CFD Modeling of Mud Flow around Drill Bit

Abstract: This project was performed on behalf of SINTEF Materials and Chemistry in close collaboration
with Lyng Drilling, part of the Schlumberger Group. The scope of the project has been to
develop a method for geometry and setup simplifications on a Computational Fluid Dynamics
(CFD) simulation made on a drill bit at work; to see if there is a possibility to implement this
type of simulations as a step in the product development process of drill bits at the company Lyng
Drilling. This in order to establish the local flow-patterns around the drill bit, that governs among
other things how the cuttings is transported away and the cooling of the drill bit. The drill bits
often have a pattern of surface erosion, caused by an increased intensity and velocity of the flow
at that area. Zones with low flow velocity, stagnation points, can cause problems to the drilling
as cuttings and mud can get stuck there subsequently leading to clogging of the drill head and
increased energy required for the overall drilling. The only success on simulating the mud flow
around the drill bit was obtained with transient simulations on a stationary drill bit. A rotating
case was simulated with dynamic mesh, but simulation time was estimated to exceed 6 months,
and this scenario was one of the limitations set initially in the project.
No industrial gain can be obtained by implementing CFD-simulations as a step in the product development process for the design of drill bits at Lyng Drilling. The simulations are far too complex and require a lot of work and simulation time, as well as the parameter assumptions are too many.