延长油田污水处理工艺升级改造研究

Upgrading and Reforming Study on the Sewage Treatment Process in Yanchang Oilfield

通过对延长油田2014—2017年污水处理工艺调研发现,水质指标是影响油田高含水开发阶段污水处理工艺的关键因素。经污水处理站处理后的水质中悬浮物含量、腐蚀速率、SRB菌含量、铁细菌及硫化氢含量均超出B2水质指标,若油田将此类未达标水回注,一方面引起油田注入与油藏开发效果不佳,徒增开发成本;另一方面还将引发注水站及注水管网与管柱的腐蚀,油田生产安全隐患系数增加。在室内分析此污水处理站进站水质特点,筛选改性药剂和净化药剂,将污水处理工艺现状与现场测试数据相结合,比较不同方案的经济效益,制定了“两级除油+化学混凝+逆流沉降+多层滤料过滤处理流程”的污水处理工艺升级改造方案。依托成熟和先进的新技术与新工艺,使得处理后污水水质符合SY/T5329—2012规定的B2级水质指标,确保污水处理安全达标并满足原油生产的可持续性。

Through the investigation of the wastewater treatment process of Yanchang Oilfield from 2014 to 2017,it is found that the water quality index is a key factor affecting the sewage treatment process in the high water cut development stage of the oilfield. The content of suspended solids, corrosion rate, SRB bacteria content, iron bacteria and hydrogen sulfide in the water after the treatment of the sewage treatment station are all beyond the B2 water quality index. If the oilfield re-injects such unqualified water, on the one hand, the oilfield injection and reservoir development are not effective, and the development cost is increased;on the other hand, the corrosion of the water injection station and the water injection pipe network and the pipe string will be caused, and the safety hazard coefficient of oilfield production will increase. The water quality characteristics of the sewage treatment station are analyzed indoors, and the modified chemicals and cleansing agents are selected. Combining the current status of sewage treatment process with the field test data, the economic benefits of different programs are compared, and a sewage treatment process upgrading and transformation plan, namely two- stage degreasing + chemical coagulation + countercurrent sedimentation + multi- layer filter filtration treatment flow. Relying on mature and advanced new technologies and new processes, the treated sewage water quality meets the B2 water quality index specified in SY/T5329-2012, ensuring that the sewage treatment safety meets the safety standards and meets the sustainability of crude oil production.