barium sulfate scaling in gas facility - flow test of the well

[rob5377]

Dear All,

One of our customers is testing the gas well at this moment. During the test they faced enormous scaling production in flowlines and separator.
I have the production water analysis in my hand. The sample was taken from the separator.
Among others the water from the separator has sulfate SO4(2-), barium (2+) and Strontium (2+) anionic and cationic species. On the other hand the TSS is low (~1500 mg/L). Considering the rapid reaction of sulfates and barium, all barium sulfate should have precipitated and no barium should be found in the remaining produced water.
I suspect, that analysis are not true, since most of the barium had precipitated upstream of the separator.

Any advices how to measure the real formation water composition?

If there are sulfate and barium species in the produced water in the separator, does it mean that at this particular conditions both species are in the equilibrium?

How is it possible that once the formation water is taken aboveground, the reaction between sulfates starts while underground every species remains at the equilibrium?

I realise that answers are not straighforward, but I will appreciate the discussion.

regards,
rob

 

[bcs5274]

i think the temperature change might be part of the equation also, gonna do some digging

 

[zdas04]

What was the pressure and temperature of the sample? What was the TDS? What was the pressure (and more importantly the temperature) of the sample when it reached the lab? How long did it take from the time the sample was taken until it was analyzed?

All of the reactions you discussed are time, temperature, and pressure dependent. I've been bitten several times by ignoring that fact.

David

 

[blacksmith37]

With Ba and Sr ,you likely have radium (which then produces some radon). I suggest you get information from API on NORM (naturally occuring radiation materials ). API can provide recommendations on what detection equipment is needed and what levels cause concern.

 

[rob5377]

zdas04 I am getting the information from the lab.
TDS was ca 273000 mg/L

Rob

 

[cacofes]

Barium sulfate scale heavily depends on temperature and pressure changes. At high temperature, both barium and sulfates will be in equilibrium in water. However, as both temperature and pressure decrease, barium and sulfate will combine together to promote scaling (barite). This of course is a function of the initial saturation of barium and sulfate in the water.

Keep in mind that barium sulfate is hard and almost insoluble in any acids. For this reason it is usually inhibited (chemical injection) before it happens. When not inhibited, piping and surface equipment may require mechanical cleaning and even be rendered unusable.

For sampling I suggest going as close to the well as possible and preserve the sample using a weak acid (HCL 10% solution). You could consult with a local lab. For treatment just consult with a chemical vendor. Usually the treatment is cheap and requires low injection rates.