The parameter sensibility analysis for fishing box tap based on the overall process of elastoplasticity in oil and gas wells

Abstract

In view that the selections of box tap and thread making parameters are still groundless and lack scientific evidence, which has caused many practical engineering problems, such as long fishing cycle and low success rate, this study establishes a mathematical model such that fish is fished by the box tap based on the theory of large deformation and principle of virtual work. The analysis and evaluation methods of the whole elastoplasticity process for tapping and fishing are proposed as well in accordance with Johnson and Cook’s experimental model and separation criterion in our study. In addition, the effects of such factors (drilling pressure, rotation speed, box tap strength, taper and pitch) on the thread making capacity of the box tap and the new thread strength of fish have been systemically analyzed. In the case study, the paper derives the safety rotation speed range of tapping, the optimal box tap tape and parameter combination of fishing, and the maximum allowable lifting power. The results obtained in our study show that the analyzing model and evaluation methods are quite reasonable and can be generally applied, which will be of great significance for the enhancement of fishing efficiency in future industry.