国内減退油ガス田のCO₂貯留可能量評価とその開発の可能性について

抄録

This study provides the CO₂ storage capacity of Japanese depleted oil and gas fields in which subsurface risks and development costs are expected to be lower than undeveloped saline aquifers. Furthermore, as opposed to the previous studies in which a volumetric method was used to estimate CO₂ storage capacity in Japan, we applied a material balance method using historical hydrocarbon production data collected for each field. This significantly reduced the uncertainty in the storage capacity estimation.

We estimated the total CO₂ storage capacity of Japanese depleted oil and gas fields to be 304 Mt, which is more than 10 times lower than the previously reported value of 3492 Mt. There are two reasons for this difference. First, we only evaluated the capacity of oil and gas bearing formations, while the previous study reported the capacity of each field including undeveloped potential saline formations. Second, we applied a material balance method incorporating historical production data. Hence, our estimated capacity can be viewed to have a higher confidence, which can be developed with lower risks and costs. We show that our estimated storage capacity is also consistent with the capacity reported in the literature in which CO₂ storage capacity was obtained based on a numerical model incorporating historical production data.

Since 76% of the total storage capacity in Japanese oil and gas fields is found within two areas with a radius of approximately 20 km in Niigata-prefecture, we discuss the feasibility of CO₂ hubs and clusters concept in these areas.

The novelty of this study is, for the first time, to provide the CO₂ storage capacity of Japanese oil and gas fields on a field-by-field basis using a material balance method. This has made it possible to discuss the application of CO₂ hubs and clusters concept in Japan.