The effect of fracture aperture and flow rate ratios on two-phase flow in smooth-walled single fracture

B B Maini,I D Gates,A A Alturki

doi:10.1007/s13202-012-0047-5

B B Maini, I D Gates + Show 1 more

Open Access

https://doi.org/10.1007/s13202-012-0047-5

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Abstract

This work experimentally examines the co-current flow of oil and water in moderately oil-wet smooth-walled single fractures. The focus of our investigation is on studying the effects of varying fracture aperture and flow rate ratios on relative permeability to oil and water. The phase distribution and flow regimes within the fracture were closely monitored and found to vary with the flow rate ratio and total flow rate, and appeared to have a direct impact on the relative permeability. Experimental relative permeability data exhibited variations in shape indicating the effects of fracture aperture and flow ratios. Also, the data show the effects of oil–water phase interference, and phase saturation changes on the relative permeabilities for each fracture configuration. A couple of two-phase relative permeability models, namely, viscous coupling model, and homogenous single-phase approach, were tested against the experimental relative permeability data. This work provides insight into the nature of two-phase flow in a single fracture and could help in better modeling of more complex fracture networks.

Highlights

In carbonate reservoirs, a rock fracture is a planar-shaped void filled with oil, water, gas, and even rock fines
In two-phase flow in smooth-walled fracture, the capillary forces play a smaller role than viscous forces, especially at larger fracture apertures and/or higher flow rates and at low saturations of either phase where the interfacial area is relatively small
To examine the relative magnitude of viscous and capillary forces, a capillary number was calculated for each steady-state So value from two-phase flow; Figs. 13 and 14 show the calculated data obtained from drainage and imbibition experiments, respectively

Summary

Introduction

A rock fracture is a planar-shaped void filled with oil, water, gas, and even rock fines. In the context of oil-bearing fractured rock reservoirs, fractures are often highly permeable flow pathways that may dominate fluid flow within the reservoir. The interfaces between the phases evolve and respond to the fracture’s walls and the driving forces that motivate flow, e.g. gravity drainage or pressure drive. For this reason, studies of multiphase flow in fractures are limited and the majority of studies focus on flow in single fractures

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