3-D Visual Experiments on Fluid Flow Behavior of Water Flooding and Gas Flooding in Fractured-Vuggy Carbonate Reservoir

Abstract

Abstract Tahe oilfield is one of the most important fractured-vuggy carbonate oilfields in China. The characteristics of this kind of reservoir are greatly complex due to its multiple flow units: matrix, fractures and vugs. The main problems during development include the complicated oil-water relationship and the lack of fluid flow mechanism etc. However, one- and two-dimensional physical models due to its limitations cannot overall reflect fluid flow status. Based on Tahe oil field geological conditions, a 3-D visual fractured-vuggy physical model was designed and fabricated according to similarity criterion. Bottom water drive, water flooding and gas flooding were conducted in this model. Multiphase flow behavior was recorded by high resolution camera system and the pressure response was monitored at different oil displacement stages. Finally, the effect of different energy complement methods was discussed. Experimental results show that the 3-D visual physical model can be used to systematically and comprehensively investigate the fluid flow status and the oil displacement process. The pressure response presented different characteristics at different flooding stages. The fractured-vuggy structure and the ratio of displacement force and gravity determine the water/gas flooding behavior. The fluid flow mechanisms were discussed combining the pressure response and dynamic displacement phenomenon. Regarding displacement effect, water breakthrough and even serious water channeling occur more easily in fracture well than vuggy well. And water cut increases dramatically in fracture well. Compared to one- and two-dimensional physical models in previous studies, the 3-D visual physical model proposed here is more representative of the real reservoir conditions. This study could provide a constructive guide for the fractured-vuggy carbonate reservoir to improve production performance.