ABSTRACT
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:
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They can provide high-density brines that are non-hazardous and appear to be compatible with oilfield hardware.
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They are environmentally responsible and readily biodegradable.
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As powerful anti-oxidants, they can protect viscosifiers and fluid-loss polymers against thermal degradation up to temperatures of at least 150°C
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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.
