长10原油析蜡特性分析及化学防蜡剂筛选

Analysis of Wax Precipitation and Inhibitor Selection for Ansai Crude Oil from Yanchang-10 Formation

安塞油田高52井区开采长10层原油,井筒和集输系统易结蜡。实验原油含蜡13.184%,含胶质1.267%,含沥青质0.029%(丙酮/苯吸附法测定),凝点18℃。用DSC方法测定了原油样由～70℃降温至-20℃的比热曲线,求得该原油析蜡点为41℃,第一、第二析蜡峰温分别为34℃、18℃;取原油结晶热为230J/g,由比热曲线得到单位温降析蜡量曲线,求得41～-20℃区间的总析蜡量为14.26%,其中41～18℃析蜡量为3.62%,约占含蜡量的25%。认为只要有效控制41～21℃区间析蜡,该原油即可安全输送。用冷指法在油温差10℃条件下测定5种防蜡剂控制该原油结蜡的效果,加量为100mg/kg,其中EP-3/35(链节结构与石蜡分子相同的支链聚合物)和多效剂9M(含表面活性剂的复配防蜡剂)效果很好,防蜡率分别为60.0%和59.8%。

In area Gao-52,Ansai,Changqing,waxy crude oil from Formation Yanchang-10 was recovered and waxing troubles in well boreholes and gathering systems were often encountered. The crude oil sample in this study contained 13.184% wax,1.267% resin,and 0.029% asphaltene as determined by adsorption method in acetone/benzene and had pour point 18℃. A curve of specific heat vs temperature from ~70℃ to -20℃ was constructed for the crude oil sample by DSC method,demonstrating wax precipitation point of 41℃ and peak precipitation temperatures of 34℃ and 18℃; a curve of wax precipitation in unit temperature interval vs temperaturewas obtained on the basis of specific heat data with crystallization heat of 230 J/g crude oil taken and it was found that the total wax precipitation in range 41—-20℃ was of 14.26% and in range 41—18℃—3.63%,or about 25% of the wax content in the crude oil. It was considered therefor that this crude oil could be transported without waxing troubles in gathering systems if the wax precipitation in range 41—21℃ was controlled effectively. The wax precipitation on cooled finger of temperature by 10℃ lower than that of oil sample was measured for the crude oil with one of five inhibitors added at dosage 100 mg/kg and inhibitor EP-3/35,a branched polymer with paraffin like chemical structure,and a polyfunctional,compounded with surfactants,chemical,9M,were shown to be effective,giving a percent wax inhibition of 60.0% and 59.8%,respectively.