Experimental Study of Pore-Scale Water Flooding with Phase Change Based on a Microfluidic Model in Volatile Carbonate Reservoirs

Carbonate reservoirs usually have strong heterogeneity, with complex pore structure and well-developed natural fractures. During reservoir development, when the formation pressure is lower than bubble point of crude oil, fluid undergoes phase change degassing. This leads to subsequent waterflooding displacement under oil–gas two-phase condition, also followed by a secondary oil gas caused increase in pressure. In this paper, glass etching model used carry out microfluidic experiments. The porous carbonate fractured are designed simulate process depletion development development. it can be observed that degassing occurrence areas order large throat area first, small area. And as follows: fractures, and, finally, converting early stage replacement reflects obvious characteristic “displace but not gas”; replenishment energy, redissolution expands from mainstream other areas, mobilization increases. characteristics water flow different stages pore-fracture clarified, migration distribution condition coexisting flooding after explored, mechanism volatile levels revealed.