The　existence　of　organic　matters　in　naturally　hydrate-bearing　sediments　would　notably　impact　the　CH4　extraction　from　reservoirs　via　CO2　swapping.　In　this　work,　the　depressurization-assisted　flue　gas　replacement　was　explored　with　artificial　hydrate-bearing　clay-silt　sediments　containing　organic　matter.　The　effect　of　organic　matter　type　and　content,　depressurization　moment　and　amplitude　was　systematically　investigated.　The　results　showed　that　the　replacement　was　promoted　at　5.0　wt%　sulfonated　lignin　(SL)　before　depressurization,　while　it　was　inhibited　at　a　lower　SL　content　and　this　inhibition　was　weakened　after　depressurization.　The　CH4　replacement　ratio　and　CO2　sequestration　ratio　increased　as　the　fulvic　acid　(FA)　content　increased.　For　the　organic　matter-contained　systems,　the　earlier　depressurization　moment　was　conducted,　the　higher　CH4　recovery　was　obtained.　The　CH4　replacement　ratio　increased　with　the　increase　of　depressurization　amplitude,　which　reached　71.48　%　in　the　3.0　wt%　FA　system　at　the　depressurization　amplitude　of　3.0　MPa.　Aspen　simulation　revealed　that　the　energy　consumption　was　mainly　caused　by　compression,　there　exist　an　optimum　injection　pressure　of　flue　gas　for　the　energy　return　on　investment.　The　findings　provide　useful　information　for　the　depressurization-assisted　flue　gas　replacement　and　would　contribute　to　the　actual　NGH　exploitation　in　the　future.　©　2024　Elsevier　Ltd