Harmless Treatment Of Waste Drilling Mud While Drilling

It inevitably produced a lot of waste in the petroleum exploration and development process.The largest amount of the waste which produced in the process of drilling was waste drilling mud.Waste drilling mud was a kind of which contained clay,chemical treating agent,sump oil and drilling cuttings multiphase colloid-suspension system,with high dispersion stability,result in difficult dehydration and low efficiency of waste mud treatment.Due to the special geographical environment,the drilling depth mostly exceed 2000m in the oil field,with a large amount of waste mud,complexity mud system,high petroleum matter content,high stable dispersion;In addition,large district,drilling operation dispersion,mud subsequent processing was difficult,it was the restricting of oil and gas field drilling development.If disposed with improperly,waste drilling mud would certainly enter the environment and pollute local environment that results in inestimable loss.Then,the development of petroleum industry will be in turn restricted by environmental pollution.Therefore,to seek a rapid,non-hazardous waste drilling mud treatment technology is more important.Based on the origin analysis origin,the pollutant characteristics,and the present state of processing technology of waste drilling mud and combining the analysis of actual conditions in production area in Dagang Oilfield;the studies have analyzed the pollutant characteristics of waste drilling mud comprehensively and put forward curing-after-gel breaking technology with ferric salt and composite solidified agent composed of fly ash,quicklime,loess soil and cement.Furthermore,the influence of the type,concentration and dosage of the treatment agent on the solid-liquid separation was studied by single factor method.The effects of stirring rate,reaction temperature and reaction time on the solid-liquid separation of the slurry were investigated by orthogonal experiments.Through the comparison of the separation process under different mechanical conditions,the best separation equipment of slurry solid-liquid separation is determined.The results show that:(1)the optimum process of fresh mud(solid content<10%):the degree of polymerization of acrylamide in solution of colloidal mud treatment,and then use the PAC to gel breaking.In the process of treatment,the stirring rate was kept at 30?50r/min,and the reaction temperature was maintained at 20?30?.The optimum dosage of treatment agent for per 100 milliliter fresh water mud was 5g acrylamide aqueous solution(concentration of 2%),12.0g PAC.Under this process,the removal rate of suspension was at least 90%.And COD value,pH value and chroma values were lower than the national emission requirements;(2)polymer mud and silicon-based ant sloughing mud:select FI as the coagulant for mud colloidal processing;H25 as gel breaking agent for gel breaking treatment;CA-2 as flocculation of suspended solids in the filtrate after separation.(3)the optimum process of polymer mud and silicon-based ant sloughing mud:when the mud was polymer mud,FI:H25:CA-2=3:4:4,the dosage of FI was 7.5g per 100g,the solid content of mud's cake reached 87.6%;when the mud was the silicon-based ant sloughing mud,FI:H25:CA-2= 5:4:6,the dosage of FI was 12.5g per 100g,the solid content of mud's cake reached 72.5%.(3)through the orthogonal experiment,the optimum conditions of harmless treatment of the polymer slurry and silicon-based ant sloughing drilling mud:the reaction temperature was 15?25?,the reaction time was 5?10min,the stirring rate for the different types of mud needed to make corresponding adjustments(the stirring rate of polymer mud was 50?100r/min;the stirring rate of silicon-based ant sloughing mud was 150?200 r/min).(4)the best filter unit for solid-liquid two-phase was plate and frame filter press,and the filtering time was changed by mud solid content.Usually,the whole operation time was not more than 20min,so it can be considered to be a fast separation process.(5)during the field application,the fresh water mud,polymer mud and silicon-based ant sloughing mud needed not be classified.The dosage of FI was 7.5%?13%of the amount of waste drilling mud;the dosage of H25 for waste drilling mud was 6%?9%;the dosage of CA-2 for waste drilling mud was 10%?15%,the solid content of sludge cake after treatment is higher than 60%,and the leaching of mud cake liquid COD,pH and the concentration of some heavy metal ions reached national standards and local solid waste emissions standards and met production requirements of enterprises.In addition the separated liquid can not only be used secondly,but can be used directly as treatment agent for oilfield waste water,suspended solids in the effluent flocculation precipitation,realizes waste utilization effect.