This dissertation aims to propose a new and practical method to obtain equivalent fracture network permeability (EFNP), which represents and replaces all the existing fractures located in each grid block for the reservoir simulation of naturally fractured reservoirs. To achieve this, first the relationship between different geometrical properties of fracture networks and their EFNP was studied. A MATLAB program was written to generate many different realizations of 2-D fracture networks by changing fracture length, density and also orientation. Next, twelve different 2-D fractal-statistical properties of the generated fracture networks were measured to quantify different characteristics. In addition to the 2-D fractal-statistical properties, readily available 1-D and 3-D data were also measured for the models showing variations of fracture properties in the Z-direction.
The actual EFNP of each fracture network was then measured using commercial software called FRACA. The relationship between the 1-, 2- and 3-D data and EFNP was analyzed using multivariable regression analysis and based on these analyses, correlations with different number of variables were proposed to estimate EFNP. To improve the accuracy of the predicted EFNP values, an artificial neural network with the back-propagation algorithm was also developed.
Then, using the experimental design technique, the impact of each fracture network parameter including fracture length, density, orientation and conductivity on EFNP was investigated. On the basis of the results and the analyses, the conditions to obtain EFNP for practical applications based on the available data (1-D well, 2-D outcrop, and 3-D welltest) were presented. This methodology was repeated for natural fracture patterns obtained mostly from the outcrops of different geothermal reservoirs. The validity of the equations was also tested against the real welltest data obtained from the fields.
Finally, the concept of the percolation theory was used to determine whether each fracture network in the domain is percolating (permeable) and to quantify the fracture connectivity, which controls the EFNP. For each randomly generated fracture network, the relationship between the combined fractal-percolation properties and the EFNP values was investigated and correlations for predicting the EFNP were proposed. As before, the results were validated with a new set of fracture networks. / Petroleum Engineering
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:AEU.10048/1623 |
| Date | 06 1900 |
| Creators | Jafari, Alireza |
| Contributors | Babadagli, Tayfun (Department of Civil and Environmental Engineering, University of Alberta), Babadagli, Tayfun (Department of Civil and Environmental Engineering, University of Alberta), Kuru, Ergun (Department of Civil and Environmental Engineering, University of Alberta), Al-Hossein, Mohamed (Department of Civil and Environmental Engineering, University of Alberta), Safouhi, Hassan (Campus Sainte Jean, University of Alberta), Asghari, Koorosh (Petroleum Systems Engineering, University of Regina) |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | 5390482 bytes, application/pdf |
| Relation | Jafari, A. and Babadagli, T., 2008. A sensitivity analysis for effective parameters on fracture network permeability. SPE 113618, Western Regional and Pacific Section AAPG Joint Meeting, Bakersfield, California, U.S.A., 31 March2 April 2008., Jafari, A. and Babadagli, T., 2009a. A sensitivity analysis for effective parameters on 2-D fracture network permeability. SPE Res. Eval. and Eng., 12(3): 455-469., Jafari, A. and Babadagli, T., 2009b. Generating 3-D permeability map of fracture networks using well, outcrop and pressure transient data. SPE 124077, SPE/EAGE Reservoir Characterization and Simulation Conference. Also accepted for publication in SPE Res. Eval. and Eng., Jafari, A. and Babadagli, T., 2010a. Practical estimation of equivalent fracture network permeability of geothermal reservoirs. in proceedings World Geothermal Congress, Bali, Indonesia, 20-25 April, 10 pp., Jafari, A. and Babadagli, T., 2010b. Calculating equivalent fracture network permeability of multi-layer-complex naturally fractured reservoirs. SPE 132431, presented at SPE Western Regional Meeting, Anaheim, California, U.S.A., 27-29 May., Jafari, A. and Babadagli, T., 2010c. Effective Fracture Network Permeability of Geothermal Reservoirs. Accepted for publication in Geothermics. |
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