Bingham Plastic Model Mean?
The Bingham plastic model consists of two parameters: yield stress and plastic viscosity (PV). The drilling fluid will resist flow initially until the shear stress exceeds a certain limit to break the inter particle bonding present in the fluid. Once the fluid begins to flow, the shear stress and shear rate have a linear relationship. This helps the drilling fluid to suspend the solids and cuttings present in the fluid when circulation is stopped.
This model is widely used because of its simplicity, and its ability to estimate pressure loss in turbulent flow.
Trenchlesspedia Explains Bingham Plastic Model
The Bingham plastic model describes the flow characteristics of different kinds of mud and is described mathematically as:
T = YP + PV(γ), where:
T – shear stress, γ – shear rate, YP – yield point and PV – plastic viscosity.
Fluids that obey this model are called Bingham plastic fluids. PV should be low by minimizing colloidal solids to enable fast drilling while YP should be high enough to carry cuttings out of the hole. Too high YP can create excessive pump pressure while starting the mud flow.