| 講演要旨(和文) | | オイルサンド層を構成する岩相は、砂層中に分布する泥岩の様式によって塊状砂岩相、泥岩礫含有砂岩相、砂岩泥岩互層相に分類され、SAGD法によるオイルサンド開発ではこれらの岩相分布の推定が重要となる。本研究では、物理探査手法を用いた岩相分布の推定に資することを目的として、粒度分析手法および岩石物理モデルを用いて各岩相の弾性特性について検討した。岩相別に実施した粒度分析の結果、岩相毎の平均粒径や分級度の特徴が、想定される堆積環境および観察された弾性波速度と整合的であることが示された。さらに、各岩相の弾性特性の定量的検討を目的として岩石物理モデルを構築した。塊状砂岩相では岩石物理モデルと観測P波速度がよく一致した。泥岩を含む岩相では、ビチューメン飽和のモデルと水飽和のモデルがそれぞれ観測P波速度の上限値および下限値にほぼ一致することが分かった。 |
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| | 講演要旨(英文) | | Vast amounts of oil reserves are proven in oil sand in Canada where SAGD is most widely used as an in-situ recovery technique for bitumen production from oil sand. Oil sand formations comprise several types of lithological facies which are divided into massive sand facies, sand with mudstone clast facies, and alteration of sand and mudstone layers facies depending on geometric nature of mudstones distributed in sand. Distributions of the lithological facies in reservoir formations are critical for SAGD production performance because mudstones can be barrier against steam injection, which is the motivation of investigating the elastic properties of oil sand to improve seismic reservoir characterization for the lithological facies. Grain size analysis was conducted to explain the different P-wave velocities observed for the different facies due to different level of sorting. Rock physics model was developed based on the massive sand facies, which is likely to be used for other two facies. The effect of mudstone clasts and mudstone layers on P-wave velocity was evaluated by the solid substitution for pore fluid from bitumen to water. Although P-wave velocities should be varied depending on the volume of mudstones and their geometry, the upper and lower bounds can be defined by bitumen-saturated and water-saturated conditions of the rock physics model, respectively. |
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