Effect of surfactants and their blend with silica nanoparticles on wax deposition in a Malaysian crude oil

The present study investigated the wax deposition tendencies of a light Malaysian crude oil（42.4° API）, and the wax inhibiting potential of some surfactants and their blends with nanoparticles. With the knowledge that the majority of the wax inhibition research revolved around polymeric wax inhibitors, which cause environmental issues, we highlighted the potential of surfactants and their blend with SiO2 nanoparticles as wax deposition inhibitors. Different surfactants including oil-based, silane-based, Gemini and bio-surfactants were considered as primary surfactants. The primary surfactants and their respective blends at a concentration of 400 ppm were screened as wax inhibitor candidates using cold finger apparatus. The screening results showed a significant influence on the paraffin inhibition efficiency on wax deposition by using 400 ppm of silane-based surfactant, which decreased the wax deposition up to 53.9% as compared to that of the untreated crude oil. The inhibition efficiency among the silane-based surfactant（highest） and bio-surfactant（lowest）revealed an appreciable difference up to 36.5%. Furthermore, the wax from the treated sample was found to deposit in a thin gel-like form, which adhered inadequately to the surface of the cold finger. A further investigation by blending the 400 ppm silane-based surfactant with a 400 ppm SiO2 nanoparticle suspension in a load ratio of 3：1 found that the wax inhibition decreased up to 81% as compared to the scenario when they were not added. However, we have shown that the synergy between the silane-based surfactant and the nanoparticles is influenced by the concentration and load ratio of surfactant and nanoparticles, residence time, differential temperature and rotation rate.

Physical properties of wax deposits on the walls of crude pipelines

Wax deposits on the wall of a crude oil pipeline are a solid wax network of fine crystals, filled with oil, resin, asphaltene and other impurities. In this paper, a series of experiments on wax deposition in a laboratory flow loop were performed under different conditions （flow rate, temperature differential between crude oil and pipeline wall, and dissolved wax concentration gradient）, and the wax deposits were analyzed, so quantitative relationships among wax content, wax appearance temperature （WAT）, shear stress, and radial concentration gradient of dissolved wax at the solid/liquid interface were obtained. Finally, a model was established to predict WAT and the wax content of the deposit.

Review of wax sedimentations prediction models for crude-oil transportation pipelines

Wax sedimentation in pipelines is a severe crude oil production and transportation challenge.Pipeline surface roughness is experienced at the early stages of the problem;with time,the effective pipe cross-sectional area is reduced due to pipeline wax plugging,causing pumping pressure increase,equipment failures,and blockages,resulting in unnecessary downtime costs and pipeline abandonments in the worst situation.This paper reviews mathematical and experimental loops models used for pipeline solid wax predictions and calculations as functions of pressure,temperature,and fluid composition;by assessing model's Assumptions,strengths and weaknesses.It is found that most mathematical models applied molecular-diffusion mechanisms in modeling and neglected shear effects;which resulted in wax over-prediction.Experimental loop was time-consuming due to mounting and dismounting of test section during wax deposition measurements;our modification has included sensor-integration to detect,measure,and analyze wax deposition;Reliable wax predictions models are essential to properly design pipelines and adopt cost-effective strategies for wax deposition prevention,control,and removal.