Amphiphilic Wax Inhibitor for Tackling Crude Oil Wax Deposit Challenges

Abstract

As waxy crude oil comes to the surface, it will cool down and causing the waxy fraction to gel. The gelled crude chokes the well, leading to restricted or blocked production and costly downtime for operators. One of the most common chemical solutions to address the wax deposit challenge is the addition of wax inhibitors or pour point depressants (PPDs) to the production stream. However, most of the PPD's used in the field are organic solvent-based polymers, which require large quantities of hazardous organic solvents such as xylene and toluene. To propose an improved solution, a water-based amphiphilic PPD polymer dispersion system, synthesized using controlled radical polymerization technology has recently been developed. This specifically designed block copolymer is synthesized with a hydrophilic polymeric head group and a hydrophobic tail. The macromolecular design was specifically optimized to control particle size to create unique and stable amphiphilic PPD dispersion. The viscosity of the PPD, at high activity of about 40%, is between 200 and 250 cps at room temperature with a milky color, and it remains stable to 200°C under 500psi. Also, the PPD dispersion itself has a pour point of −30°C, and it can be easily formulated to be pumpable under −40°C. For performance evaluation, the water-based PPD dispersion was tested using a standard cold-finger apparatus and a pour point tester on crude oils from various global regions. The results showed that this PPD dispersion not only significantly reduced crude oil wax deposition by nearly 70%, but it also reduced the pour point of the crude by typically 18°C. Overall, the current research performed on macromolecular architecture design shows that this block polymer technology allows polymer adjustment to meet application needs for various crude types, and to tackle this important flow assurance challenges.