Abstract:The inserted sealing tool is a critical downhole implement that is used to balance the downhole pressure in multistage fracturing operations and prevent fracturing fluid from overflow and/or backward flow. The sealing ring of an inserted sealing tool plays an important role in downhole sealing since a sealing failure would ail the fracturing operation. In order to improve the sealing performance and reduce the potential fracturing failures, this research aims to investigate the influence of V-shaped sealing ring geometries on sealing performance. Constitutive experiments of rubber materials were carried out and the parameters of the constitutive relationship of rubber materials were obtained. A two-dimensional axisymmetric model considering the sealing ring has been established and influences are investigated with considerations of various system parameters and operating conditions. It is found that the stresses concentrated at the shoulder and inner vertex of the sealing ring have direct impact on the damage of the sealing rings under operational conditions. Moreover, the sealing interference, among several other factors, greatly affects the life of the sealing ring. A new design of the sealing ring is suggested with optimized geometric parameters. Its geometric parameters are the edge height of 5 mm, the vertex angle of 90 • -100 • , and the interference of 0.1 mm, which show a better performance and prolonged operation life of the sealing ring.
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.
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.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.