Open Access

ARTICLE

Optimizing CO₂-EOR Strategies in Water-Sensitive Tight Conglomerate Reservoirs: Mechanisms and Field Application

Houchuan Huang¹, Ning Li¹, Shichang Ju¹, Aiping Zheng¹, Yufeng Jia¹, Pan Wang¹, Yuhui Zhou^2,3,4,*
1 PetroChina Xinjiang Oilfield Company Heavy Oil Development Company, Karamay, China
2 Western Research Institute, Yangtze University, Karamay, China
3 State Key Laboratory of Low Carbon Catalysis and Carbon Dioxide Utilization (Yangtze University), Wuhan, China
4 College of Petroleum Engineering, Yangtze University, Wuhan, China
* Corresponding Author: Yuhui Zhou. Email:

Energy Engineering https://doi.org/10.32604/ee.2026.078072

Received 23 December 2025; Accepted 29 April 2026; Published online 12 August 2026

Abstract

The sustainable development of conglomerate reservoirs in the Junggar Basin is critically constrained by low permeability, high illite content, and severe water sensitivity. Conventional water flooding has proven inefficient, characterized by rapid pressure depletion and suboptimal recovery factors (avg. 5.5%). This study systematically investigates the efficacy of CO₂ injection as an alternative Enhanced Oil Recovery (EOR) mechanism. Through integrated core-flooding experiments and numerical simulations, we evaluated the displacement efficiency of CO₂, N₂, and CH₄. Results demonstrate that CO₂ injection yields a superior ultimate recovery factor of 38.39%-substantially outperforming the historical water flooding baseline as well as N₂ and CH₄. This superiority is primarily due to CO₂ effectively extracting light hydrocarbons (contributing 80% to incremental recovery) under high pressure and inducing significant oil swelling and viscosity reduction, significantly outperforming other media due to its ability to extract light hydrocarbons (contributing 80% to incremental recovery) and reduce oil viscosity. Furthermore, numerical optimization identifies horizontal well cyclic huff-and-puff as the optimal deployment strategy for this reservoir class. Field pilots of CO₂ pre-pad energized fracturing validated these findings, achieving a 38% enhancement in initial productivity compared to conventional fractured wells. This stimulation effect sustained elevated production rates for approximately 150 days. These results provide a robust technical framework for revitalizing depleted, water-sensitive conglomerate reservoirs.

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Keywords

Conglomerate reservoir; CO₂-EOR; huff-and-puff; water sensitivity; numerical simulation; enhanced oil recovery

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