24-Pet-B4 Well Testing · Undated paper
Nivaar worked solution (AI-drafted; not reviewed by a licensed engineer)
EGBC National Exam — Petroleum Engineering, 17-Pet-B4 (May 2019, per its page footers). 3 hours duration; closed book. This paper's own cover page reads “17-Pet-B4, Petroleum Geology” and all five sections are descriptive/interpretive petroleum geology (terminology, source rocks, thermal maturation, stratigraphic traps, structural traps), no well-test pressure-transient content anywhere. The section marks are Section 1 = 30, Section 2 = 18, Section 3 = 22, Section 4 = 15, Section 5 = 15 (sum 100), used throughout below. The exam is entirely qualitative (explain/define/sketch).
Reference texts: Tissot, B.P. & Welte, D.H., Petroleum Formation and Occurrence, 2nd ed., Springer (kerogen typing, maceral groups, maturation stages, geothermometers); Selley, R.C. & Sonnenberg, S., Elements of Petroleum Geology, 3rd ed., Academic Press (petroleum terminology, source rocks, traps); Boggs, S. Jr., Petrology of Sedimentary Rocks, 2nd ed., Cambridge (source-rock petrology); Allen, P.A. & Allen, J.R., Basin Analysis: Principles and Applications to Petroleum Play Assessment, 3rd ed., Wiley-Blackwell (structural trap styles); Biddle, K.T. & Wielchowsky, C.C., “Trap Types in Petroleum Basins,” AAPG Memoir 60, ch.12 (stratigraphic and structural trap classification); Mossop, G.D. & Shetsen, I. (eds.), Geological Atlas of the Western Canada Sedimentary Basin, CSPG/Alberta Research Council, 1994 (Canadian trap examples).
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.
The Hydrogen Index (HI, mg hydrocarbon per g TOC) vs. Oxygen Index (OI, mg CO2 per g TOC) diagram – shown in the right-hand panel of the figure under Q2-3 – is the routinely-measured, Rock-Eval-pyrolysis analogue of the atomic Van Krevelen diagram, and carries the same type–maturity structure: Type I starts at very high HI (often >600, up to ≈900 mgHC/gTOC) and low OI (<50); Type II starts at HI ≈ 300–600 and OI ≈ 50–150; Type III starts at low HI (generally <300, often 50–200) and higher OI (≈150–300+); Type IV (not separately curved in the figure) sits at HI < 50 essentially independent of OI. As maturation proceeds, HI falls for every type (hydrogen is progressively converted to expelled hydrocarbon and lost from the kerogen), which is exactly why HI vs. depth/maturity is the standard practical tool for tracking how much of a rock's original generative potential has already been used up.
