BZ19-6低渗透储层反凝析污染及解除方法实验研究

Retrograde condensation pollution and removal method of BZ19-6 low permeability reservoir

BZ19-6凝析气田储量大、地露压差小、储层高温高压且低孔低渗,生产作业过程中极易产生反凝析污染。评价反凝析污染程度,采用合适的污染解除措施,对改善BZ19-6凝析气田反凝析污染具有重要意义。利用复配凝析气开展长岩心衰竭实验,模拟反凝析油污染,测试不同衰竭压力点对应的气相渗透率并评价反凝析污染程度;同时开展了注活性剂(TC281)、注甲醇、注甲醇+活性剂3组解除反凝析污染实验,及注甲醇+活性剂1组解除反凝析+水锁综合液相污染实验。实验结果表明:注活性剂(TC281)、注甲醇、注甲醇+活性剂3种方案对解除反凝析污染均有一定效果,注甲醇+活性剂1组解除反凝析污染效果最好,渗透率恢复率达84%;注甲醇解除反凝析污染渗透率恢复率为81%;注活性剂1组解除反凝析渗透率恢复率为54%;注甲醇+活性剂1组解除反凝析+水锁综合液相污染,渗透率恢复率达到80%。实验为BZ19-6凝析气田解除反凝析污染提供了方案指导。

The BZ19-6 condensate gas field,characterized by large reserves,small surface pressure differential,high temperature and pressure reservoir conditions,and low porosity and permeability,is highly susceptible to retrograde condensation contamination during production operations.Evaluating the degree of retrograde condensation contamination and adopting appropriate contamination remediation measures are crucial for improving the situation in the BZ19-6 condensate gas field.The long core failure experiment was carried out using the mixed condensate gas to simulate the reverse condensate pollution,test the gas permeability corresponding to different exhaustion pressure points and evaluate the degree of reverse condensate pollution.Additionally,experiments on remediation of retrograde condensation contamination were carried out using three different approaches:injection of surfactant(TC281),injection of methanol,and injection of a combination of methanol and surfactant.Furthermore,an experiment was conducted using a combination of methanol and surfactant to address both retrograde condensation and water blockage,a comprehensive liquid phase contamination.The experimental results indicate that all three schemes of injecting active agent(TC281),injecting methanol and injecting methanol+active agent have certain effects on removing retrograde condensation pollution.The group of injecting methanol+active agent 1 has the best effect on removing retrograde condensation and removing retrograde condensation pollution,and the permeability recovery rate is 84%.The permeability recovery rate of methanol injection to remove retrograde condensation pollution is 81%.The recovery rate of retrograde condensate permeability in the surfactant injection group 1 was 54%.The injection of methanol+active agent 1 relieved the comprehensive liquid phase pollution of reverse condensation+water lock,and the permeability recovery rate reached 80%.These experiments provide guidance for remediation strategies to address retrograde condensation contamination in the BZ19-6 condensate gas field.