Down-hole tubular string buckling is the most classic and complex part of tubular string mechanics in well engineering. Studies of down-hole tubular string buckling not only have theoretical significance in revealing ...Down-hole tubular string buckling is the most classic and complex part of tubular string mechanics in well engineering. Studies of down-hole tubular string buckling not only have theoretical significance in revealing the buckling mechanism but also have prominent practical value in design and control of tubular strings. In this review, the basic principles and applicable scope of three classic research methods （the beam-column model, buck- ling differential equation, and energy method） are intro- duced. The critical buckling loads and the post-buckling behavior under different buckling modes in vertical, inclined, horizontal, and curved wellbores from different researchers are presented and compared. The current understanding of the effects of torque, boundary condi- tions, friction force, and connectors on down-hole tubular string buckling is illustrated. Meanwhile, some unsolved problems and controversial conclusions are discussed. Future research should be focused on sophisticated description of buckling behavior and the coupling effect of multiple factors. In addition, active control of down-hole tubular string buckling behavior needs some attention urgently.展开更多
With permanent down-hole gauges （PDGs） widely installed in oilfields around the world in recent years, a continuous stream of transient pressure data in real time is now available, which motivates a new round of res...With permanent down-hole gauges （PDGs） widely installed in oilfields around the world in recent years, a continuous stream of transient pressure data in real time is now available, which motivates a new round of research interests in further developing pressure transient processing and analysis techniques. Transient pressure measurements from PDG are characterized by long term and high volume data. These data are recorded under unconstrained circumstances, so effects due to noise, rate fluctuation and interference from other wells cannot be avoided. These effects make the measured pressure trends decline or rise and then obscure or distort the actual flow behavior, which makes subsequent analysis difficult. In this paper, the problems encountered in analysis of PDG transient pressure are investigated. A newly developed workflow for processing and analyzing PDG transient pressure data is proposed. Numerical well testing synthetic studies are performed to demonstrate these procedures. The results prove that this new technique works well and the potential for practical application looks very promising.展开更多
The knowledge of in situ stress is critical in safe and optimised extraction of minerals and energy resources.In situ stresses are either measured directly(e.g.overcoring)or estimated indirectly(e.g.borehole breakouts...The knowledge of in situ stress is critical in safe and optimised extraction of minerals and energy resources.In situ stresses are either measured directly(e.g.overcoring)or estimated indirectly(e.g.borehole breakouts).Borehole breakout analysis for in situ stress estimation is considered a relatively simple and cost-efficient technique.This technique,however,poses certain limitations such as complexities with progressive formation of breakouts and it requires inputs such as rock failure parameters that are not often available.As a result,significant effort has been made to develop new indirect methods for in situ stress estimation.Borehole deformation analysis using four-arm caliper has been recently proposed for in situ stress estimation and has shown promising results.In this study,we demonstrate a new methodology that analyses the borehole televiewer data with the technique of borehole deformation analysis to estimate the in situ stresses through a field case study.The advantages and challenges of using borehole televiewer data for stress estimation based on borehole deformation analysis are discussed and the best practice to obtain the reliable results is explained.The limitations of using fourarm caliper and borehole deformation analysis for in situ stress estimation are also discussed and it is shown how televiewer data can overcome such limitations.Finally,the in situ stress results obtained from televiewer data and borehole deformation analysis are compared with independent in situ stress measurements to show the robustness and reliability of the proposed methodology.展开更多
In a deep well,under high pressure and temperature,the force,deformation,and movement of the downhole string are very complicated. In this paper,based on the analysis of the working environment and load properties of ...In a deep well,under high pressure and temperature,the force,deformation,and movement of the downhole string are very complicated. In this paper,based on the analysis of the working environment and load properties of the down-hole string in deep wells,the factors of high temperature,high pressure,and the complex structure of wells have been taken into consideration. The loads of the down-hole string,stability,back buckle configuration,dynamic characteristics,mechanical strength,and deformation have been systematically studied. On this basis,mechanical models of a down-hole string under different conditions have been established and software for aiding analysis has been developed. By using this software,deep well strings under different construction parameters can be simulated and analyzed,providing a theoretical basis and method for down-hole string assembly,as well as string down-hole construction and operation.展开更多
基金the financial support from the Natural Science Foundation of China (NSFC,51221003,U1262201)the Science Foundation of China University of Petroleum,Beijing (No.00000)supported by other projects (Grant Numbers:2014A-4214,2013AA064803,2011ZX05009-005)
文摘Down-hole tubular string buckling is the most classic and complex part of tubular string mechanics in well engineering. Studies of down-hole tubular string buckling not only have theoretical significance in revealing the buckling mechanism but also have prominent practical value in design and control of tubular strings. In this review, the basic principles and applicable scope of three classic research methods （the beam-column model, buck- ling differential equation, and energy method） are intro- duced. The critical buckling loads and the post-buckling behavior under different buckling modes in vertical, inclined, horizontal, and curved wellbores from different researchers are presented and compared. The current understanding of the effects of torque, boundary condi- tions, friction force, and connectors on down-hole tubular string buckling is illustrated. Meanwhile, some unsolved problems and controversial conclusions are discussed. Future research should be focused on sophisticated description of buckling behavior and the coupling effect of multiple factors. In addition, active control of down-hole tubular string buckling behavior needs some attention urgently.
基金Science Foundation of China University of Petroleum, Beijing (No.YJRC-2011-02)for the financial support during this research
文摘With permanent down-hole gauges （PDGs） widely installed in oilfields around the world in recent years, a continuous stream of transient pressure data in real time is now available, which motivates a new round of research interests in further developing pressure transient processing and analysis techniques. Transient pressure measurements from PDG are characterized by long term and high volume data. These data are recorded under unconstrained circumstances, so effects due to noise, rate fluctuation and interference from other wells cannot be avoided. These effects make the measured pressure trends decline or rise and then obscure or distort the actual flow behavior, which makes subsequent analysis difficult. In this paper, the problems encountered in analysis of PDG transient pressure are investigated. A newly developed workflow for processing and analyzing PDG transient pressure data is proposed. Numerical well testing synthetic studies are performed to demonstrate these procedures. The results prove that this new technique works well and the potential for practical application looks very promising.
文摘The knowledge of in situ stress is critical in safe and optimised extraction of minerals and energy resources.In situ stresses are either measured directly(e.g.overcoring)or estimated indirectly(e.g.borehole breakouts).Borehole breakout analysis for in situ stress estimation is considered a relatively simple and cost-efficient technique.This technique,however,poses certain limitations such as complexities with progressive formation of breakouts and it requires inputs such as rock failure parameters that are not often available.As a result,significant effort has been made to develop new indirect methods for in situ stress estimation.Borehole deformation analysis using four-arm caliper has been recently proposed for in situ stress estimation and has shown promising results.In this study,we demonstrate a new methodology that analyses the borehole televiewer data with the technique of borehole deformation analysis to estimate the in situ stresses through a field case study.The advantages and challenges of using borehole televiewer data for stress estimation based on borehole deformation analysis are discussed and the best practice to obtain the reliable results is explained.The limitations of using fourarm caliper and borehole deformation analysis for in situ stress estimation are also discussed and it is shown how televiewer data can overcome such limitations.Finally,the in situ stress results obtained from televiewer data and borehole deformation analysis are compared with independent in situ stress measurements to show the robustness and reliability of the proposed methodology.
基金The National Natural Science Foundation of China (Nos. 50874096 and 50474040)
文摘In a deep well,under high pressure and temperature,the force,deformation,and movement of the downhole string are very complicated. In this paper,based on the analysis of the working environment and load properties of the down-hole string in deep wells,the factors of high temperature,high pressure,and the complex structure of wells have been taken into consideration. The loads of the down-hole string,stability,back buckle configuration,dynamic characteristics,mechanical strength,and deformation have been systematically studied. On this basis,mechanical models of a down-hole string under different conditions have been established and software for aiding analysis has been developed. By using this software,deep well strings under different construction parameters can be simulated and analyzed,providing a theoretical basis and method for down-hole string assembly,as well as string down-hole construction and operation.
