江苏油田中高渗油藏聚合物驱聚合物适应性研究

Adaptability of EOR Polymers to Sandstone Reservoirs of Intermediate to High Permeability in Jiangsu Oil Fields

实验研究了聚合物对江苏油田中高渗砂岩油藏的适应性。实测了油藏温度下（70℃）相对分子质量M不同的6种聚合物，在矿化度20g／L的模拟油田地层水中的分子线团均方根回旋半径，根据文献发表的渗透率比～孔隙半径中值R50关系，由这些回旋半径值判定，Ka=0．1时的岩心不会被M≤3．5×10^7的聚合物所堵塞。在Ka为0．125-1．026μm^2的储层岩心上，考察了M为3．5×10^7、3．0×10^7、1．9×10^7，浓度为0．6、0．8、1．0、1．2g／L的聚合物溶液的注入压力～注入体积关系，在所有情况下注入压力都能达到稳定，M越高、浓度越大、渗透率越低，则注入压力越高，注入压力达到稳定值所注入体积越大，因此所用聚合物均不堵塞Kμ≥0．125时的岩心。在含有Ka=0．15、0．25和0．40时的三小层的人造平板非均质岩心上，在水驱至含水90％后注入M=3．5×107、浓度1．0g／L的聚合物溶液整体段塞0．38PV，采收率增加16．7％；维持此聚合物用量（380PV·mg／L）而采用浓度递增或递减的三个段塞注入，则采收率增加幅度升至17．2％或降至15．8％；当注入时机由含水98％逐步降至含水0％（不水驱）时，最终采收率从60．0％逐步升至70．5％。图4表4参10。

The adaptability of EOR polymers to sandstone reservoirs of intermediate to high permeability in Jiangsu oilfields is studied experimentally. For 6 commercial polymers of various molar mass, M, the mot mean square values of radius of gyration in a simulation formation water of TSD=20 g/L are determined at 70℃ and, based on these values and a core permeability, K, vz throat ra- dius median, R50, relationship published where else, it is concluded that a core of Ka = 0.1μm^2 should not be plugged by a polymer of M≤3.5 × 10^7 in solution. In polymer injection experiments on reservoir cores of Ka 0.125-1. 026 μm^2, the changes in injecting pressure （IP） with injected volume （IV） are investigated for 0.6, 0.8, 1.0, and 1.2 g/L solution of polymers of M = 3.5 × 10^7, 3.0× 10^7, and 1.9× 10^7, respectively, and it is shown that the IP reaches an equilibrium （E） sooner or later in all cases and the higher the M value, the higher the polymer concentration and the lower the core permeability, the higher the IP value and the IV needed for IP to reach its E, therefor all these polymer used would not plug cores of Ka≥0. 125 μm^2. On artificial platelike heterogeneous sandstone cores with three sublayers of Ka = 0.15, 0.25, and 0.40μm^2, respectively, after water flooding to 90% watercut, injecting 1.0 g/L solution of polymer of M = 3.5 × 10^7 in a single slug 0.38 PV in size results in enhancement in oil recovery （EiOR） of 18.7% ; the EiOR is increased to 17.2% or decreased to 15.8% when the polymer solution injected in three separate slugs of increasing or decreasing concentration at equal polymer use level of 380 PV·mg/L; the extreme oil recovery is increased gradually from 60.0% to 70.5% when polymer injection started at watercut lowered from 98% to 0%.