The deposition of high-molecular-weight paraffins in crude oil and condensates, especially with an average carbon number greater than 40, is difficult to treat using chemical methods. Expensive physical remediation methods, such as hot oil treatments and pigging, must be used in such cases. This paper describes the development of paraffin inhibitors for the targeted inhibition of waxes having an average carbon number greater than 40. The study was conducted for condensates from the South Eagle Ford shale formation.

The effect of inhibitors on deposition was studied using a cold finger testing method. A testing protocol was developed to target the deposition of high-molecular-weight waxes having an average carbon number greater than 40. The effect of paraffin inhibitors on the deposits was characterized using high-temperature gas chromatography (HTGC) and differential scanning calorimetry (DSC) techniques. The paraffin inhibitors commonly used tend to inhibit smaller chain paraffins and thus increase the relative amount of longer chain paraffins. This tends to form harder deposits, which are difficult to treat. The new class of inhibitors developed in this study showed improved performance with regard to preventing the deposition of waxes containing high-molecular-weight paraffins. HTGC analysis of the cold finger deposits showed more than a 50% reduction in the deposition of paraffins having a carbon number greater than 40 for the inhibitors tested. In addition, the use of inhibitors resulted in softer deposits. Thus, using inhibitors targeted at the heavier paraffins that soften the deposit could reduce the frequency of hot oiling and pigging operations required in field applications.

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