Research On Monitoring And Evaluation Index System Of Carbon Dioxide Oil Storage Reservoir Safety For Surface Water

With the seriours situation of globle warming,carbon capture and storage technology has become one of the most promising technologies for CO₂ emissions.And CO₂ storage reservoir plays an important role because of its mature technology,perfect infrastructure,long storage time,large storage capacity,etc.Once CO₂ leak occurs for storage,it has impact on surface water environment.Therefore,it is necessary to establish reservoirs of CO₂sequestration monitoring and evaluation system.Firstly,the study using CMG reservoir simulation software simulates carbon dioxide injection in reservoir at a block in Shengli Oilfield,and researches the migration rule of carbon dioxide.After analysis,the CO₂ diffuses faster in horizontal direction due to the pressure difference and the concentration difference,and the vertical diffusion of carbon dioxide is slower,after the carbon dioxide injected into the reservoir.100 years later,carbon dioxide will diffuse slowly in reservoirs and horizontal diffusion rate will be quckier.According to the migration rate of carbon dioxide,monitoring distribution determines to be a ciecle with 1.05km radius,and it sets up to monitor distribution points within the scope of monitoring.Monitoring frequency of each phase of the carbon dioxide injection is different.It should increase the frequency of sampling and increase the monitoring points appropriately around the injection well during the injection stage and off stage.Secondly,by controlling the rate of CO₂ leakage,CO₂ leakage time,CO₂ leakage temperature,it studies those impact on non-metallic,metal,biological indicators.Based on laboratory test results,when CO₂ leak rate was 0.4L/min in spring,after 48 hours,DO change rate was 97%,pH change rate was 35%,it proposed to choose pH and DO as an important indicator of carbon dioxide leakage.CO₂ leakage has impact on bicarbonate,COD and total number of bacteria,after 72 hours,bicarbonate change rate was 15%,COD change rate was37%,total number of bacteria was 27%,so they can be used as reference indexs of carbon dioxide leakage.Total salinity,sulfates,conductivity,total hardness,chloride and other non-metal and metal index change rate were less than 5%,they change significantly,those parameters were not recommended as reference indexs of carbon dioxide leakage.Finally,there are certain risks of the reservoir of carbon dioxide sequestration project.The risks are CO₂ leakage and technical risks.Environmental risk is lower.However,it should improve construction quality,enhance technology,strengthen the monitoring of CO₂storage.If CO₂ leaks,immediately take appropriate remedial measures to reduce danger to people and the environment.