Bent-housing motor is the most widely used directional drilling tool,but it often encounters the problem of high friction when sliding drilling in horizontal wells.In this paper,a mathematical model is proposed to sim...Bent-housing motor is the most widely used directional drilling tool,but it often encounters the problem of high friction when sliding drilling in horizontal wells.In this paper,a mathematical model is proposed to simulate slide drilling with a friction reduction tool of axial vibration.A term called dynamic effective tractoring force(DETF)is defined and used to evaluate friction reduction effectiveness.The factors influencing the DETF are studied,and the tool placement optimization problem is investigated.The studyfinds that the drilling rate of penetration(ROP)can lower the DETF but does not change the trend of the DETF curve.To effectively work,the shock tool stiffness must be greater than some critical value.For the case study,the best oscillating frequency is within 15∼20 Hz.The reflection of the vibration at the bit boundary can intensify or weaken the friction reduction effec-tiveness,depending on the distance between the hydraulic oscillator and the bit.The optimal placement position corresponds to the plateau stage of the DETF curve.The reliability of the method is verified by thefield tests.The proposed method can provide a design and use guide to hydraulic oscillators and improve friction reduction effectiveness in horizontal wells.展开更多
The mould friction is an important parameter reflecting the initial shell and mould lubrication conditions.The research of mould friction is very important to the optimization and developing of continuous casting.The ...The mould friction is an important parameter reflecting the initial shell and mould lubrication conditions.The research of mould friction is very important to the optimization and developing of continuous casting.The measured mould friction under hydraulic oscillation mode was researched with wavelet analysis to reveal its time-frequency characteristics.Firstly,the mould friction signals under different production conditions were monitored and the mould friction was calculated.Then,mother wavelet function was selected from three wavelet functions which were chosen preliminary according to the characteristics of mould friction and wavelet theory.Through wavelet transformation,mould friction signal was projected onto the wavelet domain,and the time-frequency characteristics of mould friction under different production conditions were obtained and discussed.Mould friction under different production conditions such as different oscillation mode,casting speed fluctuation,increasing and decreasing stage of casting speed and breakout occurrence was reported in detail in the wavelet time-frequency maps.The characteristics of mould friction were reflected well through wavelet transformation which proved that wavelet analysis had a good feasibility for mould friction study and can further reveal the nature of mould friction.展开更多
文摘Bent-housing motor is the most widely used directional drilling tool,but it often encounters the problem of high friction when sliding drilling in horizontal wells.In this paper,a mathematical model is proposed to simulate slide drilling with a friction reduction tool of axial vibration.A term called dynamic effective tractoring force(DETF)is defined and used to evaluate friction reduction effectiveness.The factors influencing the DETF are studied,and the tool placement optimization problem is investigated.The studyfinds that the drilling rate of penetration(ROP)can lower the DETF but does not change the trend of the DETF curve.To effectively work,the shock tool stiffness must be greater than some critical value.For the case study,the best oscillating frequency is within 15∼20 Hz.The reflection of the vibration at the bit boundary can intensify or weaken the friction reduction effec-tiveness,depending on the distance between the hydraulic oscillator and the bit.The optimal placement position corresponds to the plateau stage of the DETF curve.The reliability of the method is verified by thefield tests.The proposed method can provide a design and use guide to hydraulic oscillators and improve friction reduction effectiveness in horizontal wells.
基金Sponsored by National Natural Science Foudation of China(51204063)Natural Science Foundation of Anhui Province of China(1308085QE72)
文摘The mould friction is an important parameter reflecting the initial shell and mould lubrication conditions.The research of mould friction is very important to the optimization and developing of continuous casting.The measured mould friction under hydraulic oscillation mode was researched with wavelet analysis to reveal its time-frequency characteristics.Firstly,the mould friction signals under different production conditions were monitored and the mould friction was calculated.Then,mother wavelet function was selected from three wavelet functions which were chosen preliminary according to the characteristics of mould friction and wavelet theory.Through wavelet transformation,mould friction signal was projected onto the wavelet domain,and the time-frequency characteristics of mould friction under different production conditions were obtained and discussed.Mould friction under different production conditions such as different oscillation mode,casting speed fluctuation,increasing and decreasing stage of casting speed and breakout occurrence was reported in detail in the wavelet time-frequency maps.The characteristics of mould friction were reflected well through wavelet transformation which proved that wavelet analysis had a good feasibility for mould friction study and can further reveal the nature of mould friction.
