Deflating the shale gas potential of South Africa’s Main Karoo basin

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dc.contributor.authorde Kock, Michiel
dc.contributor.authorGötz, Annette
dc.contributor.authorGeel, Claire
dc.contributor.authorOssa, Frantz-Gerard
dc.date.accessioned2021-10-08T07:16:16Z
dc.date.available2021-10-08T07:16:16Z
dc.date.issued2017
dc.description.abstractThe Main Karoo basin has been identified as a potential source of shale gas (i.e. natural gas that can be extracted via the process of hydraulic stimulation or ‘fracking’). Current resource estimates of 0.4–11x109 m3 (13–390 Tcf) are speculatively based on carbonaceous shale thickness, area, depth, thermal maturity and, most of all, the total organic carbon content of specifically the Ecca Group’s Whitehill Formation with a thickness of more than 30 m. These estimates were made without any measurements on the actual available gas content of the shale. Such measurements were recently conducted on samples from two boreholes and are reported here. These measurements indicate that there is little to no desorbed and residual gas, despite high total organic carbon values. In addition, vitrinite reflectance and illite crystallinity of unweathered shale material reveal the Ecca Group to be metamorphosed and overmature. Organic carbon in the shale is largely unbound to hydrogen, and little hydrocarbon generation potential remains. These findings led to the conclusion that the lowest of the existing resource estimates, namely 0.4x109 m3 (13 Tcf), may be the most realistic. However, such low estimates still represent a large resource with developmental potential for the South African petroleum industry. To be economically viable, the resource would be required to be confined to a small, well-delineated ‘sweet spot’ area in the vast southern area of the basin. It is acknowledged that the drill cores we investigated fall outside of currently identified sweet spots and these areas should be targets for further scientific drilling projects.
dc.identifier.apacitationde Kock, M., Götz, A., Geel, C., & Ossa, F. (2017). Deflating the shale gas potential of South Africa’s Main Karoo basin. <i>South African Journal of Science</i>, 113(43353), 174 - 177. http://hdl.handle.net/11427/34804en_ZA
dc.identifier.chicagocitationde Kock, Michiel, Annette Götz, Claire Geel, and Frantz-Gerard Ossa "Deflating the shale gas potential of South Africa’s Main Karoo basin." <i>South African Journal of Science</i> 113, 43353. (2017): 174 - 177. http://hdl.handle.net/11427/34804en_ZA
dc.identifier.citationde Kock, M., Götz, A., Geel, C. & Ossa, F. 2017. Deflating the shale gas potential of South Africa’s Main Karoo basin. <i>South African Journal of Science.</i> 113(43353):174 - 177. http://hdl.handle.net/11427/34804en_ZA
dc.identifier.issn0038-2353
dc.identifier.issn1996-7489
dc.identifier.ris TY - Journal Article AU - de Kock, Michiel AU - Götz, Annette AU - Geel, Claire AU - Ossa, Frantz-Gerard AB - The Main Karoo basin has been identified as a potential source of shale gas (i.e. natural gas that can be extracted via the process of hydraulic stimulation or ‘fracking’). Current resource estimates of 0.4–11x109 m3 (13–390 Tcf) are speculatively based on carbonaceous shale thickness, area, depth, thermal maturity and, most of all, the total organic carbon content of specifically the Ecca Group’s Whitehill Formation with a thickness of more than 30 m. These estimates were made without any measurements on the actual available gas content of the shale. Such measurements were recently conducted on samples from two boreholes and are reported here. These measurements indicate that there is little to no desorbed and residual gas, despite high total organic carbon values. In addition, vitrinite reflectance and illite crystallinity of unweathered shale material reveal the Ecca Group to be metamorphosed and overmature. Organic carbon in the shale is largely unbound to hydrogen, and little hydrocarbon generation potential remains. These findings led to the conclusion that the lowest of the existing resource estimates, namely 0.4x109 m3 (13 Tcf), may be the most realistic. However, such low estimates still represent a large resource with developmental potential for the South African petroleum industry. To be economically viable, the resource would be required to be confined to a small, well-delineated ‘sweet spot’ area in the vast southern area of the basin. It is acknowledged that the drill cores we investigated fall outside of currently identified sweet spots and these areas should be targets for further scientific drilling projects. DA - 2017 DB - OpenUCT DP - University of Cape Town IS - 43353 J1 - South African Journal of Science LK - https://open.uct.ac.za PY - 2017 SM - 0038-2353 SM - 1996-7489 T1 - Deflating the shale gas potential of South Africa’s Main Karoo basin TI - Deflating the shale gas potential of South Africa’s Main Karoo basin UR - http://hdl.handle.net/11427/34804 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/34804
dc.identifier.vancouvercitationde Kock M, Götz A, Geel C, Ossa F. Deflating the shale gas potential of South Africa’s Main Karoo basin. South African Journal of Science. 2017;113(43353):174 - 177. http://hdl.handle.net/11427/34804.en_ZA
dc.language.isoeng
dc.publisher.departmentDepartment of Geological Sciences
dc.publisher.facultyFaculty of Science
dc.sourceSouth African Journal of Science
dc.source.journalissue43353
dc.source.journalvolume113
dc.source.pagination174 - 177
dc.source.urihttps://dx.doi.org/10.17159/sajs.2017/20160331
dc.subject.other: Ecca Group
dc.subject.otherWhitehill Formation
dc.subject.otherhydrocarbon
dc.subject.otherthermal maturity
dc.subject.otherenergy resource
dc.titleDeflating the shale gas potential of South Africa’s Main Karoo basin
dc.typeJournal Article
uct.type.publicationResearch
uct.type.resourceJournal Article
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