Analysis Of Accumulational Conditions Of Lithostratigraphy Trap And Reservoir Of Neopaleozoic In Tarim Basin

Tarim Basin located in southern Xinjiang Uygur Autonomous Region, is the largest and richest oil and gas resource of large composite basin in China. After many tectonic movements, it changed by several adding thalassogenic both horizontal and vertical. With deeper exploration, we firmly believe that the Upper Paleozoic lithostratigraphic reservoir at Tarim Basin has good prospects exploration.This thesis is based on the analysis of drilling and logging well,the explaination of earthquake,the wild outcropping and the documents of palaeophyte.Overall, this thesis is divided into three main parts. First of all, I bulid the sequence framework of Neopaleozonic on the basis of division and correlation of Sequence Layer. Second, I get a result of the location of Donghe sandstone sedimentary filling and facie. Third, I disscuss the exhibition-rules of sand-body and the development of lithostratigraphic trap.Drilling and logging well as well as the conprehensive documents of earthquake show that the Upper Paleozoic strata of rock at Tarim Basin can be divided into nine third-level sequences. As the most important one, Sq5 is a Donghetang group precipitation,which is mainly abundant in middle-west of Tarim Basin while rarely in the east.It is proved by the analysis of sedimentary facie that as a suit of sand-body developped by the sea incursion, Donghe sandstone is mainly shoreland precipitation by the reason of relatively changes of sea level.The sand-body in Donghe sandstone developped at five times and they located differently.In the middle and main-east of Tarim Basin, there are mainly the 2-times, the 3-times and the 4-times; and the 5-times is aboundant in the west.I got a recognition about the characteristics of stratigraphic trap seismic reflection based on earthquake interpretation. And I determined the stratigraphic trap development zone by combining sedimentary facies and sand-body distribution. Donghe sandstone in this area mainly developed the valley filling and overlying stratigraphic traps, and the former is distributed in the central and thesouthwest Tarim Basin, while the latter developed in the North Slope region of middle Tarim Basin and parts of the western aera of middle Tarim Basin.In the lower layer of Paleozoic Donghe Sandstone and other major stratigraphic traps , there are Cambrian gypsolyte and Upper Ordovician mudstone. So the only way to get the effective allocation between migration pathways and hydrocarbon-source kitchen is to make a fracture-cut to the source rocks. Different periods of fractures have different movement effects to different periods and different stratigraphic positions of gas. So the only way to systematic analyse the favorable development zone of stratigraphic accumulation is to combine the hydrocarbon and expulsion times of Cambrian and Ordovician hydrocarbon source rocks and the fracture forming phases and the layers.