Integrated field test and modeling study of CO2 geological storage with enhanced water recovery in Eastern Junggar Basin of Xinjiang

Abstract

Xinjiang, a primary energy export hub in China, faces substantial carbon emission pressure and severe water scarcity, making CO 2 geological storage combined with enhanced water recovery (CO 2 -EWR) a win–win strategy to foster regional development and bolster national energy security. This study leverages China’s inaugural pilot field injection test for CO 2 geological storage and deep saline water production in the Xishanyao Formation of the Eastern Junggar Basin, conducted collaboratively by the China Geological Survey and the Xinjiang Oilfield Company of China National Petroleum Corporation. Using comprehensive datasets from drilling, logging, well testing, and experimental analyses, a high-resolution 3D heterogeneous geological model of the target reservoir-caprock system was developed and validated through simulations that closely matched actual SF 6 tracer results, confirming the model’s accuracy in predicting CO 2 plume migration. Twenty-four operational scenarios were evaluated, including well spacing, production well orientation, number of production wells, injection amount, injection rate, and boundary conditions. Key findings show that reservoir heterogeneity critically governs CO 2 migration; water production initially rises and then declines with increased well spacing, peaking when production wells are aligned with the dominant CO 2 diffusion direction; increasing the number of production wells enhances deep saline water recovery efficiency, reaching 0.82 (mass ratio of CO 2 to water) under the same injection conditions; uniform-rate injection accelerates reservoir pressure release; and closed boundaries yield three times the production amount of open boundaries, independent of the number of production wells. This study validates the technical feasibility and safety of CO 2 -EWR, providing a foundational framework for large-scale implementation in Xinjiang and geologically similar regions to concurrently address carbon neutrality and water security challenges.