Multiphase throttling characteristic analysis and structure optimization design of throttling valve in managed pressure drilling

As the key equipment to achieve accurate control of wellhead pressure during managed pressure drilling, the throttle valve can ensure the bottom hole pressure accurately controllable during the migration of invading gas in the annulus. At present, most of the research focuses on the throttling characteristics of single-phase fluid, and the research on the pressure regulation characteristics of throttle valve under the condition of multiphase flow is still relatively weak. In this paper, the mathematical model and CFD model of multiphase flow in the throttle valve are established, and the multiphase throttling characteristics under different hydraulic parameters are studied. The rationality of the proposed model is verified by field full-scale experiments. The results show that throttling pressure drop shows a nonlinear trend with the opening, which is not conducive to field application. Furthermore, through the sensitivity analysis of the throttle characteristic curve under multiphase flow condi-tions, the geometric structure of the throttle valve core is optimized to realize the fine adjustment of the wellhead back pressure under multiphase flow conditions, which is of guiding significance for wellbore pressure control under gas invasion condition.

Automated summary

This paper studies the pressure regulation characteristics of the throttle valve under multiphase flow conditions, establishes corresponding mathematical and CFD models, and verifies them through experiments. The results show that the opening of the throttle valve has a nonlinear relationship with the throttling pressure drop, which is not conducive to field application. By optimizing the geometric structure of the throttle valve core, the fine adjustment of the wellhead back pressure under multiphase flow conditions is realized, which has guiding significance for wellbore pressure control.