24-Pet-A1 Principles of Stratigraphy and Sedimentation · May 2018
Nivaar worked solution (AI-drafted; not reviewed by a licensed engineer)
EGBC National Exam — Petroleum Engineering, 17-Pet-A1 Principles of Stratigraphy & Sedimentation, 2018-May. 3 hours duration; closed book, no calculator permitted. The paper has two parts: Part A (Questions 1–10, Sedimentology and Sedimentary Processes) – Questions 1 and 2 are mandatory (10 marks each, 20 marks), plus any five of the remaining eight (3–10) at 6 marks each (30 marks), for a Part A total of 50 marks; and Part B (Questions 11–19, Stratigraphy and Sedimentary Basin Analysis) – answer any six of the nine at 5 marks each, for a Part B total of 30 marks – an 80-mark maximum (50 for Part A + 30 for Part B).
Reference texts: Boggs, S. Jr., Principles of Sedimentology and Stratigraphy, 5th ed., Pearson (grain texture, sediment transport, bedforms, carbonate/evaporite systems, sequence stratigraphy, unconformities, stratigraphic principles); Tucker, M.E., Sedimentary Petrology, 3rd ed., Blackwell (sandstone/carbonate classification, diagenesis, dolomitization); Nichols, G., Sedimentology and Stratigraphy, 2nd ed., Wiley-Blackwell (fluvial/deltaic systems, sequence stratigraphy, stratigraphic units); Reading, H.G. (ed.), Sedimentary Environments: Processes, Facies and Stratigraphy, 3rd ed., Blackwell (facies models, deep-marine and shelf systems); Selley, R.C. & Sonnenberg, S., Elements of Petroleum Geology, 3rd ed., Academic Press (source rocks, basin classification, reservoir quality); International Commission on Stratigraphy, International Chronostratigraphic Chart (geological time scale).
Question text not reproduced: the examination questions are © Engineers and Geoscientists BC. Open the official past paper (linked at the top of this page) to read the question, then follow the worked solution below.
(i) Taxon-range biozone. A biostratigraphic zone defined by the total stratigraphic and geographic range of occurrence of a single taxon – the body of strata between that taxon's local first and last appearance – the simplest of the biozone categories (compare with interval, assemblage and abundance zones).
(ii) Lithofacies. A body of rock defined and distinguished from adjacent rock bodies purely by its physical characteristics (lithology, texture, physical/biogenic sedimentary structures), reflecting the depositional process and environment that formed it, independent of fossil content.
(iii) Parasequence. The fundamental building block of a sequence-stratigraphic succession: a relatively conformable, genetically related succession of beds bounded above and below by marine flooding surfaces, typically recording a single shallowing-upward (progradational) depositional pulse.
(iv) Isopach map. A map showing lines of equal true stratigraphic thickness (isopachs) of a specified rock unit, used to visualize depocentre location, syn-depositional subsidence/thinning patterns, and (by contrast with a structure-contour map, which shows elevation) sediment accumulation independent of subsequent structural deformation.
