OR/19/049 Summary initial BGS borehole information

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Kearsey, T, Gillespie, M, Entwisle, D, Damaschke, M, Wylde, S, Fellgett, M, Kingdon, A, Burkin, J, Starcher, V, Shorter, K, Barron, H, Elsome, J, Barnett, M, and Monaghan, A. 2019. UK Geoenergy Observatories Glasgow: GGC01 cored, seismic monitoring borehole — intermediate data release. British Geological Survey Internal Report, OR/19/049.

Spreadsheet of drill depths/dates/core recovery[edit]

File name: GGC01 Coring data_V6.xlsx
The same information as is presented on the summary drillers’ log is contained within a BGS spreadsheet summarising the core runs, basic recovery information and approximate lithology as recorded at the drill site. The depth intervals of the 1 m cores sub-sampled straight after drilling for geomicrobiology and geochemistry investigations are highlighted.

Note that as highlighted above depth correction of some core intervals will be needed in the poor recovery zones to align features visible in the geophysical (wireline) logs and core scans. Revised depth information will be included in the final borehole data pack.

Image of draft borehole interpretation[edit]

File name: BoreholePrognosis_GGERFS10_draft_v9_Preliminary_v2.pdf
This image compares the anticipated geology with the initial interpretation from the drillers’/BGS record. This interpretation has been greatly improved by subsequent core scanning, core logging and depth matching with the geophysical (wireline) log and is included only as a record of pre- and during-drilling information, for completeness. The depths of the geomicrobiology core samples are shown.

The drilled superficial deposits succession and depth of the lithological rockhead surface was much as expected (these parts of the geological prognosis being well constrained by existing borehole data). The bedrock part of the succession is typical of the Scottish Coal Measures Group. Coal mining is not recorded by mine abandonment plans in the vicinity of GGC01, but mine workings were considered ‘possible’ based on the records to the east of the site. On drilling, no evidence of mining was encountered in the borehole and several thick intact coals were cored.

Initial comparison of the drillers/BGS lithological records and the wireline logs indicated that there are additional coals present that were not observed during drilling operations (being inside the opaque core liner). These were confirmed on the full logging of the core, as presented in sections 2–4 above in this intermediate data release.