Research on the treatment and secondary fluid mixing technology for oil-containing drilling wastewater in gas fields

Abstract

Drilling operations in oil and gas fields will generate a large amount of highly polluted and difficult to degrade drilling wastewater. Oil drilling wastewater mainly includes diluted drilling fluid mud, heavy metals and radioactive substances. At present, the treatment methods for oily drilling wastewater mainly include reinjection into the formation, recycling and discharge after standard treatment, but the treatment effect is not good. This article describes the treatment of oily drilling wastewater through wastewater oxidation, flocculation, mechanical dehydration, intermediate water oxidation, flocculation and filtration. The experimental results show that the RR of the wastewater can reach 93.50 %, the maximum oil recovery rate (ORR) can reach 89.56 %, the light transmittance (LT) of the purified water can reach 98.40 %, the suspended solids (SS) can be reduced to 46.12 mg/L, the HBO 2 - content can be reduced to 4.20 mg/L. The water quality meets the requirements of DB61/T 1248–2019. Indoor technology was used for on-site testing, and the lowest reduction rate (RR) and ORR after wastewater treatment were 87.64 % and 84.21 %, respectively. Comparing the cost of treating the same type of wastewater, the treatment cost of the process in this article can be reduced by 1.87 USD/m 3 , which has higher economic benefits. • Application of innovative wastewater treatment technology. • Improve the separation efficiency of oily wastewater. • Optimization analysis of secondary liquid preparation technology. • Environmental Impact Assessment and Emission Reduction Measures. • On site empirical data verification of processing effectiveness.