The Research on Characterization Method of Salting Out Damage by Water Flooding in High Salt Reservoir

In this paper, the mechanism of water flooding development in high salinity reservoirs is preliminarily recognized by comparing the changes of core permeability under different formation water salinity and pressure. In the process of experiment, the water cut of core keeps rising. We analyzed the change of core permeability under different pressures and water cut, then preliminarily judged the salting out time of water flooding in high salt reservoirs. On the basis of the study on the retention rate of core permeability and the time of salting out, the relationship between the reservoir formation pressure and the retention rate of reservoir permeability is formed. Based on this achievement, we can effectively quantify the damage caused by the salting out to the reservoir permeability. Applying the numerical simulation method, the results are applied to the oilfield development process. The dynamic characterization of salting out to reservoir permeability damage is realized. The results show that the higher formation water salinity, the lower permeability retention after the salting out of the reservoir on the premise of the same reservoir permeability. On the premise of the same formation water salinity, the higher reservoir permeability, the higher permeability retention rate after salting out. For the same core, the lower the displacement pressure, the earlier the salting out time appeared. Then the final permeability retention rate will be lower. Under the same displacement pressure, permeability is positively correlated with permeability retention rate. Through the verification of oil field, it is found that the prediction results of the salting out damage characterization method in this paper are very close to the actual situation. Through using this method, the dynamic characterization of the reservoir by permeability damage is realized for the first time. This study will have a certain guiding significance for the rational development of high salt reservoirs.