24-Pet-B4 Well Testing · December 2015
Nivaar worked solution (AI-drafted; not reviewed by a licensed engineer)
EGBC National Exam — Petroleum Engineering, 2015-Dec. 3 hours duration; closed book. This sitting's own cover page reads “98-Pet-B4, Petroleum Geology” and every question is descriptive/interpretive petroleum geology (source rocks, hydrocarbon chemistry, migration/unconventional reservoirs, carbonate traps, structural traps, Canadian basin geography) – no well-test pressure-transient content anywhere. Five (5) of the paper's six 20-mark sections are marked (NOTES item 5); all six are solved in full below so this set also serves as a complete study reference. The paper is almost entirely qualitative (draw/describe/define/list), with one true numeric calculation (Q3-2, capillary seal-breach column height).
Reference texts: Selley, R.C. & Sonnenberg, S., Elements of Petroleum Geology, 3rd ed., Academic Press (source rocks, migration, traps, carbonate systems); Tissot, B.P. & Welte, D.H., Petroleum Formation and Occurrence, 2nd ed., Springer (kerogen typing, maceral groups, catagenesis); Boggs, S. Jr., Petrology of Sedimentary Rocks, 2nd ed., Cambridge (source-rock and carbonate lithofacies); Allen, P.A. & Allen, J.R., Basin Analysis: Principles and Applications to Petroleum Play Assessment, 3rd ed., Wiley-Blackwell (structural styles, unconventional systems); Biddle, K.T. & Wielchowsky, C.C., “Trap Types in Petroleum Basins,” AAPG Memoir 60, ch.12 (structural trap classification); James, N.P. & Jones, B., Origin of Carbonate Sedimentary Rocks, Wiley-Blackwell (carbonate platform/ramp/sabkha facies models); Law, B.E. & Curtis, J.B., “Introduction to unconventional petroleum systems,” AAPG Bulletin 86 (basin-centred gas); Mossop, G.D. & Shetsen, I. (eds.), Geological Atlas of the Western Canada Sedimentary Basin, CSPG/Alberta Research Council, 1994 (WCSB stratigraphy and Canadian basin geography).
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.
(a) Lignin is a complex, highly cross-linked aromatic polymer that, together with cellulose, forms the structural cell walls of woody higher (vascular) land plants. It is relatively resistant to microbial decay compared with cellulose and sugars, so it survives preferentially into the sedimentary record and is the principal chemical precursor of humic, terrestrial (Type III) organic matter and, ultimately, coal and vitrinite.
(b) Vitrinite is the most abundant maceral group in humic coals and disseminated terrestrial kerogen, formed by the humification and coalification (gelification) of lignin- and cellulose-bearing woody plant tissue. Because its optical reflectance increases progressively and irreversibly with thermal maturity, measured vitrinite reflectance (Ro) is the industry-standard proxy for source-rock thermal maturity and burial history.
(c) Sapropelic kerogen is kerogen derived from the anaerobic decay of lipid-rich algal and bacterial (aquatic) organic matter accumulated in anoxic lacustrine or marine muds (sapropel), as opposed to the woody, humic organic matter of (a)–(b). It is hydrogen-rich and oxygen-poor, corresponding to oil-prone Type I (lacustrine algal) and Type II (marine planktonic/bacterial) kerogen.
(d) Catagenesis is the thermal maturation stage of burial diagenesis – roughly 60–150 °C, following early diagenesis and preceding metagenesis – during which kerogen thermally cracks to expel liquid oil and wet gas; it is the principal hydrocarbon-generation stage of a source rock's burial history.
