This is still work in progress and will be added to  and expanded when I get time  Ian Kimber

 

Introduction

Three times over the last few years I have been asked by my local U3A to prepare and give a balanced presentation on the use of hydraulic fracturing for Oil and Gas production particularly in relation to recent discussions about using it on sites in the UK mainland to bolster our dwindling North Sea Gas production,  reduce our dependence on Natural gas imported from and through potentially unfriendly states.  

 

This page is planned to be a distillation of these presentations and allow a discussion of members feelings on this controversial topic.

 

This is the best illustration of the process that I can find.  It is drawn to scale with the distances down the side of the cube marked in miles

The thin layer at the top is the distance that is the few hundred feet that is important for all ground normal water resources. Fracking for gas is about a mile and a half down more than ten times this distance.

 

The Main aims of this page

 

• To give an unbiased presentation on the technology and its potential problems
• To assess the needs for new applications of this technology in the UK
• Both these aims are particularly difficult because most sources are not unbiased
• To look at what can and has gone wrong in the USA. 
• To look at other reasons why it would be best to avoid using fracking unless it was absolutely essential.
• To encourage discussion in the form of comments to the page
• To encourage members to add additional information to this page after the end of this presentation information. 

 

History

 

I would first like to give a brief resume of the history of oil and gas wells to dispel some misunderstandings that I have often encountered in these sort of presentations where emotion tends to dominate over rationality.  The most important of these is fracking for the production of is not a new technique.  It has been used almost ever since the beginning of drilling for oil.

 

Oil is very rarely in large pools in voids underground it is almost always saturating a solid but porous rock matrix for example a soft loosely packed sandstone, so just drilling a hole in the ground will very seldom allow it to flow easily and freely to the surface to create the image of a "gusher"  where a fountain of oil comes out of the hole and pollutes the local land.  This problem is to be avoided at almost all costs.

 

Several techniques are used to prevent the oil and gas under pressure in the ground from escaping in an uncontrolled fashion.  

 

Firstly:-         All oil wells have to be lined with strong pipes to stop the ground pressure crushing the well and prevent the oil leaking out into other porous strata as it comes up the hole.  

 

Secondly:-     A heavy mud is used to balance any hydrostatic pressures as much as possible and avoid ground pressure crushing the pipe.  This also serves as a lubricant for the drill bit and a device for removing the drilling swarf from the hole.

 

Thirdly:-       A complex blowout prevention mechanism has to be placed in top of the hole that allows the pile to be sealed if disasters happen and control is lost.  This contains several different methods of stopping the flow from very strong valves to an ultimate "use once" device that crushes the pipe flat.

 

When the drill bit is removed and "completed"  by shooting a lot of holes on the final pipework the relatively small area of porous rock exposed at the very bottom of the hole would not normally let much oil or gas flow out of the hole. So some method has to be used to open the well.  The second part of the completion process is to force fluid at extremely high pressure down the well.  This pressure extends the fractures created by the explosive process to allow more rock surface to be exposed.  This fluid also has some sand (Proppant_ in it to keep the cracks open when the extreme pressure is released.  Here are some videos of these processes involved in drilling.

 

Oil and gas well drilling

Fracking Explained 8:30

 

Fracking Explained with Animation – YouTube

 

 Drilling Technologies

          

Fracking drilling   patriot energy 1  7:14

This video is a film of actially drilling a well

 

      Fracking Well completion   2:50

https://www.youtube.com/watch?v=KR9rNzHl57Q 

This short video dhows the well completion process including the fracking

 

  What are the risks in fracking?

The risks are are best divided into two groups the deep well risks and the surface risks

 

Deep well risks

Gas fracking generally requires the wells to be very deep, around one and a half to two miles deep.  The strata at that level are very hot and under powerful compressive forces because of the large covering of rock.

Before starting the process thorough geological surveys of the underground strata and simple test bores are used  to recover samples from the critical layers for testing. these should show if there are any geological problems in the area. For example unexpected faults(cracks ) and displacements of the layers.  These must be avoided because it may cause the wells to miss the important gas containing layer of cause the fractures planned to veer off course either way the well would become unproductive ass the drilling of wells miles deep and miles horizontally is a very expensive process this is the last thing than any oil or gas company would want to do.  Problems of this nature are extremely unlikely to affect the surface because the wells are far too deep for anything to reach the surface.

 

The publicised risks of "earthquakes" due to the fracking process.  Whilst it is true that tiny ground disturbances may be detected and identified as associated with the process of fracking and gas production surface vibration detectors are extremely sensitive and part of the standard techniques used to identify the layers and structure of the rocks many miles below the earth's surface.  These are not damaging vibrations and could never be. They are of a similar level to the standard noise levels that occur almost everywhere all of the time.  This suggestion is a complete fabrication of the people who wish to create and magnify the anti fracking response in the public and really count as false news.   A truck going by some distance away probably caused more vibrations than that!

 

There is another deep well risk that is more serious and that is some form of failure of the casing and cementing of the wells this could cause the wells to effectively leak into the ground at some point.  It has been suggested by some anti fracking lobbies to be a significant risk.

https://jacksonlab.stanford.edu/sites/default/files/pnas2014_0.pdf

http://www.pnas.org/content/111/30/10955.full

These serious analyses of real wells give some assessment of this in practice and on a cursory glance it could be significant particularly in the case of gas which gets through narrower holes than the much more viscous oil.  

 

Surface Risks

These risks are far more likely than the ones caused by the deep wells and must be looked at carefully and prevented.

 

And now some videos telling other peoples stories

 

Both sides of fracking  6:45

http://www.youtube.com/watch?v=7wqJcVXxQNg

This is a reasonably balanced short news film showing arguments on both sides

 

Fracking Hell the untold story  17:00

http://www.youtube.com/watch?v=dEB_Wwe-uBM

This shows what can go wrong if pollution and safety rules are not adhered to

 

Do we Need Fracking for gas in the UK?

 

The UK has a large gas based Economy for both electricity and domestic cooking and heating

This means that whatever happens about reducing our carbon consumption we will still need a significant

 

There are known gaps in our energy supplies as coal and Nuclear wind down

 

Fracking can be carried out safely provided safety and environmental rules are obeyed

 

Natural gas is a fossil fuel and must be phased out in time

 

Other references in this topic

 

I will add other current references to this topic as they come up

 

This is one that came up as part of my membership of the IET (the Institute of Engineering and Technology)

This used to be the IEE and the I Mech E  which combined some years ago.

UK shale gas extraction limited by lack of space to develop wells 

 

Ian Kimber - April 2017