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24-Pet-B4 Well Testing · December 2015

Question 4 of 18: Hydrocarbon compound formulas and structures

Nivaar worked solution (AI-drafted; not reviewed by a licensed engineer)

Notes on this paper

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).

Section 2, Q2-1: Hydrocarbon compound formulas and structures (8 marks)

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) Heptane C7H16 – a saturated, straight-chain alkane (paraffin). (b) Toluene C7H8 (methylbenzene) – an aromatic hydrocarbon, a benzene ring with one methyl substituent; part of the BTEX aromatic suite used in petroleum geochemistry and as a solvent. (c) Isoprene C5H8 (2-methyl-1,3-butadiene) – a branched diene; it is not itself abundant in crude oil, but its polymerised/reduced form (the phytol side-chain of chlorophyll) is the biological precursor of the pristane and phytane isoprenoid biomarkers used to fingerprint source rocks and assess depositional redox conditions. (d) Phenol C6H5OH – a benzene ring bearing a hydroxyl group; an oxygenated (NSO) compound, a minor but geochemically useful constituent of some crude oils and a common contaminant of produced/formation water.

Skeletal structures: heptane, toluene, isoprene, phenol Heptane C₄H₁₆ CH₃ Toluene C₄H₈ CH₃ Isoprene C₅H₈ OH Phenol C₆H₅OH
Skeletal (line) structural formulas: heptane is an open-chain saturated alkane; toluene and phenol are benzene rings (delocalized π-system, drawn as an inscribed circle) bearing a methyl or hydroxyl substituent respectively; isoprene is a short, branched conjugated diene – the biological building block of the pristane/phytane isoprenoid biomarker family.