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) Petroleum is the generic term for any naturally occurring mixture of hydrocarbons – in the solid, liquid and/or gaseous state – found in geological formations, together with the associated non-hydrocarbon compounds and trace impurities normally produced with it.
(b) Bitumen is an extremely viscous, dense (API < 10°), heavily biodegraded hydrocarbon that is essentially immobile in the reservoir at native temperature and pressure – it will not flow to a wellbore under conventional pressure depletion and requires thermal (e.g. SAGD, CSS) or mining-based recovery, as in the Athabasca oil sands.
(c) Condensate is a light hydrocarbon liquid (predominantly C5+, API typically > 45–50°) that exists as part of the gas phase at reservoir temperature and pressure but condenses out as a separate liquid when produced and cooled/depressured at surface; it is associated with wet-gas and retrograde-gas-condensate reservoirs.
(d) Thermogenic gas is natural gas generated by the thermal cracking of kerogen and/or previously generated oil at depth during catagenesis and metagenesis (roughly >60 °C, intensifying with depth/temperature) – distinct from biogenic gas, which forms at shallow depth and low temperature by bacterial (methanogenic) degradation of organic matter.
