Wednesday, October 9, 2013

Directional Drilling (Part 2 of 2)

 
Welcome back.  So today we continue our "exploration," no pun intended, of direction drilling.  In Part 1, we went through:
  • Directional Well Types
  • Mud Motors
Today we're going to dive into the more advanced method of drilling directional wells, the Rotary Steerable System.  We will also touch base on the benefits of directional wells.  If you missed Part 1, please take a look so this makes sense!

A Rotary Steerable System (RSS) is a tool used for drilling directional wells that enables the driller to drill more precise and complex well profiles. The Rotary Steerable system gives the oil company more flexibility and allows for pinpoint accuracy. 

In contrast to the traditional Mud Motor, the RSS enables drillers to build various angles without having to pull out of the hole (POOH) to switch to different angles subs like that of Mud Motors.  The RSS is able to do this through the use of a flexible shaft and a series of concentric rings that can bend the shaft in various directions.  The position of the concentric rings is controlled by hydraulics or electronics.  There are a wide variety of RSS out there, but a majority of them operate in this manner.

To the right is a diagram I put together showing the concentric ring configuration.  This diagram is a rough example.  A majority of RSS's include a complex grouping of multiple ring sizes, but this gives you an idea.  Depending upon which direction the driller wants to go, the rings will adjust and orient the bit in the correct direction.  Below gives you an example of this...


 
That's really pretty much all there is! Don't get me wrong, this is a whole lot more complicated than I have made it out to be, but... I think this gives a good idea as to "how they do it."
 
So what are the benefits of drilling directional wells? In the past couple of years we have heard the directional drilling process hammered by many news outlets for it's method typically requiring the usage of the fracking process (we'll touch on this subject at a later date).  There are actually several benefits to drilling directional, not just for operators, but also for the environment!
 
One of the main benefits of directional wells is that they leave a smaller foot print.  This reduces the amount of environmental impact these wells have on the surrounding area.  There is not a need to clear multiple plots of land for the well pads and there is also not a needed for the added infrastructure to service these wells.  The images below give an example of that. 
 
 
The image of the directional well given above would be a typical well drilled using a mud motor system.  As you can see, while this method is more efficient than the original vertical well, the method does have room for improvement.  Below is a typical profile of a directional well drilling using a RSS.  The well is basically 100% efficient.  The driller is able to turn the system on a dime and follow the formation enabling the operator to receive maximum production and efficiency out of the well. 
 
This should wrap up our talks of directional wells! Feel free to comment if you have any additional questions.  While these posts might not make you an expert, you should be able to hold your own.  Have a great day! 



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