Visual physical simulation experiment on the water production laws of fractured-vuggy carbonate reservoirs

In order to make a profound study on the water production laws in the reservoirs of fractured-vuggy carbonate oil reservoirs, this paper designed and built up the visual physical model for three kinds of typical reservoirs, i.e., fractured reservoir, vuggy reservoir and fractured-vuggy reservoir. Then, water production laws at different fracture (width) ranges, water injection rates, oil saturations and fracture/vug dips were investigated, and the types and distribution characteristics of residual oil after the displacement were analyzed. It is experimentally indicated that as for fractured reservoirs, when the fracture range is 1, 4 and 16, the higher the range is, the sooner the water production at the end is and the higher the recovery factor is under a certain condition. As for multi-connection fractured-vuggy reservoirs, when the injection rate is 0.01, 0.1 and 0.5 mL/min, the recovery factor presents the trend of increasing firstly and then decreasing with the increase of water injection rate. What’s more, the higher the oil saturation in the swept area is, the higher the ultimate recovery factor is. As for tightly filled vuggy reservoirs, gravity segregation plays an important role in the flowing of oil and water. As the fracture/vug dip rises gradually from 0° to 45° and 90°, the recovery factor increases gradually. The experimental research results are theoretically and practically significant to guide the development of fractured-vuggy reservoirs, the water control of oil wells and the potential tapping of residual oil.