柔性转向剂性能及作用机理研究

为了遏制水驱油藏注入水通过高渗透部位时出现无效循环,研制了柔性转向剂(代号SR-3),用于改变油藏中水的流场及实现深部液流转向。这种柔性转向剂可随机发生形变,具有韧性好、不易破碎和断裂以及化学稳定性高的特点。室内物理模拟显示:SR-3转向剂能在地层高渗透率区大孔道中运移,可实现沿程调剖,SR-3在地层"大孔道"中流动遇阻时发生形变并产生堵塞压力。随压力的升高,SR-3蠕变并出现突破压力,然后又降至流动压力并趋于平衡;再遇阻又发生形变并产生堵塞,如此反复地在地层深部产生动态堵塞。大庆油田东部萨尔图和葡萄花油层的柔性转向剂现场试验验证了此机理,也说明了无裂缝砂岩油藏经长期注水开发,在水驱主流道可能冲刷出了大孔道高渗透带。对这些大孔道进行沿程堵塞,可以大幅度地改善水驱波及系数。

Characteristics and action mechanism of the flexible agent applied in fluid diversion of reservoirs

In order to restrict injection water flowing through high permeability zones and improve fluid flow field in water flooding reservoirs, a kind of flexibile agent SR-3 was developed for getting diversion of deep flooding fluid. The SR-3 with high chemical sta bility and good toughness could be deformed randomly. The physical simulation in laboratory showed that the SR-3 could migrate through channels in high-permeability zones, which resulted in profile control along the track of the SR-3 particles. The SR-3 flowing in the channels of high permeability zone can be deformed and produce a plugging pressure when it meets pore throat. The SR-3 will creep through the channels as the flow pressure increases to a breakthrough point, then it flows towards a balance with pressure drop. Afterwards, the SR-3 particles will repeat similar processes along the channels in high permeability zones, which results in a dynamic plugging in deep reservoir. A pilot test of the flexible agent injected into an oil layer in the east part of Daqing Oilfield validated above mechanism and also demonstrated that the channels and high permeability zones were produced along the primary route with long period water flooding in fissureless sandstone reservoirs. The sweep efficiency of water flooding can be improved greatly if the dynamic plugging happens along the channels.