Changes

Although shale-gas resource plays were slow to spread from the Barnett Shale into other United States and Canadian plays, a worldwide surge in interest has occurred since about 2006. The primary activity outside North America has been in Europe, where several companies including major oil and gas companies have secured land deals and have started drilling and testing of these plays. Key countries in this pursuit are Germany, Sweden, and Poland.

Although shale-gas resource plays were slow to spread from the Barnett Shale into other United States and Canadian plays, a worldwide surge in interest has occurred since about 2006. The primary activity outside North America has been in Europe, where several companies including major oil and gas companies have secured land deals and have started drilling and testing of these plays. Key countries in this pursuit are Germany, Sweden, and Poland.

The lower Saxony Basin of Germany has been studied extensively over the years. In the 1980s, the research organization KFA in Julich, Germany, was funded to drill shallow core holes into the lower Jurassic Posidonia Shale. In the Hils syncline area of the lower Saxony Basin, thermal maturity ranges from 0.49% to about 1.3% Ro.<ref name=Rllkttr>Rullkotter, J., et al., 1988, Organic matter maturation under the influence of a deep intrusive heat source: A natural experiment for quantitation of hydrocarbon generation and expulsion from a petroleum source rock (Toarcian Shale, northern Germany): Advances in Organic Geochemistry 1987: Organic Geochemistry, v. 13, no. 1–3, p. 847–856, doi:10.1016/0146-6380(88)90237-9.M</ref> (Horsfield et al., 2010). These cores and their published data provide a wealth of information on this Lower Jurassic source rock and potential resource play. The TOCo values average about 10.5%, with GOC values averaging 56% of the TOCo. Given the high oil saturations reported in the Posidonia Shale,<ref name=Rllkttr /> there may be potential for shale-oil resource plays in the oil window parts of the basin.

The lower Saxony Basin of Germany has been studied extensively over the years. In the 1980s, the research organization KFA in Julich, Germany, was funded to drill shallow core holes into the lower Jurassic Posidonia Shale. In the Hils syncline area of the lower Saxony Basin, thermal maturity ranges from 0.49% to about 1.3% Ro.<ref name=Rllkttr>Rullkotter, J., et al., 1988, Organic matter maturation under the influence of a deep intrusive heat source: A natural experiment for quantitation of hydrocarbon generation and expulsion from a petroleum source rock (Toarcian Shale, northern Germany): Advances in Organic Geochemistry 1987: Organic Geochemistry, v. 13, no. 1–3, p. 847–856, doi:10.1016/0146-6380(88)90237-9.M</ref><ref>Horsfield, B., R. Littke, U. Mann, S. Bernard, T. A. T. Vu, R. di Primio, and H-M. Schulz, 2010, [http://www.searchanddiscovery.net/documents/2010/110126horsfield/ndx_horsfield.pdf Shale gas in the Posidonia Shale, Hils area, Germany: Genesis of shale gas: Physicochemical and geochemical constraints affecting methane adsorption and desorption]: AAPG Annual Convention, New Orleans, Louisiana, April 11–14, 2010, Search and Discovery Article 110126, 33 p.</ref> These cores and their published data provide a wealth of information on this Lower Jurassic source rock and potential resource play. The TOCo values average about 10.5%, with GOC values averaging 56% of the TOCo. Given the high oil saturations reported in the Posidonia Shale,<ref name=Rllkttr /> there may be potential for shale-oil resource plays in the oil window parts of the basin.

Data for the Lower Cretaceous Wealden Shale is more difficult to locate, but some published TOC and Rock-Eval data on immature samples are available (Munoz et al., 2007). These data suggest perhaps four different organofacies for the Wealden Shale, ranging in HIo from 500 to 700 mg HC/g TOC with variable TOCo contents ranging from about 4.5% to 8.0%. Generation potentials and TOC values for select samples from the Wealden and Posidonia shales are shown in [[:File:M97FG8.jpg|Figure 8]], with the highlighted red area being indicative of the core gas-producing area values for Barnett Shale in Fort Worth Basin, Texas. These data indicate that these shales are not highly converted, at least in this data set. Given this level of conversion, some liquids would be expected with gas, thereby having higher Btu values than other areas of the basin where maturities are higher. Certainly, once the areas of gas window thermal maturity are identified, it becomes necessary to assess other risk factors such as mineralogy, petrophysics, rock mechanics, and fluid sensitivities, for example.

Data for the Lower Cretaceous Wealden Shale is more difficult to locate, but some published TOC and Rock-Eval data on immature samples are available (Munoz et al., 2007). These data suggest perhaps four different organofacies for the Wealden Shale, ranging in HIo from 500 to 700 mg HC/g TOC with variable TOCo contents ranging from about 4.5% to 8.0%. Generation potentials and TOC values for select samples from the Wealden and Posidonia shales are shown in [[:File:M97FG8.jpg|Figure 8]], with the highlighted red area being indicative of the core gas-producing area values for Barnett Shale in Fort Worth Basin, Texas. These data indicate that these shales are not highly converted, at least in this data set. Given this level of conversion, some liquids would be expected with gas, thereby having higher Btu values than other areas of the basin where maturities are higher. Certainly, once the areas of gas window thermal maturity are identified, it becomes necessary to assess other risk factors such as mineralogy, petrophysics, rock mechanics, and fluid sensitivities, for example.

ExxonMobil has now drilled at least four wells in the lower Saxony Basin for shale-gas resources, but no results are in the public domain.

ExxonMobil has now drilled at least four wells in the lower Saxony Basin for shale-gas resources, but no results are in the public domain.

In Sweden and Denmark, the Skegerrak-Kattegat Basin contains the Cambrian–Ordovician Alum Shale that has also been studied extensively (Lewan and Buchardt, 1989; Bharati et al., 1995; Buchardt et al., 1997). The Alum Shale is organic rich, with high TOC (11–22%) and HIo, yet generates primarily gas and condensate upon thermal conversion (Horsfield et al., 1992). Compositional yield data derived from immature Alum Shale with an HI of 487 mg HC/g TOC show that strictly primary kerogen and bitumen and/or oil cracking yields about 60% gas, quite unusual for source rocks of comparable HIo values that typically only yield 20 to 30% gas (D. M. Jarvie, unpublished data). Shell Oil Company has now drilled at least two wells into the Alum Shale, but no results are available.

In Sweden and Denmark, the Skegerrak-Kattegat Basin contains the Cambrian–Ordovician Alum Shale that has also been studied extensively (Lewan and Buchardt, 1989; Bharati et al., 1995; Buchardt et al., 1997). The Alum Shale is organic rich, with high TOC (11–22%) and HIo, yet generates primarily gas and condensate upon thermal conversion.<ref>Horsfield, B., S. Bharati, S. R. Larter, F. Leistner, R. Littke, H. J. Schenk, and H. Dypvik, 1992, On the atypical petroleum-generating characteristics of alginate in the Cambrian Alum Shale, in M. Schidlowski, S. Golubic, M. M. Kimerly, and P. A. Trudinger, eds., Early organic evolution: Implications for mineral and energy resources: Berlin, Springer-Verlag, p. 257–266.</ref> Compositional yield data derived from immature Alum Shale with an HI of 487 mg HC/g TOC show that strictly primary kerogen and bitumen and/or oil cracking yields about 60% gas, quite unusual for source rocks of comparable HIo values that typically only yield 20 to 30% gas (D. M. Jarvie, unpublished data). Shell Oil Company has now drilled at least two wells into the Alum Shale, but no results are available.

Data from Poland suggest a variety of shale-gas potential in various basins such as the Baltic, Lublin, and Carpathian. Shale-gas resource potential exists in the Silurian Graptolitic Shale. Comparing data from across Poland using two criteria for shale-gas prospectivity, organic richness, and level of conversion, TOCpd values range from 2 to 18%, some with gas window levels of conversion (Figure 8). It is recently announced that the first shale stimulation in Europe has been completed on the 1-Markowolain well in the Lublin Basin. No gas flow data have been reported.

Data from Poland suggest a variety of shale-gas potential in various basins such as the Baltic, Lublin, and Carpathian. Shale-gas resource potential exists in the Silurian Graptolitic Shale. Comparing data from across Poland using two criteria for shale-gas prospectivity, organic richness, and level of conversion, TOCpd values range from 2 to 18%, some with gas window levels of conversion (Figure 8). It is recently announced that the first shale stimulation in Europe has been completed on the 1-Markowolain well in the Lublin Basin. No gas flow data have been reported.

* Faqira, M., A. Bhullar, and A. Ahmed, 2010, Silurian Qusaiba Shale Play: Distribution and characteristics (abs.): Hedberg Research Conference on Shale Resource Plays, December 5–9, 2010, Austin, Texas, Book of Abstracts, p. 133–134.

* Faqira, M., A. Bhullar, and A. Ahmed, 2010, Silurian Qusaiba Shale Play: Distribution and characteristics (abs.): Hedberg Research Conference on Shale Resource Plays, December 5–9, 2010, Austin, Texas, Book of Abstracts, p. 133–134.

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* Horsfield, B., S. Bharati, S. R. Larter, F. Leistner, R. Littke, H. J. Schenk, and H. Dypvik, 1992, On the atypical petroleum-generating characteristics of alginate in the Cambrian Alum Shale, in M. Schidlowski, S. Golubic, M. M. Kimerly, and P. A. Trudinger, eds., Early organic evolution: Implications for mineral and energy resources: Berlin, Springer-Verlag, p. 257–266.

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* Horsfield, B., R. Littke, U. Mann, S. Bernard, T. A. T. Vu, R. di Primio, and H-M. Schulz, 2010, [http://www.searchanddiscovery.net/documents/2010/110126horsfield/ndx_horsfield.pdf Shale gas in the Posidonia Shale, Hils area, Germany: Genesis of shale gas: Physicochemical and geochemical constraints affecting methane adsorption and desorption]: AAPG Annual Convention, New Orleans, Louisiana, April 11–14, 2010, Search and Discovery Article 110126, 33 p.

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* Jarvie, D. M., R. J. Hill, R. M. Pollastro, D. A. Wavrek, K. A. Bowker, B. L. Claxton, and M. H. Tobey, 2005b, [http://wwgeochem.com/references/Jarvie-etal2005bcharacterizationofthermogenicgasandoilFtWorthBasinTexasEAGE-Algiers.pdf Characterization of thermogenic gas and oil in the Ft. Worth Basin, Texas]: European Association of Geoscientists and Engineers Meeting, Algiers, Algeria, April 8–10, 2005.

* Jarvie, D. M., R. J. Hill, R. M. Pollastro, D. A. Wavrek, K. A. Bowker, B. L. Claxton, and M. H. Tobey, 2005b, [http://wwgeochem.com/references/Jarvie-etal2005bcharacterizationofthermogenicgasandoilFtWorthBasinTexasEAGE-Algiers.pdf Characterization of thermogenic gas and oil in the Ft. Worth Basin, Texas]: European Association of Geoscientists and Engineers Meeting, Algiers, Algeria, April 8–10, 2005.