Practical Analysis of Drilling Mud Flow in Pipes and Annuli

<jats:p>American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc.</jats:p> <jats:sec> <jats:title>Abstract</jats:title> <jats:p>New numerical and graphical techniques permit practical assessment of drilling mud hydraulics. Developed from a sound theoretical analysis of power law fluids, they are extended by power law fluids, they are extended by a generalized model to approximate Bingham plastic and power law with yield stress behavior. Applicable equations are expressed in terms familiar to the field engineer.</jats:p> <jats:p>A proposed geometry factor reduces the hydraulic equations to a single set describing pipe, parallel plate and annular flow. It also defines a generalized Reynolds number for different geometries and flow regimes found in the circulating system.</jats:p> <jats:sec> <jats:title>Introduction</jats:title> <jats:p>Drilling muds are non-Newtonian fluids. As such, the equations describing their rheological behavior are both complex and bulky. This is true even under assumptions of isothermal, steady-state flow in circular pipes or stationary concentric annuli.</jats:p> <jats:p>There is a gap between theoretical work in mud hydraulics and its application in the field. This is unfortunate because theory and laboratory data must eventually be correlated to actual behavior in the well. Major efforts to eliminate this gap include extensive simplification of the rheological equations and use of wellsite computers. Approximations for field use are necessary; however, oversimplification can lead to errors. Most wellsite mini-computers (or programmable calculators) have limited core, making it difficult, if not impossible, to do justice to present rigorous solutions.</jats:p> <jats:p>This paper presents a practical approach to calculate surge/swab and other wellbore pressure losses. pressure losses.</jats:p> </jats:sec> </jats:sec>