涪陵页岩气开发压裂废水的污染防治技术探讨

Discussion on pollution control technologies of fracturing waste water in fuling shale gas exploitation

水力压裂技术是目前页岩气开发的主要储层改造手段,水力压裂所需水量大,返排液的总返排量大、高矿化度、高COD且返排周期长,为降低对环境的污染,返排液必须经处理再排放。根据涪陵页岩气开发压裂废水情况,本研究以"前期回用-后期排放"为方向。在开发阶段压裂返排液和采气分离水经"pH值调节/预氧化-混凝"处理在工区内重复利用,开发结束后不再利用的压裂返排液和采气废水经"pH值调节/预氧化-混凝-高级氧化-反渗透-浓水处理"深度处理后达标排放。前期回用处理采用罐装车设备,后期排放处理以罐装车与深度处理的撬装装置联用,整套设备适应性强、可重复利用且方便移动。

Hydraulic fracturing is a well stimulation technology that creates fractures in targeted zones that improves the shale formation＇s permeability. In the hydraulic fracturing amount of water required is large, and the flowback water has presence that is large displacement, high salinity, high COD and long lifespan. To reduce the environmental pollution caused by flowback water, it need to be treated before discharge. According to waste water status of the {uling shale gas exploitation, ＂pre-reuse, post discharge＂ was taken as the research route. In the devel- opment period, flowback water and produced water, that were treated by ＂pH value adjustment/pre-oxidation, coagulation＂ as the reuse treatment technology, were reused. After the development end, flowback water and pro- duced water, that are not reused and were treated by ＂pH value adjustment/pre- oxidation, coagulation, advanced oxidation, reverse osmosis, low-temperature vacuum distillation system＂ as the discharge treatment technology, were discharged. The whole discharge equipment has two parts, one of them is canned car which used in on-site for reuse treatement, the other part is skid device which was used as the further treatment system. The equipment is adaptable, reusable and removable.