Experiments on nitrogen assisted gravity drainage in fractured-vuggy reservoirs

WANG Jing,JI Zemin,LIU Huiqing,HUANG Yitao,WANG Yishuang,PU Yulong

Table 3 Types of remaining oil and formation mechanisms.

Types of remaining oil Existence form Formation mechanism Type A The blind end of vug and fracture connected to low- angle fractures, and the blind end of lower vugs Poor connectivity between fractures and vugs and poor gravity difference Type B The bottom of fracture-vug connected point Poor gravity difference Type C Below the location of the production well connected with reservoir Relationship between the production well position and reservoir Type D Small-aperture and low-angle fractures Flow resistance is higher or close to gas-oil gravity difference