Summary
Pour-point depressants (PPDs) were synthesized from natural sources and used in waxy crude oil transportation to reduce the pour point and improve flow. A biodegradable PPD (BPPD) was synthesized and tested to mitigate crude oil flow assurance problems in the present work. The transesterification process was used to synthesize coconut oil ethyl ester (COEE, termed as BPPD). Fourier transform electron spectroscopy (FTIR), proton nuclear magnetic resonance (H-NMR), and microscopic analysis were performed for better understanding of mechanisms for both BPPD and a commercially available PPD named PPD-A. The pour point of crude oil was reduced by 12 and 9°C after the addition of 800 ppm BPPD and PPD-A, respectively. The microscopic analysis confirms that the crystals of wax converted to very fine and dispersed particles during mixing of additives, which in turn increase flowability. BPPD performs better to reduce interfacial tension than PPD-A. The maximum reduction of 19% in interfacial tension was observed after the addition of 800 ppm BPPD. BPPD alters the wettability of the pipeline surface from intermediate wet to water-wet within 60 seconds, which results in reduced slip velocity and consequently lessens the deposition of wax. As a result, crude oils will not stick to the wall of the pipe surface and will experience less resistance to flow through pipelines. FTIR analysis indicated that long-chain alkane and aromatic groups are responsible for a higher pour point, and their concentration level was reduced after the addition of BPPD. The viscosity of crude oil was reduced by almost 94% after the addition of 800 ppm BPPD with crude oil, which in turn minimizes pumping costs for crude oil. As a result, the total project cost was reduced substantially. Biodegradability tests confirm that the BPPD is biodegradable and nontoxic. Due to its biodegradability and nontoxic nature, BPPD has a promising capacity to be used in the petroleum industry for easier pipeline transportation of waxy crude.
Study on the thixotropy and structural recovery characteristics of waxy crude oil emulsion
