Abstract: In this work, the factors affecting asphaltenes deposition in high-temperature and high-pressure wells were studied using backscattered light and PVT equipment customized to suit the well conditions. In an examination of the intensity of backscattered light, it was revealed that there exists a linear relationship between temperature and asphaltene precipitation within a specific temperature range. Within this range, a decrease in temperature tends to accelerate asphaltene precipitation. However, the impacts of pressure and gas-oil ratio are more pronounced. The pressure depletion induces the asphaltenes to precipitate out of the solution, followed by the formation of flocs below the bubble point. In addition, an increase in the gas-oil ratio causes a more severe asphaltene deposition, shifting the location of asphaltenes to deep well sections.