Abstract

Laboratory and field experience indicates that simple universal drilling and completion fluids, suitable for all applications, can be built around brines based on the alkali-metal salts of formic acid. The formate brines have been subjected to a thorough hazard identification and assessment procedure prior to introduction into the field. This procedure was based on accepted OECD tests, compatible with EC requirements for assessing the mammalian toxicological and ecotoxicological properties of new substances.

It has been concluded that the alkali-metal salts of formic acid pose little hazard to either users or the environment. As an additional safeguard for the environment a novel recycling process has been developed specifically for use with the formate brines, aimed at minimising product discharge and retaining a valuable non-renewable resource.

Introduction

The design of conventional drilling and completion fluids has gradually evolved through the use and adaptation of readily-available raw materials to create formulations meeting perceived performance requirements.

Over the years the demands created by new insights into performance requirements, accompanied by fresh technological challenges arising from the introduction of new drilling concepts and more stringent legislation to protect the environment, have been accommodated in drilling-fluid designs by piecemeal replacement of existing components by improved variants.

The outcome of this evolutionary process has been a proliferation of drilling-fluid types and component chemicals, each one adapted to meet a specific combination of economic, performance and legislative compliance targets. This proliferation of differentiated products can work to the advantage of the drilling-fluid and chemical suppliers, but not always to the advantage of the consumer or those having stakeholder interests in the profitability of the consumer's business.

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