Study On The Hydrocarbon Accumulation Periods Of Reservoirs In The Transitional Zone Between The Awati And Manjiaer Depressions,tarim Basin

The study of hydrocarbon accumulation period in the transitional zone between the Awati and Manjiaer depressions,Tarim Basin is helpful to restore the hydrocarbon accumula t io n process.Based on the data of geology,geochemistry,seismology,analysis and testing,restor ing the hydrocarbon generation history of source rocks by means of basin simulation technology and combining with reservoir burial history and fluid inclusion analysis,the hydrocarbon accumulation periods of reservoirs in the transitional zone between the Awati and Manjiaer depressions,Tarim Basin were determined comprehensively,and the differences of hydrocarbon accumulation periods in different areas were clarified.Lower Cambrian source rocks and Middle-Upper Ordovician source rocks are developed in Paleozoic in the study area.Lower Cambrian hydrocarbon source rocks are distributed in Manjiaer depression and Awati depression.Middle-late Caledonian,Medium Hercynian and Late Yanshanian-Himalayan are the three main hydrocarbon generation periods.Manjiaer depression and Awati depression enter the gas generation stage in the middle and late Hercynia n,respectively.The hydrocarbon generation time of Awati depression is slightly later than that of Manjiaer depression;Middle-Upper Ordovician hydrocarbon source rocks are mainly distributed in Manjiaer depression,Awati depression and Shuntoguole low uplift.They keep the hydrocarbon generation from the Middle Caledonian to present continuously.Manjiaer depression entered gas generation stage from the late Himalayan.The source rocks of Shuntoguole low uplift have been in the low mature stage,and the thermal evolution degree is lower than that of the adjacent depression.The Ordovician reservoirs show three phases of hydrocarbon inclusions.Hydrocarbon inclusions of the first stage mainly locate in early granular calcite cements and granular calcite cements with micro-fracture enlarged pore,which are sporadic or group distribution,with dark yel ow and yellow fluorescence and homogenization temperature distribution ranging from 70 to 80 ?.Hydrocarbon inclusions of the second stage mostly locate in conjugated calcite cements,with yel ow-green and blue-green fluorescence and homogenization temperature distribution ranging from 110 to 130 ?.Hydrocarbon inclusions of the third stage locate in coarse-grained mosaic calcite cements and continuous crystal calcite cements in caves,with blue and blue-white fluorescence and homogenization temperature distribution ranging from140-160 ?.Through the employment of homogenization temperature projected on a burial history diagram,three accumulation periods are determined:middle and late Caledonian,late Hercynian and late Himalayan.There are differences in accumulation ranges in different accumulation periods.The middle and late Caledonian reservoir-forming range is the smal est,while the late Hercynia n and late Himalayan reservoir-forming range are relatively large,almost cover the whole area,which are the main accumulation periods.The time of petroleum reservoirs generated in Aiding area is late Caledonian;The times of petroleum reservoirs generated in Tuofutai area of Tabei,Eastern Shunbei area and Shunxi-Shuntuo area are late Caledonian,late Hercynian and late Himalayan;The times of petroleum reservoirs generated in Yuejin area,western Shunbei area and Shunnan area are late Hercynian and late Himalayan;The times of petroleum reservoirs generated in Gucheng area is late Himalayan.