Up-to-standard discharge treatment technology of drilling wastewater from oil and gas fields

Abstract

The invention discloses an up-to-standard discharge treatment technology of drilling wastewater from oil and gas fields. The treatment technology comprises the following steps: (1) adjusting pH value of wastewater to 3-4.5; (2) adding a Fenton's reagent into wastewater treated in the step (1), degrading large molecular organic matter in the wastewater to low molecular organic matter and simultaneously removing sulfide in the wastewater and part of low molecular organic matter; (3) adjusting pH value of the wastewater treated in the step (2) to 8-10, adding a flocculating agent and a coagulant aid, and removing suspended matter and part of COD in the wastewater after gravity settling; (4) adding sodium carbonate and a flocculating agent into the wastewater treated in the Step (3), settling and removing divalent metal ion in the water; and (5) carrying out evaporative crystallization treatment on the wastewater treated in the Step (4), conducting circulating treatment on an concentrated solution and discharging condensate water up to standard. According to the invention, low-cost up-to-standard discharge treatment of drilling wastewater from a plurality of complex oil and gas fields can be realized.

Description

technical field [0001] The invention belongs to the technical field of industrial waste water treatment, and in particular relates to a treatment process for discharge of oil and gas field drilling waste water up to the standard. Background technique [0002] Drilling wastewater mainly comes from the drilling process, downhole operation process and oil (gas) production process. The main pollutants of drilling wastewater are petroleum, COD, sulfide, phenol, suspended solids, chroma, etc.; downhole operation wastewater mainly includes well washing water, fracturing flowback fluid, etc.; water extraction and transportation are produced during the production process of oil and gas fields Wastewater is mainly groundwater collected and transported from formations. [0003] The composition of drilling wastewater is complex, with high COD, relatively low BOD, high salinity, and Cl - The content is as high as 5000-200000mg / L, and the biodegradability is poor. At the same time, thi...

AI Technical Summary

Problems solved by technology

Due to the complexity of drilling wastewater, variable pollution characteristics, high salt content, poor biochemical properties, etc., especially the large fluctuations in the quality of drilling wastewater, it is difficult to guarantee the water output of biochemical treatment, and the biochemical treatment generally takes a long time. Therefore, The application of biochemical treatment technology in drilling waste fluid is currently less

[0007] (3) Adsorption process: Most of the adsorption processes are subsequent treatment processes of combined processes, and most of them are equipped with activated carbon adsorption units, but there are problems such as saturation and regeneration of adsorbents, making engineering application difficult

Membrane desalination process is easy to block and pollute, and requires high pretreatment in the early stage. At the same time, there is a problem that concentrated water needs to be further treated, and membrane treatment is not suitable for treating wastewater with TDS>50000mg / L. less salt application

The evaporative desalination process mostly uses a multi-effect evaporation system. Compared with the traditional evaporation process, the energy consumption of this system is reduced, but the process equipment occupies a large area and is not suitable for factories without surplus fresh steam.

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