Preparation and performance evaluation of oil-tolerant and easy-wetting viscoelastic system for enhancing the stability of highly viscous oil-water lubricated flow

Abstract

Based on the free sliding phenomenon of the monopterus albus in the cave, an oil-tolerant and easy-wetting viscoelastic system (A₃B₄C₃E₅F₂) was selected and compounded as a possible lubricant to enable the transportation of heavy crude oil. In the viscoelastic system, the final floating equilibrium velocity of LD1 crude oil droplets with a diameter of about 5 mm is 0.01853 mm/s, and the floating resistance coefficient (C_D) is 11067862, which shows favorable oil suspension performance. When the shear rate is approximately zero, the viscosity of the viscoelastic system is about 7000 mPa·s. However, when the shear rate is up to100 1/s, the viscosity is only about 32 mPa·s. A high viscoelastic film is formed at shutdown or low flow rates. Conversely, a low viscosity liquid ring formed at high flow rate. After being wet by easy-wetting viscoelastic system, the contact angle between LD1 crude oil and common pipe materials is wider than 160° at 30 min. The incubation time (t₀) and the wettability composite index (WCI) are shorter than 1800 s and higher than 4800, respectively. Upon stability evaluation, the system can maintain good viscoelasticity and wettability in the range of temperature (5 ∼ 90 °C), oil content (0 ∼ 15 wt.%), and shear rate (0 ∼ 1000 1/s), respectively.

Graphical Abstract

Keywords:

• Heavy oil
• oil-water lubricated flow
• contact angle
• wettability
• viscoelasticity

Additional information

Funding

This work was supported by the National Natural Science Foundation of China (Grant No. U19B2012 and 51779212).