Journal of Canadian Petroleum Technology Volume 51, Number 2, March 2012, pp. 127-136

SPE-150627-PA

A New Model for Reservoirs With a Discrete-Fracture System

View full textPDF ( 1,840 KB )

DOI  10.2118/150627-PA http://dx.doi.org/10.2118/150627-PA

Citation

• Zeng, F., Zhao, G., and Liu, H. 2011. A New Model for Reservoirs With a Discrete-Fracture System. J Can Pet Technol  51 (2): 127-136. SPE-150627-PA. http://dx.doi.org/10.2118/150627-PA.

Discipline Categories

• 6.10.2 Naturally-Fractured Reservoirs
• 6.1.10 Reservoir Geomechanics
• 6.2.2 Fluid Modeling, Equations of State

Keywords

• fluid flow in porous medium, discrete fracture systems, well testing, naturally fractured reservoir, tight gas

Summary

Dual-porosity and dual-permeability models for naturally fractured reservoirs assume that the fractures in the reservoir are connected with each other and uniformly distributed. However, in some cases, the reservoir characteristics exhibit a discrete-fracture system, which means that the fractures might be unconnected and their distribution is not uniform. In this paper, a new computational model is developed to compute the transient-pressure behaviour for reservoirs with a discrete-fracture system. This computational model is based on Laplace transforms. The fluid flow in the fracture system and reservoir are computed separately, and flux and pressure equivalent conditions in Laplace space are applied in the fracture wall to couple the fluid flow in both systems.

The results suggest that the pressure response in a reservoir with a discrete-fracture system has three flow regions: fluid flow near the wellbore, fracture-dominated fluid flow, and fluid flow in the matrix away from the fracture. The distance between the fracture and the well, fracture parameters (fracture conductivity and non-Darcy effects), and fracture distribution are the main factors affecting the pressure response. In some particular situations, the fracture-dominated fluid-flow region in the pressure-derivative curve may present two valleys, which has been observed in some field cases (Clarkson 2009). The transient-pressure behaviour of a discrete-fracture system is also compared with that for a composite model. It is suggested that in these two scenarios, the early- and middle-time transient-pressure behaviour may be similar and latetime behaviours are quite different. The model provides a tool for identifying the fracture pattern in a specific reservoir.

View full textPDF ( 1,840 KB )

History

• Original manuscript received: 26 March 2009
• Meeting paper published: 16 June 2009
• Revised manuscript received: 20 June 2011
• Manuscript approved: 28 June 2011
• Published online: 12 December 2011
• Version of record: 14 March 2012