Due to the high price and formation damage of the guargum fracturing fluid, many oilfields are more and more interested in surfactant based fracturing fluids. The rheological properties of erucicamide dimethyl amidopr...Due to the high price and formation damage of the guargum fracturing fluid, many oilfields are more and more interested in surfactant based fracturing fluids. The rheological properties of erucicamide dimethyl amidopropyl betaine （EDAB）-HC1 acid blended system and its suitability as fracturing fluid were investigated in this work. The effects of pH, concentration of EDAB, and temperature on the rheological properties of the blended system were studied. The results show that addition of EDAB improved the viscosity of the system from less than 10 mPa. s to about 400 mPa. s, which could retard the acid-rock reaction to about one half at 60℃ and one quarter at 90℃ comparing to straight HC1 acid, suggesting that there is sufficient time for the blended fluid to react with formation rock when it is used as fracturing fluid in an oil field. Core flow tests demonstrated that the EDAB-acid blended fluid could divert itself from high permeability formation core to low permeability one, thus ensuring proper acid placement in the target reservoirs.展开更多
Cracking gas compressor is usually a centrifugal compressor. The information on the performance of a centrifugal compressor under all conditions is not available, which restricts the operation optimization for compres...Cracking gas compressor is usually a centrifugal compressor. The information on the performance of a centrifugal compressor under all conditions is not available, which restricts the operation optimization for compressor. To solve this problem, two back propagation (BP) neural networks were introduced to model the performance of a compressor by using the data provided by manufacturer. The input data of the model under other conditions should be corrected according to the similarity theory. The method was used to optimize the system of a cracking gas compressor by embedding the compressor performance model into the ASPEN PLUS model of compressor. The result shows that it is an effective method to optimize the compressor system.展开更多
In this paper,the fracture problem of a functionally graded piezoelectric material strip(FGPM strip) containing two coplanar cracks perpendicular to its boundaries is considered.The problem is solved for an FGPM strip...In this paper,the fracture problem of a functionally graded piezoelectric material strip(FGPM strip) containing two coplanar cracks perpendicular to its boundaries is considered.The problem is solved for an FGPM strip that is suddenly heated from the bottom surface under static mechanical loading.The top surface is maintained at the initial temperature.The crack faces are supposed to be completely insulated.Material properties are assumed to be exponentially dependent on the distance from the bottom surface.By using the Laplace and Fourier transforms,the thermoelectromechanical fracture problem is reduced to a set of singular integral equations,which are solved numerically.The stress intensity factors for the cases of the two embedded cracks,two edge cracks,and an embedded crack and an edge crack are computed and presented as a function of the normalized time,the nonhomogeneous and geometric parameters.展开更多
基金Supported by the Fundamental Research Funds for the Central Universities(2652013107)the Laboratory Open Funds of China University of Geosciences(Beijing)
文摘Due to the high price and formation damage of the guargum fracturing fluid, many oilfields are more and more interested in surfactant based fracturing fluids. The rheological properties of erucicamide dimethyl amidopropyl betaine （EDAB）-HC1 acid blended system and its suitability as fracturing fluid were investigated in this work. The effects of pH, concentration of EDAB, and temperature on the rheological properties of the blended system were studied. The results show that addition of EDAB improved the viscosity of the system from less than 10 mPa. s to about 400 mPa. s, which could retard the acid-rock reaction to about one half at 60℃ and one quarter at 90℃ comparing to straight HC1 acid, suggesting that there is sufficient time for the blended fluid to react with formation rock when it is used as fracturing fluid in an oil field. Core flow tests demonstrated that the EDAB-acid blended fluid could divert itself from high permeability formation core to low permeability one, thus ensuring proper acid placement in the target reservoirs.
基金Supported by the National Natural Science Foundation of China (20976048, 21176072)the Fundamental Research Funds for the Central Universities
文摘Cracking gas compressor is usually a centrifugal compressor. The information on the performance of a centrifugal compressor under all conditions is not available, which restricts the operation optimization for compressor. To solve this problem, two back propagation (BP) neural networks were introduced to model the performance of a compressor by using the data provided by manufacturer. The input data of the model under other conditions should be corrected according to the similarity theory. The method was used to optimize the system of a cracking gas compressor by embedding the compressor performance model into the ASPEN PLUS model of compressor. The result shows that it is an effective method to optimize the compressor system.
文摘In this paper,the fracture problem of a functionally graded piezoelectric material strip(FGPM strip) containing two coplanar cracks perpendicular to its boundaries is considered.The problem is solved for an FGPM strip that is suddenly heated from the bottom surface under static mechanical loading.The top surface is maintained at the initial temperature.The crack faces are supposed to be completely insulated.Material properties are assumed to be exponentially dependent on the distance from the bottom surface.By using the Laplace and Fourier transforms,the thermoelectromechanical fracture problem is reduced to a set of singular integral equations,which are solved numerically.The stress intensity factors for the cases of the two embedded cracks,two edge cracks,and an embedded crack and an edge crack are computed and presented as a function of the normalized time,the nonhomogeneous and geometric parameters.
