After more than 30 years of development and refinement, the technology for formulating halide-based brines for drilling and completion-fluid duty is relatively mature. Nevertheless, the halide brines still exhibit certain performance deficiencies that can significantly limit their utility.
Laboratory tests indicate that a series of organic brine systems based on the alkali metal salts of formic acid have a promising range of properties that are superior to those of the halide brines in nearly all respects. The outstanding features of the formate salts are:
They can provide high-density brines that are non-hazardous and appear to be compatible with oilfield hardware.
They are environmentally responsible and readily biodegradable.
As powerful anti-oxidants, they can protect viscosifiers and fluid-loss polymers against thermal degradation up to temperatures of at least 150°C
They are compatible with formation waters containing sulphates and carbonates.
It is anticipated that formate brines will soon find application as high-performance drilling and completion fluids in a number of demanding operational environments where conventional fluids have difficulties in meeting the required performance specifications.