Ensemble relative permeability in naturally fractured rocks: the role of wettability

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  • University of Melbourne

Abstract

Where fractures provide the permeability and the rock matrix the storage for oil and gas, fracture-matrix transfer has a decisive impact on recovery and capillary-driven transfer. However, while most modeling assumes constant (often zero) fracture capillary pressure, in actuality, fracture aperture varies among and within individual fractures, so will capillary pressure. Here we contrast and compare relative permeability curves derived from simple and more realistic fracture capillary pressure treatments applied in discrete fracture and matrix simulations (DFM) of pervasively fractured layered rock mapped in meter- to kilometer-scale outcrops. Fracture aperture is obtained by mechanical modeling. Imbibition simulations are performed with the Finite Element-Centered Finite Volume Method (FECFVM). Resulting fracture-matrix ensemble relative permeability curves highlight the importance of wettability: ultimate recovery is 2-3 times higher in the water-wet than the oil-wet case. With increasing wetting angle, counter-current-imbibition (CCI) rate decreases gradually because small fractures that contribute to the most of the fracture-matrix transfer area have small fracture-matrix capillary pressure differences.

Details

Original languageEnglish
StatePublished - 14 Sep 2017
Event SIAM Conference on Mathematical and Computational Issues in the Geosciences - Erlangen, Germany
Duration: 11 Sep 201714 Sep 2017
http://www.siam-gs17.de/

Conference

Conference SIAM Conference on Mathematical and Computational Issues in the Geosciences
CountryGermany
CityErlangen
Period11/09/1714/09/17
Internet address