Study On The Relationship Between Paleo-tectonic Evolution Of The Top Surface Of Ordovician And Oil-Gas In The Northern Tarim Basin

In recent years,denudation and palaeotectonic research of Tarim Basin are concerned widely.Northern Tarim Basin is particularly important.It is very important to calculate the denudation of each period for studying paleostructure and its influence on hydrocarbon accumulation.Based on a large number of predecessors'research,guiding by drillings and logs of basic geological data in Northern Tarim Basin,integrating seismic data,the distribution characteristics of unconformity surface are analysed,denudation amount of top Ordovician?T₇⁰ unconformity?in Northern Tarim Basin during each major tectonic epochs is calculated by using the trend thickness method,palaeotectonic characteristics of T₇⁰ unconformity in each major tectonic epochs is restored by using marker layer-thickness analysis method,clarifying the palaeotectonic evolution process,and palaeotectonic evolution model in Northern Tarim Basin therefore is established.Finally,the influences of paleotectonic evolution on hydrocarbon accumulation are summarized,it was mainly known that:?1?Northern Tarim Basin is affected by the multi-period tectonic movement,there are several types of structural styles such as extrusion,tensioning,strike-slip,and muddy rock plastic fluid.And the fracture in this region is extremely developed,of which are primary NNE,NNW,and EW.North slope of Awati depression mainly develop“Y”shaped fault,Shuntuoguole lower uplift mainly develop“X”shaped conjugate fault,Kuche depression mainly develop flower-shaped fault,these faults provided an important channel for hydrocarbon migration.?2?T₇⁰ unconformity in Northern Tarim Basin is identified,the denudation amount of target layer in each corresponding tectonic period is calculated,and the corresponding denudation amount distribution is formulated.During Caledonian,the Tabei area suffered severe erosion.The denudation center is located in the uplift of the shaya,and Maximum thickness up to 1300m.In the early Hercynian period,the heavily denuded areas were mainly concentrated in the vicinity of the T₇⁰ pinch line,and the denuded thickness in the Tahe area was 150 to 300 m.In the later Hercynian era,the denudation range developed in the northwest of the TS2,and the most severely denuded point migrated northwards.In Indosinian-Yanshanian period,The extent of erosion is further reduced,mainly in Wells A1 and northwest of the TS2.In Himalayan period,only a small amount of erosion occurred the northwest of the TS2.?3?During Caledonian,the uplift of Northern Tarim Basin was buried at100-900m,and the depth of the two northern regions was between 500¹200m.In hercynian,Akekule and Shaya uplift to be shaped,the fall of the Manjiaer depression are obvious,showing that the overall characteristics is higher in the North,which is conducive to the formation of the storage space.The Hercynian period is destructive and new constructive to the storage space.In Indosinian-Yanshanian period,the buried depth of the Awati depression is 4500⁷000m,and the burial depth of the Shuntuoguole depression is 3500⁵000m,and the uplift and depression of Akekule and Awati are further shaped and developed.In Himalayan period,the burial depth of the Awati depression is 5500⁷5000m,and the burial depth of Manjiaer depression is 5500⁸500m,and the burial depth of Shuntuoguole is 4500⁵500m,and the buried depth of the Northern Tarim Basin uplift is 2500⁴500m.The multi-stage tectonic movement has formed the present tectonic characteristics in Northern Tarim Basin.