ABSTRACT

Oil field chemicals are incorporated into a fluid design to solve a specific technical wellbore or matrix problem in a well, such as stimulation; water, sand, and scale control; or damage removal. By their chemistry, some chemicals have primary active ingredients that may be harmful if discharged to the environment. Improving the characteristics of these chemical products to marine life requires changes in previously acceptable products, such as elimination of restricted chemicals as well as incorporating chemical components with reduced ecotoxieity. Additional chemical alternatives should be provided to reduce the potential effects of the total chemical/fluid system. This paper focuses on the last four years of an aggressive product development for acid corrosion inhibition and application. Product improvements were achieved by eliminating restricted chemicals, decreasing product toxicity, and improving biodegradability. The aim of the paper is to demonstrate that for a complete solution, chemical reformulation and development of new chemistry must be considered hand in hand with improved operational practices to provide a maximum overall risk reduction. This paper recognizes that regulation of the use of hazardous chemicals offshore for oilfield stimulation and completion applications is one method for protecting the marine environment; however, for the long term, aggressive technical chemical improvements must continue. Development of more environmentally acceptable products does not arbitrarily mean that products are less efficient and less cost effective. More efficient products with improved ecotoxicity performance have been developed. Chemical replacement schemes are important but may be limited in what they can ultimately achieve. More important are process management and the more efficient use of chemicals with the goal of no waste.

INTRODUCTION

Regulations for the offshore use of hazardous chemicals for oilfield stimulation and completion applications are an important.., but not a total.., solution to reducing marine pollution. For a complete solution, chemical reformulation must be considered hand in hand with improved operational practices and engineering to provide a maximum overall risk reduction. Numerous chemical additives are recommended for the drilling, completion, and stimulation of the well. These products have a defined purpose for efficient fluid placement, cuttings removal, and stimulation. If a reconunended drilling fluid results in a more efficient drilling operation, then costs are reduced and a reduced total volume of fluid is used with less potential for a fluid spill and a reduced risk to the environment. Similarly for stimulation, chemicals aid to remove the damage and/or prevent the damage from forming in the rock matrix. If these chemicals, such as acid corrosion inhibitors, solvents and nonemulsifiers, are omitted from the stimulation fluid, decreased oil production may ultimately result. Over the years, acid treating fluids have become more complex to improve performance in the designed application, such as corrosion inhibition of new metallurgy, timed release of chemical activation/deactivation to obtain optimum fluid properties, and control scale and organic deposit precipitation. The role of chemicals for use in completion and stimulation dictates the applicable chemistries. For example, corrosion inhibitors are designed to inhibit the corrosion of oilfield tubulars. Most recently, corrosion-resistant alloys (CRAs) have been used to minimize corrosion during production. Acid stimulation of these wells requires using an inhibitor to protect the expensive tubulars in place. Technology has advanced to allow protection of the pipe, resulting in more comple

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