Regional differences in risk and control limits for road utilization of oil and gas extraction wastes in arid and semi-arid regions
Utilizing oilfield cuttings drilling residues(OCDRs)as roadbed fill material represents a significant pathway for the recycle of wastes from oil and gas extraction.However,the current resource utilization risk assessment and control limits adopt a unified national parameter model,failing to consider the differences in meteorological and geographical environments across regions,it greatly limits the resource utilization,especially in arid and semi-arid areas where the risk of pollutant release is relatively lower due to less rainfall.This paper employs leaching and percolation experiments,an exponential decay source strength model,and a transient pollutant migration and diffusion model,combined with the Monte Carlo method,to conduct an in-depth analysis of potential environmental risks,control limits,and regional differences in using OCDRs as roadbed fill in arid and semi-arid regions.The results indicate that the data obtained from three types of leaching experiments are very unstable compared to the percolation experiments.using the percolation method to predict the exposure point concentration of OCDRs under road use conditions in 14 provinces in arid and semi-arid areas resulted in a zero probability of exceeding the standard,indicating an acceptable risk.However,the risk of using traditional methods to predict was too high,with the exposure concentration of Pb being 3.1 times the limit set for Class III groundwater quality.There were significant differences in exposure risks and control limits among the 14 provinces,with the coefficient of variation for the exposure concentrations of eight heavy metals ranging between 0.53 and 1.2,and the coefficient of variation for control limits ranging between 1.3 and 2.7,both showing a high degree of dispersion.Moreover,control limits show a strong negative correlation with rainfall,consistent with the pattern of exposure concentrations.The study demonstrates that the uniform model parameters in traditional leaching and risk assessment methods cannot accurately assess the potential risks of pollutants in OCDRs in different regions.There is an urgent need to establish standardized risk assessment methods for solid waste resource utilization,taking into account the significant differences in risks and control limits across different regions in arid and semi-arid areas.It is recommended to implement differentiated control of hazardous substances according to the specific conditions of each region,promoting the development of a classified and graded control system for solid waste resource utilization risk based on regional zoning.
de-oiled wastearid and semi-arid regionsresourcinguncertainty analysisrisk management and control
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