| With a large number of exploration and development of shale gas,oil-based drilling fluid has been widely applied,which has a strong ability to stabilize the wall,and inhibits shale hydration expansion,and has a little impact on reservoir.However,because of it,the environment problem has been becoming more serious.Based oil(diesel or mineral oil)as the continuous phase was used to configure the oil-based drilling fluid which needed a variety of chemical additives to meet the different needs of drilling.When it was abandoned after several cycles,in waste residue,there was a lot of oil which had great value of recycling.On the other hand,there were a variety of substances which were harmful to the surrounding environment,such as heavy metals,organic polymer compound and its decomposition products.Therefore,this paper studied that solvent extraction method treated the waste oil-based drilling fluid and drilling cuttings,and solidified residue which had been extracted in order to achieve the purpose of harmless and recycling.This paper mainly focused on waste oil-based drilling fluid which was produced from Weiyuan area(Sichuan)as well as waste oil-based drilling fluids and drill cuttings which were produced from Chongqing Fuling shale gas development demonstration zone.It contained three kinds of samples.This paper determined the component of samples,screened the different extraction agents.Through the indicators of extraction rate,extraction agent toxicity and recovery temperature,petroleum ether(60?90 0C)was selected as extraction agent.The effects of extraction rate were influenced by three factors(solvent dosage,extraction time and extraction temperature).This paper discussed the effects of the interaction between factors by response surface methodology,and optimized extraction conditions.It fitted a curved surface which could simulate the real limit state through the multiple regression analysis.This paper investigated the effect of centrifugation speed and time on extraction rate.For the waste oil-based drilling fluid from Weiyuan area(Sichuan),the measured value was 81.1%by the optimum extraction conditions of the liquid-waste ratio 1.8:1,extraction time 20 min,extraction temperature 40 ?,centrifugation speed 3000 r/min and centrifugation time 10min.For the waste oil-based drilling fluid from Fuling area(Chongqing),the measured value was 85.0%by the optimum extraction conditions of the liquid-waste ratio 2.5:1,extraction time 22.5 min,extraction temperature 20 ?,centrifugation speed 3000 r/min and centrifugation time 10min.For the drilling cuttings from Fuling area(Chongqing),the measured value was 89.0%by the optimum extraction conditions of the liquid-waste ratio 1.75:1,extraction time 25 min,extraction temperature 40 ?,centrifugation speed 3000 r/min and centrifugation time 10min.This paper analyzed the recovery of diesel oil and recovering extractant by infrared spectroscopy.The result showed that the quality of the recycled diesel obtained from Weiyuan area(Sichuan)was poor,and it needed further purification treatment.The quality of two recycled diesel obtained from Fuling area(Chongqing)was good,and they could be used to reconfigure oil-based drilling fluid or as fuel oil through the simple process.In order to realize the hazardous waste harmless,this paper detected the pollution indices of the remaining residues,and took the case of the waste oil-based drilling fluids and drill cuttings from Fuling area(Chongqing)which had been extracted,and optimized the curing formulation(residual:cement:lime:fly ash = 6:1.5:0.5:1.5)to make the leachate of solidified waste meet the first and second class criteria specified in Integrated Wastewater Discharge Standard(GB 8978-1996).According to the experimental condition of the laboratory,combining with the actual conditions,extraction process for waste oil-based drilling fluid and drill cuttings were designed.Economic feasibility analysis of solvent extraction provided a theoretical basis for the realization of industrial production. |
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