Regression Approach to Calculated the Effective Mud Annular Viscosity during Drilling Oil Wells.

Document Type : Research Studies

Author

Petroleum and Mining Engineering Department., Faculty of Engineering., Suez Channel University., Suez., Egypt.

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.  

Main Subjects

MEJ- Mansoura Engineering Journal
Volume 21, Issue 4
VOL 21 has two issues issue 2 consist of two parts from(September to December)
December 1996
Pages 74-91

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