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Zinc Bromide precipitation in H2S well.
13 February 2021

Hello everyone!

Does anyone had an experience with formation damage caused by the reaction of ZnBr2 with the sour gas (H2S) present in the reservoir and consequent Zn2S precipitation?


1 answer(s)
ianpetitt
(retired) Well Fluids Team leader
SPREAD Associates
Total Posts: 58
Join Date: 14/06/06

Albina,

I used zinc bromide in HTTP wells in the North Sea in the1980s until HSSE issues prevented further use. 
As zinc oxide or carbonate are used as one of the main scavengers in water based muds for H2S control. Then the reaction produces zinc sulphide which is then removed by the solids removal equipment. As size of particles is similar to drilled solids then the particles must be considered as damaging.  

Zinc bromide brine although a clear liquid has to be managed carefully to minimise formation damage with filtration units on board.
In addition to the cost and value of the brine a couple of other factors need to be considered.  You need  a specific corrosion inhibitor and the inhibitor depends on both the temperature and the steel and tubing types you have exposure to in your well. Often you may well find solids content  above 2%v/v. 
Choice of inhibitor is critical to minimising solid content. 

Besides the cleanliness of surface pits - zinc bromide will cause corrosion at HTTP conditions generating hydrogen gas and precipitated solids. These solids are more likely the source of your solid content. 

I have sat for a week-end offshore watching an HTHP well bubbling hydrogen gas for the corrosion reaction and not methane from a possible leaking liner lap.  


Best Wishes Ian 





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