双河油田欠注井注聚堵塞研究

Research of clogging in polymer injection wells of Shuanghe Oilfield

关键词:  注聚井  注入特征  注入参数  堵塞程度  双河油田 

Key words:  polymer injection well  injection characteristics  injection parameter  plugging degree  Shuanghe Oilfield

摘要:

根据双河油田北块Ⅳ1-3层系注聚井欠注和注入压力过高的状况,开展了聚合物注入特征的研究,其中包括聚驱过程中的注入速度、浓度、压力梯度、岩心渗透率和溶液黏度对注入性的影响。实验表明,注聚浓度对注入性的影响最大,注入速度对注入性的影响最小。渗透率对聚合物的注入性以及在储层中的传播能力均会产生影响,当岩心渗透率<0.8 μm²时,机械捕集和吸附共同作用,岩心后部堵塞程度大于前部；当岩心渗透率>0.8 μm²,聚合物溶液会进入到岩心深部,只有吸附发生作用,导致孔喉轻微堵塞。同时在注聚实验中岩样后部的压力梯度达到了最大值,说明在后部产生了堵塞。在现场实施聚合物浓度调节后,发现油田现场欠注下降率最大达到35%,说明可以有效改善注聚井注入性,是实现提压增注的有利途径。 

Abstract:

According to the short of injection volume and high injection pressure in polymer injection block of Shuanghe Oilfield, the characteristics of the polymer injection such as injection speed, the pressure gradient, polymer concentration, the core permeability, as well as the effect of polymer viscosity on injection properties were studied. The experimental results showed that the polymer injection concentration was the most influential factor, and the injection rate was the least one. Rock permeability affected the injection of polymer solutions and propagation in the formation. When core permeability was less than 0.8 μm², the rear plugging was greater than the front because of the combined action of mechanical trapping and adsorption. With the core permeability increased (> 0.8 μm²), polymer solution could be injected further and the plugging mechanism was only adsorption of polymers, which caused minor blockage. At the same time, the pressure gradient at the rear of the core in the polymer flooding was the highest, which indicated that the blocking part mainly occurred in the posterior part of the core. After adjusting the polymer concentration in the field, it was found that the maximum drop rate of the short of injection volume is 35%, which showed that the injection properties of polymer injection wells could be improved effectively. It is a favorable way to increase the pressure and increase the injection.