Oil and Gas Wells

The hydro carbon oil wells are producing either a mixture of oil and gas, oil with some gas, or only gas together with so called condensate and traces of oil. As wells are getting older a lot of wells are producing more and more water, the so called water cut. This can reach well above 95%. 

There are 3 major types of wells:

  • self flowing wells, where as the oil comes out because of the overpressure in the reservoir
  • pumped wells, where a pump, either mechanically or electrically, is used to bring up the oil
  • wells with a gas lift, where gas is introduced at a certain depth of the well to increase the flow

All types of wells share often several common problems. There is of course the problem of the waxing, depending on the quality of the crude and the steel, there is corrosion and some wells tend as well to scaling or fouling, if there are such impurities in the crude itself.
It varies from well to well, but in certain wells the tubing has to be cleaned periodically. For this the production has to stop, and there are used so called wire lines, which are cleaning all the way down, to ensure the whole length of the tubing is clean again and can be taken in operation again. Such wireline runs has to be done several times in order to get rid of all the wax and other build up.
This wirelines services takes some effort and produces costs. Not only there is no production during cleaning, as well the wires can’t be used too often, and there is a lot of time required cleaning oil wells with hard wax.

 

Merus has two solutions to reduce the servicing on the wells

A) Merus Downhole tool

There is a so called down hole tool, where Merus Rings are brought down the well itself, together with the piping during a regular service. The device is just fixed from outside  on top of the tubing. By doing so the tubing itself is not affected at all. The inner diameter of this tool is fitting to the outer diameter of the tubing itself, so there are no restrictions in the flow or stability of the pipe. See as well 3rd picture to the right.

The downhole tool has in between its outer chamber and the inner chamber enough space to put in a special designed Merus Ring. This rings in manufactured out of pure silver. We have to use this better and far more expensive material, because of the limited available volume inside the tool, and silver is a better carrier of the oscillations. The silver cylinder inside is protected against the environment down in the well, so the crude itself don’t come in direct contact with the silver.
Several very successful trails have been done, and less waxing and less corrosion was observed, compared to the untreated wells. A statement about emulsion can’t be given, because this data are not monitored. Today we have equipped around 300 oil wells with this technology.

B) Merus equipped at the gas lift line

Gas lift is a secondary recovery method to lighten the well fluid for it to flow. How is this done, the lift gas is injected into the casing and injected at specific depth to lift the crude. The gas which is lighter than the crude will carry up the crude and so the flow of the well is increased.
Here a Merus Ring is installed at the surface direct on the gas lift line. The gas carries the oscillations all the way down and improves the oil. In order to do use the gas as the carrier of the oscillations, there have to be traces of humidity in the gas. Experience shows, values of around 20ppm liquid in the gas are enough.
Here as well it was observed far less wax was forming in the tubing. Also there were indications; the wells equipped with Merus have produced significant less emulsion, then wells without Merus.


Merus is able to save operating costs

Assumed a well has to be cleaned only every 3 weeks instead of every second week, the savings are obvious. How much this actually will be depends, on the cost of manpower, how easy it is to access the well, the crude not produced when the well is shut-in for wax cleaning, etc.

If there are not only the savings of servicing the well, but as well there is a reduction of the corrosion, which increases the life time of the tubing. The installation of the Downhole tool in a very critical environment, show first indications the lifetime of the tubing which has been before only 8 month, have been at least doubled. In such a case the savings will be very high, especially as steel tubing have increased a lot in price lately. Offshore one time cleaning a well might easy cost several 10.000 USD, as the cleaning crew and all the equipment has to be brought to the platform, either by ship or by helicopter.

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Further images (click to enlarge)