In the Baltic-Podlasie-Lublin Basin, four potential lower Paleozoic shale reservoirs are identified: the Piaśnica, Sasino and Jantar formations, as well as the Mingajny shale. These units were diachronously deposited during the starved stages of Caledonian foredeep basin development, in the course of rising or high eustatic sea level. Across most of the basin, the shale formations analysed are saturated with light oil and condensate, and they are buried to depths of 2300–3500 m. The shale reservoirs reach the wet gas window at burial depths of 2800–4000 m, while dry gas accumulations occur at depths exceeding 3500–5000 m, except in the Bilgoraj-Narol Zone. The shale analysed might be generally classified as a moderate to low quality, and locally high quality, unconventional reservoir. Within the shale net pay zones, the average TOC content is 2–5 wt.% TOC. The exceptions are the Piaśnica Formation, for which this is 5–12 wt.%, and the Mingajny shale, which is TOC-lean (1.4–1.7 wt.%). The thickness of the shale net pay intervals in the most favourable locations, mainly on the Łeba Elevation, generally reaches 20 m, and locally exceeds 35 m. The shale reservoirs are saturated with hydrocarbons of good quality. Their permeability is low to moderate, often in the range of 150–200 mD, while total porosity average per borehole is commonly exceeds 6 %, reaching up to 10% at maximum, which might be considered as moderate to good. The clay minerals content is moderate to high (30–50%), and geomechanical characteristics of the shale formations are intermediate between brittle and ductile. No overpressure occurs in the basin, except for a dry gas zone in the SW Baltic Basin. In the Bilgoraj-Narol Zone, and to a lesser degree also in the Lublin region, pronounced tectonic deformation significantly limits shale gas/oil potential. Among 66 exploration boreholes drilled in the basin so far, only 5 were lateral boreholes with representative production test results. Hydrocarbon flow from the best boreholes was low to moderate, equal to 11.2 to 15.6 thousand m3/day for gas, and 157 bbl/day (~21.4 ton/day) for oil. There is, however, high potential to improve production flow rates, connected with the fracturing of two net pay intervals at one time, as well as with significant technological progress in the exploitation of shale basins during the last 5 years. Commercially viable production might be achieved for a single borehole with estimated ultimate recovery exceeding 30–50 thousand tons of oil, or 60–90 million m3 of gas.

中文翻译：

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波罗的海-波德拉西-卢布林盆地（中欧和东欧）下古生界油气页岩——综述

在波罗的海-波德拉西-卢布林盆地，确定了四个潜在的下古生界页岩储层：Piaśnica、Sasino 和 Jantar 地层，以及 Mingajny 页岩。这些单元是在加里东前深盆地开发的饥饿阶段，在上升或高海平面的过程中历时沉积的。在盆地的大部分地区，所分析的页岩地层被轻质油和凝析油饱和，埋藏深度为 2300-3500 m。页岩储层在 2800-4000 m 的埋藏深度到达湿气窗口，而干气聚集发生在超过 3500-5000 m 的深度，Bilgoraj-Narol 区除外。所分析的页岩通常可归类为中等至低质量、局部优质的非常规储层。在页岩净产区内，平均 TOC 含量为 2–5 wt.% TOC。例外是 Piaśnica 地层，其含量为 5-12 wt.%，以及 Mingajny 页岩，TOC 贫化（1.4-1.7 wt.%）。最有利位置的页岩净产层厚度，主要在热巴海拔，一般达到 20 m，局部超过 35 m。页岩储层中富含优质碳氢化合物。它们的渗透率低到中等，通常在 150-200 mD 范围内，而每个钻孔的平均总孔隙度通常超过 6%，最大可达 10%，这可以被认为是中等到良好的。粘土矿物含量中等至高（30-50%），页岩地层的地质力学特征介于脆性和韧性之间。盆地内无超压，除了西南波罗的海盆地的干气区。在 Bilgoraj-Narol 地区，以及在较小程度上也在卢布林地区，明显的构造变形显着限制了页岩气/石油的潜力。目前在盆地已钻探的66个勘探钻孔中，只有5个是侧向钻孔，具有代表性的生产测试结果。来自最佳钻孔的碳氢化合物流量低至中等，相当于天然气 11.2 至 1.56 万立方米/天，石油 157 桶/天（~21.4 吨/天）。然而，提高产量的潜力很大，这与一次压裂两个净产层段以及过去 5 年页岩盆地开发的重大技术进步有关。