Electric submersible pumps were widely used in agricultural fields,petroleum and various other industries. The pressure pulsation caused fatigue failure due to vibration in electric submersible pump and affects the li...Electric submersible pumps were widely used in agricultural fields,petroleum and various other industries. The pressure pulsation caused fatigue failure due to vibration in electric submersible pump and affects the life and performance of its system. The objective of this study was to experimentally investigate the characteristics of pressure pulsation which were generated at various stages of a multistage electric submersible pump during closed valve operation at different speeds. An electric submersible pump with five stages was selected for conducting experiments. A variable frequency drive( VFD)was used to operate the electric submersible pump at five different speed settings from 40 to 60 Hz. Piezoresistive pressure transducers were mounted at each stage of the electric submersible pump to capture the unsteady pressure signals. At each speed setting,the electric submersible pump was operated at the shut-off condition and the signals of unsteady pressure from all the five stages were captured. A fast fourier transformation( FFT) was carried out on the pressure signals to convert into frequency domain.From the spectra of pressure pulsation signals,the characteristics of pressure pulsation are obtained for each stage and for various speed settings which were then used to understand its variation with speed and stages.展开更多
During gel treatments for fractures, the leak-off behavior of gelant has a great effect on the water shut-off performance of gel. Experiments were carried out using a polymer/chromium(Cr^(3+)) gel system to explore th...During gel treatments for fractures, the leak-off behavior of gelant has a great effect on the water shut-off performance of gel. Experiments were carried out using a polymer/chromium(Cr^(3+)) gel system to explore the leak-off behavior and the water shut-off performance of gel in fractured media. Results of the gelant leak-off study show that the gelant leak-off from fracture into matrix contributes to the formation of the gelant leak-off layer during the gelant injection. Moreover, because of the gradual formation of the gelant leak-off layer along fracture, the initial leak-off ratio of gelant is relatively high, but it declines and finally levels off with the increase of the injection volume. The polymer concentration of gelant has a great effect on the chromium output in fluids produced from fractures. With the increase of the polymer concentration, the chromium concentration first decreases and then increases, and the leak-off depth of gelant into matrix is gradually reduced. Results of the water shut-off study present that the decrease of the chromium concentration inside the fracture greatly reduces the water shut-off performance after the gel formation. Therefore, because of the relatively high degree of chromium leak-off, enough injection volume of gelant is essential to ensure the sufficient chromium concentration inside the fracture and to further achieve a favorable water shut-off performance. On the premise of gel strength assurance inside the fracture, the water shut-off performance of gel gradually declines with the extension of the distance from the fracture inlet, and different leak-off degrees of gelant along the fracture are responsible for this phenomenon. Therefore, a proper degree of gelant leak-off contributes to enhancing the water shut-off performance of gel for fractures.展开更多
Excess water production is one of the crucial complications in the oil industry,leading to a rapid decline in oil production.To overcome this problem,different polymer gels are used to block the water's path to re...Excess water production is one of the crucial complications in the oil industry,leading to a rapid decline in oil production.To overcome this problem,different polymer gels are used to block the water's path to reduce water production.In the present work,polymer gel systems were prepared with polymers namely partially hydrolyzed polyacrylamide(PHPA),organic crosslinkers like hexamine,and hydroquinone with the incorporation of silica and alumina nanoparticles.Nanoparticles are used to enhance the stability of the gel framework in high salinity and high temperature reservoir environment.When designing the polymer gel system,factors such as pH,thermal stability,brine composition,injection rate,and chemical concentration were considered.Concentrations of PHPA and nanoparticles were varied from 1 to 2 wt% and 0.25e1.0 wt% respectively for the preparation of different gel systems.The concentration of the organic crosslinker was extended from 5000 to 11000 ppm for investigating the effect on gelation time.Brine concentration was chosen from 2 to 8 wt% to find the impact of high salinity.Succinic acid as an accelerator was also used to study the effect on gelation time,and it was found that the gelation time is reduced as the concentration of succinic acid increases.The prepared polymer solution was taken in a test tube and was kept inside a hot air oven at 95℃ to perceive the gelation time and nature of the produced gel.Results showed that nanoparticles do not influence the gelation time,but they considerably affect gel stability.However,concentrations of polymer,accelerator,and salt(salinity)have significant effects on the gelation behavior of the gel systems.展开更多
文摘Electric submersible pumps were widely used in agricultural fields,petroleum and various other industries. The pressure pulsation caused fatigue failure due to vibration in electric submersible pump and affects the life and performance of its system. The objective of this study was to experimentally investigate the characteristics of pressure pulsation which were generated at various stages of a multistage electric submersible pump during closed valve operation at different speeds. An electric submersible pump with five stages was selected for conducting experiments. A variable frequency drive( VFD)was used to operate the electric submersible pump at five different speed settings from 40 to 60 Hz. Piezoresistive pressure transducers were mounted at each stage of the electric submersible pump to capture the unsteady pressure signals. At each speed setting,the electric submersible pump was operated at the shut-off condition and the signals of unsteady pressure from all the five stages were captured. A fast fourier transformation( FFT) was carried out on the pressure signals to convert into frequency domain.From the spectra of pressure pulsation signals,the characteristics of pressure pulsation are obtained for each stage and for various speed settings which were then used to understand its variation with speed and stages.
基金Project(51404280)supported by the National Natural Science Foundation of ChinaProject(2014D-5006-0203)supported by the Petro China Innovation Foundation,China
文摘During gel treatments for fractures, the leak-off behavior of gelant has a great effect on the water shut-off performance of gel. Experiments were carried out using a polymer/chromium(Cr^(3+)) gel system to explore the leak-off behavior and the water shut-off performance of gel in fractured media. Results of the gelant leak-off study show that the gelant leak-off from fracture into matrix contributes to the formation of the gelant leak-off layer during the gelant injection. Moreover, because of the gradual formation of the gelant leak-off layer along fracture, the initial leak-off ratio of gelant is relatively high, but it declines and finally levels off with the increase of the injection volume. The polymer concentration of gelant has a great effect on the chromium output in fluids produced from fractures. With the increase of the polymer concentration, the chromium concentration first decreases and then increases, and the leak-off depth of gelant into matrix is gradually reduced. Results of the water shut-off study present that the decrease of the chromium concentration inside the fracture greatly reduces the water shut-off performance after the gel formation. Therefore, because of the relatively high degree of chromium leak-off, enough injection volume of gelant is essential to ensure the sufficient chromium concentration inside the fracture and to further achieve a favorable water shut-off performance. On the premise of gel strength assurance inside the fracture, the water shut-off performance of gel gradually declines with the extension of the distance from the fracture inlet, and different leak-off degrees of gelant along the fracture are responsible for this phenomenon. Therefore, a proper degree of gelant leak-off contributes to enhancing the water shut-off performance of gel for fractures.
文摘Excess water production is one of the crucial complications in the oil industry,leading to a rapid decline in oil production.To overcome this problem,different polymer gels are used to block the water's path to reduce water production.In the present work,polymer gel systems were prepared with polymers namely partially hydrolyzed polyacrylamide(PHPA),organic crosslinkers like hexamine,and hydroquinone with the incorporation of silica and alumina nanoparticles.Nanoparticles are used to enhance the stability of the gel framework in high salinity and high temperature reservoir environment.When designing the polymer gel system,factors such as pH,thermal stability,brine composition,injection rate,and chemical concentration were considered.Concentrations of PHPA and nanoparticles were varied from 1 to 2 wt% and 0.25e1.0 wt% respectively for the preparation of different gel systems.The concentration of the organic crosslinker was extended from 5000 to 11000 ppm for investigating the effect on gelation time.Brine concentration was chosen from 2 to 8 wt% to find the impact of high salinity.Succinic acid as an accelerator was also used to study the effect on gelation time,and it was found that the gelation time is reduced as the concentration of succinic acid increases.The prepared polymer solution was taken in a test tube and was kept inside a hot air oven at 95℃ to perceive the gelation time and nature of the produced gel.Results showed that nanoparticles do not influence the gelation time,but they considerably affect gel stability.However,concentrations of polymer,accelerator,and salt(salinity)have significant effects on the gelation behavior of the gel systems.
