Map showing the assessed areas in the Polish part of the Polish-Ukrainian Foredeep Basin. The area in green represents the Polish Foredeep Lower Paleozoic oil assessment unit; the area in red represents the Polish Foredeep Lower Paleozoic gas assessment unit. Graphic courtesy of U.S. Geological Survey
The potential for highly needed gas supplies produced from shales in Poland has made news headlines for some time now – and now additional data have been added to the discussion.
Some of the most recent findings aren’t necessarily the kind of information industry wants to hear.
Owing to the intense interest in the productive potential of the shales, various groups have engaged in geologic studies of shale beds and what they might or might not produce, both in Poland and other European areas.
Using a performance-based geological assessment methodology, the U.S. Geological Survey assessed potential technically recoverable shale gas and shale oil resources in the Devonian and Silurian-age shales in the Polish part of the Polish-Ukrainian Foredeep basin.
Resources in the Ukrainian part of the basin will be considered in a subsequent assessment, according the agency.
“The Potential for Technically Recoverable Unconventional Gas and Oil Resources in the Polish-Ukrainian Foredeep, Poland 2012,” is part of a USGS project to evaluate the potential for unconventional oil and gas resources in priority geological provinces worldwide.
The estimated resources in the Polish assessment area that are recoverable with existing technology range from 0-4,086 Bcf of gas (0-4 Tcf) – mean estimate 1,345 Bcf (1.3 Tcf); 0-172 MMbo – mean estimate 62 MMbo; 0-368 MMbngl – mean estimate 106 MMbgnl.
The Polish Geological Institute has zeroed in on recoverable natural gas volumes of 346 billion cubic meters up to 768 billion cubic meters, or about 14 Tcf and 30 Tcf, respectively.
Glass Half-Empty or Half-Full?
In stark contrast to both of these conclusions, an EIA-funded study on world shale gas recoverable resources, performed by Advanced Resources International, estimated 187 Tcf of gas for the Silurian trend across Poland, or about three orders of magnitude higher than the USGS.
“We just finished the Poland study,” noted USGS assessment team participant and AAPG member Don Gautier. “It has been regarded as the most prospective thing in all of Europe for unconventional resources.
“In our view, there’s essentially nothing there,” he said. “If we’re right, it has a lot of consequences both economic and political.”
At the end of the day, actions do tend to speak louder than words.
ExxonMobil created quite a stir recently when it exited Poland after drilling only a couple of non-commercial wells that apparently suggested to the organization that it was not the place to be.
Still, it ain’t over ‘til it’s over, and the glass-half-full folks will be encouraged because Chevron and ConocoPhillips reportedly will continue to operate their shale licenses, and some large independents are said to have accumulated substantial acreage.
According to the USGS, potentially productive organic-rich Ordovician and Silurian-age shales occur beneath the European Plain surface in a band 20-200 kilometers wide that extends from beneath the Baltic Sea northwest of Gdansk southeastward across Poland near Warsaw and Lublin and into western Ukraine.
For the USGS assessment, shale geologic attributes were inferred from core and well log data collected in 56 pre-1990 wells that were analyzed and interpreted by the Polish Geological Institute.
Data and samples from wells drilled since 2008 to test shale gas and shale oil potential were not available to the USGS.
Shale gas and oil accumulations in the United States were used as analogs in the assessment. Analog data included:
- Mean EURs from populations of shale and shale oil wells.
- Mean drainage areas of directionally drilled wells.
- Ranges of average well success ratios.