含硫气田水达标外排处理技术新进展

气田水普遍具有污染物组分复杂、矿化度高等特征,如何对其进行妥善有效的处置,一直是油气田环境保护领域关注的焦点。为此,针对四川盆地某气藏采出气田水矿化度较高且含有较多硫化物等污染物的水质特征,以处理后达标外排为目的,通过实验室试验研究,分析了混凝—脱硫复合处理工艺、化学氧化除氨氮工艺以及低温多效蒸馏工艺处理该气田水的适应性和有效性。结果表明:(1)采用聚合硫酸铁(PFS)作为混凝剂,同时配合使用TS-1脱硫剂,硫化物及石油类的去除率超过90%;(2)采用CA-1作为氧化剂,氨氮去除率超过96%;(3)经低温三效蒸馏工艺处理,蒸馏水中氯化物浓度低于150 mg/L,CODcr浓度低于60 mg/L。结论认为:经全流程工艺处理后,该气田水中主要污染物指标可以达到GB 8978—1996《污水综合排放标准》一级标准的要求,氯化物浓度满足GB 5084—2005《农田灌溉水质标准》的要求,使用上述组合工艺能够对含硫气田水进行高效处理。

New progress in wastewater treatment technology for standard-reaching discharge in sour gas fields

Gas field water is generally characterized by complex contaminant components and high salinity. Its proper treatment has always been the great concern in the field of environmental protection of oil & gas fields. In this paper, the wastewater from a gas field in the Sichuan Basin with high salinity and more contaminants (e.g. sulfide) was treated as a case study for the standard-reaching discharge. Lab experiments were carried out to analyze the adaptability and effectiveness of coagulation–desulfurization composite treatment technology, chemical oxidation based ammonia nitrogen removal technology and cryogenic multi-effect distillation technology in the treatment of wastewater in this field. The results show that the removal rate of sulfide and petroleum oils is over 90% if polymeric ferric sulfate (PFS) is taken as the coagulant combined with TS-1 desulfurization agent. Besides, the removal rate of ammonia nitrogen is over 96% if CA-1 is taken as the oxidant. Finally, after the gas field water is treated by means of cryogenic three-effect distillation technology, chloride concentration of distilled water is below 150 mg/L and CODcr concentration is less than 60 mg/L. It is concluded that after the whole process treatment, the main contaminant indicators of wastewater in this case study can satisfy the grade one standard specified in the Integrated Wastewater Discharge Standard (GB 8978-1996) and chloride can reach the Standards for Irrigation Water Quality (GB 5084-2005). To sum up, the above mentioned composite technologies are efficient to the wastewater treatment in sour gas fields.