The Distribution Characteristics of Gas at the Bottom of Plain Reservoir and the Gas Induced Reservoir Bottom Leakage Mode
Under the influence of changes in reservoir water level and fluctuations in groundwater level,the shallow gas at the bottom of plain reservoirs has the potential risk of breaking through the compac-ted clay at the bottom of the reservoir for seepage prevention,resulting in leakage at the bottom of the reservoir.Identifying the spatial distribution of shallow gas at the bottom of the reservoir and dividing its distribution hotspots,clarifying the mode of shallow gas induced leakage at the bottom of the reser-voir,can provide theoretical support for the safety analysis and long-term operation protection of plain reservoirs.This study takes one plain reservoir as the research area,and conducts research on the above issues based on drilling,shallow stratum cross-section results,and theoretical analysis.The results show that the shallow stratum cross-section method can effectively detect the distribution of shallow gas at the bottom of plain reservoirs.The shallow gas at the bottom of the reservoir currently exhibits an independent distribution pattern in multiple regions in the sediment of the reservoir center.The changes in temperature,groundwater level in the past three years,and fluctuations in reservoir water level can-not cause shallow gas to break through the compacted clay layer at the bottom of the reservoir.Howev-er,if the maximum amplitude of groundwater level rise increases from 1.1～1.2 m to 1.4～1.6 m,or the minimum water depth of reservoir storage decreases from 3.8～4.1 m to 0.5～3 m,the compacted clay at the bottom of the shallow gas hot spot distribution area will have the risk of failure.The spatio-temporal evolution of gas distribution at the bottom of a plain reservoir and its resulting leakage can be divided into four stages since the completion of the reservoir:the initial stage of gas convergence to-wards the center of the reservoir;The stage of gas release caused by a special extreme event causing the gas at the bottom of the reservoir to break through the compacted clay layer.The stage where the gas discharge channel/leakage channel is restricted or closed after the special extreme event;After repeating the previous two stages multiple times,the sediment at the bottom of the reservoir becomes saturated,and the leakage points at the bottom of the reservoir formed.
shallow gas at the bottom of reservoirshallow stratum cross-section methodplain reser-voirreservoir bottom leakagesoil tension failure
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维普
