| Based on the research on the source rocks and the geo-chemical properties of the hydrocarbon in Duqiaobai area in Dongpu depression, this paper systematically analyzed the formation principle of the deeply buried oil and gas. The fluid properties in different injection periods were studied by analyzing geo-chemical properties of the free hydrocarbon in the pores of oil-bearing sandstone, the hydrocarbon adsorbed in grains, in inclusion enclaves, and in clay minerals. The injection periods and injection time were also studied by testing authigene K/Ar isotope and homogeneous temperature of oil and gas in inclusion enclaves. Moreover, it discussed the principle for reservoir formation and brought out the accumulating laws of hydrocarbon.Composition of natural gas is different between Baimiao and Qiaokou. though they are both wet gas. In Qiaokou area, the content of methane CH4% is less than 80%, the ratio between methane and heavy hydrocarbon is about 5, while in Baimiao area, the content of methane is more than 88%, and the ratio is more than 10. This difference is caused not only by maturity but also by source rock. Natural gas in Baimiao area is mainly derived from Tertian source rock and Carboniferous Permian formation in Qianliyuan sag, which is near the structural high on Lanliao fracture belt. The ES2-ES32 gas producing zone shallowly buried has a high value of 40Ar/36Ar, which generates coal-type gas or mixed gas: while in the lower part off the Lanliao fracture belt, ES31-ES34 gas producing zone has a low value of 40Ar/36Ar, which generates oil-type gas. The ES/ and ES34 in Qiaokou structure are mainly oil-type gas.Natural gas helium isotope analyze shows that natural gas in deep layers of Qiaokou area is of shell source. In Baimiao area gas reservoir is mainly a combination of coal-type and oil-type gas reservoir, with little mantle source helium.The correlation between oil source rock shows that oil source for the shallow ESHower ES2 in Qiaokou area mainly comes from Qianliyuan sag in the east and Haitongji sag in the west. In Qiaokou structure, well Qiaol4, 20, 23, 25, 60 are related to source rock in Gegangji sag, while oil in well Qiao38 is related to source rock in Qianliyuan sag. In Baimiao structure, oil in well Qian8 and Bai12 is related to source rock of ES33-ES34 in Qianliyuan sag; in the central of the structure, the condensate in well Bai54, 17, 9 is related to the source rock in ES32 in Qianliyuan sag and oil in well Bai16 and Bail8 is from the oil kitchen in Gegangji. oil in well Bai55 is related to the source rock in nearby ES3.Saturation hydrocarbon is high in oil and oil sand extraction in Qiaokou-Baimiao area, which is often above 80%. There is also a large amount of was in oil sand extraction, with little nonhydrocarbon and asphaltene. This suggests that the oil is high-wax in this area. By analyzing components of oil-bearing sandstone, components grain adsorption and hydrocarbon inclusion enclave, we can obtain geochemical changes of organic fluids during the processof filling, understand the reservoir formation and redistribution and get reliable analysis on reservoir formation in geologic history. Hydrocarbon inclusion enclave and grain adsorption mainly showed early phase state of reservoir fluids and pore free showed current property of fluids. For the reservoir that was restructured later after several fillings by various fluids, three fluids in thereservoir are obviously different, such as Litun gas reservoir. For the reservoir which has stable and certain source, the fluids with three phase states are not obviously different.Iillite age testing and inclusion enclave temperature testing have been used to predict the formation time of reservoir in Qiaokou-Baimiao area. The reservoir formation time in the shallow layer at the top of Qiaokou structure was 24Ma~20Ma, analogous to the end of Dongying deposit to early erosion. In the south-central, the western flank, and eastern horst area, the formation time was near 33.5Ma~20Ma, analogous to Dongying deposit to the early peri...
|
PDF Full Text Request