorously the scale associated with each: matrix, fractures, and vugs. This permits determining more-realistic values of the cementation or porosity exponent, m, for the composite system and consequently improved values of water saturation and reserves evaluations. The values of m for the triple-porosity reservoir can be smaller than, equal to, or larger than the porosity exponent of only the matrix blocks, mb, depending on the relative contribution of the vugs and fractures to the total porosity system.
It is concluded that not taking into account the contribution of matrix, fractures, and vugs in the petrophysical evaluation of triple-porosity systems can lead to significant errors in the determination of m, and consequently in the calculation of water saturation, hydrocarbons in place, and recoveries, and ultimately can lead to poor economic evaluations--either too pessimistic or too optimistic. This is illustrated with two examples from Middle East carbonates.
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Aguilera, R. 1976. Analysis of naturally fractured reservoirs fromconventional well logs. J Pet Technol 28 (7): 764-772.SPE-5342-PA. http://dx.doi.org/5342-PA.
Aguilera, R. 2010. Effect of Fracture Dip and Fracture Tortuosity onPetrophysical Evaluation of Naturally Fractured Reservoirs. J Can PetTechnol 49 (9): 69-76. SPE-139847-PA. http://dx.doi.org/10.2118/139847-PA.
Aguilera, R. and Aguilera, M.S. 2003. Improved Models for PetrophysicalAnalysis of Dual Porosity Reservoirs. Petrophysics 44 (1):21-35.
Aguilera, R.F. and Aguilera, R. 2004. A triple porosity model forpetrophysical analysis of naturally fractured reservoirs. Petrophysics 45 (2): 157-166.
Archie, G.E. 1942. The electrical resistivity log as an aid in determiningsome reservoir characteristics. SPE-942054-G. Trans., AIME, 146:54-62.
Berg, C.R. 2006. Dual Porosity Equations From Effective Medium Theory.Paper SPE 101698 presented at the SPE Annual Technical Conference andExhibition, San Antonio, Texas, USA, 24-27 September. http://dx.doi.org/10.2118/101698-MS.
Lucia, F.J. 1983. Petrophysical Parameters Estimated from VisualDescriptions of Carbonate Rocks: A Field Classification of Carbonate PoreSpace. J Pet Technol 35 (3): 629-637. SPE-10073-PA. http://dx.doi.org/10.2118/10073-PA.
Rasmus, J.C. 1983. A variable cementation exponent, m, for fracturedcarbonates. The Log Analyst 24 (6): 13-23.
Serra, O. 1989. Formation Micro Scanner image interpretation, SMP-7028.Houston: Schlumberger Educational Service.
Towle, G. 1962. An analysis of the formation resistivity factor-porosityrelationship of some assumed pore geometries. Paper C presented at the SPWLASymposium on Logging, Houston, 16-18 May.
Wafta, M. 1987. Current Affairs in Water Saturation. Middle East and AsiaReservoir Review 3 (2 November 1987).