三元复合驱硅酸盐垢的影响因素及结垢机理研究

Research on Influencing Factors and Mechanism of Silica Scale in ASP Flooding

在三元复合驱驱油过程中,碱剂使地层及采出系统中形成硅酸盐垢,不仅对地层造成伤害,还给生产带来不便。本文模拟现场采出液,研究了单一硅体系、钙/镁/硅共存体系、钙/镁/铝/硅共存体系、钙/镁/硅/聚丙烯酰胺体系等4个体系,得到相应的硅结垢相图。结果表明:硅结垢的形态和过程受其他离子影响,在所考察范围内,温度越低,pH值越低,硅越易成垢;硅酸盐垢吸附在碳酸盐垢表面上,形成混合垢;铝离子与硅形成硅铝酸盐;聚丙烯酰胺将碳酸盐和硅酸盐缠绕在其内部,共同聚沉。

During the alkaline-surfactant-polymer（ASP） flooding,the alkaline led to silica scaling in the reservoir and produced system,which did great harm to the formation and brought the inconvenience for the production.The four produced liquids simulated in laboratory were experimented including the single-silicon solution;Ca2 ＋,Mg2 ＋ and silicon co-existing solution;Ca2 ＋,Mg2 ＋,Al3 ＋ and silicon co-existing solution;Ca2 ＋,Mg2 ＋,polyacrylamide and silicon co-existing solution.The phase diagram of silicon-ion scaling was obtained under the different conditions.The results showed that,the ions had serious influences on the structures of scale and scaling process.In the range of the study,the lower the temperature,the lower pH,the more the silica is easily to form scale.Silicate scale was absorbed in the surface of carbonate scale,resulting in the formation of mixing scale.Aluminum ions reacted with silicon to form aluminosilicate;carbonate and silicate were wrapped by polyacrylamide molecules,in the end,they coagulated together.