Glossary

Glossary of petroleum engineering terms used throughout PetroBench. Terms are organized alphabetically for easy reference. Click any term from the platform’s help tooltips to jump directly to its definition.

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A

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Abandonment Pressure

Minimum economic reservoir pressure at which a well is no longer profitable to produce.

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Additional Pump Load

Additional tension to be added to the anchor to account for the forces caused by a pump on tap.

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Anchor Depth

Distance from the surface to the tubing anchor along the wellbore path, measured in feet.

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Anchor Tension

The minimum tension required at the tubing anchor to prevent tubing movement during pumping operations.

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Azimuth

Compass direction of the wellbore measured clockwise from north (0-360 degrees). Used with measured depth and inclination to calculate the 3D wellbore trajectory.

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API Gravity

Oil density measure developed by the American Petroleum Institute. Higher API = lighter oil. Classification: Heavy (less than 22°), Medium (22-31°), Light (greater than 31°).

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API Number

American Petroleum Institute unique well identification number assigned by regulatory agencies. Format varies by state/country.

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API Pump Type

API classification of pump type based on configuration. Letters indicate: R=Rod, T=Tubing, W=Wall-anchored, A=Traveling barrel, B=Stationary barrel, H=Heavy wall, C=Cup-type, M=Metal plunger, P=Soft-packed. Example: RWBC = Rod pump, Wall-anchored, stationary Barrel, Cup-type.

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Axial Loading

Tensile/compressive axial loads on rod string by depth. Shows load distribution and identifies critical stress zones.

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B

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Ballooning Effect

Increase in tensile force due to differential pressure between tubing and annular pressure causing tubing expansion.

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Beam Weight

Weight of the walking beam in pounds. Used for HGC unit calculations and structural load analysis.

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Belt Length

Calculated length of drive belt connecting motor sheave to gearbox input sheave.

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Bottomhole Temperature

Temperature at the bottom of the well, typically measured at total depth or pump setting depth.

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Bubble Point Pressure

Pressure at which dissolved gas begins to evolve from oil, forming free gas bubbles.

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Buckling Tendency

Shows critical buckling load percentage vs depth. Values greater than 100% indicate compression and buckling risk.

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Buoyant Rod Weight

Weight of rod string submerged in fluid (air weight reduced by buoyancy). Used to calculate net downhole loads.

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C

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Calculate Fluid Load

Option to automatically calculate fluid load from fluid level measurement.

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Calculate Guides

Automatically calculates the number of rod guides needed to prevent buckling and contact with tubing.

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Calculated SPM

Calculated strokes per minute based on simulation parameters and actual unit performance.

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Casing ID

Internal diameter of the production casing in inches.

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Casing Pressure

Pressure in the casing annulus at surface. Often vented in rod pump wells to maximize drawdown.

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Casing Type

Type of casing string (Surface, Intermediate, Production) based on its function in the well.

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Center Distance

Distance between motor sheave center and gearbox input sheave center.

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Centralizers

Number of centralizer devices installed to keep casing centered in the wellbore for proper cement placement.

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CO2 Content

Percentage of carbon dioxide in the gas stream. Affects fluid properties and corrosion rates.

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Component OD

Outside diameter of a component (rod, tubing, etc.) inside the casing.

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Counterbalance Effect

Effective counterbalance force in pounds. Represents the load relief provided by the counterbalance system.

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Coupler OD

Outside diameter of the tubing coupling in inches. Must clear casing restrictions.

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Coupler Type

Type of coupling used to connect tubing joints (Regular, Slim-hole, or specific manufacturer type).

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Crank Hole

Position of crank arm connection on counterweight. Changes stroke length. Lower numbers = shorter stroke.

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Cumulative Oil

Total oil produced from well since startup. Used to calculate remaining reserves and decline curves.

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Cumulative Probability

Statistical probability for reservoir analysis and production forecasting.

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Cylinder ID

Internal diameter of the hydraulic pump cylinder in inches.

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D

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Damping Factor Down

Damping coefficient for downstroke. Removes energy from the rod string system.

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Damping Factor Up

Damping coefficient for upstroke. Removes energy from the rod string system.

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Directional Survey

Wellbore directional survey data used to calculate true vertical depth and dogleg severity along the wellbore path.

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Dogleg Severity

Wellbore curvature severity measured in degrees per 100 feet. High dogleg severity causes increased rod wear and fatigue.

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Down Stroke Time

Time duration for downward stroke in seconds (hydraulic units).

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Drift

Minimum internal diameter guaranteed for passage of tools, accounting for manufacturing tolerances.

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Dynamometer

Load vs position diagram showing polished rod load, permissible load, and pump load throughout the pumping cycle.

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E

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East-West

East-West displacement from the wellhead in feet, calculated from measured depth, inclination, and azimuth using the minimum curvature method.

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Elastic Modulus

Young’s Modulus - measure of material stiffness in psi. Higher values indicate stiffer material.

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Elevation

Well site elevation above sea level affecting air density and engine performance.

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EUR Oil

Estimated Ultimate Recovery - total oil expected to be produced from the well over its lifetime.

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F

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Fillage

Percentage of pump barrel filled with fluid during upstroke. Normal: 70-95%. Low values indicate gas interference or worn pump.

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Fluid Above Pump

Height of annular fluid column above the pump in feet.

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Fluid Gradient

Change in pressure per unit depth, typically in psi/ft. Pressure increases predictably with depth in normally pressured zones.

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Fluid Level

Depth to fluid surface in the annulus, measured from surface. Used to calculate pump intake pressure.

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Fluid Load

Total weight of fluid column above pump in pounds. Calculated from fluid specific gravity and pump depth.

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Fluid Production

Total liquid (oil + water) production rate in barrels per day.

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Fluid Shot Data

Acoustic fluid level survey data. Use Most Recent, 30, or 90 day average to determine fluid above pump.

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Fluid Specific Gravity

Combined specific gravity of produced fluids (oil + water blend).

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Foam Column Top

Depth where foam/gas accumulation begins above pump.

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Friction Coefficient

Dynamic friction coefficient between rod guides and tubing wall. Typical range: 0.2-0.4.

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Full Pump

Indicates if the pump is operating at 100% fillage during the upstroke.

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G

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Gas Free Height

Height of liquid column if all gas were removed from foam.

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Gas Specific Gravity

Ratio of gas density to air density at standard conditions. Used for gas calculations.

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Gear Reducer Ratio

Gear reduction ratio of the pumping unit gearbox. Reduces motor RPM to pumping speed.

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Gearbox Loading

Analysis of gearbox torque loading percentage. Evaluates if unit is appropriately loaded.

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Gearbox Torque

Net torque on gearbox throughout 360° rotation. Dashed line shows gearbox rating.

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GOR

Gas-Oil Ratio in standard cubic feet per barrel (scf/bbl). Higher GOR reduces pump efficiency.

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Gross Pump Stroke

Actual plunger travel distance in inches, accounting for rod/tubing stretch and geometry.

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Ground Elevation

Ground level elevation above sea level in feet at the well site.

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Guide Type

Material type of rod guide: N70 (nylon), PPS (polyphenylene sulfide), PPA (polyphthalamide). Selection depends on temperature and well conditions.

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Guide Weight

Weight of rod guides included in total rod string weight calculations.

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Guides Per Rod

Number of rod guides installed per rod joint. Typically 1-2 guides per joint depending on well deviation.

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H

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H2S Content

Percentage of hydrogen sulfide in the gas stream. Affects material selection and safety requirements.

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Hole Diameter

Diameter of each perforation tunnel in inches.

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Hydraulic Pump

Displacement volume of the hydraulic pump per revolution.

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Hydraulic Timing

Time parameters for hydraulic units including turn-around time, acceleration, and deceleration settings.

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I

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Inclination

Wellbore angle from vertical in degrees. 0 degrees is vertical, 90 degrees is horizontal. Used with measured depth and azimuth to define the wellbore trajectory.

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Inner Diameter

Inside diameter of tubing in inches. Determines flow area and rod clearance.

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Intake Pressure

Pressure at the pump intake. Critical for determining pump submergence and efficiency.

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K

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KB Elevation

Kelly Bushing elevation above sea level in feet. Reference point for all depth measurements.

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L

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Largest Dogleg Above

Maximum dogleg severity value encountered in the wellbore section above the pump.

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Latitude

Geographic latitude coordinate of the well location in decimal degrees. Range: -90 to 90.

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Length

Length of rod or tubing section in feet.

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Length Difference

Difference between PSN depth and total rod length. Should be 0.00 for proper rod string design.

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Liquid Rate

Total liquid production rate including oil and water in barrels per day.

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Longitude

Geographic longitude coordinate of the well location in decimal degrees. Range: -180 to 180.

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M

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Measured Depth

Distance along the actual wellbore path from the Kelly Bushing to a given point, measured in feet. Unlike true vertical depth, measured depth follows the borehole trajectory including any deviations.

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Manufacturer

Manufacturer of rods, tubing, or pumping unit equipment.

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Manufacturer Line

Product line designation from equipment manufacturer (e.g., Lufkin C-Series).

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Max CB Moment

Maximum counterbalance moment in inch-pounds needed to balance pumping loads.

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Max Dogleg Above PSN

Maximum DLS tolerance for rod string cycling through the wellbore.

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Max Dogleg Severity

Maximum dogleg severity tolerance for pump setting location.

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Max Inclination

Maximum inclination tolerance for pump setting depth.

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Max Load

Maximum load rating for the pumping unit.

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Max PSN Depth

Maximum allowable pump setting depth based on well geometry constraints.

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Min Pump Length

Minimum barrel length required to accommodate gross pump stroke and clearances.

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Model

Specific model designation of pumping unit (e.g., C-160D-173-74).

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Motor Type

Type of prime mover driving the pumping unit (Electric Motor, Gas Engine, VFD Electric).

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MPRL

Minimum Polished Rod Load - minimum load at surface during downstroke. Negative values indicate counterbalance issues.

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MPRL/PPRL

Ratio of minimum to peak polished rod loads. Ideal range: 0.25-0.50 for proper counterbalance.

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N

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Neutral Point

Additional tension required at anchor to counter thermal, piston, and ballooning effects.

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North-South

North-South displacement from the wellhead in feet, calculated from measured depth, inclination, and azimuth using the minimum curvature method.

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Nitrogen Content

Percentage of nitrogen in the gas stream.

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O

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Oil API Gravity

Density of oil measured in degrees API. Lighter oils have higher API gravity values.

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Oil Production

Oil production rate in barrels per day.

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Oil Production Rate

Daily oil production in barrels (BOPD). Key metric for well performance.

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Outer Diameter

Outside diameter of tubing or casing in inches.

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Overpull

Distance the tubing is pulled past desired tension point to set the tubing hanger.

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Overpull Hookload

Pulling force required at surface to achieve proper overpull.

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P

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Parameter One

Primary simulation parameter selection (e.g., Stroke Rate, Desired Production).

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Parameter Two

Secondary simulation parameter for result estimation method.

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Peak Gearbox Torque

Maximum torque applied to gearbox during pumping cycle in inch-pounds.

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Peak Load

Maximum upstroke load measured at the polished rod.

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Permissible HP

Maximum safe horsepower for the pumping unit based on API ratings and structural limitations.

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Piston Effect

Decrease in tensile force caused by falling sucker rods and pump plunger.

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Plunger Diameter

Diameter of the pump plunger in inches.

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Plunger Length

Length of the pump plunger in inches.

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Polished Rod Diameter

Diameter of the polished rod at surface. Must match stuffing box size.

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Polished Rod HP

Horsepower delivered at the polished rod. Represents actual power for lifting fluids.

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PPRL

Peak Polished Rod Load - maximum upward load at surface during upstroke in pounds.

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PRHP/PLHP

Ratio of Polished Rod HP to Permissible HP. Should be less than 1.0 for safe operation.

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Prime Mover

Engine or motor driving the hydraulic pump or pumping unit.

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Prime Mover RPM

Motor or engine speed in revolutions per minute. Reduced to pumping speed through gearbox.

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Producing Level

Depth to fluid level when well is producing.

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Producing Temp

Temperature of produced fluid at wellhead during production operations.

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Production Data

Historical production volumes for oil, water, and gas with calculated metrics.

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PSN Depth

Pump Seating Nipple depth - measured depth from Kelly Bushing to pump intake in feet.

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PSN Dogleg

Dogleg Severity in degrees per 100ft at the Pump Seating Nipple location.

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PSN Inclination

Wellbore inclination angle at the Pump Seating Nipple location.

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PSN TVD

True Vertical Depth at the Pump Seating Nipple.

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Pump Condition

Operating condition when pump is not full. Options: Gas Interference or Fluid Pound.

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Pump Diameter

Internal diameter of the pump plunger in inches. Common sizes: 1.25”, 1.5”, 1.75”, 2.0”, 2.25”, 2.5”.

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Pump Fill

Pump fillage percentage. Default 85% when gas interference is expected.

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Pump Friction

Friction coefficient between plunger and barrel.

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Pump Separator TVD

Vertical depth from surface to pump or separator installation point.

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Pump Slippage

Volume of fluid lost due to pump inefficiency from plunger-barrel clearance.

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Pump Space

Clearance between plunger and pump seating assembly at bottom of stroke.

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Pumping Unit Type

Type of surface pumping unit (Conventional, Air Balanced, Mark II, etc.).

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Q

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Quantity

Number of identical tubing joints or rod joints in a section.

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R

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Rec Plunger Length

Recommended plunger length for optimal pump performance and seal life.

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Required HP

Minimum horsepower required at motor to lift design production rate.

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Reservoir Pressure

Formation pressure driving fluids into wellbore. Used for IPR calculations.

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Reservoir Temp

Temperature of the in situ reservoir fluid.

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Rod Buckling

Analysis of compression forces on rod string. High buckling stress causes rod/tubing wear.

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Rod Class

API rod class designation (e.g., C, K, D, KD). Defines material grade and strength properties.

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Rod Diameter

Nominal diameter of rod in inches. Common sizes: 5/8”, 3/4”, 7/8”, 1”.

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Rod Grade

API rod grade classification. Manufacturers have internal grades aligned with API use classes.

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Rod Guided

Whether rod section uses rod guides to prevent rod-tubing contact.

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Rod Loading

Percentage of rod ultimate strength being used. Safe range: less than 70% for continuous operation.

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Rod Manufacturer

Manufacturer of sucker rods.

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Rod Stress Calc

Stress calculation method for rod loading (e.g., T/4, T/2.8 for steel; Fiberflex API for fiberglass).

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Rod Taper

Position of rod section in string (1 = top section). Each taper represents different diameter.

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Rod Tensile Strength

Ultimate tensile strength in ksi. API grades: D=60ksi, K=85ksi, C=90ksi, KD=115ksi.

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Rod Top Max Stress

Maximum tensile stress at top of rod section during upstroke in psi.

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Rod Top Min Stress

Minimum tensile stress at top of rod section during downstroke. Negative indicates compression.

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Rod Type

Type of sucker rod (Steel, Fiberglass, Coated, Sinker Bar).

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Rotation

Direction of pumping unit rotation as viewed from wellhead (Clockwise or Counterclockwise).

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Run Time

Total operating time for simulation. Cannot exceed 24 hours.

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S

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Service Factor

Safety factor applied to steel rod string design. Typical values: 0.50-0.75.

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Set Depth

Depth where casing shoe is set, measured from Kelly Bushing.

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Set Tension

Tension applied to casing string when cemented.

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Sheave Diameter

Belt pulley diameter in inches. Determines speed reduction ratio.

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Shots Per Foot

Perforation density, typically 4-16 shots per foot.

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Side Loading

Lateral forces on rod string by depth indicating rod-to-tubing contact.

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Slippage

Volume of fluid lost due to pump inefficiency.

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Specific Gravity

Ratio of fluid density to water density.

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SPM

Strokes Per Minute. Typical range: 3-12 SPM for beam pumps.

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Static Level

Depth to fluid level when well is shut in.

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Static Temp

Stabilized temperature at wellhead when well is static.

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Step Length

Calculation interval length in feet. Smaller values increase precision but slow computation.

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Stress Load

Percentage of rod ultimate strength being used. Safe: less than 70%, Caution: 70-80%, Risk: greater than 80%.

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Stroke Length

Length of pumping unit stroke in inches. Typical range: 30-168 inches.

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Stroke Rate

Strokes per minute (SPM) of the pumping unit. Typical range: 3-12 SPM.

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Structure Load

Percentage of unit structural rating being utilized. Greater than 100% indicates overloading.

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Stuffing Box Friction

Friction from the stuffing box on the polished rod.

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Stretch Loss

Production loss due to tubing stretch in barrels per day.

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System Efficiency

Overall system efficiency combining mechanical, volumetric, and electrical losses. Typical: 40-55%.

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T

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Taper

Position of rod section in string. Tapered strings use larger rods at top, smaller at bottom.

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Target Depth

Optimal pump depth for the well.

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Target Fluid Level

Estimated operating fluid level from surface in tubing.

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Target Intake Pressure

Target pressure at pump intake in psi.

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Target Level

Desired fluid level for optimization.

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Target Pressure

Target casing pressure for optimization.

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Target Production

Desired daily production rate in barrels.

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Target Stroke Rate

Reasonable maximum stroke speed for selected pumping unit.

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Tensile Strength

Ultimate tensile strength of rod material in ksi.

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Thermal Effect

Drop in tensile force from tubing expansion from static to production temperature.

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Thickness

Total thickness of perforated interval (bottom - top depth).

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Thread Type

Thread connection type at tubing joint (e.g., EUE, NUE, Premium).

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Top Depth

Measured depth from Kelly Bushing to top of section in feet.

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Top Max Stress

Maximum tensile stress at top of rod section during upstroke.

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Top Min Stress

Minimum stress at top of rod section during downstroke.

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Total Hookload

Total tension required when setting anchor to achieve desired anchor tension on production.

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Total Length

Sum of all rod section lengths. Should match PSN depth.

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Tubing Anchored

Whether tubing is mechanically anchored to prevent movement during pumping.

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Tubing Description

Descriptive name or identifier for tubing string section.

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Tubing Grade

Steel grade designation (e.g., J55, N80, P110). Higher grades have greater tensile strength.

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Tubing ID

Inside diameter of tubing in inches.

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Tubing OD

Outside diameter of tubing body in inches.

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Tubing Pressure

Pressure inside tubing string at surface, also called flowing wellhead pressure or flowline pressure.

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Tubing Stretch

Elastic elongation of tubing string under tensile load during upstroke.

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Tubing Weight

Weight per foot of tubing string in pounds.

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Turn Around Time

Time delay at stroke reversal points for hydraulic units.

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TVD

True Vertical Depth - actual vertical distance from surface reference point.

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U

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Unit Model

Specific model designation of the pumping unit.

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Unit Structural

Pumping unit structural load rating. Values greater than 100% indicate overloading.

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Unit Type

Type of surface pumping unit (Conventional, Air Balanced, Mark II, etc.).

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Up Stroke Time

Time duration for upward stroke in seconds.

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Use Fluid Level

Option to use fluid level for calculations.

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V

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Vertical Friction Down

Friction coefficient for vertical rod-tubing contact during downstroke in directional wells.

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Vertical Friction Up

Friction coefficient for vertical rod-tubing contact during upstroke in directional wells.

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Viscosity

Fluid viscosity affecting pump efficiency and slippage.

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Volumetric Efficiency

Percentage of theoretical pump displacement actually produced. Default 85% for gas interference.

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W

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Water Cut

Percentage of water in total liquid production. Critical at greater than 95%.

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Water Gravity

Specific gravity of produced water. Fresh: 1.0, Brine: 1.02-1.08.

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Water Production Rate

Daily water production in barrels (BWPD).

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Water Specific Gravity

Ratio of water density to fresh water density.

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Weight

Weight per foot of tubing or rod in pounds.

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Weight in Water

Expected hook load exerted by tubing string hanging in water.

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Well Depth

Total measured depth of well from Kelly Bushing to bottom.

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Well Name

Unique identifier for the well. Typically includes lease name and well number.

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Wellbore

3D visualization of wellbore trajectory showing MD, TVD, and lateral displacement.

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Additional Terms

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Actions

Available operations for a record including edit, duplicate, delete, and view details.

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Air Balanced

Type of pumping unit that uses compressed air cylinders for counterbalance instead of conventional counterweights. Minimum cylinder volume ensures adequate counterbalance force.

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Bottom Depth

Measured depth from Kelly Bushing to the bottom of a section in feet.

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Bottom Min Stress

Minimum stress at bottom of rod section in psi. Negative values indicate compression and potential buckling risk.

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Calculators

Engineering calculation tools within PetroBench for analyzing well performance and equipment sizing.

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Casing

Steel pipe installed in the wellbore to prevent collapse and isolate formations.

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CF Elevation

Cellar Floor elevation above sea level in feet.

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Comparison

Side-by-side analysis of multiple simulation results to evaluate different rod string designs.

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Country

Country where the well is located.

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County

County or parish where the well is located.

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Created

Date when a record was created in the system.

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Created By

User who created a record in the system.

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Equivalent Gas Free Liquid

Height of liquid column if all gas were removed from foam above the pump.

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EUR

Estimated Ultimate Recovery - total oil expected to be produced from the well over its lifetime.

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Flow Velocity

Speed of fluid flow in tubing or annulus. Used to assess flow regimes and erosion risk.

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Foam Column

Gas-liquid mixture above the pump that affects fluid level measurements and pump performance.

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Hydraulic Lift

Hydraulic pumping unit calculations including power requirements and cycle time analysis.

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Installed

Indicates if a simulation is currently installed on the well as the active rod string design.

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IPR

Inflow Performance Relationship - describes the relationship between bottomhole pressure and production rate.

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KB-CF Distance

Distance from Kelly Bushing to Cellar Floor.

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KB-Ground Distance

Distance from Kelly Bushing to ground level, typically 10-15 feet.

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Last Modified

Date and time when a record was last updated.

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Lease Name

Name of the lease or property where the well is located.

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Maximum Rated Load

Maximum load rating for a pumping unit in pounds.

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Name

Identifier for a simulation, comparison, or other record.

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Neutral Point Tension

Additional tension required at anchor to counter thermal, piston, and ballooning effects.

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Operator

Company or entity responsible for operating the well.

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Organization

Company or organizational unit within PetroBench. Can be structured as HQ → Division → Region.

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Owner

User who created and owns a simulation or record.

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Perforation Bottom

Bottom measured depth of perforated interval.

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Perforation Thickness

Total thickness of perforated interval (bottom - top depth).

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Perforation Top

Top measured depth of perforated interval.

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Perforations

Holes made through casing and cement into the formation to allow fluid flow.

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Permissions

Access controls that define what actions users can perform in PetroBench.

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Plunger Barrel Clearance

Clearance between pump plunger and barrel walls affecting slippage.

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Producing Fluid Level

Depth to fluid level when well is actively producing.

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Producing Wellhead Temperature

Temperature of produced fluid at wellhead during production operations.

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Pump Intake Pressure

Pressure at the pump intake (PIP). Calculated from fluid level and fluid gradient. Critical for pump submergence.

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Pumping Unit

Surface equipment that provides reciprocating motion to the rod string for lifting fluids.

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Reservoir Temperature

Temperature of the in situ reservoir fluid.

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Rod Pump Production

Theoretical and actual production rates from rod pump systems based on displacement and efficiency.

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Rod String

Complete assembly of sucker rods from surface to pump, including tapered sections.

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Simulation

Rod string design calculation that models equipment performance and predicts stresses.

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State

State or province where the well is located.

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Static Fluid Level

Depth to fluid level when well is shut in and not producing.

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Static Wellhead Temperature

Stabilized temperature at wellhead when well is static/shut in.

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Tubing

Production tubing string through which fluids are produced to surface.

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Tubing Weight in Water

Expected hook load exerted by tubing string when submerged in water.

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Well

Oil or gas producing wellbore with associated equipment and production data.

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Well Performance

Historical performance data including fluid levels and production rates.