Ordovician Buried Hill Reservoir Of The Formation Mechanism

The buried-hill of Ordovician carbonate rock in Lunnan area was tectoniclly located on the middle-east portion of northern uplift of Tarim Basin. This region was uplifted for a long period, making it a district for migration and accumulation of petroleum. The oil and gas recovered from this region mostly originated from the Cambrian and Lower Ordovician source rock. In this area, the buried-hill of Ordovician carbonate rock is buried deep, the source rocks are very old in geological history and their hydrocarbon generation time is early. The accumulation time of petroleum is also early. With multi-period tectonic evolvements, the physical properties of petroleum accumulated there differ from each other greatly and its distribution is hardly commanded. Moreover, the seismic data are not good in quality, the reservoir inhomogeneity is strong and the good reservoirs are not easy to predict, therefore the petroleum exploration risk is very high.In order to find more petroleum reserves, it is necessary to conduct detail and system researches on the accumulation and distribution of petroleum in Ordovician carbonate rock reservoir in this region, especially on its oil and gas source. Under the guidance of petroleum system, , the research on the genesis of Ordovician carbonate rock reservoir was made with the means of reservoir geochemistry. Based on the correct source rocks, tectonic evolution history, reservoir pore evolution history and all the geochemical evidences of petroleum migration and accumulation, the comprehensive researches were carried out on the reservoir formation of oil and gas to - understand the time of petroleum accumulation, distribution and the genesis of the petroleum with different physical property, and to establish finally the mode of petroleum accumulation. In combination with other research results, the prediction of potential exploration prospect was made to guide the exploration. There are the following newly created results in this thesis:1) The standard was broken out that the biomarker is the traditional, only, and most qualified compound the correlation of oil and gas. The role of the biomarker was challenged. A whole series of correlation methods and theory were established to study the oil and gas in the area with multi-period migration and accumulation.2) It is the first time that the source of oil and gas in the area was studied in detail and it concluded that the dominated source rock is Cambrian and Lower Ordovician. It is the most important result in the exploration of petroleum in this region. This idea can explain the distribution of petroleum better and has an importantrole in the exploration in this region. .3) It is pointed out first that the petroleum with different physical properties iscontrolled by the faults.