Zhe Research On Technology Of Waste Drilling Mud Treatment And Residue Ecological Remediation

Waste Drilling Mud is the main pollutant in the drilling process,which contains high COD_Cr,BOD,oil,salt,suspended solids and some heavy metal ions.If it is directly discharged without effective treatment,it will cause serious pollution to the surrounding environment of the well site and restrict the sustainable development of oil and gas field development and environmental protection.Over the years,the treatment of waste drilling mud that has been established includes direct discharge method,pit sealing method,injection into safe formation or annular space of well,MTC technology,solidification treatment method,chemical solid-liquid separation method,incineration method,land cultivation method,microorganism.Due to the narrow scope of application,high processing cost,long processing time,etc.Its large-scale application is subject to certain restrictions.In order to realize the purpose of resource utilization of waste,this paper takes the waste drilling mud produced after drilling in an oil and gas field in northern Shaanxi as the research object.The waste drilling mud is oxidized and flocculated,and the treated residue is greened to form an abandoned drilling.Mud reduction-resource treatment process.The research work analyzed the physical and chemical properties and pollutant indicators of the abandoned drilling mud,and measured the color,COD_Cr,suspended solids,and heavy metal content of the mud leaching liquid;explored the influence of the oxidation-flocculation method on the dewatering effect of the abandoned drilling mud,and analyzed the salt tolerance.The growth of alkali alfalfa and mung bean waste mud residue after treatment has formed a greening treatment method for waste drilling mud residue after treatment.The water content of the waste drilling mud is 64.38%,the COD_Cr and color of the leaching fluid are 21333mg/L,15750 degrees,and the heavy metal ion content of Cr,Ni,Cu,Zn,As,Cd and Pb are 3.53,1.93,1.96,2.27,0.83,0.21,2.04mg/L,it is a system with high stability,heavy metal content,and certain pollution.The waste drilling mud was treated by oxidative flocculation experiments,and the best treatment conditions were obtained:after pH 2,H₂O₂ dosage was 0.3%（W）,Fe SO₄ dosage was200mg/L,and oxidation treatment time was 1 h.Then adjust the pH to 10,and when the PAC（Poly Aluminum Chloride）dosage is 800mg/L and the molecular weight is 8 million cationic PAM（polyacrylamide）20mg/L,the water content of the residue after treatment can be reduced to28.05%,and the COD_Cr,the chromaticity is reduced from the initial 21333mg/L to 4533mg/L,15750 degrees is reduced to 2556 degrees,the water quality after treatment has been significantly improved.Through the determination of plant nutrients,the analysis of the germination rate and plant height of salt-tolerant alfalfa and mung bean,and the changes of plant nutrient content before and after planting,the residue after treatment was greened.When Residue after treatment:soil=1:6,alfalfa and mung bean are planted for 30 days,the germination rate of alfalfa in the mixed soil is80%,the plant height is 5.5cm,the germination rate of mung bean is 96.67%,and the plant height is 25cm.The total amount of soil water-soluble salt,EC value,and total alkalinity in the mixed soil decreased significantly.After alfalfa planting,heavy metal ions such as Cr,Ni,Cu,Zn,As,Cd,and Pb increased from 12.01,27.42,26.12,171.17,6.73,2.51,24.17mg/L were reduced to 11.65,27.07,25.63,0.68,6.56,2.24,23.89 mg/L,and mineral oil was reduced from 574.57 mg/L to 456.45 mg/L.After mung bean planting,heavy metal ions such as Cr,Ni,Cu,Zn,As,Cd,and Pb decreased from12.01,27.42,26.12,171.17,6.73,2.51,24.17mg/Lto11.64,27.12,25.76,170.43,6.53,2.36,23.91 mg/L,mineral oil reduced from 574.57mg/L to 482.28mg/L.The contents of invertase,urease,and catalase in the mixed soil all increased to varying degrees compared with those before planting.The plant nutrients of alfalfa mung bean were close to the plant nutrients without adding the residue after treatment.The mixed soil after greening treatment.Compared with before planting,the biological activity of soil quality and soil fertility are increased.Alfalfa and mung bean can purify the heavy metals and mineral oil in the soil mixed system differently.