Technical Paper: Well Treatment Fluids Prepared with Oilfield Produced Water: Part II

Society: SPE
Paper Number: 133379
Presentation Date: 2010
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As fresh water becomes more expensive, production and service companies have been trying to use low-quality water such as produced water. Broadly defined, produced water may include any unclean oilfield water that often contains bacteria and high salinity/hardness. Preparation of polysaccharide-based well treatment fluids with produced water frequently results in poor viscosity even when the water is pre-treated with biocides, possibly due to the polysaccharide degradation by bacterial enzymes in the water. This paper presents our continuous success in solving the produced water reusing problems, and discusses the chemistry and case histories of the treatments in North America. A new fluid stabilizer has been developed recently that dramatically extends the lifetime of polysaccharide when used in produced water containing bacteria, possibly because the stabilizer denatures bacterial enzymes. This stabilizer has made it possible to prepare a variety of treatment fluids with produced water.

Since its introduction, the fluid stabilizer has brought greatly enhanced performance for the borate-crosslinked polysaccharide fracturing and sand-control fluids, as reported in SPE 124212. In this paper we continue to explore the new and broader applications of the stabilizer. The polysaccharide fluids with metal crosslinker have been successfully prepared with the stabilizer-treated produced water. The fluids can endure higher temperatures. At the same time, the fluid pH can go below 4, making it possible to energize the fluids with carbon dioxide. The stabilizer has also been used to treat water contaminated with high counts of bacteria, which in turn has been successfully made into crosslinked polysaccharide fluids with improved high-temperature stability.

The expanded applications of this fluid stabilizer have further lowered operating costs for the production and service companies, and contributed to environmental improvement by saving fresh water and recycling produced water in oilfield operations.

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