Abstract
The mechanism of buckling has been extensively studied in pipes and tubings. But these studies more often has been restricted to continuous or straight body pipes. In reality most pipes and other drillstring elements have end couplings or connections known as tool joint. Tool joint presence changes the annular geometry, hydraulics and stress distribution of the pipe or tubulars in the wellbore. Modelling drillstring in highly deviated wells with no regards to the tool joint effects has been a major source of error in many drilling mechanics analysis. This has often led to misleading information on buckling and bending of the pipe which could lead to drilling and completion problems and costly well interventions. Thus it becomes necessary to model tool joint effect in the drillstring as it is subjected to downhole forces and stresses. In this study, emphasis is made on the determination of tool joint effect on pipe buckling for highly deviated extended reach wells (ERWs). WellPlan T&D spreadsheet software was used for the simulation. The simulation was runned for pipe with tool joint and the same pipe with the tool joints removed. Results show that jointed pipes has similar buckling behaviour with continuous straight body pipes with buckling starting from sinusoidal buckling mode and gradually entering the helical buckling mode for both types of pipes. Furthermore, result revealed that tool joint presence increases the critical buckling force by an average of 28.9% for helical as well as (AWA) sinusoidal buckling modes.
Highlights
With the increasing complexity of petroleum geological formations, and the decreasing oil price, it becomes paramount to optimize as well as (AWA) gas operations
The complexity of extended reach wells (ERWs) becomes more pronounced as the well becomes threedimensional in shape, in this case, both the azimuth and inclination is changing continuously with the wellbore path
Tikhonov et al, (2000) provided experimental evidence to collaborate tool joint effects on buckling/post buckling behaviour of drill pipes constrained in straight horizontal wellbores [21]
Summary
With the increasing complexity of petroleum geological formations, and the decreasing oil price, it becomes paramount to optimize AWA gas operations. ERWs are wells in which the horizontal departure is at least two times the true vertical depth [1, 4] These high angle wells prove very challenging to drill and complete especially during tripping and sliding operations. Gao (2006) used energy method to analyze pipe helical buckling with tool joints and demonstrated that the tool joints presence increase the buckling loads by 20-40% while pipe pads reduce the contact force by 10-30% [20]. Tikhonov et al, (2000) provided experimental evidence to collaborate tool joint effects on buckling/post buckling behaviour of drill pipes constrained in straight horizontal wellbores [21]. Duman et al, (2003a) experimentally determined tool joint effect on axial AWA and contact force transfers in horizontal wellbores [22]
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