New design method of SET—Based on collapse strength under plastic formation

Abstract

Excellent collapse strength of solid expandable tubular (SET) after plastic forming is an advantageous guarantee for casing repair, plugging, repeating fracturing and other processes. This performance indicator is not only relevant to factors such as expansion, residual stress, and material, but also closely to the SET selected in the initial design. At present, there are few related studies on the initial design and selection of SET. This paper uses the CAE software to establish SET expansion to collapse process three-dimensional kinetics finite element model, and analyzes the collapse strength of different specifications under different expansion ratios, from the perspective of theoretical and simulation, derives the prediction formula. The results illustrate that the finite element simulation result of this paper and the error of the experiment is below 2%, the form of collapse is consistent with the experiment, the reliability is good; the wall thickness and expansion ratio parameters of the pipe have a more important impact on the types of collapse. When the SET specification is confirmed, the greatest collapse strength is presented a secondary relationship with the expansion ratio. Each specification of SET has the maximum collapse strength, its maximum value is closely connected to the wall thickness and expansion ratio, etc. Combined with a large number of simulation data obtained a linear fitting formula between the original radius ratio D0/t and the optimum expansion ratio. This paper derives D0 theoretical calculation formula based on maximum collapse strength by combination with the optimal expansion ratio, the nominal expansion ratio and geometric theoretical analysis. The results of this paper provide a certain theoretical guidance and research ideas for initial selection and design of SET.