A Multifaceted Laboratory Approach to Screen Paraffin Inhibitors for Canadian Unconventional Resources

Abstract Paraffin deposition during oil and gas production is a common challenge and may partially or completely plug the wellbore, production tubing and flowlines. This results in significant reduction in well production and frequent paraffin remediation jobs. Chemical treatment is used widely and is one of the most practical ways to mitigate paraffin deposition. In previous studies, conventional test methods such as cold finger testing have been implemented to screen paraffin inhibitors for field applications. However, poor correlations between laboratory results and field observations challenge the reliability of the method. Developing a comprehensive laboratory protocol is imperative for screening effective paraffin inhibitors. In this study, we introduce a systematic laboratory procedure to assess the performance of paraffin inhibitors on oil samples produced from formations located in the Western Canadian Sedimentary Basin (WCSB). These formations include Duvernay, Montney, and Cardium. The laboratory protocol is composed of three test procedures. First, we measure the viscosity of the oil samples mixed with paraffin inhibitors over a wide range of temperature values. Second, we perform cold finger tests using oil samples mixed with the various paraffin inhibitors. Lastly, we quantify the fouling tendency of oil samples with and without paraffin inhibitors using a para-window instrument by dynamically measuring near-infrared light transmittance on a temperature controlled reflective surface. Several polymeric chemical families including ethylene vinyl acetate (PI-1), maleic ester (PI-2), maleic amide (PI-3), and alkylphenol (PI-4) are evaluated using this laboratory protocol. The measured performance of the paraffin inhibitors varies depending on the technique used and the temperature at which the evaluation is performed. In the case of experiments performed on the Montney oil sample, it is found that inhibitor containing maleic ester (PI-2) demonstrates 31% of reduction in viscosity testing, 75% of inhibition from cold finger testing, but only 8% of fouling reduction in the para-window testing. As this protocol is implemented over a wide range of temperature values, it provides valuable insights about the effectiveness and versatility of paraffin inhibitors at different operational conditions. In the case of PI-2, it shows higher inhibition at temperature near 0°C, rather than near the Wax Appearance Temperature (WAT) of 30°C, indicating that it might not be a suitable candidate for inhibiting the more problematic high molecular weight paraffins generated at 30°C. The laboratory protocol developed in this study helps narrow the gap between laboratory results and field observations. It highlights the importance of matching representative field temperature conditions within the laboratory; and provides new insights about the performance of paraffin inhibitors for oil field applications.

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