Preliminary simulation of flow patterns in single fissure-cavern system

A great many solution caves developed in the Ordovician carbonate reservoir of Tahe Oilfield,with their maximal diameter reaching tens of meters each.So oil reserves in the caves is huge and it is important to probe into the flow pattern of the fluid in caves.Laboratory trace experiment is conducted first to research the change of the flow pattern in caves as the fluid velocity increases during the displacement of water with water and the process of waterflooding.Then the streamline distribution of single-phase displacement is studied on the basis of numerical simulation,with an aim to obtain a preliminary cognition of the regular pattern of flow in caves.Results show that,for single-phase displacement under high velocity,jet will occur in caves,which will increase the fluid flow loss,however,for two-phase displacement(displacement of oil with water),jet will not appear even under high velocity due to the viscous force of oil.But the displacement efficiency will be low.Therefore,proper flooding rates need to be selected to adapt to different oil viscosity.