The supercritical carbon dioxide （SC-CO2） drilling is a novel drilling technique developed in recent years. A detailed study of temperature and pressure distributions of the SC-CO2 jet on the bottom of a well is ess...The supercritical carbon dioxide （SC-CO2） drilling is a novel drilling technique developed in recent years. A detailed study of temperature and pressure distributions of the SC-CO2 jet on the bottom of a well is essensial to the SC-CO2 drilling. In this paper, the distributions of pressure and temperature on the bottom of the hole during the SC-CO2 jet drilling are simulated experimentally and numerically, and the impacts of the nozzle diameter, the jet length, and the inlet pressure of the SC-CO2 jet are analyzed. It is shown that, the bottom hole temperature and pressure increase with the increase of the nozzle diameter, and the bottom hole temperature reduces and the pressure increases first and then decreases with the increase of the jet length, indicating that the jet length has an optimum value. The increase of the inlet pressure can increase the temperature and pressure on the bottom, which has a positive effect on the drilling rate.展开更多
Although several theoretical calculation methods for high-pressure jet are available,there is currently no theoretical model for the high-pressure CO_(2)jet based on the high-precision equation of state(EOS).To invest...Although several theoretical calculation methods for high-pressure jet are available,there is currently no theoretical model for the high-pressure CO_(2)jet based on the high-precision equation of state(EOS).To investigate the flow field of the high-pressure CO_(2)jet in cases of the composite rock-breaking under the high-pressure CO_(2)Jet and PDC cutter,a semi-analytical approach of the high-pressure CO_(2)jet is developed based on the Span-Wagner EOS and CO_(2)jet theory.The semi-analytical calculations and the physical property calculations under the action of the high-pressure CO_(2)jet are conducted with consideration of the jet pressure,the jet distance,the nozzle diameter and the jet angle.The results indicate that the distribution of the physical properties calculated by the semi-analytical approaches is similar to that obtained by experimental monitoring and numerical simulation,which indicates that the calculation method of the high-pressure CO_(2)jet presented in this paper is effective and reliable.The properties of the CO_(2)jet obtained by the theoretical calculation see a significant difference between the initial region and the jet impact region.At the temperature of 300 K,the increase of the initial pressure can effectively increase the impact force and the cooling ability of the jet.The proportion of the jet core lengths in the jet on the axis increases with the increase of the ratio of the nozzle diameter to the jet length,accompanied with the increase of the impact force of the jet.The increase of the jet angle can effectively increase the impacting force of the jet,but hampers the fluid diffusion.The study combines the theoretical calculation of the jet with the calculation of the physical properties of the high-pressure CO_(2),for comprehensively understanding the CO_(2)jet field in the composite rock-breaking under the action of the high-pressure CO_(2)jet and PDC cutter.This theoretical calculation of the CO_(2)jet based on the high-precision EOS provides an option for the convenient calc展开更多
An atmospheric-pressure carbon dioxide(CO_2) plasma jet(CPJ) produced by alternating current driven non-thermal arc plasma torch is presented.The discharge features of CPJ and their non-linear behavior are analyzed ba...An atmospheric-pressure carbon dioxide(CO_2) plasma jet(CPJ) produced by alternating current driven non-thermal arc plasma torch is presented.The discharge features of CPJ and their non-linear behavior are analyzed based on the temporal evolution of voltage and current.With the increase of gas flowrate,the quantities of the current and voltage spikes increase in an operation cycle of power supply.The spatial gas temperature distribution is obtained by the gray value method,which basically agrees well with that of determined by the diatomic molecule of OH fitting method in experimental errors.展开更多
基金supported by the Major State Basic Research Development Program of China(Grant No.2014CB239202,2010CB226700)the National Natural Science Foundation of China(Grant No.51034007)the Natural Science Foundation of Shandong Province(Grant No.ZR2011EEZ003)
文摘The supercritical carbon dioxide （SC-CO2） drilling is a novel drilling technique developed in recent years. A detailed study of temperature and pressure distributions of the SC-CO2 jet on the bottom of a well is essensial to the SC-CO2 drilling. In this paper, the distributions of pressure and temperature on the bottom of the hole during the SC-CO2 jet drilling are simulated experimentally and numerically, and the impacts of the nozzle diameter, the jet length, and the inlet pressure of the SC-CO2 jet are analyzed. It is shown that, the bottom hole temperature and pressure increase with the increase of the nozzle diameter, and the bottom hole temperature reduces and the pressure increases first and then decreases with the increase of the jet length, indicating that the jet length has an optimum value. The increase of the inlet pressure can increase the temperature and pressure on the bottom, which has a positive effect on the drilling rate.
基金This work was supported by the Sichuan Science and Technology Program(Grant No.2021JDRC0114)the Starting Project of Southwest Petroleum University(Grant No.2019QHZ009)+2 种基金the China Postdoctoral Science Foundation(Grant No.2020M673285)the Open Project Program of Key Laboratory of Groundwater Resources and Environment,Ministry of Education,Jilin University(Grant No.202005009KF)the Chinese Scholarship Council funding(Grant No.202008515107).
文摘Although several theoretical calculation methods for high-pressure jet are available,there is currently no theoretical model for the high-pressure CO_(2)jet based on the high-precision equation of state(EOS).To investigate the flow field of the high-pressure CO_(2)jet in cases of the composite rock-breaking under the high-pressure CO_(2)Jet and PDC cutter,a semi-analytical approach of the high-pressure CO_(2)jet is developed based on the Span-Wagner EOS and CO_(2)jet theory.The semi-analytical calculations and the physical property calculations under the action of the high-pressure CO_(2)jet are conducted with consideration of the jet pressure,the jet distance,the nozzle diameter and the jet angle.The results indicate that the distribution of the physical properties calculated by the semi-analytical approaches is similar to that obtained by experimental monitoring and numerical simulation,which indicates that the calculation method of the high-pressure CO_(2)jet presented in this paper is effective and reliable.The properties of the CO_(2)jet obtained by the theoretical calculation see a significant difference between the initial region and the jet impact region.At the temperature of 300 K,the increase of the initial pressure can effectively increase the impact force and the cooling ability of the jet.The proportion of the jet core lengths in the jet on the axis increases with the increase of the ratio of the nozzle diameter to the jet length,accompanied with the increase of the impact force of the jet.The increase of the jet angle can effectively increase the impacting force of the jet,but hampers the fluid diffusion.The study combines the theoretical calculation of the jet with the calculation of the physical properties of the high-pressure CO_(2),for comprehensively understanding the CO_(2)jet field in the composite rock-breaking under the action of the high-pressure CO_(2)jet and PDC cutter.This theoretical calculation of the CO_(2)jet based on the high-precision EOS provides an option for the convenient calc
文摘An atmospheric-pressure carbon dioxide(CO_2) plasma jet(CPJ) produced by alternating current driven non-thermal arc plasma torch is presented.The discharge features of CPJ and their non-linear behavior are analyzed based on the temporal evolution of voltage and current.With the increase of gas flowrate,the quantities of the current and voltage spikes increase in an operation cycle of power supply.The spatial gas temperature distribution is obtained by the gray value method,which basically agrees well with that of determined by the diatomic molecule of OH fitting method in experimental errors.
