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Zachary Cotter_MS Thesis.pdf (12.49 MB)

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Depositional Controls Of A Guelph Formation Pinnacle Reef Debris Apron And Their Effect On Reservoir Quality: A Case Study From Northern Michigan

Cotter, Zachary M.K.
http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1587141486161428

Abstract Details

2020, Master of Science (MS), Bowling Green State University, Geology.
The Middle Silurian-aged Guelph Formation pinnacle reefs and associated deposits of the Michigan basin (U.S.A.) are a prolific hydrocarbon play, valued for its potential for enhanced oil recovery (EOR) and carbon sequestration. Recent work has aided in resolving reef growth models and complex architecture, however previous studies have been focused on reef development, largely overlooking depositional controls of the leeward debris apron development and implications for reservoir development. This study hypothesizes that the leeward debris apron of Guelph Formation pinnacle reefs accumulated with depositional controls and architectural elements like those of larger, line-fed slope apron systems of carbonate platform margins. This study utilizes a case study well, which was laterally deviated leeward of the reef pinnacle and captured the leeward slope profile of a Guelph Formation pinnacle reef. This study uses 70 m of whole core, 117 core plugs, 16 mercury injection capillary pressure (MICP) curves, 21 thin sections, in addition to a suite of geophysical wireline logs, including borehole image logs, to build a depositional model for the leeward debris apron and evaluate controls on reservoir quality. Core analysis of sedimentary deposits recovered from the well identified 16 lithofacies, interpreted to have been deposited within six facies associations including reef zone, tempestite, debrite-turbidite, subtidal back-reef, intertidal, and supratidal. Stratigraphic analysis revealed that the leeward debris apron developed within two distinct growth stages: (1) a stage correlative to active reef growth and accumulation of the debris apron and (2) a peritidal stage of deposition. Reef growth deposits (stage one) consisted of deepening upward sedimentary successions comprised of skeletal framestones, floatstones, rudstones, grainstones, wackestones and intraclastic conglomerates. The vertical succession of these deposits was interpreted to represent the lateral shift of environments downslope from active carbonate factory settings to more distal segments of the leeward slope. Sediment gravity flows, partial Bouma sequences (Ta and Tde), and well-preserved tempestite successions were present in a significant volume of recovered core, interpreted to suggest that off-bank transport via storm-wave resuspension and sediment gravity flows triggered by events of slope destabilization were the primary sediment transport mechanisms feeding development of the leeward debris apron. The vertical succession of deposits of the leeward debris apron of Guelph Formation reefs was found to resemble those of larger, line-fed slope apron systems associated with carbonate platform margins. Guelph Formation peritidal successions (stage 2) were observed to unconformably overlie subaerially-exposed reef stage deposits and the bottommost contact was interpreted as transgressive surface of erosion. Guelph Formation peritidal deposits consisted of mudstones, cryptalgal bindstones, and skeletal packstones which were interpreted to represent a shallowing-upward transition from subtidal-to-supratidal environments. The contact between the Guelph Formation and Ruff Formation was observed as a sharp, erosive unconformity interpreted to be a second transgressive surface of erosion with evidence of micro-karsting occurring just below the contact, suggesting the leeward slope underwent a second period of subaerial exposure. A generalized reservoir characterization effort was conducted on Guelph Formation sediments to characterize reservoir quality. Reservoir characterization revealed capillary behavior that can be generalized by three type curves, and the primary pore architecture and textures of sampled Guelph Formation sediments were overprinted by diagenetic processes including dolomitization, recrystallization, dissolution, stylolitization and fracturing. Tempestites were found to exhibit the best petrophysical character and highest degrees of petrophysical predictability, interpreted to be a result of high initial bioclastic content and well-sorted textures generated by wave-suspension processes.
James Evans (Advisor)
Margaret Yacobucci (Committee Member)
Yuning Fu (Committee Member)
Kurt Panter (Other)
217 p.
Geology; Petroleum Geology; Sedimentary Geology
Pinnacle Reefs; Carbonates; Debris Aprons; Stratigraphy; Silurian; Guelph Formation; Brown Niagaran

Recommended Citations

Citations

  • Cotter, Z. M.K. (2020). Depositional Controls Of A Guelph Formation Pinnacle Reef Debris Apron And Their Effect On Reservoir Quality: A Case Study From Northern Michigan [Master's thesis, Bowling Green State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1587141486161428

    APA Style (7th edition)

  • Cotter, Zachary. Depositional Controls Of A Guelph Formation Pinnacle Reef Debris Apron And Their Effect On Reservoir Quality: A Case Study From Northern Michigan. 2020. Bowling Green State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1587141486161428.

    MLA Style (8th edition)

  • Cotter, Zachary. "Depositional Controls Of A Guelph Formation Pinnacle Reef Debris Apron And Their Effect On Reservoir Quality: A Case Study From Northern Michigan." Master's thesis, Bowling Green State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1587141486161428

    Chicago Manual of Style (17th edition)

bgsu1587141486161428
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This open access ETD is published by Bowling Green State University and OhioLINK.