Chuanxian Li

Influences of different functional groups on the performance of polyoctadecyl acrylate pour point depressant

ABSTRACT The polyoctadecyl acrylate (POA), polyoctadecyl acrylate-vinyl acetate (POA-VA), polyoctadecyl acrylate-maleic anhydride (POA-MA), and polyoctadecyl acrylate-styrene (POA-St) were synthesized and used as pour point depressants (PPDs). The performance of the PPDs first increases with the increase of polar group (MA or VA) content, and then decreases with the further increase of polar group (MA or VA) content. The POA-VA PPDs show the best performance at the OA:VA molar ratio 3:1, whereas the POA-MA PPDs shows the best performance at the OA:MA molar ratio 7:1. The performance of POA-St PPDs decreases outstandingly with the increase of the nonpolar St molar fraction.

Effective flow improving agents for waxy crude oil

ABSTRACT The comb-like copolymer-polyhedral oligomeric silsesquioxane (POSS) nano-composite PPDs, including POA-POSS, POA-VA-POSS, POA-MA-POSS and POA-St-POSS, were first synthesized via in-situ reversible addition-fragmentation chain transfer (RAFT) polymerization and characterized by FT-IR, NMR and TGA methods. Subsequently, the effects of the nanocomposite PPDs on rheology of a waxy crude oil were studied. Results showed that POA-VA-POSS is the most efficient PPD among the nanocomposite PPDs, which can depress the pour point, gelation point, apparent viscosity and yield stress of the crude oil to the lowest. Associated with the microstructure of crude oil, the rheo-logical improving mechanisms of the copolymer-POSS nanocomposite PPDs are discussed.

Effect of drag reducer and pour point depressant on the wax deposition of crude oil pipeline

ABSTRACT In this paper, the data of wax precipitation before and after the addition of the additives showed that the addition of the drag reducing agent (DRA) and the pour point depressant (PPD) cannot change the wax appearance temperature (WAT) of crude oil. When the dosage of DRA is small, the DRA cannot increase, stop, or slow down the precipitation of wax crystals. The addition of PPDs has no influence on the amount of precipitated wax crystals. From the GPC analysis, the molecular weight of the wax deposit samples in Linpu pipeline is from 500 to 76,800, which indicates that there is no enrichment of DRA in wax deposit samples. The results of IR show that the C˭O group was not detected in the wax deposit sample of the Wei Jing pipeline, which indicates that there is no enrichment of the PPDs in wax deposit samples. The results showed that the DRA and PPD have no obvious effect on crude oil pipeline wax deposition.

An experimental design approach for investigating and modeling wax deposition based on a new cylindrical Couette apparatus

ABSTRACT The authors report an experimental study carried out through a newly developed Couette apparatus on evaluating the influence of important operating factors such as wall oil temperature, temperature difference (△T) and flow rate. It is found that wax crystal solubility coefficient, temperature gradient, and sheer stress at the wall play leading roles on the internal mechanism. CFD software is adopted for numerical calculation and the result agrees well with the distribution of the flow and temperature field in actual pipelines so that precise parameter values under related experimental conditions are obtained. An improved dynamic wax deposition model considering the enhance effect of resin and asphaltene as well as static deposition condition is established with an average error of 5.6%. Thus the feasibility of the method based on the new apparatus for further research is implied.

Effect of dispersing time on the prediction equation of drag reduction rate and its application in the short distance oil pipeline

ABSTRACT The effect of the drag reducer, which is a kind of effective chemical additive for the pipelines, is closely related to its dissolution dispersity in the oil product. In this paper, the effects of oil viscosity, temperature and concentration of the drag reducer on the dispersion rules of drag reducer in crude oil and refined oil are analyzed and the modified Equation for prediction of the drag reduction rate was proposed. For short distance pipeline, a method of drag reducer dispersed beforehand was developed and proved in diesel pipeline, which effectively promotes the application effect of drag reducer in short distance pipeline.