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Open CalculatorAll Petroleum PE Equations (8)
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Darcy Linear Flow (Single-Phase)
Single-phase steady-state volumetric flow using Darcy’s law in linear flow geometry.
intermediateHigh Frequency -
Exponential Decline Curve
Exponential production decline for constant percentage decline rate.
intermediateHigh Frequency -
Mud Hydrostatic Pressure vs TVD
Hydrostatic pressure at true vertical depth (TVD) from mud density.
basicHigh Frequency -
Original Gas in Place (OGIP)
Volumetric estimate of original gas in place in a gas reservoir.
intermediateHigh Frequency -
Original Oil in Place (OOIP)
Volumetric estimate of original oil in place in a reservoir.
intermediateHigh Frequency -
Present Value of a Single Future Cashflow
Present value of a single future cashflow at discount rate i and time n.
basicHigh Frequency -
Productivity Index and IPR (Linear)
Simple linear inflow performance relation using productivity index J.
basicHigh Frequency -
Pump Hydraulic Horsepower
Hydraulic horsepower required to deliver flow Q against pressure P.
basicHigh Frequency
Frequently Asked Questions
How do I use Darcy Linear Flow (Single-Phase) on the PE exam?
Critical for PE Petroleum exam - appears frequently in reservoir engineering problems. Remember this is for single-phase flow only. Watch units carefully - permeability conversion from mD to consistent units is essential. Often combined with material balance equations.
How do I use Exponential Decline Curve on the PE exam?
Exponential decline is the most optimistic decline model and often overestimates reserves. PE exams frequently test conversion between decline constants (D in 1/day vs 1/year) and recognition of when exponential vs hyperbolic decline is appropriate. Remember that exponential decline assumes constant percentage decline rate.
How do I use Mud Hydrostatic Pressure vs TVD on the PE exam?
CRITICAL: Always use TRUE VERTICAL DEPTH (TVD), not measured depth. The 0.052 constant is specific to field units (psi, ppg, ft). Remember this gives bottom hole pressure from mud column only - add surface pressure if applicable.
How do I use Original Gas in Place (OGIP) on the PE exam?
Always verify units carefully - the 43560 conversion factor only applies to English units (acres to sq ft). For SI units, no conversion factor is needed. Bg values are typically small (0.001-0.01), so double-check decimal placement. Remember that OGIP represents total gas originally in place, not recoverable reserves.
How do I use Original Oil in Place (OOIP) on the PE exam?
The constant 7758 converts acre-feet to barrels in field units. Always use Bo at initial reservoir pressure, not at surface conditions. Watch for net pay vs gross pay - only use net pay thickness. Porosity and saturations are fractions, not percentages.