| As the fractured-vuggy carbonate reservoir in Tahe oilfield has entered the stage of high water cut,the oil well water is fast and the recovery rate is low.Gas injection can effectively enhance oil recovery.However,because of the diversity and discontinuous distribution of the reservoir space in the fractured reservoir,the law of gas injection and the distribution of the remaining oil are unclear.This paper based on the analysis of vuggy reservoir geological characteristics and dynamic production data of joint Tahe oilfield,with the actual reservoir seismic attribute data as the basis,using 3D modeling method to design three typical joint physical structure model and carry out gas injection experiment to research the influencing factors of gas injection and the distribution characteristics of remaining oil.The study shows that for fractured-vuggy reservoir,high injection and low production of gas injection flooding effect is better than the low high seam mining;mining hole injection flooding has good hole injection seam mining;for fractured reservoirs,increasing gas injection rate is conducive to overcome the crack resistance and increase the range of wave;recovery degree is slightly larger than the constant speed gas injection method using intermittent gas injection method.Using the three-dimensional model of karst experiment shows that,with small displacement and multi round development of karst model is sufficient;gas injection rate has an optimal value of the gas drive efficiency is the highest and the best the gas injection rate is 5ml/min;gas water mixed injection injection the recovery degree is highest,followed by intermittent gas injection mode and constant gas injection method.The use of three-dimensional fractured well group model of gas injection displacement experiment,experimental results show that the irregular well pattern mining well pattern is greater than the cross distribution;different cave relations have great influence on the gas displacement effect on the hole seam type connection is most conducive to gas injection flooding,seam hole cracks with karst transverse connection,the connection of fracture and cave cave is oil recovery level of key factors relative position.Three different types of joint physical model of structure was carried out before and after the experimental study of gas flooding remaining oil distribution based on reveals different cave structure before and after gas flooding remaining oil distribution,and analyzes the factors affecting the distribution of remainin g oil,experiments show that the gas injection wells position on the remaining oil distribution has great influence;connected mode of different sewing hole is an important factor affecting the distribution of remaining oil;The local high part of the karst cave and the extension hole of the side wall are the main areas of residual oil enrichment.The results of the paper provide some reference for the development of gas flooding oil flooding in fractured reservoir. |
