石油树脂悬浮体调剖剂性能及其堵水机制

Water plugging mechanism of petroleum resin suspension profile modification and its performance

针对传统冻胶类调剖体系在高温高盐油藏中稳定性差、封堵效率低、无机类调剖剂油水选择性差的问题,采用不同软化点的石油树脂,制备石油树脂悬浮体调剖体系,分别通过物模驱替实验考察该体系对油、水两相的选择性封堵性能,进而通过高温流变性实验和高温高压下的微观形貌分析验证其堵水机制。结果表明:石油树脂悬浮体调剖体系具有良好的油水选择性,对于渗透率大于8μm^2的水层具有较好的封堵性能,封堵率大于80%,而对油层伤害率仅为5.29%;对于级差为3.0的填砂管,随着石油树脂悬浮体注入量的增加高、低渗层的流量比逐渐降低,当注入0.5V_P(V_P为孔隙体积)调剖剂后高、低渗层的分流量比小于1,发生反转;当环境温度大于树脂软化点后,石油树脂转变为牛顿流体,其黏度随着温度的升高而降低,但在150℃下整体黏度仍然大于2.2 Pa·s,石油树脂可以通过吸附在多孔介质表面依靠其黏滞力起到堵水的作用。

The conventional organic gels present poor stability, low plugging efficiency, and weak oil-water selectivity of the inorganic agents in the high-temperature and high-salinity conditions. In this paper, the petroleum resin suspension with different softening points was prepared. And the plugging efficiency and oil-water selectivity were evaluated with core-flooding experiments. Furthermore, the rheological property and the suspension morphology were conducted to investigate the plugging mechanism at high temperature and pressure. The results show that this petroleum resin system has good oil-water selectivity. When the permeability is over 8 μm^2, the plugging efficiency is more than 80% for the water channel, whereas the reservoir formation damage is only 5.29%. For the sand packs with the permeability ratio of 3.0, it is found that the fractional flow ratio of the high permeability layer decreases gradually with injecting the petroleum resin suspension. And the reversal flow is observed after injecting 0.5V_P solutions, since the fractional flow ratio between the high and low permeability layers is below than 1. The petroleum resin changes to Newtonian fluid once the temperature is over than its softening point and the viscosity decreases obviously with higher temperature. However, the viscosity is still over 2.2 Pa·s at 150 ℃. When the temperature is over the softening point, the viscous force could account for the firm adsorption at sand surface, which plays the key role in the plugging process.