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Corresponding Author

Farahat, Mohamed

Subject Area

Mechanical Power Engineering

Article Type

Original Study

Abstract

In this paper, a non-linear multidimensional. dimensionless mathematical drilling mud annular viscosity approach for oil well drilling applications, consisting of one equation, was developed. This utilizes the Rayleigh algebraic method for dimension analysis. Also. this approach reflects the effects of mud rheological properties in terms of plastic viscosity and yield point mud hydraulics in terms of the nominal average velocity of that mud: and geometry of the well-bore annulus on the effective mud viscosity in the annulus. This approach was evaluated by first deriving the unknown proportionality constant and one exponent added by dimensional analysis technique . This is utilizes the statistical regressional curve of the least-squares fitting method and using the pre pared input field data by the author from 121 drilled intervals in six wells in the North Sea drilling region, so as to provide data base required to derive the approach's equation constant and its exponent. A further evaluation of the approach was involved parametrically. This parametric study shows that the effective mud annular viscosity increases when the yield point and plastic viscosity of that mud increase. Also, it was found that the mud annular viscosity increases as the annular space between {he wall of hole and drill-pipe increases. In addition. the mud annular viscosity decreases when the nominal average velocity of drilling mud increases. Also, the opproach's equation was verified using actual field data and was compared with existing models such as Bingham plastic model. Thus, this approach may be called as "Regression Model" similar to Bingham plastic model. Power-law model, and Polynomial model" Accordingly, this approach is considered as the fourth model for predicting the values of viscosity of drilling fluid in [he annuli of well· bores during drilling. Thus, it was concluded that the approach's predictions were more realistic and reasonable which may give a recommendation that the approach could be used by the oil-well drilling industry.

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