費用対効果の高いCCS-EORに向けて：統合組成シミュレーション枠組みによる不純CO2圧入のマルチスケール評価

Unofficial AI-generated summary based on the public title and abstract. Not an official translation.

🔬研究者:不純物混合系の非線形な相挙動・MMP評価に統合シミュレーション手法を提供する。

🏢実務担当者:不純物許容型の圧入設計により、分離精製コストを抑えつつ回収率と貯留性能を両立する指針が得られる。

🏛政策担当者:CCS許認可におけるCO2純度要件と貯留効率のトレードオフを検討する際の技術的根拠となる。

Carbon dioxide enhanced oil recovery (CO2-EOR) has emerged as a key technology for extending the productive life of mature oil reservoirs while simultaneously enabling geological carbon storage, making it an important component of carbon capture, utilization, and storage (CCUS) strategies. In practical field applications, however, injected CO2 streams are rarely pure and often contain impurities such as nitrogen (N2), methane (CH4), and hydrogen sulfide (H2S), originating from carbon capture processes, transportation, recycling operations, or source-dependent gas compositions. These impurities significantly influence phase behavior, minimum miscibility pressure (MMP), fluid properties, and multiphase displacement mechanisms, thereby affecting both oil recovery and long-term CO2 storage performance. Despite their practical importance, the combined effects of single and mixed impurities remain insufficiently understood, particularly under realistic reservoir conditions. This study presents an integrated compositional simulation framework to systematically evaluate the impact of impure CO2 streams on enhanced oil recovery and carbon storage efficiency. The workflow combines numerical slim-tube simulations for miscibility evaluation, a large ensemble of two-dimensional (2D) compositional reservoir simulations for impurity screening, and high-resolution three-dimensional (3D) field-scale compositional simulations for validation under realistic geological heterogeneity. The results demonstrate that inert impurities, including N2 and CH4, consistently increase MMP, reduce oil swelling, accelerate gas breakthrough, and consequently decrease displacement efficiency and ultimate oil recovery. In contrast, moderate concentrations of H2S improve miscibility, reduce MMP, and partially compensate for the adverse effects introduced by inert gases. Mixed-impurity systems exhibit strongly nonlinear behavior, indicating that reservoir performance cannot be reliably predicted by extrapolating single-impurity trends alone. The optimization identifies impurity compositions capable of achieving recovery factors comparable to those of pure CO2 injection while maintaining favorable CO2 storage performance. Furthermore, field-scale simulations confirm that impurity-tolerant injection strategies identified during the screening stage remain effective under realistic heterogeneous reservoir conditions, providing balanced improvements in sweep efficiency, and long-term CO2 retention. Therefore, the proposed integrated workflow offers a scalable and computationally efficient methodology for the design and optimization of impurity-aware CO2-EOR projects.

• semanticscholar https://doi.org/10.2118/235843-msfirst seen 2026-11-05 06:00:53 · last seen 2026-11-06 05:32:09