24-Pet-B4 Well Testing · December 2016
Nivaar worked solution (AI-drafted; not reviewed by a licensed engineer)
EGBC National Exam — Petroleum Engineering, 2016-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, oil sands and tight-oil development, shale gas and coalbed methane, carbonate traps, siliciclastic/deltaic traps) – 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. This sitting's Section 6 is a Siliciclastic Traps section (wave-dominated delta, grain-size–permeability–porosity relations, sandstone diagenesis). The paper is entirely qualitative (draw/describe/define/list), with no numeric given data anywhere.
Reference texts: Selley, R.C. & Sonnenberg, S., Elements of Petroleum Geology, 3rd ed., Academic Press (source rocks, migration, traps, carbonate systems, oil sands); 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, deltaic and carbonate lithofacies; sandstone diagenesis); James, N.P. & Jones, B., Origin of Carbonate Sedimentary Rocks, Wiley-Blackwell (carbonate platform/ramp/sabkha facies models); Butler, R.M., Thermal Recovery of Oil and Gas, Prentice Hall, 1991 (SAGD, CSS, oil sands thermal recovery); Green, D.W. & Willhite, G.P., Enhanced Oil Recovery, SPE Textbook Series Vol. 6 (thermal EOR mechanisms); Law, B.E. & Curtis, J.B., “Introduction to Unconventional Petroleum Systems,” AAPG Bulletin 86, 2002 (shale gas, tight gas, coalbed methane); Lee, W.J. & Wattenbarger, R.A., Gas Reservoir Engineering, SPE Textbook Vol. 5 (unconventional gas reservoir characterization).
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) Tight oil. Light-to-medium oil (typically >30° API) held in a very low permeability (generally <0.1 mD matrix) siliciclastic or carbonate reservoir that requires horizontal drilling and multistage hydraulic fracturing to produce at economic rates – the oil-window analogue of shale/tight gas, and the target of Q3-2.
(b) Halo oil. A lighter, more mobile oil rim or fringe that surrounds (forms a “halo” around) a bitumen or heavy-oil accumulation, typically at its structurally higher or updip margin, formed by partial biodegradation/gravity segregation gradients within a single charged column – it is often the first zone targeted or avoided in delineating the boundary of a heavy-oil/bitumen pool.
(c) Bitumen. Extra-heavy, highly viscous crude oil with API gravity below 10° that, at reservoir temperature, will not flow to a well under primary (cold) production – it requires thermal stimulation (steam) or solvent injection, or surface mining where shallow enough, to be recovered (Q3-3).
(d) SAGD (Steam-Assisted Gravity Drainage). A thermal in-situ recovery process using a pair of parallel horizontal wells – an upper steam-injection well and a lower production well – in which continuously injected steam forms an expanding steam chamber that heats and mobilizes the surrounding bitumen, which then drains by gravity to the lower producer (detailed in Q3-3).
