To　develop　extra-heavy　oil　is　of　great　importance　for　China＇s　crude　oil　supply　and　security.　However,　due　to　the　original　high　pressure　and　high　oil　viscosity,　deep　extra-heavy　oil　cannot　be　exploited　efficiently　by　the　existing　technologies,　for　example　steam　flooding　and　in-situ　combustion.　This　paper　proposed　to　develop　extra-heavy　oil　by　supercritical　water　flooding.　First,　a　new　kind　of　tubular　sand　pack　was　developed　to　simulate　the　heating　and　displacing　process　simultaneously.　Then　supercritical　water　flooding,　steam　flooding　and　hot　water　flooding　were　carried　out　for　comparison.　The　results　indicated　that　supercritical　water　flooding　can　significantly　enhance　oil　recovery　compared　with　steam　flooding,　and　the　displacement　efficiency　reached　97.07%　when　injection　parameters　were　25　MPa　and　400.　Additionally,　the　temperature　field　and　pressure　field　in　supercritical　water　flooding　were　examined.　The　phenomenon　of　supercritical　water　override　was　found,　and　it　promoted　enhanced　oil　recovery　(EOR)　because　of　its　later　occurrence　and　shorter　duration　relative　to　steam　override.　©　2020,　Science　Press.　All　right　reserved.