Development of a novel and computationally-efficient discrete-fracture model to study IOR processes in naturally fractured reservoirs

Ali Moinfar, Abdoljalil Varavei, Kamy Sepehrnoori, Russell T. Johns

Research output: Chapter in Book/Report/Conference proceedingConference contribution

51 Scopus citations

Abstract

Many naturally fractured reservoirs around the world have depleted significantly and improved oil recovery (IOR) processes are necessary for further development. Hence, the modeling of fractured reservoirs has received increased attention recently. Accurate modeling and simulation of naturally fractured reservoirs is still challenging owing to permeability anisotropies and contrasts. Non-physical abstractions inherent in conventional dual porosity and dual permeability models make them inadequate for solving different fluid-flow problems in fractured reservoirs. Also, recent technologies of discrete fracture modeling suffer from large simulation run times and the industry has not found applications for them yet, even though they give more accurate representations of fractured reservoirs than dual continuum models. We developed a novel discrete fracture model for an in-house compositional reservoir simulator that borrows the dual-medium concept from conventional dual continuum models and also incorporates the effect of each fracture explicitly. In contrast to dual continuum models, fractures have arbitrary orientations and can be angled or vertical, honoring the complexity of a typical fractured reservoir. Likewise, the new discrete fracture model does not need mesh refinement around fractures and offers computationally-efficient simulations compared to other discrete fracture models. Examples of water-flooding and gas injection are presented in this paper to demonstrate the accuracy, robustness, and applicability of the developed model for studying IOR processes in naturally fractured reservoirs. Simulations show that favorable rock wettability along with capillary pressure contrasts between matrix and fractures causes noticeable incremental oil recovery in water floods. Likewise, simulations of gas injection demonstrate that high-permeability fractures not only expedite gas breakthrough, but also increase segregation of gas towards the top of the reservoir, leading to very low sweep efficiency. Furthermore, oil recovery from naturally fractured reservoirs is found to be sensitive to the fracture inclination angle.

Original languageEnglish (US)
Title of host publicationSociety of Petroleum Engineers - 18th SPE Improved Oil Recovery Symposium 2012
PublisherSociety of Petroleum Engineers (SPE)
Pages1277-1293
Number of pages17
ISBN (Print)9781618399625
DOIs
StatePublished - Jan 1 2012
Event18th SPE Improved Oil Recovery Symposium 2012 - Tulsa, OK, United States
Duration: Apr 14 2012Apr 18 2012

Publication series

NameProceedings - SPE Symposium on Improved Oil Recovery
Volume2

Other

Other18th SPE Improved Oil Recovery Symposium 2012
CountryUnited States
CityTulsa, OK
Period4/14/124/18/12

All Science Journal Classification (ASJC) codes

  • Energy Engineering and Power Technology
  • Geotechnical Engineering and Engineering Geology

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    Moinfar, A., Varavei, A., Sepehrnoori, K., & Johns, R. T. (2012). Development of a novel and computationally-efficient discrete-fracture model to study IOR processes in naturally fractured reservoirs. In Society of Petroleum Engineers - 18th SPE Improved Oil Recovery Symposium 2012 (pp. 1277-1293). (Proceedings - SPE Symposium on Improved Oil Recovery; Vol. 2). Society of Petroleum Engineers (SPE). https://doi.org/10.2118/154246-ms