The Development of a Novel Environmentally Friendly Dual Function Corrosion and Scale Inhibitor

Abstract

Production chemicals being discharged into the natural environment are increasingly becoming scrutinized for their impact on the environment. New and existing chemicals for scale and corrosion control are likely to be impacted by the developing legislation and regulatory control. Therefore, there exists an urgent need to bring the marketplace new chemistry that is able to reduce the environmental impact while still retaining its excellent efficiency. This paper describes the development of novel polymeric chemistry, which has a dual functionality acting as both a scale and corrosion inhibitor under oil field conditions. This chemistry can be readily biodegradable and has achieved the stringent standards required for its use in the North Sea. Laboratory studies demonstrate that this chemistry can inhibit both carbonate and sulfate based scales. Corrosion experiments with or without flow suggest that greater than 90% of inhibition in a carbon dioxide rich environment can be achieved. The calcium compatibility of this chemistry far exceeds the performance of most commercially available scale inhibitors. The impact on oil and water separation, and subsequent oil in water content, is minimal. Introduction The development of multifunctional production chemicals has several strong drivers. First of all, significant cost savings can be achieved both in terms of chemical use and in facility requirements (e.g., a reduction in subsea umbilicals, hoses, and tiebacks). Secondly, using one chemical to replace at least two chemicals minimizes the potential compatibility problems. Finally, environmental discharges are substantially reduced. While all this is true there is one even stronger driver for the development of novel production chemicals. This is the green agenda. The oil industry has to be prepared for increasingly restrictive legislation concerning the use and disposal of oil-field chemicals. In the area of oil-field production chemicals, only Norway currently has formal legislation covering the environmental impact of the products used. The Norwegian Pollution Control Authority (SFT) administers the various requirements. Elsewhere, the situation is less well developed. For example, in the UK sector of the North Sea, the Department of Trade and Industry (DTI) is currently organizing a voluntary scheme of notification for production chemicals. More rigorous acceptance criteria are pending in line with Norway and the Paris Commission. In the US section of the Gulf of Mexico, a critical dilution factor is assigned to each platform. This factor dictates the amount of chemicals allowed to discharge into the ocean. The factor also is greatly influenced by the "greenness" of the chemicals involved in the oil production. Most recently, the CHARM (1,2) model was recommended in both the UK and Norwegian sections of the North Sea. The CHARM model calculates the ratio of the Predicted Environmental Concentration vs. the Predicted No Effect Concentration (PEC/PNEC ratio). The ratio relates to each chemical's discharge under standardized platform conditions. A ratio of less than unity is most desirable. Again, greener chemicals result in smaller ratios in the calculation and therefore less restriction of employing the chemical. Given that the concern of the protection of the environment is likely to accelerate rather than decline in the near future, there is a need for the oil industry to develop a new generation of environmentally friendly oil-field production chemicals.

Synthesis and Characterization of Modified Aliphatic Polycarbonates as Environmentally Friendly Oilfield Scale Inhibitors

“…However, many of the classic phosphonate SIs, such as diethylenetriaminepentakis­(methylenephosphonic acid) (DTPMP) and aminotris­(methylenephosphonic acid) (ATMP), show poor biodegradability, which means they are not allowed for use in regions with strict environmental regulations, such as offshore Norway or Denmark. ,− In general, classic carboxylate SIs, such as those based on acrylates and methacrylates, as well as many maleic-based SIs are also poorly biodegradable as a result of the polyvinyl backbone. A few more biodegradable polycarboxylate SIs are commercially available and include polyaspartic acid (PAsp), polyepoxysuccinic acid (PESA), and carboxymethylinulin (CMI). − The first two of these SIs have linear backbones but contain heteroatoms to improve the biodegradability compared to polyvinyl-based polymers (Figure ).…”