Estimation of the CO₂ storage potential of gas-bearing shales in the Lower Paleozoic Baltic Basin is at an early stage of reservoir exploration and production, based on data from one vertical exploration borehole, supplemented with some information from adjacent boreholes. The borehole section examined is 120 m long and comprises three intervals enriched with organic matter separated by organic-poor intervals. In our approach, the storage capacity is represented by: (1) sorption potential of organic matter, (2) open pore space and (3) potential fracture space. The potential for adsorbed CO₂ was determined from Langmuir isotherm parameters taken from laboratory measurements and recalculated from CH₄ adsorption curves. The pore space capacity was estimated in two ways: by utilizing results of laboratory measurements of dynamic capacity for pores >100 nm and using results of helium porosimetry, the first of these being considered as the most relevant. Due to the low permeability of the shale matrix we have adopted the standard assumption that the CO₂ is able to reach effectively only 10% of the theoretical total sorption and pore volume. For hydraulic fracture space, the theoretical maximum opening of vertical fractures in the direction of minimum horizontal stress was considered, decreased by the expected portion of fracturing fluid flowback and by partial fracture closure by burial compaction. The effectiveness of three CO₂ storage categories for the individual organic-rich and organic-poor shale units shows an obvious positive correlation of TOC content with the storage efficiency by sorption and within pore space, and a negative correlation with the storage efficiency in hydraulic fractures. It was estimated that sorption, over the maximum storage interval (120 m thick), is responsible for ~76% of total storage capacity, pore space accounts for 13% (for the most relevant porosity model) while the contribution of fractures is about 11%. In the minimum storage interval (35 m thick, including the best quality shales) the estimated proportions of sorption, pore space and fractures in the total storage capacity are 84, 10 and 6% respectively. Finally, the result for the best quality storage interval (35 m thick) was compared with the Marcellus Shale of similar thickness (average ~38 m) and with other options of CO₂ storage in Poland. The most organic-rich units in the area studied have a CO₂ storage capacity efficiency (i.e. storage capacity per volume unit of shale) only slightly less than average for the Marcellus Shale, because sorption capacity – the dominant component – is comparable in both cases. However, the open pore space capacity in the Marcellus Shale appears to be far higher, even if the potential fracture space calculated for the borehole studied is taken into consideration, probably because the free gas content in the Marcellus Shale is far higher than in the Baltic Basin. CO₂ storage in depleted shale gas wells is not a competitive solution compared to storage in saline aquifer structures or in larger hydrocarbon fields.

在下一个古生代波罗的海盆地中，含气页岩的CO ₂储存潜力的估算是在油藏勘探和生产的早期阶段，其基础是一个垂直勘探井眼的数据，再加上邻近井眼的一些信息。所检查的井眼段长为120 m，包括三个富含有机物的层段，这些层段被有机质差的层段分隔开。在我们的方法中，存储容量表示为：（1）有机物的吸附势，（2）开放的孔隙空间和（3）潜在的裂缝空间。吸附CO ₂的潜力由实验室测量的朗缪尔等温线参数确定，并由CH ₄重新计算吸附曲线。孔隙空间容量的估算有两种方法：利用实验室对大于100 nm的孔隙的动态容量的测量结果，以及利用氦孔隙率法的结果，其中第一种被认为是最相关的。由于页岩基质的渗透率低，我们采用了标准假设，即CO ₂只能有效达到理论总吸附量和孔体积的10％。对于水力压裂空间，考虑了在最小水平应力方向上竖向裂缝的理论最大张开量，该降低量是由于压裂液回流的预期部分以及通过埋藏压实而部分闭合裂缝所致。三种CO ₂的功效富含有机质和贫有机质页岩单元的储层类别显示，TOC含量与孔隙空间内的吸附和吸附效率呈显着正相关，而与水力压裂裂缝的存储效率呈负相关。据估计，在最大存储间隔（120 m厚）内，吸附占总存储容量的约76％，孔隙空间约占13％（对于最相关的孔隙度模型），而裂缝的贡献约为11％。 ％。在最小存储间隔（35 m厚，包括质量最好的页岩）中，吸附，孔隙空间和裂缝在总存储容量中的估计比例分别为84、10和6％。最后，₂在波兰的存储。研究区域中有机物含量最高的单元的CO ₂储存容量效率（即页岩每体积单位的储存容量）仅略低于Marcellus页岩的平均值，因为这两种情况下的吸附容量（主要成分）是可比的。但是，即使考虑到为研究的钻孔计算的潜在裂缝空间，马塞勒斯页岩中的开孔空间容量似乎仍要高得多，这可能是因为马塞勒斯页岩中的游离气体含量远高于波罗的海地区盆地。与在盐水含水层结构中或在较大的油气田中进行存储相比，在枯竭的页岩气井中存储CO ₂并不是一种竞争解决方案。