Now,the static push-the-bit rotary steerable system(SRSS)developed in China is being put into field tests and primary applications.During its normal drilling,higher frictional forces generated by the static pushing fo...Now,the static push-the-bit rotary steerable system(SRSS)developed in China is being put into field tests and primary applications.During its normal drilling,higher frictional forces generated by the static pushing forces of the rotary ribs on the wellbore wall influence the weight-on-bit(WOB)transmission efficiency and the rate of penetration(ROP).In this paper,analytical models of the WOB transmission efficiency were established for the wellbore wall with and without ladders respectively based on the structure and working principle of the SRSS.And the variation rules of the WOB transmission efficiency with the nominal WOB,the frictional coefficient of wellbore wall,the pushing force and the front chamfer of the steerable rib were analyzed.And the following research results were obtained.First,the nominal WOB of this SRSS has to satisfy the minimum requirement and it is conducive to the increase of WOB transmission efficiency by increasing the nominal WOB appropriately.Second,whether there are ladders on the wellbore wall or not,the WOB transmission efficiency decreases as the total pushing forces of steerable ribs and the frictional coefficient of wellbore wall increase.And the WOB transmission efficiency in the case of wellbore wall with ladders is much lower than that without ladders.Third,if there are ladders on the wellbore wall,the front chamfer of steerable rib has a significant effect on the WOB transmission efficiency.The larger the front chamfer is,the lower the WOB transmission efficiency is(even self-locking).In conclusion,the research results play an important role in guiding the rational selection and control of the WOB at drilling site.展开更多
This paper investigated the failure cause of phantom downlinks of a flow rate detection mechanism in a rotary steerable system and developed a prevention algorithm.Downlinking is the process of controlling a drilling ...This paper investigated the failure cause of phantom downlinks of a flow rate detection mechanism in a rotary steerable system and developed a prevention algorithm.Downlinking is the process of controlling a drilling tool from the surface by sending commands to downhole.Directional drillers send downlinks to the rotary steerable system to adjust steering parameters to achieve the desired well plan.The downlink demodulation of downhole tools is achieved through the measurement of flow rate and correlation of waveform with predefined command models;downlink acceptance is based on the correlation rate.One case study revealed that phantom downlinks were due to the variation of turbine rotation speed,which was the result of alternator load changes.A prevention algorithm of conducting a signal energy check was proposed and implemented.The algorithm can successfully prevent phantom downlinks that are usually of low-level energy and only accept authentic downlinks.The work improved the downlinking reliability of the rotary steerable system.This methodology can be further applied to other downlink demodulation mechanisms using collar speed or pressure measurement.展开更多
基金Project supported by the National Research Council of Science and Technology Major Project“Rotary Steering System Research and Development”(No.:2016ZX05022-002)the Surface Project of the National Natural Science Foundation of China“Study on Borehole Collission Prevention Mechanism Based on Magnetic Field Distribution and Passive Magnetic Ranging of Downhole Casing String”(No.:51674284)the Changjiang Scholars and Innovative Team Development Program of the Ministry of Education of the People's Republic of China.
文摘Now,the static push-the-bit rotary steerable system(SRSS)developed in China is being put into field tests and primary applications.During its normal drilling,higher frictional forces generated by the static pushing forces of the rotary ribs on the wellbore wall influence the weight-on-bit(WOB)transmission efficiency and the rate of penetration(ROP).In this paper,analytical models of the WOB transmission efficiency were established for the wellbore wall with and without ladders respectively based on the structure and working principle of the SRSS.And the variation rules of the WOB transmission efficiency with the nominal WOB,the frictional coefficient of wellbore wall,the pushing force and the front chamfer of the steerable rib were analyzed.And the following research results were obtained.First,the nominal WOB of this SRSS has to satisfy the minimum requirement and it is conducive to the increase of WOB transmission efficiency by increasing the nominal WOB appropriately.Second,whether there are ladders on the wellbore wall or not,the WOB transmission efficiency decreases as the total pushing forces of steerable ribs and the frictional coefficient of wellbore wall increase.And the WOB transmission efficiency in the case of wellbore wall with ladders is much lower than that without ladders.Third,if there are ladders on the wellbore wall,the front chamfer of steerable rib has a significant effect on the WOB transmission efficiency.The larger the front chamfer is,the lower the WOB transmission efficiency is(even self-locking).In conclusion,the research results play an important role in guiding the rational selection and control of the WOB at drilling site.
基金by the Scientific Research Program Funded by Shaanxi Provincial Education Department(Grant No.20JS125).
文摘This paper investigated the failure cause of phantom downlinks of a flow rate detection mechanism in a rotary steerable system and developed a prevention algorithm.Downlinking is the process of controlling a drilling tool from the surface by sending commands to downhole.Directional drillers send downlinks to the rotary steerable system to adjust steering parameters to achieve the desired well plan.The downlink demodulation of downhole tools is achieved through the measurement of flow rate and correlation of waveform with predefined command models;downlink acceptance is based on the correlation rate.One case study revealed that phantom downlinks were due to the variation of turbine rotation speed,which was the result of alternator load changes.A prevention algorithm of conducting a signal energy check was proposed and implemented.The algorithm can successfully prevent phantom downlinks that are usually of low-level energy and only accept authentic downlinks.The work improved the downlinking reliability of the rotary steerable system.This methodology can be further applied to other downlink demodulation mechanisms using collar speed or pressure measurement.
