| The domestic crude oil is mostly high pour point oil with highparaffin content, and rich in glial and asphaltene. At present, as thedevelopment of oil fields has developed to the late, the yield and qualityof crude oil is declined, and the ratio of high pour point and viscositycrude oil is increased. When the temperature of crude oil falls below thewax appearance temperature, paraffin crystal particles will precipitatefrom the crude oil. The paraffin crystals generally grow as thetemperature decreases, creating a crystalline net which begins to trapthe light component of crude oil so that the oil cannot flow. Currently,the method that the chemical pour point depressant (PPD) is added tothe crude oil is widely concerned and used to reduce the pour point andviscosity. This method has the advantages of simple operation, easylater processing and low energy consumption.Because of the complexity of the components of crude oil, as wellas the different natures of crude oil in different regions, the differentpour point depressants have different sensitivity with the crude oil. Inaddition, the high dispersion groups are introduced into the molecularof PPD， such as amine salt and amide, that make wax crystal dispersedin the crude oil and improve the dispersion of PPD. In this paper,selecting the different long chain fatty amines modified maleicanhydride copolymer PPD by the amidation, investigated the effect ofthe PPD to the crude oil of Yanchang Petroleum Group in reducing thepour point and viscosity, and found suitable crude oil PPD.Firstly, the reaction intermediate, styrene-maleic anhydridecopolymer(SMA), was prepared of styrene and maleic anhydride inacetone solution and the initiator condition. The polymerization wasconducted under the conditions that n(maleic anhydride):n(styrene)=1:1, the reaction temperature was80℃, the dosage of acetone solvent was90%, and the dosage of benzoylperoxide (BPO) was1.0%. Under aboveconditions, the polymerization yield reached88.64%. Structure of theproduct was characterized by IR spectrum, and confirmed.Secondly, the prepared SMA was amidated individually with fattyamines (C12H25NH2, C16H33NH2, C18H37NH2and mixture amines) incatalysis of p-toluene sulfonic acid as the catalyst, and synthesized thecrude oil PPD. The modified PPD was used for doing depression effecttest on the crude oil, and it showed that the depression effect of the PPDmodified by mixed amine is better than that by single amine. Theamidation reaction was conducted under the conditions thatn(SMA):n(high carbon amine)=1:1.5, the amounts of the catalyst was1.5%, the reaction time was5hours, and the reaction temperature was80℃. Under above conditions, the prepared PPD modified by mixedamine can make the freezing point of crude oil to reduce9℃. Thestructure of the product was characterized by IR spectrum, and that wasin accordance with the expected molecular design.Thirdly, in different additive condition, the crude oil PPD modifiedby mixed amine were tested for the properties of the crude oil such asthe freezing point, viscosity and wax crystal morphology. By comparingthe modified PPD with the EVA pour point depressant, the resultshowed that when the dosage of the PPD is0.3%and additivetemperature is60℃， the modified PPD had good depression effect onthe crude oil, and was better than the EVA pour point depressant in theproperties. The PPD modified by mixed amine was mixed with theseries of surfactants, and it was applied to the crude oil, the resultshowed that the quaternary ammonium salt cationic gemini surfactantshas good compatibility with the PPD, makes PPD dispersed anddissolved in crude oil better, and improves the depressive effect. |
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