Permeability prediction in digital core with curved fractures based on combined plate model

Key words:  carbonate rock  digital core  micro-fracture system  fracture dip  fracture opening  absolute permeability

Abstract:

It is difficult to simulate the fluid flow in micro-fracture system because of the sophisticated characteristics of the fractures in carbonate reservoirs. A method was developed to predict the absolute permeability of carbonate rock samples using a digital or numerical rock technique, in which curved fractures were considered. Firstly, a numerical simulation model of fluid flow in a system with flat fractures was established, and the effects of its basic parameters (i.e. fracture dip and fracture opening) on the flow behavior were determined using a lattice-Boltzmann method. Secondly, the absolute permeability of curved fractures was predicted based on the combination of fluid low in the flat model and the basic characteristics of a curved fracture system. Experimental work was also conducted to prove the accuracy of the numerical method. The results show that this method is accurate and effective. The absolute permeability can be directly predicted when the fracture parameters are identified, and the calculation efficiency is improved.