A five-well HTHP plug-and-abandonment campaign required high-density brines and cement spacers. An engineered alternative to Sodium Bromide reduced total campaign costs by 60% and individual well costs by up to 90%.
The Challenge
A series of five high-temperature, high-pressure plug-and-abandonment wells required kill fluids ranging from 9.04 to 12.61 ppg at temperatures up to 204°C. Standard Sodium Bromide brine at the required densities would have been extremely expensive — formates and heavier brines are typically leased rather than purchased due to cost.
The Approach
MI SWACO Drilling Fluid Specialist Andrew Bilton worked with the client to design an engineered alternative. Using DUO-VIS suspension agent, PTS-200 polymer temperature extender, SAFE-SCAV H2S scavenger, and M-I BAR barium sulphate weighting agent, the team blended a kill fluid that initially achieved 9.8 ppg with Sodium Chloride, then used M-I BAR additions to reach the required densities — avoiding the switch to expensive Sodium Bromide.
The Outcome
The engineered fluid system reduced costs on the 12.61 ppg well by approximately 90%, and total campaign costs by approximately 60%. The approach demonstrates how an engineered alternative to commodity brines can dramatically change the economics of plug-and-abandonment operations.
The Full Story
We're always very passionate about talking about mud. Our clients see that every day. Some fluid discussions are simple, and others are more complicated. A recent Gas Well Program we worked on was challenging, requiring a sophisticated engineered mud program. We thought you might like to know about some of the various projects we are involved with and some of the higher-level technical drill fluid systems that are a part of what we do.
Blick was recently contacted by a customer to provide high-density brines, cleaning and perforating fluids, and cement spacers for a series of plug-and-abandonment (P&A) operations.
When a well is to be closed permanently, usually after either logs determine there is insufficient hydrocarbon potential, or after production operations have drained the reservoir, cement plugs are placed within the wellbore. Whilst plugging operations can differ depending on the regulatory body, typically cement plugs are placed across open hydrocarbon-bearing formations, across all casing shoes, freshwater aquifers, and other areas near the surface, including the top 6m to 15m of the wellbore.
As part of the initial preparation for a P&A well, a high-density drilling fluid is circulated in the wellbore. These fluids are typically clear brines formulated with chlorides, bromides and formates, with the key driver being well control (ensuring no formation fluids or gas comes to surface).
MI SWACO Drilling Fluid Specialist, Andrew Bilton, worked with the client to design a fluid program for the five HTHP (high temp high pressure) well campaign proposing fluids, blended to specifications based on bottom hole pressures and service temperatures.
Required densities of the 'kill' fluids ranged from 9.04ppg to 12.61ppg and temperatures up to approximately 204 degrees Celsius. Fluid densities up to 9.8ppg can be achieved easily and cost effectively using Sodium Chloride (NaCl), but weighting up over this requires switching to heavier brines. Calcium Chloride (CaCl2) to 11.6ppg, Sodium Bromide to 12.7ppg or a Calcium Bromide (CaBr2) or formates greater than 12.7. Heavier clear brines (especially formates) are very expensive, and are often leased rather than purchased. The recovered fluid is returned to the supplier, filtered and leased out for other operations.
After considering the operational parameters, a kill fluid was blended using a combination of DUO-VIS suspension agent, PTS-200 polymer temperature extender, SAFE-SCAV (H2S scavenger) and M-I BAR (barium sulphate) weighting agent. Using this suite of products, the client was able to weight up initially to the maximum 9.8ppg with NaCl and then make M-I BAR additions as required to achieve the required density.
Using this engineered fluid solution as a substitute for the Sodium Bromide, it is estimated that the client was able to reduce their costs on the 12.61ppg well by approximately 90% and on the total campaign by approximately 60%.
Success isn't just about winning the job. It's built through ongoing collaboration. By working closely with your team, reviewing performance weekly, and making targeted improvements, we can achieve better penetration rates, reduce tooling wear, and lower fluid costs. Our commitment to continuous optimisation, rather than settling for initial results, sets Blick apart.