某油田不同来源采出水回注处理工艺技术研究与优化

Research and optimization of re-injection treatment technology of produced water from different sources in an oilfield

针对某油田采出水处理设备和注水管道中存在的结垢严重问题,为提高回注水质达标率,满足国家安全环保的相关要求。利用Scale Chem结垢预测软件对不同来源采出水中的成垢离子进行调和,定量测算结垢类型和结垢量,结合室内实验和现场验证对阻垢剂、絮凝剂进行工艺优化,最后进行水质评价。结果表明,混合水样结垢量随注水井筒深度的增加而减少,在近井口地带的结垢量最大;混合水样在水处理设备中的结垢类型为CaCO_(3)、BaSO_(4)、SrCO_(3),温度超过40℃时,CaCO_(3)的结垢量快速上升至672 mg/L;复配阻垢剂(ATMP∶TPA=2∶1)总浓度为40 mg/L时,阻垢效果最好;PAC为90 mg/L、PAM为1 mg/L,搅拌时间6 min、加药间隔30 s时,絮凝效果最好;处理工艺优化后水质得到较大改善,满足SY/T 5329—2016中关于二级回注水质指标的要求。研究结果可为同类水处理工艺的优化提供实际参考。

In view of the serious scaling problems existing in the produced water treatment equipment and injection pipeline of an oilfield,in order to improve the water quality standard rate and to meet the relevant requirements of national safety and environmental protection,the Scale Chem scaling prediction software is used to reconcile the scale ions in the produced water from different sources,and the scaling types and amounts are quantitatively measured.What's more,the scale inhibitors and flocculating agent are optimized by combining laboratory experiments and field verification,and the water quality is evaluated at last.The results show that the scaling amount of mixed water samples is decreased with the increasing depth of injection wellbore.In particularly,the scaling amount is the largest near the wellhead.The scaling types of mixed water samples in water treatment equipment are CaCO_(3),BaSO_(4)and SrCO_(3).When the temperature exceeds 40℃,the scaling amount of CaCO_(3)will be rapidly increased to 672 mg/L.When ATMP∶TPA=2∶1 and the total concentration is 40 mg/L,the scale inhibition effect is the best.When PAC is 90 mg/L,PAM is 1 mg/L,stirring time is 6 min and dosing interval is 30 seconds,the flocculation effect is the best.After the optimization of the treatment process,the water quality has been greatly improved and met the requirements of SY/T 5329—2016 on the water quality index of secondary re-injection.Most importantly,the research results can be provided practical reference for the optimization of similar water treatment process.