Hydrocarbon Accumulation Periods Study Of Ordovician In The Hetanhe Region And Its Adjacentareas,Tarim Basin

The Hetanhe region and its adjacent areas are located in the Bachu uplift area of Tarim Basin.In this paper,using Ordovician carbonate strata layer as target strata to research clearly hydrocarbon infill injection period times and accumulation periods in the Hetanhe region and its adjacent areas by analyzing the structural characteristics of rock and diagenesis of core and thin in the area and relying on experiments of inclusions hosting in the minerals and veins.The main diagenesis in the Hetanhe region and its adjacent areas are cementation,dissolution(karst),compaction pressure solution,dolomitization,fracture,and weathering and the like.There are four tectonic fractures in Ordovician: Late Caledonian-Hercynian tectonic fractures(Stage ?),Late Hercynian tectonic fractures(Stage ?),Indosinian tectonic fractures(Stage ?),Yanshan-Himalayan tectonic fractures(Stage ?).In addition,five kinds of hydrocarbon inclusions are found distributed in three tectonic fractures: brown asphalt and brown hydrocarbon inclusions with brown fluorescence was charged in the stage ?tectonic fractures(Stage ? hydrocarbon inclusions);hydrocarbon inclusions with yellow fluorescence was charged in the stage ? tectonic fractures(Stage ? hydrocarbon inclusions);there are three different hydrocarbon inclusions in the stage ? tectonic fractures:black gas and liquid hydrocarbon inclusions(stage ?-1hydrocarbon inclusions),gray gas-liquid hydrocarbon inclusions with blue fluorescence was charged(stage ?-2hydrocarbon inclusions),gray gaseous hydrocarbon inclusions(stage ?-3hydrocarbon inclusions).Experimental results show that: stage ? hydrocarbon inclusions are high mature heavy oil,forming temperature 90 ? 100 ?,about the depth of 2980 m at the end of the Devonian.stage ? hydrocarbon inclusions are mature oil,forming temperature 90 ? 100 ? and depth of 3419 m,during the Permian;stage ?-1hydrocarbon inclusions forming temperature is 90 ? 100 ?,the depth of 3557 m,Cretaceous,early Paleocene;stage ?-2 hydrocarbons inclusions are high mature light oil,forming temperature 90-120 ?,the formation depth of 4387 m,the Paleogene-early Neogene;Generally forming temperature of stage ?-3hydrocarbons inclusions is 110-120 ? and 4603 m depth,were formed during the Paleogene-Neogene advanced.Comprehensive analysis showed that: the Hetanhe region and its surrounding areas had the presence of oil reservoirs filled by hydrocarbon represent stage ?hydrocarbon inclusions and stage ?-2 hydrocarbon inclusions,but later destroyed.The oil and gas in current reservoirs mainly from stage ?-2 hydrocarbons,followed by stage ? hydrocarbon inclusions.The oil and gas migration paths for stages are those: oil and gas represented by Late Caledonian-Hercynian Stage ? hydrocarbon inclusions and late Hercynian stage ? hydrocarbon inclusions from the north,from north to south migration;oil and gas represented by Yanshan-Himalayan stage ?-2hydrocarbon inclusions from multiple directions,in addition to inheriting the previous migration path from north to south,there are also oil and gas from the Migaiti slope from south to north migration,cracking hydrocarbon under Cambrian traps upward migration.Oil and gasrepresented by stage ?-1 hydrocarbon inclusions and stage ?-3 hydrocarbon inclusions are from the northern part of the Tanggu depression.