Experimental Testing of Initial Hook Load During Tripping in Horizontal Well
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One of the major problems in drilling operations occur during tripping out of the well. Inside the well there are often restrictions making it difficult or impossible to pull out the drill string including its bottom hole assembly, especially in extended reach wells. The consequences of not recognizing the problem in time could be a deformed drill string, or worse, a severed drill string. By understanding the causes of the problems it becomes easier to deal with them. The focus in the present work was on the initial hook load peak showing up during tripping operations in horizontal wells. The major part of the work was put into the building of a custom designed laboratory environment that simulated tripping operations. The work was based on previous work on the subject. The hook load was measured by tension meters and recorded with a custom designed program created in a computer software; LabView. The hook load was also modelled mathematically to be able to compare theoretical results with the laboratory results as well as with field data.The experiments were performed with variables like drill string elasticity, velocity and wellbore wall surface. The laboratory design was also created for future development to better understand the hook load during tripping operations. The model lacked initial elastic condition data, which made it impossible to properly simulate the laboratory tripping operation. The final custom designed program (LabView) produced results from the experimental runs that were much like the acquired field data.