Expert: Carl Alexander - 1/15/2008

Question
QUESTION: I'm looking for advice on how to economically maintain my natural gas well.  Is there equipment like ACS which is available to private owners by which the well can be more easily maintained?  Having the well swabbed is getting more expensive and I have read may not be good for the well.

ANSWER: Isaac,
I may or may not be able to help.
First, what is ACS? I am not familiar with that abbreviation. I can't find it in my Desk & Derrick Dictionary and haven't heard it used in my area. Doesn't mean I may not know, some terms that are not API vary with area and/or manufacturer. Please post a follow up with a description.
Secondly; I am not sure it can be done economically. Swabbing is bad for the well. Repeated swabbing results in diminishing returns. The well makes water, the tubing loads up with water, the load of the water chokes back or kills the well and the surface pressure drops to zero or near it. You then swab the water from the tubing, gas re-enters the tubing and the well comes back on line.
The swabbing operation moves the water up and out of the tubing but while that is happening, the lower pressure which allows the gas to move to the surface also allows the water to move forward, just like standing in line to buy a ticket. Sands are held together by natural cementation and the movement of the water degrades this and the casing will eventually fill with sand (this also happens with water wells just quicker). Over time, as the well produces gas, the level of the gas near the well bore drops. This is called "coning". Oil companies combat this by a technique called "squeezing" which plugs the perforations with cement. The casing is then re-perforated at the new gas/water interface. I have worked over a lot of wells and don't know of any other way to combat water production. Research done on wells that have been shut in for a couple of years has shown that the coning near each well eventually equalizes and levels out at a new, lower level than when the well was new. However, they still needed to be re-perforated. As water production increases, the disposal of the salt water costs more than the gas production. Some offshore wells that have high gas production in addition to water production use a technique called "gas lifting". Special valves are installed in the tubing, part of the produced gas is injected into the casing and the gas enters the tubing through an orifice in the gas lift valve. This is not practical on low producers as all of the produce gas would be needed for the gas lifting leaving no gas for production. I have clients that have pumping wells that pump water with gas entrained in it. The gas is separated and sold profitably because they also have old wells nearby that can be used to inject the water back where it came from. Sooner or later, unless you have the rare well that has fresh water associated with it, you will be faced with the same problem of water disposal. In E. Texas this is about $6 per 42 gallon barrel.

Since most private wells are shallow you should be able to squeeze the perforations, clean out the cement residue and re-perforate for $3,000 or so. This is if you know the exact depth of the the new gas/water interface. If you are not absolutly sure you will have to run an electric log and have a log analyst determine the location of the new perforations. Electric logs are expensive, this will have to be done first and will cost 2 or 3 times the amount spent to re-perforate the well.

---------- FOLLOW-UP ----------

QUESTION: This is a response to your question about ACS.  One of the web sites that mentions this system is http://epa.gov/gasstar/pdf/gasstarpdf.pdf

Answer
OK,
I am a member of the SPE Environmental Technical Interest Group but I missed that article. In fact, I have forwarded the article to the client I am presently working with as we are developing some leases in the Cotton Valley and Travis Peak formations.
During well pumping, a little gas leaks from the pump rod packing into the atmosphere. The article is proposing that these emissions can be reduced by using a different pumping method. It seems to me as if you also looked on it as an alternate method of gas production in a well that makes water. This is true.

In my first answer I mentioned gas lifting. That is what the article is referring to as DGL (Deep Gas Lifting). The mandrels that the article referred to is the place the gas lift valve is seated. Gas lift is expensive as it requires separators and pumps to inject and re-cycle the work gas. It also requires more maintenance.
The other term is the one I questioned, ACS (Automatic Casing Systems). This is a form of Tubing Plunger Lift, also mentioned in the article, which has been around for years. I have worked on several projects that used tubing plunger lift. Not installing them but removing them. Squeezing the perforations, re-perforating and then going on line with the well flowing with little or no water and getting rid of the plunger lift. This was done in order to gain the production a gas company would require. Installing and staying with a plunger lift system would be quite practical for a private well.

A casing or tubing plunger system would probably work fine for you. If your well has tubing and a packer set inside casing and the casing has perforations below the packer at the pay zone, a tubing plunger would be called for. I am not sure how much it would cost. It would take a workover rig, aka pulling unit to fill the casing and tubing with water then pull the tubing and packer in order to install the lower plunger catch seat. If the tubulars were in good condition they would then be run back in the casing and the tree with the upper catch seat installed on it. With the well swabbed in the plunger would start operating. This could be done in one day to a 1000 ft well. I have no idea of the cost of a tubing pulling unit in your area. In central Texas about $3,000/day for the unit and pumps to kill the well.
If it is a tubingless, aka barefoot completion you will have tubing that has been run into the well bore to just above the pay zone and then cemented in place with no packer. Since the tubing/casing can not be pulled,this would call for a casing system with the seat installed in one joint of smaller tubing and set in place by wire line. This would cost less because there would be done with wire line and no need to kill the well first.

You have done some good homework. A plunger would keep your well in operation longer but it would still be making water.
You would still have water to dispose. A catch tank installed nearby until it fills and  a vacuum truck called to haul it off