Quantitative Study On The Generation Degradation Gas Of Crude Oil

The crude oil degraded by bacteria that is also called heavy oil degraded by bacteria or gas degraded by bacteria is formed by the crude oil suffering the anaerobic microbial degradation, including methane primarily and another gas such as carbon dioxide. The crude oil degraded by bacteria that belongs to the secondary natural gas resource distributes in the shallow layer.Base on the massive domestic and foreign studying the mechanism and in the controlling factor to crude oil degraded by bacteria. It was further studied the infection factor of forming the crude oil degraded by bacteria. These factors include oil-water interface position, characteristic of Formation Water, characteristic of the reservoir, the stratum of Oxidation-Reduction and so on.In this study, we adopt the material-balance method model and establish Quantitative Calculation Method of crude oil degraded by bacteria in the first time. In the model process, two steps to complete. First, According to the various relations and constraints condition in the initial state of the degradation of crude oil composition change between initial state and final state, establishes the crude oil degeneration process various group composition losses computation model and the computational method, quantitative Calculation the he crude oil degeneration process various group composition losses. Second, crude oil degraded by bacteria and biological gas generated by chemical reaction process under different redox conditions, as well as the material-balance method, establish a compute method of various groups in the crude oil degraded by bacteria. In this way, according to the loss of crude oil degradation process of the number of various groups, it is quantitatively calculated the generated gas amount of degradation.Based on the above model established, it has been carried on the practical application in mid-shallow layer of the north basins of Songliao. Computes the total amount of crude oil degraded by bacteria in the area. According to the characteristics of existing data for basins of Songliao, carries on the simple point computation to each crude oil or the oil sand sample, then carries on the statistics to sample in identical local and the layers, obtains this area crude oil degeneration distributed and the corresponding crude oil degeneration to produce the being gas rate distribution, then the gas production rate with the crude oil amount of resources multiplication in identical local, obtains the gas production rate distribution. Through the above method computation, the result: Under the 50% probability confidence level, the total amount of crude oil degraded by bacteria is 7.06×1011m3, mainly in uplift Taikang, Xizhao as well as Putaohua area, amount of crude oil degraded by bacteria respectively is 4.21×1011m3, 1.96×1011m3, 0.88×1011m3 in the above three area.