注水对沙20东储层损害机理综合研究

Comprehensive research on mechanism of Sha-20 East reservoir damage by water injection

利用储层岩矿分析、岩石物性测定、室内岩心模拟实验评价等方法,结合注入水的流体性质、水质指标、矿场注水工艺、注入压力等参数,综合分析了沙20东阜宁组(E1f)储层损害机理与规律。研究结果表明:水敏性损害为清水不能正常注水的根本原因;注入水水质不达标是造成储层损害的关键因素之一;污水与地层水混合易结钙质垢,是污水造成储层损害的另一关键因素。针对性地提出了降压增注措施和建议,部分措施已经在矿场上得到了成功应用。

The mechanism and the law of reservoir damage in Funing formation (E1f) of Sha-20 East are comprehensively analyzed by means of rock and mineral analysis, petrophysical measurement, and laboratory core simulation and evaluations, etc., combining with parameters of injection water property, water quality index (WQI), field water injection technology and injection pressure. The result of this research demonstrates that water sensitivity damage is the fundamental cause that fresh water can’t be injected normally; the quality of injected produced water is out of standard is one of the key factors causing reservoir damage; the mixing of produced water and formation water tends to produce calcic scale, being another key factor of causing reservoir damage. Measures for reducing pressure and increasing injection are presented and some have been successfully applied in the field.