Study On Well Pattern Reconstruction And Enhanced Oil Recovery By Chemical Flooding After Polymer Flooding In The Type ? Oil Layer Of X Block

Most of the oil fields show high water content,severe development of dominant seepage channels and fragmented distribution of residual oil after polymer drive,and the extraction of this residual oil has been a key research topic in the oil industry.After more than 50 years of development,the X block of Daqing oilfield has reached the end of polymer drive development,and the current integrated water content is 98.61%,so there is no big difference in the effect of continuing to use polymer drive development.Therefore,it is necessary to clarify the characteristics of the remaining oil distribution in the reservoir and identify which parts of the formation form the dominant seepage channels,so as to provide a theoretical basis for the formulation of countermeasures to tap the remaining oil after aggregation and drive and to solve the actual production problems in the oilfield.In this paper,a geological model and a numerical simulation model of the X Block were established,and the fitting of the geological reserves,fluid production,water content and degree of recovery of the block were completed.The characteristics of the residual oil distribution at different sedimentary phases in the plane,different sedimentary units in the longitudinal direction and the main diversion line after aggregation and drive in the block are clarified,and a total of six types of residual oil are classified as imperfect injection and extraction,planar disturbance,inter-stratigraphic disturbance,top of thick formation,stagnant zone and residual oil,and each type of residual oil is quantified.At the same time,the relative permeability curves were applied in accordance with the actual field practice and combined with the cumulative probability method to classify all oil wells with water saturation values into five classes: Class I,Class II,Class III,Class IV and Class V.In addition,static reservoir parameters such as permeability,permeability protrusion coefficient,permeability variation coefficient and effective thickness,and dynamic development parameters such as specific water absorption intensity,specific fluid production intensity and injection water seepage rate after poly-drive are introduced to classify the grading criteria of each evaluation index parameter according to the water saturation limits of different water flooding levels and the principle of main diagonal predominance,so as to accurately identify the water flooding conditions in the block.On the basis of a comprehensive understanding of the oil and water distribution within the formation,three well network reconfiguration schemes and five chemical drive drive systems were designed in conjunction with the actual reservoir conditions in the block,and the predicted effectiveness of the schemes was carried out.The results show that the best economic benefit is achieved by using 133 m well spacing of the encrypted area well network combined with weak alkaline ternary composite drive in the X Block,and the predicted recovery rate is increased by 8.29% after agglomeration drive.