The Study On The Mechanism And The Effect Of Development Of Sewage Polymer Flooding In Class Ⅱ Reservoirs

Compared with major reservoirs, Classâ…¡reservoirs in west to the easr block of north area 1 of Daqing Oilfield have the features with smaller thickness ,lower permeability, limited lateral development scale, significant beterogeneity and shorter development time. It has no accurate forecast on the index of displacement after putting into production of Classâ…¡reservoirs. It is very important for understanding the development law of Classâ…¡reservoirs, especially the oil displacement efficiency made with sewage polymer flooding. Based on physical simulations in laboratory ,compatibility between the Classâ…¡reservoirs and polymer prepared by sewage ( mother fluid made up with clean water and polymer diluted by sewage ) was research, and inaccessible pore volume of ploymer flooding was clear. According to the sthdy of lab experiments and injection-production patterns, the oil displacement efficiency and adaptability of sewage ploymer flooding of Classâ…¡reservoirs were evaluated comprehensively. Experimental results show that the gyration radius of polymer molecule is relatively small and has good compatibility with Classâ…¡reservoirs in simulated sewage system. As long as the reasonable polymer flooding parameters are selected,recovery factor will also be higher. After comprehensive consideration, fresh water prepared polymer is recommended and the diluted polymer solution with produced water of 1500mg/L, the sizes of injected sluges are 1.6PV or so.