Research On Mechanism Of Oil And Gas Of Bell Depression

Due to former limited research, which is only confined within the area of depression, on reservoir forming rules of Hailar Basin there reaches no agreement on understanding Basin scale. Therefore this paper is based on "Reservoir-Forming Rules of Oil-Rich Rifted Basin in the Middle Part of Hailar-Tamtsag Basin", a scientific research subject which is developed by the Northeast Petroleum University entrusted by Hailar Headquarters of Petroleum Exploration and Development, Daqing Oil Field Company LTd.Hailar-Tamtsag Basin is typically fault-depressed, and its oil geological conditions are complicated, each depression is featured with multi-and near-sources, narrow and greatly changeable facies. Bell depression is the widest basin of Hailar, moreover it has been the most important oil-containing depression since discovered. However, its internal fault-constructing activity is intense, so is its fragmentation so as to diversify both migrations of oil and gas and types of reservoir. Main source rocks are in the layers of nls and tsyxd.Mainly focused on the genesis problems of petroleum, this paper studies about the features of oil and gas, and its origin and forming mechanism. With the application of GC and GC-MS, carbon isotope analytic techniques and identification techniques of composition of biomarkers, by statistical analysis of the geochemistry features of crude oil we can categorize the oil in Bell Depression. Making use of oil properties and index of maturity to further sub-divide oil, under the help of geologic data, the forming mechanism of oil and gas in Bell Depression will be found out.Firstly, getting a preliminary understanding of crude oil with application of oil properties and index of maturity, then by statistics and relevant diagrams and appended maps, we make analysis of its geochemical features, some of which are more or less consistent with that of the source rocks. Its property rests on maturity and nature of source rock. After that we take parameters of Pr/Ph, index of maturity, Ts/(Ts+Tm) and laws of∑C27 and rearranged∑C27. And it comes to a result that the oil in Bell Depression mainly comes from the source rocks of nls and tsyxd. Finally by group composition, geology data, and forming mechanism of oil and gas, with features of subjecting to accumulate near the source and short distance of lateral migration, the oil in Bell Depression is basically thought to come from the source rocks of its own. Most low mature crude oil is generated early and accumulated in the marginal area.