| Popis: |
Determination of pressure drop at the bit is one of the major concerns for establishing proper hydraulic design. Little has been known about pressure drop estimation at the bit for single phase muds, and even less is known about gasified fluids. The aim of this study is to fulfill this gap in the literature. Although there are numerous studies on this subject available in the literature, they are either valid for high gas flow rates or developed using very strong assumptions. The proposed theory, which is valid for both sonic (critical) and subsonic (sub-critical) regimes, is based on the solution of the general energy equation for compressible fluid flow. Unlike the existing models in the literature, the proposed model takes the change in kinetic energy, compressibility factor, and internal energy terms into consideration. Moreover, the model uses "a mixture sound velocity" approach for determination of the sonic boundary of the fluid. Based on the proposed model, a computer program is developed for calculating the pressure drop through a nozzle at subsonic flow region. The performance of the proposed model is tested by comparing the model results with existing models estimations using realistic field data. It is observed that, as much as 9% difference occurs between the results of the proposed and existing models. |
