Physical simulation of waterflooding development in large-scale fractured-vuggy reservoir considering filling characteristics

Abstract

The Fractured-vuggy reservoir is one of the world's most important reservoir types and has great exploration and development potential. However, due to the unique geological characteristics of the fractured-vuggy reservoir and limited understanding of its waterflooding development law, it is more difficult to develop. To strengthen the study of the oil-water flow mechanism and the waterflooding development law of fractured-vuggy reservoirs, we built a large-scale 3-D physical model that can reflect the geological morphology and structure of typical well groups. On the basis of the similarity theory, we determined the parameters of the model and its physical simulation. The physical model was applied to the experimental study of the waterflooding development process and the analysis of relevant influencing factors. The results show that the low-high mode can effectively touch the reserves in high parts, and the development effect is better than that of the high-low mode. There is an optimal water injection rate in waterflooding development to maximize the recovery. Weak bottom water energy at the bottom of the reservoir plays a positive role in waterflooding development, whereas strong bottom water energy increases the risk of premature water breakthrough, which is not conducive to waterflooding development. The substantial difference in oil and water viscosities makes viscous fingering more obvious, which reduces the stability of the displacement process and reduces the efficiency of waterflooding development. This study may provide strong guidance to further understand the oil-water flow law and improve waterflooding development efficiency for fractured-vuggy reservoirs.