Very interesting job yesterday afternoon! Early yesterday I was on a Vac truck job that was canceled and we where sent to a new well that had just been finished in order to do some rain water clean up work. I was asking a lot of questions about the new well while we where cleaning up the big puddle around the well head.
Later yesterday we where called back to that well specifically asking for our truck to come back and do some more rain water clean up. When we got there we cleaned up the big puddle that had reformed around the well head and several rough neck workers came over and started taking the well head apart. OH Wow! I got to part of a well head replacement job!
What that entails is taking those massive valves and fitting completely off of the well casing.
Unfortunately this work is considered high risk and a level of security is imposed so I was not given permission to photograph any of it again.
But I can at least give you a description of what I saw while we where there!
Two massive valves are held in place by a large threaded collar that screws onto the well casing just below ground level. The casing is 16 inches in diameter and roughly 3/4 of an inch thick. It has an inner set of stepped flanges and grooves that mate up with a the first adapter assembly that everything bolts onto above that. That flange assembly has several levels of O ring seals that keep it from leaking. There are multiple inner O rings that seal around an 8 inch inner casing and multiple rings that seal around the outer flange steps and other overlapping points also. They are rated for a working pressure of 5000 PSI but are pre tested to over 20,000 PSI before they are certified.
Everything is massive and has to be moved by a chain hoist and a pay-loader. The threaded ring that holds the two parts together is about 5/8 if an inch thick and is double threaded for clockwise threads on one end and counter clockwise threads on the other. This is so that its not possible to ever unscrew a well head off of the casing. Once the collar is screwed down several pins inside the casing flanges and adapter interlock so that it can not be turned either direction. The big collar itself gets pinned in place and it too can not be turned afterwords once the well pressure is applied to it.
The reasons for all of this is to give it multiple redundant levels of sealing and tamper proof protection. The guys say the the well heads and casing connection are so strong the could be hit by a speeding semi truck and likely survive without leaking!
So what does an exposed well casing look like? Basically its just a big pipe with threads on it sticking about 1 foot out of the ground with a inner flange and collar assembly inside that with a 8 inch center hole. To look down it it just looks like a open pipe that is really deep!
The well is temporarily sealed by a single large service plug some distance down inside the casing. It works on the same principal as those expansion plugs that are used on sewer pipes. An inner screw assembly expands and anchors the plug into the casing wall and holds it in place while several layers of seals keep the oil and gas from leaking up from below it. Thats all that is keeping the high pressure natural gas and crude oil from blowing out while the head is being replaced.
They told me that if the plug came loose there is a good chance those of us standing near the well would probably never know it. But we would be on the world news by the next morning!
During the well work up to this point they found that this well is producing over 3000 PSI at the surface!
I will try and get some pictures of a complete well head of this type this week that has all the same components on it so that I can give everyone here a referance point to what I was working around. There are different heads that go on at different times during the well work and I dont have any referance pictures as of yet for this type that has these massive valve assemblies on it. The finished wells have a much smaller head unit like whats in the picture of the red well head in the earlier post.
I have such a cool job some days!