SPE Reservoir Evaluation & Engineering
Volume 15, Number 4, August 2012, pp. 473-485

Summary

This paper examines the effects of matrix microfractures on the effective matrix permeability of a dual-porosity medium. An analytical model is presented, with composite matrix blocks consisting of a core in which unconnected microfractures do not contribute considerably to flow capacity and a surface layer where the microfractures connected to the matrix surface (resembling wormholes) cause a stimulation effect. The composite matrix flow is coupled with the flow in a network of macrofractures, as in the conventional dual-porosity idealizations of fractured media. This paper investigates the effect of matrix-surface stimulation and demonstrates improved fluid transfer from the matrix medium to the fracture network because of matrix microfractures. It is shown that matrix microfractures accelerate production by providing earlier and more-effective contribution of the matrix into flow rates. This contribution of the matrix because of microfractures cannot be simulated by enhanced matrix permeability because the microfractured surface layer of the matrix causes flow characteristics different from those of a homogeneous (unfractured) matrix. The effect of the microfractured surface layer of the matrix cannot be taken into account by a triple-porosity model used to incorporate two sets of connected natural fractures or connected fractures and vugs.

© 2012. Society of Petroleum Engineers

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History

• Original manuscript received: 24 August 2011
• Meeting paper published: 16 November 2011
• Revised manuscript received: 12 March 2012
• Manuscript approved: 11 May 2012
• Published online: 27 June 2012
• Version of record: 7 August 2012