一种新型深部调驱用无机复合转向剂的研制及性能评价

Preparation and properties of in-situ inorganic composite gel system for deep profile control

关键词:  IGS  成胶性能  乳液聚合物  配方优化  封堵性能

Key words:  inorganic gel system (IGS)  gelling property  emulsion polymer  formulation optimization  plugging performance

摘要:

针对海上油田非均质性较强、矿化度高及“低油价调驱”的需求,结合仪器测试和机理分析方法,研究了无机复合转向剂(IGS)的制备思路、成胶特征和封堵性能。结果 表明,液体硅酸钠质量分数为0.4 %～3.0%,液体硅酸钠溶液与渤海油田高矿化度区块注入水中的钙镁离子自发反应,可生成悬浮在水中的无机IGS转向剂。该体系为液体体系,强度可控,可实现在线注入,具有快速溶解、耐温、抗盐、环保、廉价等特点。配合使用低浓度的乳液聚合物体系(500 mg/L)及0.1%(w)的屏蔽剂,形成的无机复合体系可进一步增强体系的黏度和强度。岩心封堵性实验表明,IGS+乳液聚合物体系能够大幅度增加流动阻力,岩心各长度区间封堵率为24.73%～70.38%,表现出良好的深部液流转向能力,在海上及其他作业空间受限的高矿化度油田具有应用推广价值。

Abstract:

Aiming at the needs of stronger heterogeneity, high salinity and low oil price for offshore oilfields, this paper uses experimental measurements and mechanism analyses to study the preparation, gelling characteristics, and plugging effects of inorganic gel system (IGS). The results show that when the liquid sodium silicate is between 0.4% and 3%, after being injected into the Bohai formation, the agent reacts with Ca²⁺ and Mg²⁺ in the formation water, and forms inorganic silicate gel with a density approximating to formation water. The agent is a kind of liquid system, which the strength is controllable and can be injected online. The new agent features fast solution, temperature resistance, salt resistance, environmental friendly, and cost-effective. When low concentrations of liquid polymer (500 mg/L) and chelating agents (0.1%) are added, a more strengthened inorganic composite gel system is obtained and it can further improve the viscosity and strength of system. Results of the core flooding experiment show that IGS+ emulsion polymer system can significantly improve the flow resistance. The plugging efficiency is between 24.73%～70.38%, showing a good deep profile control ability. This study might be practical to apply the new agent in high salinity offshore oilfield.