Research On Fracture-vug Model Improving Water Flooding Methods Based On 3D Printing

At present,the development level of carbonate fracture-vug reservoirs is still low,Due to the complex structure of the reservoir,the water flooding efficiency is relatively low.It is urgent to carry out experimental research on improving the water flooding methods for different types of remaining oil to meet the requirements of enhancing oil recovery.Therefore,the experimentals were carried on improving the water flooding method for the remaining oil after water flooding in a typical fracture-vug combination model.The paper is based on the investigation of physical simulation experiments and mine practices in fracture-vug reservoirs at home and abroad.Combined with the actual geological conditions of Tahe Oilfield,the data modeling method was used to solve the problem of establishing a three-dimensional fracture-vug reservoir model based on the geologic model coordinates of the Tahe Oilfield.A typical fracture vug model was preferred for 3D printing to produce filled and unfilled models.And the testing technology of non-visual 3D model was improved.Then,the physical simulation experiment of water flooding was carried using the model,and different waterflooding measures were proposed for different types of residual oil.Research results indicate,(1)Attic oil is mainly controlled by the shape of the fracture vug.For the inter-well attic oil that is not filled with karst holes,the water injection reversal can only displace the attic oil around the injection well.The attic oil between the wells can be displace by the gas injection method.Changing the water injection intensity has little effect on the remaining oil.(2)For the refilling of the filling cave,the inversion oil around the injection well can be used,and the effect on the attic oil in the well is still poor.As the number of reversal injections increases,the amount of remaining oil between wells decreases.(3)To the joint hole with poor connectivity,changing the intensity of water injection,increasing the flow rate in the horizontal direction can effectively increase the degree of recovery.However,it is not conducive to the gravity difference of the oil and water in the longitudinal direction,and it is easy to cause more residual oil to be formed in the longitudinal direction;(4)For the reversal of injection and production,the injection reversal effect is better at the moment of seeing the water.The first injection reversal has the better effect on improving the recovery degree,and the subsequent effect is weakened.However,there is still a certain inter-well attic oil between the injection and reversal.(5)Besides,the periodic water method can improve the oil washing efficiency,and can effectively reduce the residual oil saturation in the filling medium.The periodic water injection method improves the recovery degree slightly better than the variable strength water injection.