Study On The Key Parameters Of Basin Modeling In The Upper Triassic Of Sichuan Basin

Having studied the analog parameter of the upper Triassic Xujiahe series in Sichuan basin, we get a series of useful parameters including the burial history paremeter, thermal maturity parameter, the geochemistry parameter of the resource rock and the hydrocarbon-generating kinetics parameter.Firstly, we can get some information from the burial history parameter. Since Neogene the stratum in Sichuan basin has been disintegrated about 1000m thickness, and the erosion thickness even reach 3000m in some area. Also, we can conclude that the erosion thickeness is much higher in the north and south than that in the east and west in general; The erosion of the Penglaizhen, Suining and Shaximiao Formation mainly happened in the west and middle of Sichuan basin, and the erosion thickness are all over 150m, even 500m;The upper Triassic series have not been disitegrated widely, except the stratum in the north of Deyang -Mianyang-Nanjiang section, whose erosion thickness even reach 500m.Sichuan basin is an obvious"cold basin", and the geothermal gradient ranges from 20 to 25℃.The geothermal gradient is higher in the central of Sichuan than that in the east and west, also the geothermal gradient is higer in the south than that in the north, which present apparent zonation in plane. The temperature in The Chuandong–Chuannan transition zone is always the highest in the basin, and decrese towards the margin. Compared to the geothermal gradient nowadays, the paleogeothermal gradient is much higher, ranging from 2.48℃per 100m to 4℃per 100m, with an average of 3.3℃per 100m, which indicted that in the early Sichuan basin is a basin with high geothermal gradient rather than the"cold basin", and since the Mesozoic Sichuan basin has been colder and colder.The heat flow in different time also has the zonation character in plane in Sichuan basin.Generally, the heat flow value decrease from the south-west of the basin to the northeast. The character of the value in different areas are as follows:Chuanxi and Chuannan always lie in the highest heat flow value zone, and the value of the basin decreased from the late Triassic dopositional stage to the end of the early Cretaceous depositional stage except from the Xujiahe Formation, and after the late Jurrasic depositional stage, the value keeps steady, which also indicts the lithosphere tends to thicken gradually before the late Jurrasic period,then keeps steady;The variation chatacteras of the value in the middle of Chuanxi is similar to that in the south-west of Sichuan,except a lower background value (12mWm-2), compared to the value in Chuannan;The heat flow value in Chuanbe are the lowest, not more than 50 mWm^-2;The value variation characteristic in Chuanzhong-Chuannan transition zonation is different from other areas:from the late Triassic period to the early Cretaceous period, the value increase gradually, which indicts the thickness of lithosphere is thinner and thinner in Chuanzhong.The thermal conductivity of the layers in Sichuan Basin distribute between 1.4³.326w/mk, while the average is 2.44w/mk. The plane distribution of the heat flow shows a higher value in central and southern areas than peripheral areas. The palae-heat flow decreased from both south-west to north-east and east to west.Organic carbon content is higher and quality is better in Xujiahe Formation of Sichuan Basin, organic type is mainly forⅢ, there are a certain content mixedⅡand mixedⅠkerogen in Central Sichuan Basin and South Sichuan Basin.Hydrocarbon source rocks thickness is maximum in west Sichuan Basin,and gradually thin from West Sichuan Depression to other areas of Sichuan Basin.Through test of activation energy of hydrocarbon source rock specimen, and summarize predecesser success, standardise Hydrocarbon-generating dynamic model of kind of different types, different Raw oil and gas phase hydrocarbon source rock, provide the basis for calculating amount.