Oil-Gas Distribution And Key Control Factors Of The Central Grabens In Tamuchage Basin

Based on the analysis of the Tamuchage Basin in different periods sedimentary filling characteristics and tectonic evolution processes, and systematically analyzes the coupling relationship between them,we can conclude that they controlled the effective configuration of reservoir-formed elements together. With the lithologic features of different layers and the match of reservoiring elements, the layers is divided into eight reservoir-cap combination and three sets of petroleum system from top to bottom. The reserves of reservoir-cap combinationⅡ,Ⅲin the lower primary petroleum system accounted for 60% of the total reserves, it is the main production reservoir.Through studying the distribution of oil-gas reservoirs in this area, we think "source-reservoir" control the oil distribution in the plane,"faults-cap rock"control oil accumulation stratigraphic position,"faults-uplift-fan"control oil accumulation space position. The reservoir type can be divided into three types six subtypes: three types are tectonic reservoir, composite reservoir and lithologic reservoir; six subtypes means palaeoburied reservoirs, antithetic faults screened reservoirs, small anticline reservoirs, ult-unconformity screened reservoirs, faults- lithologic reservoirs, lithologic updip pinchout reservoirs. They appears "tectonic - lithology– tectonic-lithology" change rule from bottom to top.Through comprehensive research of the hydrocarbon source conditions, assemble of soure-reservior-roof, migration modes, reservoiring period and evolutionary process , hydrocarbon pooling patterns classification of this area should be focused on basin structure, sedimentary environment and trap types.The patterns can be divided into three kinds from bottom to top: reverse fault against the lower uplift hydrocarbon pooling patterns, the representative reservoirs are northern subsags of eastern sag in South Bell Depression,northern subsag of central sag in Tanan Depression and western buried hill fault zone of Tanan Depression; conversion parts of subsags-fan body hydrocarbon pooling patterns, the representative reservoirs are southern subsags of eastern sag in Tanan Depression; reverse fault control secondary hydrocarbon pooling patterns , the representative reservoirs are Ta19-67—Ta19-69 oil accumulation zone of Damoguaihe Formation in South Bell and oil accumulation zone of Damoguaihe Formation in central sag of Tanan Depression.