Research On Monitoring Of Soil For The Leakage Of Carbon Dioxide During Reservoir Storage And The Evaluation Index System

Under the background of global CO₂ concentration rising,carbon capture and sequestration technologies CCS as the most economical,the most reliable CO₂ emission reduction technology has been widely accepted in today’s international society,but also in the process of large-scale application of a series of environmental security problems,can have a major threat on the soil environment,so it is very urgent to research on the safety of CO₂reservoir storage.This topic research a certain area of SLOF（shengli Oil Field）by means of indoor simulation test and numerical modeling experiment,explore the law of leakage of CO₂sequestration in specific reservoir,research the monitoring indicators of characterization of leakage situation in environmental elements when CO₂ leaks to the ground soil,establish a complete set of scientific and standardized,economically viable CO₂ sequestration safety monitoring and evaluation index system.We draw the following conclusions:（1）Based on the numerical simulation of CO₂ leaks to the soil,determine the sampling range is centered around the injection point and simulation of CO₂ leakage flow rate is 1L/min within the gradient of concentration,sampling depth is 0.1-0.5m above the leak point,make sure every 4 h sampling time,until the leak at 48 h.（2）The influence on soil non-metallic index:with the temperature increases,soil moisture,organic carbon decreased and soil bacteria increased;with the increase of CO₂ leak time and the increase of CO₂ leak rate,soil moisture,pH,organic carbon and total nitrogen decreased and soil bacteria and HCO₃^–increased.（3）The influence on soil metallic index:with the temperature increases,the content of soil effective state K increased,other metal ions content basically unchanged;with the increase of CO₂ leak time and the increase of CO₂ leak rate,soil effective state of Ca,Mg decreased and soil effective state of Fe,Mn,Zn,Cu increased,soil effective state of K,Na,Pb,Cr basically unchanged;With deepening of soil sampling depth,soil effective state of Fe,Mn,Zn,Cu increased and soil effective state of K,Na,Ca,Mg,Pb,Cr basically unchanged.（4）The CO₂ sequestration index system of safety monitoring and evaluation:the non-metal indicators were moisture,pH,organic carbon,total nitrogen,HCO₃^-and the total number of bacteria,the change of water,organic carbon,soil bacteria was more obvious in summer;the metal indicators were soil effective state of K,Ca,Mg,Fe,Mn,Zn,Cu,effective state of K can only as the indicator in summer.