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Drilling Highly Deviated Wells

The Problems We Face When Drilling Highly Deviated Wells Are Self Imposed…

Why the issues we face may be self imposed

The issues may derive from lack of experience, incorrect choice of tools, and/or poor supervision.

The problems we create when drilling top-hole sections will compound and complicate operations all the way to TD. This diminishes the chances of delivering a wellbore that others can effectively work in and work over long after the drilling operation has been completed.

The approach the industry takes is much to blame. For the nonchalant attitude of the once proud and highly committed directional drilling professionals, who have been deprived of using the skills and intuition honed from many years of experience by computerised BHA modelling programs. This modelling, in many cases, is generated off location with little input from the directional drillers and frequently by people with little to no drilling experience.

Don’t shoot me for my opinion, I was one.

Do not misunderstand me, these models can be an invaluable aid. There are, however, too many variables in the complex task of navigating a directional wellbore to its target for modelling program alone to be taken as definitive.

Points for improvement

  1. Insufficient stabilization points, unsuitable stabilizer spacing, poorly designed and destructive stabilizer profiles are the key instigators of numbers drillstring and wellbore problems.
  2. Sharp edges and spiral profiles generate vibration which, then trap drilled cuttings when rotating. The inhibition of cutting’s transportation creates additional rotary torque and increases ECD.
  3. Let’s also not forget the costly damage to the filter cake and wellbore when tripping with spiral blade stabilizers.

The industry is in turmoil; oil prices are hovering around $ 30 a barrel and tens of thousands of people have been laid off. Yet the industry is losing countless millions per day in NPT caused by vibration or premature, torque related, drill string component failure.

The buzz words at every workshop or conference we attend are, improve efficiency, shoe to shoe drilling, and suboptimal drilling, the list goes on and on.

While, as Fred Dupriest mentioned in his publication “Thus, The Lowly Stabilizer”, the low hanging fruit is in keeping the bit on bottom, avoid trips instigated by vibration related premature drillstring component failures. This is one way to improve performance and efficiency. Until someone is willing to buck the trend, stand up and be counted, nothing will change.

We are all aware of the damaging effects of drill string vibration and its costly effect on performance. However, until we can identify the source of the problem we cannot fix it. We need to deploy the readily available shock and vibration sensors currently on the market, to obtain a better understanding of drillstring behaviour and, as a result, where and how best to stabilize it.

Sensors deployed in the MWD alone do not give us the full picture as the MWD is typically stabilized above and below the tool. We need to monitor other critical areas of the drillstring to get a better, more thorough understanding.

If you are a service provider, try explaining this to the operators drilling manager, he will most likely ask you who is going to pay for the additional costs. At a time when some operators refuse to pay for vibration related damage. One way or another, we all pay the costs.

While we are mechanically cutting and crushing rock, we will have to live with vibration. The challenge is in managing vibration to an acceptable level.

Tom Newman, 1st February 2016

This post was originally written in response to an SPE Connect discussion.