低盐水配制酚醛树脂冻胶在高盐水中的稳定性

Sability of phenolic resin gel prepared with low salt water in high salt water

关键词:  冻胶  水溶性酚醛树脂  AM-AMPS聚合物  高温高盐油藏  脱水收缩 

Key words:  gel  water-soluble phenolic resin  AM-AMPS polymer  high temperature and high salt reservoir  dehydration shrinkage

摘要:

目的 塔河碳酸盐岩油藏地层温度高(110 ℃以上)、地层水盐质量浓度高(22×10⁴ mg/L,其中,钙镁离子近2×10⁴ mg/L)。针对塔河油田高温、高盐的苛刻油藏条件,现有堵剂选择性单一,封堵时间较短,需研发新类型堵剂进行封堵。方法 设计在低盐含量模拟注入水中,以AM-AMPS共聚物为成胶剂,以水溶性酚醛树脂为交联剂,加入纳米SiO₂做稳定剂配制成胶液,测定成胶时间和冻胶强度,并将130 ℃形成的冻胶老化3天后放于高盐含量模拟水浸泡,考查其长期稳定性。另外,为探索冻胶的稳定性和脱水收缩机理,将在高盐含量水中老化前后的冻胶逐级脱水并干燥后进行了SEM和IR、XPS分析。结果 在相同的交联剂与聚合物用量下,增加纳米SiO₂的含量,冻胶稳定性增加,可在高盐含量模拟水中保持60天脱水率低于10%；脱水程度随交联剂质量分数的增加而降低。冻胶在高盐水中浸泡后,由于伯酰胺的水解及其生成的羧酸根与地层水中钙镁离子的交联作用,冻胶网格变密,储能模量增加。结论 在低盐水中制备的AM-AMPS40-水溶性酚醛树脂满足塔河油田堵水的要求,该结果可为高温高盐油藏用堵剂选择提供指导。 

Abstract:

Objective Tahe carbonate reservoir has high formation temperature (above 110 ℃) and high salt mass concentration of formation water (up to 22×10⁴ mg/L, in which calcium and magnesium ions are nearly 2×10⁴ mg/L). In view of the harsh reservoir conditions of high temperature and high salinity in Tahe oilfield, the existing plugging agent has single selectivity and short plugging time, a new type of plugging agent needs to be developed for plugging. Methods In this study, the glue solution in simulated injection water with low salt content was prepared, using AM-AMPS copolymer as the glue agent, using water-soluble phenolic resin as the crosslinking agent, and adding Nano silica as the stabilizer. The gel forming time and gel strength were measured, and soaked the gel formed at 130 ℃ in simulated water with high salt content after aging for 3 days to investigate its long-term stability. In addition, in order to explore the mechanism of gel stability and dehydration shrinkage, the gel before and after aging in high salt content water was dehydrated step by step and dried for SEM, IR and XPS analysis. Results It was found that with the same amount of crosslinking agent and polymer, the stability of the gel was increased by increasing the content of nano silica and the dehydration rate was less than 10% in the simulated water with high salt content for 60 days. The degree of dehydration decreased with the increase of mass fraction of crosslinking agent. After the gel was soaked in high salt water, due to the hydrolysis of primary amide and the cross-linking of carboxylate radical generated from primary amide with calcium and magnesium ions in formation water, the gel grid became denser and the storage modulus increased. Conclusion sAM-AMPS40 water-soluble phenolic resin prepared in low salt water can meet the water plugging requirement of Tahe oilfield. The results can provide guidance of the selection of plugging agents for high temperature and high salinity reservoirs.