Optimization Scheme Design Of Polymer Flooding Of Zhen35-Block In Zhenwu Oilfield

After long-term water-flooding development, Zhen 35 fault block in Jiangsu oilfield has stepped into high water cut stage. Totally speaking, some reasonable adjust distributions, such as transferring to injection of production well, well pattern improvement and layer system subdivision, have improved the development effect significantly. However, in virtue of poor physical property, apparent interlamination and plain difference, serious water breakthrough, as well as restricted formation conditions, most of the producer response in the single direction, and injector producer framework is not reasonable. During high water cut stage in the recent years, these situations above make development effects poor, when oil production rate is within 0.3 to 0.8 percent and oil daily production rate is about 12 to 18 tons per day. The relation curve of water cut and reserve recovery degree shows that it rises in the tendency of serration and slanted line. It can be found that lots of injected water is produced with low efficient by evaluation analysis of water cut, which indicates sufficiently, it can't attain the target of cost and water cut reduction, as well as efficiency and oil production improvement, by traditional adjustment methods of secondary recovery development in the E2d2 Unit of Block Zhen 35, regardless of economically or technologically. Now, present situations of the oilfield apparently cannot meet EOR in the production tail, and sustainable development of it is faced with rigor challenge. A top priority task is to find valid and feasible tap the latent power technologies for recoverable reserves improvement during the stage, and it is necessary to take relevant measures of tertiary recovery for EOR. Polymer flooding is an oil displacement method by injecting high molecular weight and water-soluble polymer into the reservoir. The main mechanisms of polymer flooding to enhance the oil recovery include: viscosifying action, which can improve mobility ratio of oil to water, adjust injection profile, and so enlarge swept volume; changing the viscoelastic property of water-oil interface, which make the oil droplet or oil slug stretch elongation easy, go through the narrow throat with smaller resistance, and so increase the displacement efficiency. Therefore, the injection of high viscosity polymer solution can widen the advancing distance of waterline in the low permeability layer when it breakthrough in the high permeability layer, adjust injection profile, expand swept volume of displacing agent, and so increase the oil recovery.In view of the current exploitation status of Zhen 35 fault block, this thesis analyzed the problems encountered in the development process by studying the reservoir structure and characteristics and evaluating the development effect of water flooding. On the basis of investigating polymer flooding home and abroad, adjustment and deployment of well pattern and evaluation of polymer have been carried out according to the geologic characteristics and development features of E2d2 layer system in Zhen 35 fault block. The producing reserves state and remaining oil distribution rule have been described quantitatively by means of fine modeling and history matching. Moreover, some injection parameters, such as the different slug, concentration, and injection rate of polymer, have been optimized using the chemical flood module of the ECLIPSE software and the optimum scheme was determined.