A treatment method for deep well polysulfide mud drilling wastewater

Abstract

The invention relates to a treatment method for deep-well polysulfide slurry drilling waste water, belonging to the technology for treating waste water of oil and gas field. The method comprises the following steps of: (1) coagulation treatment: pumping the drilling waste water into a coagulation reactor, and orderly adding inorganic coagulant, coagulant aids and flocculating agent; (2) secondaryflocculation: pumping the waste water processed in the coagulation treatment step into a secondary flocculation reactor, and directly adding secondary flocculation flocculant, coagulant aids and flocculating agent; (3) absorption treatment: pumping the waste water processed in the flocculation step into an active carbon adsorptive filtration reactor; (4) oxidation treatment: pumping the water filtered by the active carbon into an oxidation reactor for oxidation, and adding oxidant. The method takes the active carbon absorption and the oxidation treatment with inorganic chlorate type strong oxidizer as technical core processes, each index of the treated water can meet the level-1 technical standard requirements of a 'comprehensive sewage discharge standard' GB8978-1996.

Description

technical field [0001] The invention relates to a treatment method for deep well polysulfide mud drilling wastewater, which belongs to oil and gas field wastewater treatment technology, in particular to an advanced treatment technology for deep well polysulfide mud drilling wastewater. Background technique [0002] In the process of deep well drilling, due to the influence of geothermal gradient and formation pressure gradient, in order to achieve safe and fast drilling, composite metal ion polysulfide anti-slump drilling fluid and high-temperature drilling fluid are generally used. The salt-resistant and temperature-resistant synthetic There are many types of treatment agents, high dosage, complex composition, high concentration of organic pollutants in wastewater, high content of suspended solids, and abnormally stable colloidal system. The conventional chemical coagulation treatment technology can realize the complete removal of suspended matter and oil, and the partial r...

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Problems solved by technology

[0002] In the process of deep well drilling, due to the influence of geothermal gradient and formation pressure gradient, in order to achieve safe and fast drilling, composite metal ion polysulfide anti-slump drilling fluid and high-temperature drilling fluid are generally used. The salt-resistant and temperature-resistant synthetic There are many types of treatment agents, high dosage, complex composition, high concentration of organic pollutants in wastewater, high content of suspended solids, and abnormally stable colloidal system

The conventional chemical coagulation treatment technology can realize the complete removal of suspended matter and oil, and the partial removal of chroma and organic matter content; further use of catalytic oxidation technology, the removal rate of chroma and organic matter does not change much, and the effect is not obvious; Adsorption and filtration technology can be used for deep removal, and the chroma can be removed, but the content of organic matter, that is, COD, still cannot meet the first-level technical requirements of the "Comprehensive Wastewater Discharge Standard" (GB8978-1996)

[0003] In order to achieve environmental protection standards for drilling wastewater, people began to use chemically enhanced destabilization coagulation / catalytic oxidation technology for treatment as early as the end of the 1980s. This type of combined process has a better treatment effect on ordinary polymer mud drilling wastewater. The water pollutant index can meet the technical requirements of level 1-2 of the "Comprehensive Wastewater Discharge Standard" (GB8978-1996), but when sulfonate fluid loss reducers are contained, the chroma and COD content of the purified water from drilling wastewater often exceed the standard

In the 1990s, the adsorption and filtration technology was introduced on the basis of the above-mentioned coagulation / catalytic oxidation combination technology, which effectively solved the purification treatment of ordinary polymer mud and shallow well polysulfide mud wastewater, but for the drilling wastewater of deep well polysulfide mud system , using coagulation / secondary flocculation / adsorption filtration technology, chromaticity and other indicators can meet the first-level technical requirements of GB8978-1996, but the content of organic matter, that is, COD, often exceeds the second-level technical requirements of GB8978-1996 (that is, COD≥150 mg / L), it is difficult to achieve the first-level treatment standard, and the main technical problem is the deep removal of organic matter in wastewater

[0004] The advanced treatment process after super-oxidation requires biological cultivation and domestication, and the processing steps are complicated and the cycle is long

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