Multilateral　horizontal　wells　(MHW)　can　enhance　gas　production　by　expanding　the　natural　gas　hydrate　(NGH)　decomposition　area,　but　inevitably　leading　to　larger　changes　in　reservoir　pressure　and　rock　stresses,　causing　subsidence　or　disasters.　Therefore,　this　study　established　a　THMC　model　that　evaluated　the　production　effect　and　geomechanical　response　of　MHW　in　Class-I　reservoirs　with　different　permeability　and　proposed　a　CO2　reinjection　repair　strategy　to　achieve　subsidence　recovery　and　carbon　storage.　Results　indicate　that　MHW　with　vertical　branch　arrangements　performs　best　in　short-term　production　for　low-permeability　reservoirs,　while　the　temperature　and　pressure　evolution　in　high-permeability　reservoirs　is　more　drastic　than　in　low-permeability　reservoirs,　producing　many　unfavorable　factors.　Higher　capacity　also　results　in　larger　strata　subsidence　and　stress　changes,　affecting　the　reservoir　stability　and　wellbore　safety:　(i)　subsidence　occurs　mainly　in　the　NGH　sediment　and　the　upper　zone　of　the　wellbore;　(ii)　normal　stresses　around　the　wellbore　increase　most　significantly　in　the　vertical　direction,　while　shear　stresses　generally　decrease.　The　repair　indicators　of　subsidence　recovery　rate,　energy　recovery　rate,　and　hydrate　conversion　rate　suggest　that　reinjecting　CO2　into　depleted　NGH　reservoirs　can　improve　the　mechanical　properties　of　the　strata　and　achieve　carbon　storage　via　the　hydrate　method　as　well.