Oil Recovery And Harmless Treatment For Waste Oil-based Drilling Fluid

Oil-based drilling fluids have good lubrication,temperature and salt resistance,and fluid loss resistance,and are widely used in the development of difficult oil and gas reservoirs.However,the oil-based drilling fluid has degraded its performance after repeated use,and it has become difficult to use and become oily waste.The waste oil-based drilling fluid has the characteristics of high p H value,high COD value,etc.,and must be harmlessly treated.At the same time,the value of resource recovery is high due to its high oil content.In view of the environmental pollution of waste oil-based drilling fluid,this paper analyzes the oil content,water content,solid content and heavy metal content of waste.The results show that the oil content of waste oil-based drilling fluid is 43.1%?volume fraction?,which needs to be harmless processing.Based on the analysis of pollution characteristics,this paper studied the treatment of waste oil-based drilling fluid demulsification,waste water and residue.Demulsification study of waste oil-based drilling fluid mainly determines the best demulsification formula and process conditions by single factor experiment and orthogonal experiment method:the ratio of demulsifier AX01 and AX07 is 1:2,the amount is 0.8%,and the amount of OT-75 is 0.5%,PAC added 1500mg/L,PAM?mass fraction 0.1%?added 0.4%,dilution ratio 1:1,demulsification temperature 65?,demulsification time 45 min,centrifugal speed 5000r/min,centrifugation time 5 min,and finally the oil removal rate reached 87.6%.Degreasing waste water used coagulant PAC?addition of 500mg/L?and Fenton's reagent?30%H₂O₂ added 1800mg/L,and the molar ratio of H₂O₂ and Fe SO₄.7H₂O is2.5:1?for flocculation oxidation treatment.The waste residue is treated by solidification.After processing,the COD value of waste water is reduced from 2144mg/L to 113mg/L,and the COD value of waste leaching solution is 96mg/L.The detection indexes all meet the secondary standard of GB 8978-1996 Integrated Wastewater Discharge Standard.Therefore,The harmless treatment and resource recycling of waste oil-based drilling fluids are realized.