Influence laws of crude oil composition on wax precipitation characteristics of waxy crude oil

Accurate prediction on wax precipitation characteristics is very important to seize the right time to clean and prevent from wax. Three series of simulated crude oils were prepared on the basis of crude oil composition and its analysis. The composition of the oil sample and the carbon number distribution of the wax composition were analyzed with high temperature gas chromatography. Differential scanning calorimetry (DSC) was used to measure the variation of wax precipitation point, wax precipitation peak temperature and average exothermic enthalpy of these simulated oils. The results show that the increased mass fraction of resin and asphaltene has little effect on wax precipitation point and wax precipitation peak temperature, whereas the increased mass fraction of aromatic hydrocarbon can significantly reduce the wax precipitation point and wax precipitation peak temperature though the asphaltene may be precipitated at a certain mass fraction. The increase of wax content will cause significant rises in the wax precipitation point and the wax precipitation peak temperature, which are not conducive to the removal of wax blockage near the well by heating method. The test results could contribute to the thermodynamic prediction of wax precipitation characteristics of high waxy crude oil and guiding the oil well wax removal.