24-Pet-B3 Petroleum Geology · May 2016
Nivaar worked solution (AI-drafted; not reviewed by a licensed engineer)
National Exams, May 2016 — 98-Pet-B3, Oil and Gas Evaluation and Economics (3 hours, closed book, approved non-programmable calculator only). The exam's own cover page is titled "Oil and Gas Evaluation and Economics" and every question is property valuation / reserves & production economics / DCF-NPV screening content — no geology anywhere.
Reference texts: Thompson & Wright, Oil Property Evaluation; Canadian Oil and Gas Evaluation Handbook (COGEH), Vol. 1 (Society of Petroleum Evaluation Engineers, Calgary Chapter); National Instrument 51-101, Standards of Disclosure for Oil and Gas Activities (Canadian Securities Administrators); SPE/WPC/AAPG/SPEE Petroleum Resources Management System (PRMS); Economides & Nolte, Reservoir Stimulation; Ahmed, Reservoir Engineering Handbook.
The exam's own instructions ask for only 7 of the 10 short-answer questions and note the Cash-Flow/Future-Value tables are graded by column; for "choose N of M" exams, every item below is answered in full as a study resource. Questions 1–10 correspond to the exam's printed Short-Answer items 1–10; Questions 11–20 correspond to the printed Multiple-Choice items 1–10; Question 21 is the Future Value table; Question 22 is the Cash Flow table.
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.
(1) Non-associated (free) gas. Gas occurring by itself in a reservoir with no significant crude oil present — the reservoir fluid is entirely in the gas phase at initial conditions, and reserves are estimated by gas-in-place volumetrics or p/Z material balance.
(2) Associated (gas-cap) gas. Free gas that overlies and is in direct contact with an oil column in the same reservoir, forming a distinct gas cap above the oil-gas contact — produced by pressure depletion of the cap, usually managed carefully to avoid encroaching gas coning into oil producers.
(3) Dissolved (solution) gas. Gas held in solution within the crude oil below the bubble-point pressure; as reservoir pressure falls below the bubble point during production, this gas comes out of solution in the reservoir (or at surface separators) and is produced along with the oil, quantified by the solution gas-oil ratio Rs.
