Abstract
Solid expandable tubular was a field-proven technology in workover operation in China, however its ultimate goal, mono-diameter well, has yet been realized, to achieve this goal, large expansion ratio, enhanced mechanical properties and scientific evaluating method were necessary ingredients.
In this paper we presented the theoretical and experimental study of expandable tubular for well drilling purpose, first it was reported the ABAQUS simulation process of tubular expanded by different ratio, 10%, 20% and 30% respectively, then the relationship of post expanded tubular's properties and expansion ratio was established, the outcome demonstrated that 13% expansion ration brought about the maximum post expanded mechanical strength, reaching N80 casing; second it examined the reliability of expandable thread as it is expanded in the state of being bended at 15°/30m, its structure was redesigned to guarantee 20MPa pressure from outside could be resisted, this paper also introduces the study of residual stress as the tubular was expanded and measures aimed at minimizing it are described.
Field operation was finished in China, the Φ140mm casing well was sidetracked with the maximum dog leg of 11.6°/30m, expandable tubular of Φ108×7mm was delivered into the position and the expansion length was 398m, Φ108mm wellbore size was obtained and all the well tests were up to the standard after operation.
The study offers a new option in the field of well completion, its outcome contributes to the further development of solid expandable tubular.
