(672c) Experimental Study on the Deposition Characteristics of Wellbore with Highly Resin and Asphaltene Crude Oil

Wax deposition is one of the core issues in the flow assurance study of oil and gas wellbores, particularly in deep and ultra-deep water conditions. The component properties of the crude oil vary widely in different seas, which further complicates wax deposition issue. Although recent advances have been made in understanding the performance and mechanism of wax deposition, the influence of asphaltene and resin, remains an open question.

In this work, the effects of asphaltene and resin on the wax deposition layer in J and B oil wellbores with the variation of different production rates were investigated by using the cold finger and HTGC. Compared to the deposition results of the two wellbores, the initial deposition layer of J oil is thicker and the increase of deposition thickness with time is smaller, and the deposition also occurs when the wall temperature is higher than the wax appearance temperature (see Figure 1A), and the distribution of carbon number of wellbore plug and oil sample is basically the same (see Figure 1C), so the aging effect is weaker. The gelling effect caused by the high asphaltene content of J oil cannot be ignored. However, the deposition characteristics of oil B are in accordance with the typical wax deposition law, i.e., the deposition thickness increases when the temperature decreases/the temperature difference increases (see Figure 1B), and the content of recombination (C40-C60) in the wellbore plug is significantly higher than that of the oil sample, while the content of lighter components (C7-C40) is lower than that of the oil sample, obeying the aging law.

This work adds to growing evidence of the coexistence of crude oil gelling and wax deposition. These conclusions also provide theoretical reference for the wax prevention and removal methods.