In the design of a shale-gas cluster horizontal well,it is necessary to consider the bypass of the fracturing influence domains of existing wells and the interference between fracturing influence domains when the well...In the design of a shale-gas cluster horizontal well,it is necessary to consider the bypass of the fracturing influence domains of existing wells and the interference between fracturing influence domains when the wellbore trajectories of infill adjustment wells in the fracturing areas are designed.In order to quickly evaluate the rationality of the design scheme of fracturing wellbore trajectory in an infill adjustment well,this paper adopted the vector algebra method to build a geometric model of the obstacles in the shale gas fracturing area.In this geometric model,the influence domains of hydraulic fractures are taken into account.Then,based on this geometric model,the optimization design model of bypass trajectory in the shale gas fracturing area was established by taking the minimization of total trajectory length and trajectory potential energy as the optimization objective and the anti-collision between trajectories as the constraint.Besides,the geometric check method to judge if there is any interference between fracturing influence domains was provided.Finally,the established optimization design model was verified based on the actual drilling data of Fuling Shale Gas Field in the Sichuan Basin.And the following research results were obtained.First,the obstacle sizes in fracturing areas will be seriously underestimated if the fracturing influence domains are neglected.Second,if the fracturing influence domains are neglected,the designed bypass trajectory can bypass the wellbore trajectories of old wells,but may intersect the fracturing influence domains of existing wells,thus inducing drilling accidents.In conclusion,the proposed optimization design model of bypass trajectory in the shale gas fracturing area can satisfy the constraint of anti-collision and bypass and achieve the optimization objective of minimizing total trajectory length and trajectory potential energy,and the corresponding design calculation avoids complex calculation and check.展开更多
Space debris have become exceedingly dangerous over the years as the number of objects in orbit continues to increase.Active debris removal(ADR)missions have gained significant interest as effective means of mitigatin...Space debris have become exceedingly dangerous over the years as the number of objects in orbit continues to increase.Active debris removal(ADR)missions have gained significant interest as effective means of mitigating the risk of collision between objects in space.This study focuses on developing a multi-ADR mission that utilizes controlled reentry and deorbiting.The mission comprises two spacecraft:a Servicer that brings debris to a low altitude and a Shepherd that rendezvous with the debris to later perform a controlled reentry.A preliminary mission design tool(PMDT)was developed to obtain time and fuel optimal trajectories for the proposed mission while considering the effect of J2,drag,eclipses,and duty cycle.The PMDT can perform such trajectory optimizations for multi-debris missions with computational time under a minute.Three guidance schemes are also studied,taking the PMDT solution as a reference to validate the design methodology and provide guidance solutions to this complex mission profile.展开更多
This paper investigates the heliocentric time-optimal rendezvous performance of Sun-facing diffractive solar sails with various deflection angles and acceleration capabilities.Diffractive solar sails,which generate ta...This paper investigates the heliocentric time-optimal rendezvous performance of Sun-facing diffractive solar sails with various deflection angles and acceleration capabilities.Diffractive solar sails,which generate tangential radiation pressure force,are proposed and schematically designed to achieve diverse radiation pressure distributions.The radiation pressure force model and the time-optimal control problem for these innovative Sun-facing diffractive solar sails are established.Utilizing an indirect method and the optimal control law,we explore typical heliocentric rendezvous scenarios to assess the variational trends of transfer time in relation to different deflection angles and acceleration capabilities.The results for Sun-facing diffractive sails in specific rendezvous missions are compared to reflective sails with the same area-to-mass ratio,focusing on transfer trajectory and attitude control.Our findings reveal that diffractive sails exhibit significant advantages over reflective sails,particularly in the context of normal acceleration,paving the way for more efficient space exploration.展开更多
文摘In the design of a shale-gas cluster horizontal well,it is necessary to consider the bypass of the fracturing influence domains of existing wells and the interference between fracturing influence domains when the wellbore trajectories of infill adjustment wells in the fracturing areas are designed.In order to quickly evaluate the rationality of the design scheme of fracturing wellbore trajectory in an infill adjustment well,this paper adopted the vector algebra method to build a geometric model of the obstacles in the shale gas fracturing area.In this geometric model,the influence domains of hydraulic fractures are taken into account.Then,based on this geometric model,the optimization design model of bypass trajectory in the shale gas fracturing area was established by taking the minimization of total trajectory length and trajectory potential energy as the optimization objective and the anti-collision between trajectories as the constraint.Besides,the geometric check method to judge if there is any interference between fracturing influence domains was provided.Finally,the established optimization design model was verified based on the actual drilling data of Fuling Shale Gas Field in the Sichuan Basin.And the following research results were obtained.First,the obstacle sizes in fracturing areas will be seriously underestimated if the fracturing influence domains are neglected.Second,if the fracturing influence domains are neglected,the designed bypass trajectory can bypass the wellbore trajectories of old wells,but may intersect the fracturing influence domains of existing wells,thus inducing drilling accidents.In conclusion,the proposed optimization design model of bypass trajectory in the shale gas fracturing area can satisfy the constraint of anti-collision and bypass and achieve the optimization objective of minimizing total trajectory length and trajectory potential energy,and the corresponding design calculation avoids complex calculation and check.
基金supported by the Ministry of Business,Innovation and Employment(MBIE)study:Astroscale/Rocket Lab/Te Punaha Atea-Space Institute Active Debris Removal Study。
文摘Space debris have become exceedingly dangerous over the years as the number of objects in orbit continues to increase.Active debris removal(ADR)missions have gained significant interest as effective means of mitigating the risk of collision between objects in space.This study focuses on developing a multi-ADR mission that utilizes controlled reentry and deorbiting.The mission comprises two spacecraft:a Servicer that brings debris to a low altitude and a Shepherd that rendezvous with the debris to later perform a controlled reentry.A preliminary mission design tool(PMDT)was developed to obtain time and fuel optimal trajectories for the proposed mission while considering the effect of J2,drag,eclipses,and duty cycle.The PMDT can perform such trajectory optimizations for multi-debris missions with computational time under a minute.Three guidance schemes are also studied,taking the PMDT solution as a reference to validate the design methodology and provide guidance solutions to this complex mission profile.
基金supported by the National Natural Science Foundation of China(Grant No.12372044).
文摘This paper investigates the heliocentric time-optimal rendezvous performance of Sun-facing diffractive solar sails with various deflection angles and acceleration capabilities.Diffractive solar sails,which generate tangential radiation pressure force,are proposed and schematically designed to achieve diverse radiation pressure distributions.The radiation pressure force model and the time-optimal control problem for these innovative Sun-facing diffractive solar sails are established.Utilizing an indirect method and the optimal control law,we explore typical heliocentric rendezvous scenarios to assess the variational trends of transfer time in relation to different deflection angles and acceleration capabilities.The results for Sun-facing diffractive sails in specific rendezvous missions are compared to reflective sails with the same area-to-mass ratio,focusing on transfer trajectory and attitude control.Our findings reveal that diffractive sails exhibit significant advantages over reflective sails,particularly in the context of normal acceleration,paving the way for more efficient space exploration.
