To achieve different demands for pressure control in managed pressure drilling (MPD), the relationship between the pressure difference and the valve opening was analyzed in the working process of MPD throttle. The throttle flow area equation and the flow area isosurface equation at different openings were derived. Then, the mathematical model of the throttle valve surface shape was established by solving the envelope curve of isosurface cluster. Furthermore, the shape curve equation of the valve core surface was derived and modified by applying this mathematical model. Finally, to verify the performance of this investigation, the comparison of the results between simulation and design values was performed. The results showed that the correlation between the throttle pressure difference and the valve opening is linearly related, which proves the correctness of the mathematical model for the throttle valve surface.

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This paper is concerned with experimental investigation of the linear opening-pressure drop ( −Δ ) relationship of new valve core in managed pressure drilling (MPD). Based on the linear − Δ relationship in theoretical results, the actual − Δ relationships are obtained by testing the flow rate, displacement of the valve core, and pressures at the import and export. Under all three working conditions, the theoretical −Δ relationship almost agrees with the experimental result, and the accuracy of the theoretical design is validated. In addition, the flow coefficient ( V ) is also tested in the experimental process to judge the throttling characteristics of the new valve core and the proper working conditions.