The Main Tectonic Movement And The Types Of Traps Of The North Of Caohu Area Of Tarim Basin

In this article, with the guide of multidisciplinary theory, on the basis of previous research results, well drilling and logging data and seismic data, using basic theories as petroleum geology, seismic stratigraphy and tectonics, focusing on structural evolution process, deformation feature, fracture interpretation and fracture system, the author studied the geological conditions and trap types of Caohu Depression in Tarim Basin, especially the tectonic evolution and the structural characteristics, and got the achievement below:1. The area has experienced multiple tectonic movements: Caledonian, Hercynian, Indo-China and Yanshan, in which early Hercynian has great impact on the area, but Indo-Chinese has the largest impact. the reformation of the multiple tectonic movements lead evolutionary process of Caohu area to be complicated.2. On the basis of previous studies, the structural feature of Caohu area was carefully explained. the result is that the nowadays structure of the main horizon of Caohu Area is more clear:①the nowadays structural feature of the top of the Cambrian(T80) is: in Korla nose it is east to west plunge of the nose-shaped bulge, its southern margin is the Baliying faults and Caohu depression, its northern margin is Luntai faults and contact with Luntai fault bulge, at the east of Puhui it is a southern slop.②the nowadays structural feature of the top of the Middle-Ordovician(T74) shows that it is high in its north, low in its south, high in its east and west, and low in its center. There are a series of large-scale noselike secondary bulge and sone small-scale noselike structural zone.③the nowadays structural feature of the top of the Upper-Ordovician(T70) is that its southwest slope has two northeast direction noselike secondary secondary bulges.④the nowadays structural feature of the top of the Silurian(T60) turns from slop to depression. the center of the depression is the downthrow blok o f Baliying fault, which surrounding descent to the center, and its south is bositan low-beam and then Mangier depression.⑤t he top of the Devonian(T57) east-river sandstones mainly located in some part of Caohu depression, which is to the of well Cao2#-Yuqi8#, and overlap piching out to east and north, pich out to the west and form porosity trap.3. The feature of faults: the fracture in Caohu area is relatively developed, including NWW, nearly EW and NE-NNE group of faults. On the SN and NE-SW direction there are compression in both directions, which form pression and transpression faults. The breakthrough formations are mostly on the unconformable surface of Mesozoic and ante-Mesozoic, including Palaeozoic and Mesozoic structural layers. The faults grow different in different district in the plane.4. After interpretation and comprehensive study, new discovery and awareness has been acquired:①t he fault Puhui1# is detected and confirmed, which actived in Haixi-Yanshan period. In the south of the Caohu area, the East-ManjiaerⅠb lock of Mangier depression has onlap phenomenon along Md-N415 line and on T70 unconformable surface, its direction is to the south. The Silurian layers are thinner to the south, which might become onlap trap. It is shown that the ancient-city-ruins uplift in the south of Manjiaer depression is initially formed under the Middle JialidongⅡtectonic action, which has certain control action to its overlying Silurian.③t he boundary line of the top of Middle/Lower Ordovician(T74) has been adjusted. After that, the thickness of T74-T90 layers are more harmonize and proper. the layer's upper and lower reflecance signature are more obvious, the upper is foreset reflection, and the lower is paralleling continuous reflection.④according to the plane analysis of MD-E348 line T50 surface, there is overlap from south to north in the Triassic layers, which shows that the north is higher and control the sedment of Triassic, and there might be souce in the south.