Year: 2025
Type: conference-paper
Abstract: Lukqin Triassic heavy oil reservoir belongs to deep heavy oil reservoir. After more than 20 years of technical research and field test, a ‘combination of secondary and tertiary oil recovery’ technique series for heavy oil extraction has been established. In the past several years, large-scale implementation of N2 huff ‘n’ puff for enhanced oil recovery has yielded positive results. However, the diminishing effectiveness of multiple cycles of huff ‘n’ puff has become increasingly prominent. To improve development efficiency, PVT phase behavior experiments (including gas injection swelling experiment and pseudo-bubble point pressure test), numerical simulation and field test were conducted. Additionally, parameters of huff ‘n’ puff process has been optimized. The experimental results of PVT phase behavior show that CO2 significantly enhances the volume expansion of heavy oil and demonstrates superior viscosity reduction compared to N2; In comparison to N2, CO2 injection into heavy oil provides a larger foam oil range, facilitating the formation of foam oil during huff ‘n’ puff. Numerical simulation results indicate that the optimal parameters for CO2/N2 compound huff ‘n’ puff after multiple cycles of N2 huff ‘n’ puff are: the ratio of N2:CO2:N2 is between 1:4:1 and 1:10:1, the injection sequence is N2-CO2-N2, the injection volume is 4×105 m3, the injection speed is greater than 5×104 m3/d, and the soaking time is 20 d. A total of over 20 wells have implemented CO2/N2 compound huff ‘n’ puff in this reservoir, resulting in significant water control and oil enhancement, effectively improving the development performance of multiple cycles of huff ‘n’ puff. The research verifies the feasibility of implementing CO2/N2 compound huff ‘n’ puff and provides practical guidance for optimizing CO2/N2 compound huff ‘n’ puff in industrial applications.
Authors: Xifan Zhang, Hai Huang, Jian Zhao, Bing Yang, Jing Zhang, Wenkai Li
Institution: Xi'an Shiyou University
Language: English
Subfield: Ocean Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: diamond
OpenAlex ID: W4414126571