基于水质矩阵的石油压裂废水处理性评价

Treatability evaluation of oil-fracturing fluid sewage based on the water matrix

结合石油压裂废水水质特征与评价指标及其污染物范围因子,建立了石油压裂废水的水质评价矩阵,表明石油压裂废水中的COD和黏度是影响其处理的主要污染因子。以混凝为预处理工艺,分别采用臭氧催化氧化、吸附和Fe/C微电解等对压裂废水进行处理。结果表明,混凝预处理工艺可以有效去除水中的悬浮性污染物和石油类物质,臭氧催化氧化和Fe/C微电解工艺不仅能有效去除水中的有机污染物,且能降低压裂废水的黏度。以国家污水综合排放标准和污水反应处理时间为约束条件,建立了石油压裂废水处理性评价矩阵,指出压裂废水可采用的基本工艺为混凝、臭氧催化氧化组合处理工艺。

The paper is inclined to introduce the research work of its authors on the treatability evaluation of oil-fracturing fluid sewage based on the water matrix. As a matter of fact, fracturing operation widely used in the petroleum fields is one of the main measures to im- prove production. However, as the main pollution source for the wa- ter body around the petroleum fields, fracturing fluid sewage generat- ed in the petroleum extraction process is characteristic of high COD, high chrominance and high viscosity. The COD in this kind of sewage is near 10 000 mg/L, with its viscosity being twice and even thrice of the conventional sewage. In order to make a better water quality as- sessment of the matrix of oil fracturing fluid sewage, we have estab- lished an evaluation system to evaluate the following factors, including water quality features, evaluation indexes and the range of the pollu- tants. The results of our work indicate that COD and viscosity were the major pollutant factors in the oil-fracturing fluid sewage. The weight factor of COD and viscosity are 10.24 and 2.03 respectively. It is also found that high viscosity of fracturing fluid sewage is the chief factor affecting the mass transfer process of sewage treatment, which results in a long-time response and dissatisfactory treating ef- fect. If it is treated by ozone catalytic oxidation, adsorption, and Fe/ C micro-electrolysis, it has to be done after coagulation pretreatment, which helps to remove the suspended pollutants and petroleum sub- stances effectively. However, it would be better to adopt ozone oxida- tion and Fe/C micro-electrolysis treatment, which can not only effec- tively remove the organic pollutants but also facilitate the reduction of the viscosity of the fracturing sewage. But the Fe/C micro-electrolysis process needs regulating pH to 1 with sulfuric acid and finishing the reaction in 5h. After that, the sewage can be adjusted to neutral state with lime, though there lies some potential security risks and com- plexity with the process. With the constraint conditions of the national sewage discharge standard and sewage processing time, the estab- lished water treatability matrix of oil fracturing fluid sewage we have developed demonstrates that the hybrid treatment of coagulation, ozone catalytic oxidation are expected to be a leading treatment process for oil-fracturing fluid sewage.