原油组成对原油管道结蜡规律的影响

Influence of crude oil composition on wax deposition on tubing wall

利用旋转式动态结蜡装置,对不同组成的人工油样(胶质和沥青质含量不同或蜡含量不同)进行了不同条件下的实验研究。通过对管壁沉积物取样并利用差式扫描量热法(DSC)和四组分法进行分析,探究了不同原油组成对结蜡的影响规律。结合胶质和沥青质在结蜡过程中的作用机理,发现胶质和沥青质的存在虽然总会削弱蜡分子的迁移动力,阻碍蜡分子的沉积,但在含量较小时会协同蜡分子的沉积作用,而当含量较大时会以粘壁的形式附着于管壁。对蜡含量不同原油的结蜡规律研究发现:原油所含蜡分子的碳数越高,结蜡层中的蜡含量就越少。但由于碳数较高的蜡分子具有相对较长的碳链,更容易与原油中的胶质和沥青质发生共晶作用,故更易与胶质和沥青质一起沉积于壁面。

The wax deposition was studied for man-made crude oil with various compositions （different contents of resin, asphaltene and wax） under various conditions in a rotary wax deposition facility. The influence of the compositions was explored by sediment sampling from tubing wall, analyzing with the differential scanning calorimetry （DSC） and using four components method. Combined with mechanism of the wax deposition initiated by resin and asphaltene, it was found that lower content resin and asphaltene in crude oil could have a synergistic effect with paraffin molecules on the wax deposition, while for higher content resin and asphaltene they were attached to the pipe wall in the form of paste, although the existence of resin and asphaltene could weaken the driving force for paraffin molecule migration and impede deposition of paraffin molecules. The results obtained from studying on the effect of various wax contents on wax deposition showed that higher average carbon number of paraffin molecules in man-made crude oil was, less content of wax in the wax layer deposited. But the paraffin molecules with more carbon number could take place eutectic roles with resin and asphaltene easily, due to they were of longer carbon chain, leading to they was easier to deposit on the pipe wall with resin and asphaltene together.