Reservoir characterization using seismic data serves large contributions to oil and gas development projects and CO₂ sequestration projects. Rock physics analysis has been one of pivotal disciplines in such reservoir characterization because it plays a role in connecting physical properties of rocks and reservoir properties. Laboratory experiment is the central part in a rock physics analysis because it reveals various physical properties on a single rock sample. In this paper, we introduce two rock physics case studies using results of core velocity measurements conducted at Japan Organization for Metals and Energy Security （JOGMEC） Technology and Research Center （TRC）’s lab. The first study is the estimation of velocity anisotropy at a gas field offshore Australia. We measured elastic propagation velocities of rock samples from the field with a tri-axial compression test apparatus and estimated both intrinsic anisotropy and stress-induced anisotropy. With synthesized CMP gathers, it was revealed that the estimated stress-induced anisotropy would affect seismic inversion and subsequent reservoir characterization. The second case is the interpretation of time-lapse walkaway VSP （Vertical Seismic Profile） conducted in a CO₂-EOR pilot at an oil field onshore Abu Dhabi. Based on the results of velocity measurements performed on rock samples from carbonate reservoirs and dynamic reservoir models, we modeled changes in elastic properties associated with the CO₂-EOR pilot between the time of the baseline and monitoring VSP. The modeling of elastic property changes allowed us to deepen the understanding about 4D response obtained through time-lapse full waveform inversion applied to the walkaway VSP data. JOGMEC TRC offers continuous supports for improving reservoir characterization in E&P and CCS projects.

シェール層は，二酸化炭素の地中貯留（CCS）においては遮蔽層，在来型油ガス田においてはシール岩の役割を果たし，効果的な地下評価や掘削を行うためにその弾性的特性を理解する必要がある。シェール層の弾性的特性として強い異方性が挙げられるが，これは粘土鉱物の異方性やその配列によるものである。この異方性が地震探査データに及ぼす影響についてはこれまで多く議論されてきており，異方性を考慮したデータ解析を行うことの重要性が示されてきた。一方で，ジオメカニクス分野における異方性の影響についてはあまり議論されておらず，等方性を仮定した解析のピットフォールについて十分に整理されていない。本講演では，まずシェール層の弾性特性的特徴や岩石物理について述べる。次に，シェール層の異方性がジオメカニクス解析に及ぼす影響について議論し，等方性を仮定した解析の問題点を挙げる。最後に，実フィールドで異方性を考慮したジオメカニクス解析を適用する際の課題について述べ，岩石物理が果たす役割について議論する。

In oil and gas industry, 3D seismic techniques and rock physics analysis have enabled integrated reservoir evaluations. These evaluations have played a crucial role in optimizing development strategies and guiding investment decisions. Similar analytical methods are now being explored for subsurface evaluations and monitoring in Carbon Capture and Storage （CCS） projects.

Despite the extensive experience in applying rock physics-based analysis and evaluation technologies within Exploration and Production （E&P） industry, there has been little public discussion about practice and misunderstandings in reality. In this talk, I presented practical examples of subsurface evaluations based on rock physics in E&P operations. I also discussed key factors towards effective subsurface assessments in CCS projects.