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.
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.