The prediction of pressure losses is very important in many oil-field operations, including drilling, completion, fracturing, acidizing, workover and production. In this study, a utility hydraulic calculation method has been developed that requires as input the raw fluid rehological data and relevant hydraulic parameters. This new method is based on three important developments.

First, this paper presents a new and powerful rheological model, named four-parameter model. A brief introduction was given to the determination of rheological parameters. Calculation model for rheological parameters was built based on regression method. Using a variety of data from literature, it is shown that four-parameter model could precise represent the rheogram of the time-independent fluids.

Second, a generalized hydraulic calculation model is developed based on power law extension method, which is independent of the form of the rheological model of choice. For laminar flow, pressure drop formula is derived based on characteristic method of pipe flow. And turbulent pressure loss is calculated by semi-empirical formulas. Flow regime determination method is established by quoting generalized flow behavior index.

Third, for pressure drop calculation precisely, the approach includes the additional pressure loss due to the effect of tool joints, accommodates drilling pipe rotation effects and accounts for the effects of annular eccentricity. Furthermore, simple, explicit and general formulations for approximation pressure losses over measurement while drilling tools are also presented to augment the suite of expression required for complex hydraulic calculation.

The predictions of the developed method have been compared with several sets of experimental hydraulic data from different sources. The tested cases include laminar and turbulent flow of various drilling fluids in both pipe and annular geometry. The generalized hydraulic calculation model is shown to be quite accurate and superior to those obtained by the currently available standard techniques.

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