陕北旦八油区注水井堵塞原因分析及治理措施

Cause Analysis and Treatment Measures of Water Injection Well Plugging in Danba Oilfield,Northern Shaanxi

为了解决旦八油区长6储层部分注水井注水压力高、注水不够的问题,通过对该储层注入水和地层水水质分析,研究注入水与地层水配伍性及固相颗粒和乳化油对储层渗透率的伤害,分析注水井堵塞原因,提出负压返吐的解堵方法并进行室内研究与现场试验。结果表明:该储层注入水和地层水都属于CaCl_2水型,注入水矿化度(27 226. 73 mg/L)高于储层临界矿化度(3 556. 54 mg/L),不会引起储层水敏伤害。注入水与地层水混合后存在较强的CaCO_3结垢趋势。固相颗粒存在侵入伤害和外滤饼堵塞伤害。乳化油伤害主要以注入端面堵塞为主。负压返吐解堵方法能够使岩心渗透率恢复至原始的73. 81%,并且现场试验效果良好。

In order to solve the problems of high water injection pressure and insufficient water injection amount in Chang 6 reservoir of Danba Oilfield, the damage of the compatibility between injected water and formation water, solid particles and emulsified oil to reservoir permeability were studied by analyzing the quality of injected water and formation water. The negative pressure plugging removal method is put forward by analyzing the plugging reasons of injection wells, and corresponding laboratory experiments and field tests were carried out. The results show that the injected water and formation water are all Gag12 type water,and the salinity（27 226.73 mg/L） of injected water is higher than the critical salinity（ 3 556.54 mg/L） of the reservoir, which does not lead to the water sensitive damage of the reservoir. There is a strong CaCO3 scaling tendency after the injected water is mixed with the formation water. There are invasive damage and cake plugging damage of solid particles. The damage of emulsified oil is mainly the plugging of injection end surface. The negative pressure plugging removal method can make core permeability restore 73.81% ,and the field test results are good.