Thanks for that explanation of the process of well-drilling and how it can fail.
When you drill a well it is done in sections – each one smaller than the other and each one is then cased off and cemented with smaller and smaller casing. So in the end you have a structure that looks rather like an extended telescope stuck in the ground.
One of the problems that develops is a bad cement job at one of the casing points. Cement is pumped down the inside of the casing and should displace back up the outside a certain amount so that you end up with the end of the casing and several thousand feet outside filled with cement. The trouble is that this is not always very effective and it is possible for leaks to develop where gas or oil can percolate up through the cement into an open annulus and so reach the surface. To counter this the cement job is pressure tested to very high pressures (normally 5000psi) prior to the well being completed. But this does not mean that several years down the line you won't get a leak – particularly in an area subject to tremors which could weaken a cement job.
It sounds as if the cement job on the last casing just above the reservoir has failed and it is that which is allowing gas to bypass the rest of the well and reach the surface.
Rich.
From: californiadisasters@yahoogroups.com [mailto:californiadisasters@yahoogroups.com]
Sent: 29 December 2015 16:49
To: californiadisasters@yahoogroups.com
Subject: Re: [californiadisasters] Porter Ranch gas leak a catastrophe not seen since ...
I'm still trying to figure out how that one figure is correct... did it say the pipe was 8,000 feet underground? How? Why?
Redhart in Tehachapi
--------------------------------------------
--Check out http://groups.yahoo.com/group/californiadisasters/
Read my blog at http://eclecticarcania.blogspot.com/
My Facebook: http://www.facebook.com/derkimster
Linkedin profile: http://www.linkedin.com/pub/kim-noyes/9/3a1/2b8
Follow me on Twitter @CalDisasters
__._,_.___
Posted by: Kim Noyes <kimnoyes@gmail.com>
Be sure to check out our Links Section at http://groups.yahoo.com/group/californiadisasters/links
Please join our Discussion Group at http://groups.yahoo.com/group/californiadisasters_discussion/ for topical but extended discussions started here or for less topical but nonetheless relevant messages.
__,_._,___
No comments:
Post a Comment