Study of asphaltene dispersion and removal for high-asphaltene oil wells

Many wellbores are blocked by asphaltene deposits, which lead to production problems in the oilfield development process. In this paper, methods such as elemental analysis, and solvent extraction are adopted for the study of wellbore blockages. The content of organic matter in blockages is higher than 96% and asphaltene is the main component of the organic matter with n-heptane asphaltene content of 38%. Based on the above analyses, an agent for asphaltene dispersion and removal (named as SDJ) was developed. The performance of the SDJ agent was evaluated, and it was found that the dissolution rate of asphaltene can reach 2.9 mg·mL-1·min-1 at 60 oC. SDJ agent (1wt%) was added to crude oil with a colloid instability index greater than 0.9 can effectively inhibit asphaltene deposition in the wellbore. By the viscosity method, the dissolution amount of SDJ agent was calculated, and it was found that when the viscosity of the system is around 2,000 mPa·s (the common viscosity of crude oil), the amount of SDJ agent added to the blockage was at least 96 g per 100 g blockages. Therefore, SDJ agent has promising application for dispersion and removal of asphaltene deposition in high-asphaltene wells.