CFD and the Advancement of Drill Bit Technology

Today we are going to talk about Computational Fluid Dynamics (CFD) in PDC Drill Bit Design.

The concept of CFD has been around for a long time, since 1922.

The basis of modern CFD was created by Lewis Fry Richardson to help with weather forecasting. A brief history of CFD and basic introduction to it is provided in a blog article by Radu Crahmalic from SIMSCALE.

For anyone unfamiliar with CFD, the technology is utilized in many different industries.

Marine engineers can use CFD to prevent cavitation when developing products that move through liquids. 

Aerospace engineers perform simulations to model turbulence to enable planes to better handle different weather patterns. This saves serious cash compared to real life building and testing.

In construction, architects and civil engineers perform simulations with CFD to ensure buildings and other structures can mitigate wind loads before they break ground.

In the drilling world, CFD has been used to rapidly advance products and technology. So much so, that CFD has been disrupting the design of drill bits over the last few years for the better.

So, how does CFD relate to the drill bits used in oil & gas, geothermal, helium, potash, and mining wells?

Well, more than you may think.

Firstly, a drill bit has a few key components. So, let’s dive into these in the following sections.

Parts of a PDC Drill Bit

Drill Bit PDC Cutters

Polycrystalline Diamond Composite (PDC) cutters are the main point of contact for a drill bit. PDC bits remove the rock mainly by shearing.

The PDC cutters are exposed to a lot of heating and cooling down the well, a very challenging environment.

PDC cutters that have lower thermal degradation and more thermal stability generally achieve higher ROP and increased wear resistance. So, optimizing the cutter is important.

Drill Bit Nozzles

Drill bit nozzles help clear the cutting area and cool the Polycrystalline Diamond Composite (PDC) cutters.

Effective placement of these nozzles along with the angle they are set at (Trendon Article: Depth of Cut) plays a critical role on how efficient the drill bit performs.

Fluid channels also complement nozzle placement to improve the clearing of cuttings.

Drill Bit General Design

The drill bit is the main body that the PDC cutters and nozzles are built into.

Efficient cutting removal is determined by several factors that involve complicated multiphase flow behavior.

Ensuring that a PDC drill bit has the most accurate channeling allows flow performance to have a positive impact on the cuttings transport efficiency. This level of efficiency is essential at all wellbore stages. This is because the flow can be impacted in vertical, deviated, or horizontal angles of a wellbore stage.

How does CFD help with PDC Drill Bit Design and Optimization?

Before CFD was used in drill bit design, research and development relied on manufacturing each variation of drill bit and testing it out in a real-life scenario. This is costly and takes longer to optimize a design for a certain application.

CFD drill bit simulations can be used to test many drill bit design variations such as:

• Nozzle placements and angle.
• Optimization of fluid channels.
• Test the thermal effects from drilling on PDC cutters of a drill bit, especially heating and cooling rates.
• The general design of a PDC drill bit to optimize cutting removal performance.

Using CFD technology and simulations in the drilling industry has allowed for drill bit improvements to reach the marketplace faster and make products lower in cost.

CFD Flow Patterns for PDC Drill Bit

The above image shows the flow patterns across the PDC drill bit. The areas with the red colour have a higher velocity, pressure drop and forces. The lower velocities are shown by the orange, yellow then green colours.

Using readily available and consistently proven technology like CFD to develop proof of concept models is essential in evolving the drilling industry.

These tools also help with the design of drill bits, helping you address complex and high-risk scenarios safely and confidently. Something that was inherently risky in terms of time and costs before CFD was used.

These simulations save thousands of dollars, and greatly decreases the turnaround time to take a new design to market.