Chemical Injection

[lorenzo67]

hello at everybody,
someone know what kind of chemical are necessary inject at head well?
Thanks

 

[brimmer]

You might want to be a little more specific, you won't get an answer to this question. There are several chemicals for several different reasons to inject at well head, scale inhibitors, corrosion inhibitors, for asphaltenes, prevent for sulfur deposition, surfactant, biocide, etc. etc., what are you trying to prevent?

 

[lorenzo67]

I don't know exactly what is the problem. I have a oil composition but I don't know if the are scaling problems or other like foaming or fouling. I'd like to know, in general, what kind of chemical are injected in the head well to prevent a number of chemical injection system. I think that your answer is good for solve my problem but if you have documentation or link where I can study the problem please tell me. Best regard

 

[TheSnorkler]

A good place to start is to check the chemical signature of your oil composition.

Some suggestions:

If resin content >10% then there is likelihood of strong emulsion forming so you will need emulsion breaker injection (downhole if there is hydraulic, ESP or PCP pumps in place)
If CO2 > 3% and there are no CRA in the flowline then consider corrosion inhibitor
If your flowline temperatures will approach the pour point then look at pour point depressant
If you have high carbonate content in the produced water and some CO2 then scale inhibitor injection is likely needed

Above is just a nominal guide for my current situation but each oil fluid is unique and you have to look at the process conditions too and usually engage experts to look at flow assurance.

Regards,
TheSnorkler

 

[DrillerNic]

Lorenzo, firstly, are you sure you want to inject chemcials at the wellhead rather than downhole?

Downhole chemcial injection is usualy scale inhibitor, to stop the well scaling up from water either as water cut increases or from condensate water in gas wells. Other chemcials injected downhole may be corrosion inhibitors (especailly in gas wells) and hydrate inhibitors in gas wells. Wax or asphaltenes are usually not a problem downhole (unless you are very unluky or in a heavy oil reservoir) as the wellbore temperature is usually high enough to keep out of trouble. It would be unusual to inject all these things though- the highest number of chemcial injection lines I've put in a completion is two (as well as a line for a downhole gauge, a line for the ASV and a line for the TRSSSV- what a delightful completion that was to run....)

Injection at the wellhead is only to deal with a problem in a pipeline or flowline- ie subsea wells or long tieback onshore wells. The same kind of things as downhole apply at the wellhead, but wax and asphaltene deposition become a lot more critical as the temperatures are lower, especially subsea (there are several long 'candles' in the North Sea!) and scale is perhaps less of a concern (often because the thermodynamics of scale formation mean the scale has already formed in the tubing!)

A hunt on Google via the speciality chemical suppliers like Clairant or BJ Chemical Services will tell you more about what chemicals are available, what they are used for, if they are batch or continously injected and so on.