Multi-well　patterns　and　complex　structural　wells　can　enlarge　the　contact　area　between　the　wellbore　and　natural　gas　hydrate　(NGH)　to　improve　productivity　significantly,　but　the　construction　cost　of　drilling　is　still　too　high.　The　previous　study　has　proposed　a　self-entry　exploitation　device　(SEED)　with　an　enlarged　device　diameter,　allowing　more　NGHs　to　dissociate　simultaneously.　While　for　conventional　wellbore,　a　large-diameter　casing　may　be　applied　in　NGH　development　to　enlarge　the　wellbore　diameter　of　the　production　section.　This　work　continued　to　study　the　influences　of　enlarged　device/wellbore　diameter　on　gas　production　characteristics,　temperature-pressure　evolutions,　and　the　dissociation　front　movement　pattern.　The　sensitivity　analysis　was　also　carried　out　by　various　reservoir　and　depressurization　parameters　under　different　wellbore　diameters.　Results　show　that　the　enlarged　wellbore　diameter　can　enlarge　the　drainage　area　and　increase　the　dissociation　efficiency.　The　temperature　and　pressure　around　the　wellbore　remain　relatively　stable,　meeting　the　conditions　for　long-term　production.　Also,　the　dissociation　front　moves　farther　away　faster　as　the　wellbore　diameter　enlarges,　accelerating　NGH　dissociation　at　distant　wells.　Finally,　the　sensitivity　analysis　reveals　that　the　enlarged　wellbore　diameter　enhances　gas　production　significantly　in　unfavorable　production　parameters:　poor　production　pressure,　low　permeability,　low　NGH　saturation,　and　narrow　reservoir　thickness.　©　2022　Elsevier　Ltd