摘要
为了实现对大裂缝水窜通道的高效封堵，提高低渗透油藏的水驱效果，开展了凝胶颗粒与聚合物本体凝胶联合封堵技术研究。先利用凝胶颗粒将大裂缝通道转变为多孔颗粒介质通道，再利用聚合物本体凝胶封堵颗粒介质间的通道。结果表明：对于开度为1.8 mm的裂缝，凝胶颗粒在粒径为2.5 mm、质量浓度为8 000 mg/L、注入速度为1.0 mL/min的注入参数条件下，可密集均匀地分布在裂缝通道中，并呈活塞式均匀向前推进；当凝胶颗粒充填整条裂缝后，所形成的多孔颗粒介质的渗透率为2 300.0×10-3 μm2。基于裂缝性岩心基质的渗透率，要求优选的聚合物本体凝胶在渗透率为2 300.0×10-3 μm2的多孔颗粒介质中的封堵压力梯度应大于 3.3 MPa/m，从而启动基质中的流体。以此为依据，所需聚合物本体凝胶的强度应大于66 Pa，所用的聚合物本体凝胶的组成为质量浓度4 000 mg/L的HPAM+质量浓度150 mg/L的Cr3+。这一调剖方法在延长油田5088￣3井组取得了较好的增油效果，可以为裂缝性低渗透油藏的可持续高效开发提供技术支撑。
Abstract
In order to efficiently plug the large fracture water channels and enhance oil recovery of the fractured low-permeability reservoirs by water flooding, the combination plugging technology of gel particles and polymer gels is studied. Firstly, the large fracture channel is transformed into a porous particle media channel by using gel particles, and then the polymer gel is used to plug the particle medium channel. The results show that the gel particles can be densely and uniformly distributed in the fracture channel with the aperture of 1.8 mm under the injection parameters of particle size of 2.5 mm, concentration of 8,000 mg/L and flow rate of 1.0 mL/min. Besides, the gel particles advance evenly in a piston-like manner in the fracture channel. When the whole fracture is filled with the gel particles, the permeability of the formed porous particle media is 2,300.0×10-3 μm2. According to permeability of fractured core, the plugging pressure gradient of the preferred polymer gel in the porous media with the permeability of 2,300.0×10-3 μm2 is required to be greater than 3.3 MPa/m so as to start fluid in the matrix. Based on this, the strength of the required polymer gel should be more than 66 Pa and the composition of the used polymer gel is 4,000 mg/L HPAM and 150 mg/L Cr3+. The method of profile control achieved a better effect of oil increasing in 5088-3 well group of Yanchang Oilfield, which can provide a technology support for the sustainable and efficient development of fractured low-permeability reservoirs.
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