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Brine preparation for DST in deepwater exploration wells
26 February 2018

Dear all,


I’m in the process of planning DST in a deepwater exploration well. Brine is planned to be used as packer fluid. Pore pressure of target formation is expected up to 12.5-14.0 ppg. Under the circumstances, potassium formate (KHCO2) or calcium bromide (CaBr2) would be candidate brine, which is very expensive. Due to the nature of DST materials, brine has to be prepared in advance for the operations at remote areas like Japan regardless of whether it is used or not. How can such brine (potassium formate or calcium bromide) be obtained by the least expensive way from the market? Is it possible / common to obtain it by consignment or buy-back contract?

I’d like to know your experience of high-density brine preparation for DST.




4 answer(s)
Drilling Fluids Superintendent (retired)
Total Posts: 1
Join Date: 27/02/18


For 12.5 ppg up to (realistically)  12.95 ppg you can use potassium formate.  Above that weight range you are looking at either a straight calcium bromide brine, a straight cesium formate brine, or a blend;  calcium bromide/calcium chloride, or potassium formate/cesium formate are possibilities.  However, writing as both as an ex operator fluids superintendent and as an ex-Cabot engineer, you are very unlikely to be able to negotiate a rental or buy-back agreement for an intermediate-weight brine unless you opt to use pure (diluted as necessary) cesium formate unblended with any other salt.  To recondition any other brine is probably not cost-effective for the brine company, unless the brine is particularly exotic and/or very heavy. Cabot Specialty Fluids would be able to help you further regarding cesium brines although (unless their policy has changed) they are unlikely to contract with you directly.

You will need to be aware of the surface and downhole environmental conditions of your well, not just in terms of potential discharges but also in terms of the temperatures at which your brine (whichever one it is) is to be blended, used and stored;  crystallisation could be an issue.

Managing Director (
Relentless Pursuit Of Perfection Ltd.
Total Posts: 416
Join Date: 10/01/05

I know that BP Egypt are procuring Cesium Formate (CsF) brine from Cabot on a rental basis, but I am unfamiliar with the commercial agreement (and I'm happy to keep it that way).

BP chose CsF 100% out of respect to personal safety and the environment.

It's OK to discuss technical matters here on the site, but I'm reluctant for commercially-sensitive information to appear here. These are all private matters between the two contracting parties.

If people wish to help you with 'numbers', then I am happy to put you in direct contact with them if they come forward and offer to do so.

I hope you get some great answers.

Best wishes


Drilling Engineer
Total Posts: 3
Join Date: 23/02/18
Was used Formate brine bought back with 29/30th of the original price?
In our case, we will mobilize Potassium Formate brine with IBC tanks.
We would like to return some of brine which is unused for some reason such as dry hole.
Isn't it common in recent years to obtain Formate brine on a buy-back base?

FCW Coordinator
N Operating Company
Total Posts: 8
Join Date: 19/10/14
When I was in charge, on site (as Fluids & Cement Supervisor) of the first use of large volume (300 m3) of Formate brine as Completion Fluid (Total-Dunbar-D22-1999, an ERD HPHT Well) the contract was on a buy-back base.
At that time, the by-back price was based on volume and density only, it look to have change now (as far as I know) since a daily rental is added.
At that time, the final Fluids cost of the operation did represent 1/30th of the Brine(s) cost, thanks to a very effective planing of all displacements using intermediate brines as pills to reduce the cost of contamination of our (very) dear Caesium Formate brine, displacements to brine as well as recovering of the brines.

As far as I remember, CaBr2 was not even an option, for HSE as well as Technical reasons.

An ideal choice for the Oil Company I was representing then, not for the service company providing some technical advices as well as the brines.
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