PEC EPE Petro-Gas flashcards
PEC EPE Petro-Gas · Build recall with a focused review session.
32 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Material balance equation
- Relates initial hydrocarbons in place to produced volumes, remaining fluids, water influx, and rock/fluid expansion; used to estimate OOIP, drive mechanism, and aquifer support.
- Mobility ratio
- Ratio of water mobility to oil mobility, M = (krw/μw)/(kro/μo); values above one indicate unfavorable displacement and greater fingering risk.
- Buckley-Leverett front
- The sharp saturation front in immiscible displacement; its velocity equals (q/(φA)) times the derivative of fractional flow with respect to water saturation.
- Arps decline curves
- Empirical rate-time relations: exponential q = qi e^(−Dt), hyperbolic q = qi/(1+bDt)^(1/b), and harmonic when b = 1; used to forecast production and reserves.
- Hydrostatic pressure formula
- In oilfield units, hydrostatic pressure in psi equals 0.052 times mud weight in ppg times true vertical depth in feet; measured depth must not be used.
- Equivalent circulating density
- ECD = mud weight plus annular pressure loss divided by (0.052 × TVD); it represents the effective mud weight exerted on the formation during circulation.
- Kick indicators
- Signs of formation fluid influx include pit gain, flow with pumps off, gas-cut mud, increasing rate of penetration, and reduced pump pressure; shut in and confirm.
- Leak-off test
- A low-rate pressure test below the casing shoe to determine fracture initiation pressure; fracture gradient equals leak-off pressure plus hydrostatic divided by shoe TVD.
- Vogel IPR
- Inflow performance relationship for solution-gas-drive wells: q/qmax = 1 − 0.2(Pwf/Pr) − 0.8(Pwf/Pr)^2; it predicts rate at any flowing bottomhole pressure.
- Productivity index
- J = q/(Pr − Pwf), the steady-state ratio of production rate to drawdown; it is constant for undersaturated oil when Pwf exceeds bubble point.
- Nodal analysis
- A production optimization method that combines inflow performance and outflow performance at a chosen node to find the operating rate and pressure.
- Skin factor
- A dimensionless pressure drop near the wellbore; positive skin indicates damage, negative skin indicates stimulation or fracturing, and zero indicates no alteration.
- Real gas law
- PV = ZnRT corrects ideal gas behavior with the compressibility factor Z; R is 10.73 psia·ft³/(lbmol·°R) in oilfield units.
- Gas compressibility
- cg = (1/P) − (1/Z)(∂Z/∂P)_T; it measures change in gas volume with pressure at constant temperature and is used in material balance.
- Gas deliverability equation
- Rawlins-Schellhardt equation q = C(Pr² − Pwf²)^n; a log-log plot of rate versus pressure-squared difference gives exponent n and coefficient C.
- TEG dehydration
- Triethylene glycol absorbs water from natural gas; lean glycol contacts gas in an absorber, then is regenerated by heating, typically below glycol degradation temperature.
- Wobbe index
- W = heating value divided by square root of gas specific gravity; it compares the interchangeability of fuel gases at the same pressure.
- MAOP
- Maximum allowable operating pressure of a pipeline, set by design pressure, class location, and hydrostatic test; exceeding it risks rupture.
- Petroleum system
- The source rock, reservoir, seal, trap, migration pathway, and timing required for a commercial accumulation; all elements must be present and properly sequenced.
- Oil window
- The temperature range of roughly 60–120°C where kerogen generates oil; higher temperatures and time drive thermal cracking toward gas.
- AVO analysis
- Amplitude variation with offset uses seismic reflection amplitudes at different angles to infer lithology and gas saturation; Class III anomalies brighten with offset.
- Sequence stratigraphy
- Correlation method using unconformities and flooding surfaces to divide strata into lowstand, transgressive, and highstand systems tracts.
- Archie equation
- Sw = [(aRw)/(φ^m Rt)]^(1/n); it estimates water saturation from resistivity, porosity, and formation water resistivity in clean formations.
- Density porosity
- φD = (ρma − ρb)/(ρma − ρf); it uses bulk density, matrix density, and fluid density and is common for sandstone and carbonate evaluation.
- Neutron-density crossover
- A log response where neutron porosity reads low and density porosity reads high; it indicates gas-filled pore space in the flushed zone.
- Cement bond log
- An acoustic log that measures amplitude behind casing; low amplitude indicates a good cement-to-formation bond, while high amplitude indicates free pipe or poor bond.
- Net present value
- NPV discounts all project cash flows to present value using a hurdle rate; positive NPV means the project adds value.
- Expected monetary value
- EMV = sum of probability-weighted outcomes; used in decision trees to compare exploration or development alternatives under uncertainty.
- P90 reserves
- The estimated volume with a 90% probability of being equaled or exceeded; it is a conservative high-confidence estimate used for proved reserves.
- ALARP principle
- Risk should be reduced as low as reasonably practicable, weighing the cost of further controls against the risk reduction achieved.
- HAZOP study
- A structured hazard review using guide words and process parameters to identify deviations, causes, consequences, and safeguards in a facility.
- Professional ethics
- Engineers must disclose conflicts, protect confidential data, report unsafe conditions, and practice only within their competence.