基于多级反渗透的页岩气压裂返排液处理技术  

Treatment Technology of Shale Gas Fracturing Flowback Fluids Based on Multi-stage Reverse Osmosis Process

作　　者：熊颖[1,2] 宋彬 唐永帆[1] 周厚安[1] XIONG Ying;SONG Bin;TANG Yong-fan;ZHOU Hou-an(Research Institute of Natural Gas Technology, PetroChina Southwest Oil & Gas Field Company, Chengdu 610213, China;Shale Gas Exploitation and Evaluation Key Laboratory of Sichuan Province, Chengdu 610213, China)

机构地区：[1]中国石油西南油气田分公司天然气研究院,成都610213 [2]页岩气评价与开采四川省重点实验室,成都610213

出　　处：《科学技术与工程》2021年第18期7814-7819,共6页Science Technology and Engineering

基　　金：国家重点研发计划(2018YFF0213802);中国石油勘探与生产分公司科研计划(kt2020-17-01)。

摘　　要：针对页岩气压裂返排液处理过程中常规反渗透膜脱盐难以满足高总溶解性固体含量(total dissolved solids,TDS)需要,结晶蒸发存在换热器结垢,而氧化处理不能实现脱盐效果等问题和页岩气压裂返排液急需处理的现状,分析了川南页岩气压裂返排液的水质,并以水质软化与絮凝沉降、多级过滤为预处理工艺,高、低压反渗透膜串联为深度处理工艺,形成了一种基于多级反渗透脱盐的页岩气压裂返排液处理技术。返排液预处理后的硬度降至120 mg/L,悬浮物含量(total suspended sotids,TSS)降至7~20 mg/L;利用超级反渗透(SRO)膜与反渗透(RO)膜串联,依靠其导流盘设置的大量凸点,使滤液形成湍流,避免膜堵塞,实现了TDS达6×10^(4)mg/L的返排液脱盐处理。该技术在长宁页岩气区块开展了现场试验,结果表明:TDS为2×10^(4)~6×10^(4)mg/L的返排液采用该技术进行处理后,清水产率达56.5%~81.36%,清水的TSS、氯化物含量、化学耗氧量(chemical oxygen demand,COD)、氨氮等指标均达到GB8978—1996和DB51/190—93的一级指标要求,实现了页岩气压裂返排液的减量化外排处理。Aiming at the problems in shale gas fracturing flowback fluid treatment process,such as conventional reverse osmosis membrane desalination is difficult to meet the demand of high total dissolved solids(TDS),crystallization evaporation heat exchanger scaling and oxidation treatment cannot achieve desalination effect and so on,and combining the urgent need for treatment of shale gas fracturing flowback fluid,the water quality of shale gas fracturing flowback fluid in South Sichuan was analyzed and a shale gas fracturing flowback fluid treatment technology based on multi-stage reverse osmosis desalination was formed by using combination of water softening,flocculation-sedimentation,and multi-stage filtration as pretreatment process and using high and low pressure reverse osmosis membrane in series as advanced treatment process.After the pretreatment,the hardness and total suspended solids(TSS)of the flowback fluid can be reduced to be 120 mg/L and 7~20 mg/L,respectively.Furthermore,after the advanced treatment by connection of super reverse osmosis(SRO)membrane and reverse osmosis(RO)membrane,the desalination treatment of the flowback fluid with TDS of 6×10^(4)mg/L can be realized by taking advantage of a large number of bumps set on the guide plate,which make the filtrate to form turbulence and to avoid membrane blockage.The field test of this technology was carried out in Changning shale gas block.The results show that when the flowback fluid with TDS of 2×10^(4)~6×10^(4)mg/L is treated by this technology,the yield of clean water reached 56.5%~81.36%,and the TSS,chloride content,chemical oxygen demand(COD),ammonia nitrogen and other indexes of clean water all met the first-class index requirements of GB8978—1996 and DB51/190—93,realizing the reduction of shale gas fracturing flowback fluid.

关 键 词：页岩气 压裂返排液 反渗透 絮凝 过滤 水质软化 

分 类 号：X703[环境科学与工程—环境工程]