Constant-rate mercury penetration was used to study the microscopic pore space of tight sandstone reservoir in Shahezi formation of Xujiaweizi depression, and distribution of pore and throat and their control on reservoir physical were analyzed．The results show that the distribution range of pore radius is mostly 100~200 μm and is barely influenced by reservoir physical. The correlation of pore radius and reservoir physical is not significant, thus the pore radius has the secondary control on petrophysical property. Throat radius varies greatly with the reservoir permeability, and the distribution range of throat radius tends to increase with the reservoir permeability. However, the distribution range of throat radius is no more than 5μm in value. Throat radius is correlated with porosity slightly, while it is strongly influenced by permeability, indicating that throat is the main factor that controls reservoir. The porethroat connectivity of sandy conglomerate samples is not well, with pore throat ratio ranging form 20~600. The throat favorable for reservoirs is mainly over 0.5 μm in radius and less than 200 in pore throat ratio.

        Given the frequent accidents attributed to abnormal pressure fluctuation and the less effectiveness of preventive measures of complex pipe network, the FTA method of graph theory was applied to solve this problem. Induced mechanism of abnormal pressure fluctuations was interpreted and the FTA model of pressure abnormal fluctuations in complex pipeline network was firstly proposed and established in this paper. An imported crude oil pipe network was taken as a case study by using the Delphi method and fuzzy mathematics theory to solve the model. Results agree well with the actual statistics. Then K-means clustering method was carried on to analyze the three importance of typical basic events and the three-tier structure of the abnormal fluctuations is proposed using the DTA method, which lies a theoretical basis for the analysis on abnormal events as well as the optimization of the prevention and control measures. This paper mainly offers a new research idea in the field of operation security and integrity management of the large, complex pipe network especially when the historical data is far from complete.

        In recent years, a series of pipeline leakage accidents frequently occur due to aging, corrosion and manmade damage. At present, most of related software focuses on the qualitative accidental assessment and localization of the leaking point while the study correlated with practical calculation of leakage volume is rare. An efficient quantitative calculation of the volume of leakage is essential to provide guidance for subsequent accidental management, environmental evaluation and division of the hazardous area. Connected with the alarm system and the online calculation module, a software with the function of online and offline calculation is developed on the basis of transient flow model coupled with hydraulic and thermal factors. A real case study is presented to demonstrate the relative error which is less than 5% and the results prove that it is of practical value and able to offer reference and guidance for engineers.