Formula Repository

1154 items

API gravity

Average permeability for linear flow - Layered beds

Average permeability for linear flow - Series beds

Average permeability for parallel-layered systems

Average permeability in radial systems

Average temperature of a gas column

Calculation of fractional flow curve

Capillary number

Capillary pressure

Characteristic time for linear diffusion in reservoirs

Cole plot

Communication between compartments in tight gas reservoirs

Communication factor in a compartment in tight gas reservoirs

Compressibility drive in gas reservoirs

Correction factor - Hammerlindl

Critical rate for horizontal Wells in edge-water drive reservoirs

Crossflow index

Cumulative effective compressibility - Fetkovich

Cumulative gas production - Tarner's method

Cumulative oil production - Undersaturated oil reservoirs

Deliverability equation for shallow gas reservoirs

Dimensionless pressure - Kamal and Brigham

Dimensionless radius of radial flow - Constant-rate production

Dimensionless time - Myhill and Stegemeier's method

Dimensionless time for interference testing in homogeneous reservoirs - Earlougher

Dimensionless vertical well critical rate correlations - Hoyland, Papatzacos, and Skjaeveland

Dimensionless wellbore storage coefficient of radial flow - Constant-rate production

Effective compressibility in undersaturated oil reservoirs - Hawkins

Effective wellbore radius of a horizontal well - Method 1- Anisotropic reservoirs

Effective wellbore radius of a horizontal well - Method 1 - Isotropic reservoirs

Effective wellbore radius of a horizontal well - van der Vlis et al. method

Effective wellbore radius of a well in presence of uniform-flux fractures

Effective wellbore radius to calculate slant well productivity - van der Vlis et al.

Estimation of average reservoir pressure - MDH method

Formation temperature for a given gradient

Fraction of the total solution gas retained in the reservoir as free gas

Fractional gas recovery below the critical desorption pressure in coal bed methane reservoirs

Free gas in place

Gas adsorbed in coal bed methane reservoirs

Gas bubble radius

Gas cap ratio

Gas cap shrinkage

Gas drive index in gas reservoirs

Gas expansion factor

Gas expansion term in gas reservoirs

Gas flow rate into the wellbore

Gas flow under laminar viscous conditions

Gas formation volume factor

Gas hydrate dissociation pressure

Gas material balance equation

Gas produced by gas expansion

Gas saturation - Water-drive gas reservoirs

Gas solubility in coalbed methane reservoirs

Geertsma's model for porosity/transit-time relationship

Geothermal gradient

Hagen Poiseuille equation (1)

Hagoort and Hoogstra gas flow in tight reservoirs

Hammerlindl method for gas in place

High-pressure region gas flow rate

Horizontal well breakthrough time-With gas cap or bottom water

Horizontal well critical rate correlation - Chaperon

Horizontal well critical rate correlations - Efros

Horizontal well critical rate correlations - Giger and Karcher

Horizontal well critical rate correlations - Joshi method for gas coning

Hydrocarbon pore volume occupied by evolved solution gas

Hydrocarbon pore volume occupied by gas cap

Hydrocarbon pore volume occupied by remaining oil

Hydrostatic pressure

Incremental cumulative oil production in undersaturated reservoirs

Ineffective porosity

Initial gas cap

Initial gas in place for water-drive gas reservoirs

Injectivity index

Instantaneous gas-oil ratio

Interporosity flow coefficient

Interstitial velocity

Isothermal compressibility of oil - Vasquez-Beggs correlation - P>Pb

Isothermal compressibility of oil - Villena-Lanzi correlation - P<Pb

Isothermal compressibility of water - Osif correlation

Kerns method for gas flow in a fracture

Klinkenberg gas effect

Kozeny equation

Kozeny-Carman relationship

Leverett J-function

Line-source solution for damaged or stimulated wells

Low-pressure region gas flow rate for non-circular drainage area

Material balance for cumulative water influx - Havlena and Odeh

Maximum height of oil column in cap rock

Modified Cole plot

Modified Kozeny-Carman relationship

Normalized saturation

Oil bubble radius of the drainage area of each well represented by a circle

Oil density - Standing's correlation

Oil formation volume factor - Standing's correlation

Oil formation volume factor - Beggs-Standing correlation 1 - P<Pb

Oil formation volume factor - Beggs-Standing correlation 2 - P>Pb

Oil in place for undersaturated oil reservoirs without fluid injection

Oil in place in saturated oil reservoirs

Oil lost in migration

Oil saturation at any depletion state below the bubble point pressure

Original gas in place

Payne method for intercompartmental flow in tight gas reservoirs

Performance coefficient for shallow gas reservoirs

Poisson's ratio

Pore throat sorting

Pore volume occupied by injection of gas and water

Pore volume through squared method in tight gas reservoirs

Porosity determination - IES and FDC logs

Produced gas-oil ratio

Productivity index for a gas well

Pseudo-steady state productivity of horizontal Wells - Method 1

Pseudo-steady state productivity of horizontal Wells - Method 2

Pseudo-steady state productivity of horizontal wells - Method 3

Pseudo-steady state radial flow equation

Relative permeability - Corey exponents

Remaining gas in place in coalbed methane reservoirs

Roach plot for abnormally pressured gas reservoirs

Rock expansion term in abnormally pressured gas reservoirs

Shape factor - Earlougher

Solution gas oil ratio - Beggs-Standing correlation - P<Pb

Solution gas oil ratio - Standing's correlation

Solution gas water ratio

Somerton method for formation permeability in coalbed methane reservoirs

Specific gravity of gas hydrate forming components

Time to reach the semi-steady state for a gas well in a circular or square drainage area (1)

Time to the end of infinite-acting period for a well in a circular reservoir

Torcaso and Wyllie's correlation for relative permeability ratio prediction

Total compressibility

Total pore volume compressibility

Transmissibility between compartments

Transmissibility of a compartment

Transmissivity

Trapped gas volume in water-invaded zones

Two-phase formation volume factor

Underground fluid withdrawal - Havlena and Odeh

Vertical well critical rate correlations - Craft and Hawkins method

Vertical well critical rate correlations - Hoyland, Papatzacos, and Skjaeveland - Isotropic reservoirs

Vertical well critical rate correlations - Meyer, Gardner, and Pirson - Simultaneous gas and water coning

Vertical well critical rate correlations - Meyer, Gardner, and Pirson - Water coning

Vertical well critical rate correlations - Meyer, Gardner, and Pirson - Gas coning

Viscosibility

Viscosity of crude oil through API

Viscosity of dead oil - Standing's correlation

Viscosity of dead-oil - Egbogah correlation - P<Pb

Viscosity of live oil - Beggs/Robinson correlation

Viscosity of oil - Vasquez/Beggs correlation - P>Pb

Viscosity of water at atmospheric pressure - McCain correlation

Viscosity of water at reservoir pressure - McCain correlation

Volume of gas adsorbed in coalbed methane reservoirs

Volumetric heat capacity of a reservoir

Water breakthrough correlation in vertical wells - Bournazel and Jeanson

Water breakthrough correlations in vertical wells - Sobocinski and Cornelius

Water content of sour gas

Water cut - Stiles

Water-drive index for gas reservoirs

Water-drive recovery

Water expansion term in gas reservoirs

Water formation volume factor - McCain correlation

Water influx - Pot aquifer model

Water influx constant for the van Everdingen and Hurst unsteady-state model

Water two-phase formation volume factor

Waxman and Smits model - Clean sands

Welge extension - Fractional flow

Accumulator capacity

Accumulator precharge pressure

Amount of additive required to achieve a required cement slurry density

Amount of cement to be left in casing

Amount of mud required to displace cement in drillpipe

Angle of twist - Rod subjected to torque

Annular capacity between casing and multiple strings of tubing

Annular capacity between casing and multiple tubing strings

Annular velocity - Using circulation rate in Gpm

Annular velocity - Using pump output in bbl/min

Annular velocity for a given circulation rate

Annular velocity for a given pump output

Annular volume capacity of pipe

API water loss calculations

Area below the casing shoe

Axial loads in slips

Beam force

Bit nozzle pressure loss

Bit nozzle selection - Optimized hydraulics for two and three jets

Borehole torsion - Cylindrical helical method

Bottomhole annulus pressure

Bottomhole assembly length required for a desired weight on bit

Bulk density of cuttings - Using the mud balance

Bulk modulus using Poisson's ratio and Young's modulus

Buoyancy weight

Buoyancy factor

Buoyancy factor using mud weight

Calculations for the number of feet to be cemented

Calculations required for spotting pills

Capacity formulas - bbl/ft

Capacity formulas - gal/ft

Capacity of tubulars and open-hole

Combined solubility - Hydrocarbon gas, CO2, and H2S - in each of the mud components

Control drilling - Maximum drilling rate

Conversion of pressure into the mud weight

Cost per foot during drilling

Cost per foot of coring

Critical annular velocity and critical flow rate

Critical flow rate for flow regime change

Critical velocity for change in flow regime

Crown block capacity

Current drag force - Offshore

Curvature radius for a borehole

Cutting slip velocity

Cuttings produced per foot of hole drilled - bbls

Cuttings produced per foot of hole drilled - lbs

D-Exponent

Depth of a washout - Method 1

Depth of a washout - Method 2

Derrick efficiency factor

Difference in pressure gradient between the cement and mud

Differential hydrostatic pressure between cement in the annulus and mud inside the casing

Dilution of a mud system

Direction of dip

Directional curvature for a deviated well

Downward force or weight of casing

Drill pipe or drill collar capacity

Drill pipe or drill collar displacement and weight

Drill string design - Drill pipe length for bottomhole assembly

Drilled gas entry rate

Drilling cost per foot

Drilling ton miles - Coring operation ton miles

Drilling ton miles - Drilling/connection ton miles

Drilling ton miles - Round trip ton miles

Drilling ton miles - While making short trip ton miles

Drilling ton miles - Setting casing ton miles

Duplex pump factor

Duplex pump output - Using liner diameter

Duplex pump output - Using rod diameter

Duplex pump output by using liner and rod diameters

Dynamically coupled linear flow - Formation invasion

Effective weight during drilling

Effective wellbore radius for finite-conductivity fractures

Effective wellbore radius in infinite-conductivity fractures

Efficiency of block and tackle system

Equivalent area of pipe subject to uniform axial force

Equivalent circulating density

Equivalent density of a wellbore fluid

Equivalent formation water resistivity from SP log

Equivalent mud weight - Deviated well

Equivalent mud weight - Vertical well

Evaluation of centrifuge

Evaluation of hydrocyclone

Fluid volume required to spot a plug

Force applied to stretch material

Force exerted by the fluid on the solid surface of flow through an annulus

Friction factor in drill pipe

Front displacement of a particle in the reservoir - Formation invasion

Gas migration velocity

Gas solubility in a mud system

Gas/mud ratio

Gel strength - Optimal solid removal efficiency

Gel strength - Solid control efficiency

Gel strength - Solids build-up in system

Height of cement in the annulus

Hydraulic horsepower

Hydraulics analysis

Hydromechanical specific energy

Hydrostatic pulling

Hydrostatic pulling wet pipe out of the hole

Hydrostatic pressure in annulus due to slug

Hydrostatic pressure decrease at total depth caused by gas-cut mud

Impact force - Nozzle hydraulic analysis

Impringing jet

Increase mud density by barite

Increase mud density by calcium carbonate

Increase mud density by hematite

Increase volume by barite

Increase volume by calcium carbonate

Increase volume by hematite

Initial volume required to achieve a volume with barite

Initial volume required to achieve a volume with calcium carbonate

Initial volume required to achieve a volume with hematite

Injection/casing pressure required to open valve

Input power of a pump - Using fuel consumption rate

Jet velocity - Nozzle hydraulic analysis

Kick analysis - Influx

Kick analysis - Formation pressure with well shut-in on a kick

Kick analysis - Maximum pit gain from a gas kick in water-based mud

Kick analysis - Maximum surface pressure from a gas kick in water-based mud

Kick analysis - Shut-in drill pipe pressure

Kick analysis - Height of influx

Kill weight mud determination - Moore equation

Kinetic friction

Laser specific energy

Lateral load imposed on a casing centralizer - Cementing

Lateral load imposed on a casing centralizer with a dogleg - Cementing

Linear annular capacity of pipe

Linear capacity of pipe

Load to break cement bond - Cementing

Mass rate of flow through annulus

Matching conditions at the cake-to-rock interface - Formation invasion

Maximum allowable mud weight

Maximum drilling rate - Larger holes

Maximum equivalent derrick load

Maximum length of a slanted well in a given reservoir thickness

Maximum length of drillpipe for a specific bottomhole assembly

Maximum recommended low-gravity solids

Maximum recommended solids fractions in drilling fluids

Maximum weight on bit

Mechanical energy balance for wellbore fluids

Mechanical specific energy

Mud rheology - Herschel and Buckley law

Mud rheology - Power-law model - Consistency index

Mud rheology - Power-law model - Power-law index

Mud rheology - Power-law

Mud rheology calculations - Bingham plastic model

Mud weight increase required to balance pressure

Mud weight reduction by dilution - Water/diesel/any liquid

Mudcake growth equation - Formation invasion

Mudcake growth equation 2 - Formation invasion

Mudcake permeability - Formation invasion

New pump circulating pressure

Nozzle area calculation

Number of sacks of cement required

Number of sacks of cement required for a given length of plug

Number of sacks of lead cement required for annulus

Number of sacks of tail cement required for casing

Open-ended displacement volume of pipe

Overall efficiency - Diesel engines to mud pump

Overall power system efficiency

Penetration rate - Drill-rate model - Alternative equation

Penetration rate - Drill-rate model - Basic equation

Percentage of bit nozzle pressure loss

Plastic viscosity - Bingham plastic model

Plug length to set a balanced cement plug

Polar moment of inertia

Polished rod horsepower - Sucker-rod pump

Pore-pressure gradient - Rehm and McClendon

Pore-pressure gradient - Zamora

Pressure analysis - Pressure by each barrel of mud in casing

Pressure analysis - Surface pressure during drill stem test

Pressure gradient

Pressure required to break circulation - Annulus

Pressure required to break circulation - Drill string

Pressure required to overcome gel strength of mud inside the drill string

Pressure required to overcome mud's gel strength in annulus

Pump calculation - Pump pressure

Pump calculations - Power required

Pump displacement

Pump flow rate

Pump head rating

Pump output - gpm

Pump output triplex pump

Pump pressure/pump stroke relationship

Radial force related to axial load - Cementing

Range of load - Sucker-Rod pump

Rate of fuel consumption by a pump

Rate of gas portion that enters the mud

Relationship between traveling block speed and fast line speed

Rock removal rate

Rotating horsepower

Side force at bit in anisotropic formation

Sinusoidal buckling

Slurry density for cementing calculations

Solids analysis-High-salt content muds

Solids analysis low-salt content muds

Spacer volume behind slurry required to balance the plug

Specific gravity of cuttings by using mud balance

Stripping/snubbing calculations - Breakover point between stripping and snubbing

Stripping/snubbing calculations - Height gain and casing pressure from stripping into influx

Stripping/snubbing calculations - Maximum Allowable surface pressure governed by casing burst pressure

Stripping/snubbing calculations-Maximum allowable surface pressure governed by formation

Stripping/snubbing calculations - Minimum surface pressure before stripping

Stripping/snubbing calculations - Constant BHP with a gas bubble rising

Stroke per minute required for a given annular velocity

Stuck pipe calculations - Method-1

Stuck pipe calculations - Method-2

Subsea considerations - Adjusting choke line pressure loss for higher mud weight

Subsea considerations - Casing burst pressure-subsea stack

Subsea considerations - Choke line pressure loss

Subsea considerations - Maximum allowable mud weight - Subsea stack from leakoff test

Subsea considerations - Casing pressure decrease when bringing well on choke

Subsea considerations - Velocity through choke line

Surface test pressure required to frac the formation

Total amount of solids generated during drilling

Total heat energy consumed by the engine

Total number of sacks of tail cement required

Total water requirement per sack of cement

Triplex pump factor

Upward force acting at the bottom of the casing shoe

Vertical curvature for deviated wells

Viscous shear stress at the outer mudcake boundary

Volume of cuttings generated per foot of hole drilled

Volume of dilution water or mud required to maintain circulating volume

Volume of fluid displaced for duplex pumps

Volume of fluid displaced for single-acting pump

Volume of fluid displaced for triplex pump

Volume of liquid (oil plus water) required to prepare a desired volume of mud

Volume of slurry per sack of cement

Volumes and strokes-Annular volume

Volumes and strokes - Drill string volume

Volumes and strokes - Total strokes

Weight of additive per sack of cement

Weighted cementing calculations

Analysis of a flow test with smoothly varying rates

Analysis of a post-fracture - Constant-rate flow test with boundary effects

Analysis of a post-fracture pressure buildup test with wellbore-storage distortion

Analysis of a well from a PI test

Analysis of DST flow data with Ramey type curves

Average fracture permeability (pseudo-steady state case for pressure build-up test)

Bottomhole flowing pressure during infinite-acting pseudoradial flow

Calculation of pressure beyond the wellbore (line-source solution)

Conventional DST design without a water cushion (collapse pressure calculation)

Diffusion depth in a geothermal well

Dimensionless buildup pressure for field calculations

Dimensionless buildup pressure for liquid flow

Dimensionless buildup pressure for steam or gas flow

Dimensionless buildup time

Dimensionless cumulative production (radial flow constant-pressure production)

Dimensionless drawdown correlating parameter by Carter

Dimensionless length (linear flow constant rate production/hydraulically fractured wells)

Dimensionless length (linear flow/constant-rate production/general case)

Dimensionless pressure (linear flow/constant rate production/general case)

Dimensionless pressure (linear flow/constant rate production/hydraulicallyfractured wells)

Dimensionless pressure (radial-flow/constant pressure production)

Dimensionless pressure (radial-flow/constant rate production)

Dimensionless pressure drop across a skin at the well face

Dimensionless pressure drop during pseudo-steady state flow for a fractured vertical well in a square drainage area

Dimensionless pressure drop during pseudo-steady state flow for a horizontal well in a bounded reservoir

Dimensionless production time

Dimensionless rate (radial flow/constant pressure production)

Dimensionless shut-in time for MDH method

Dimensionless storage constant for gases

Dimensionless storage constant for liquids

Dimensionless time (linear flow/constant rate production/general case)

Dimensionless time (linear flow/constant rate production/hydraulically fractured wells)

Dimensionless time (radial flow/constant rate production)

Dimensionless time function (transient heat transfer to the formation)

Dimensionless wellbore storage coefficient (compressible fluids for pressure build-up test)

Flow period duration (hydraulically fractured wells)

Fracture conductivity (bilinear-flow regime in gas wells)

Fracture conductivity during bilinear flow

Inflow performance relationship (IPR) for horizontal wells in solution gas-drive reservoirs (Fetkovich)

Inflow performance relationship (IPR) for horizontal wells in solution gas-drive reservoirs (Vogel)

Interporosity flow coefficient in pressure build-up test

Minimum shut-in time to reach pseudo-steady state for tight gas reservoirs being hydraulically fractured

Permeability and reservoir pressure from buildup tests

Permeability and skin factor from a constant-rate flow test

Pressure buildup equation (Horner equation)

Radius of investigation

Radius of investigation (flow time)

Radius of investigation (shut-in time)

Raymer hunt transform (porosity/transit time relationship)

Reservoir permeability

Shut-in time for pressure build-up test (Dietz method)

Skin during infinite-acting pseudoradial flow for vertical wells

Skin estimation type-1 (pressure buildup test)

Slope of Horner plot in pressure buildup test

Slope of pseudo-steady state flow in pressure buildup test

Time to pseudo-steady state (single well-circular reservoir)

Time to reach the semi-steady state for a gas well in a circular or square drainage area (2)

True wellbore storage coefficient (pressure build-up test)

Well flow efficiency (geothermal well)

Well shut-in pressure during buildup (Horner plot)

Acid penetration distance (acidizing)

Additional pressure drop in the skin zone

Additive crystalline salt amount to increase the density - Method I (single-salt systems)

Additive crystalline salt amount to increase the density - Method II (single-salt systems)

Additive crystalline salt and water amount to increase the density - Method I (two-salt systems)

Annulus pressure loss due to friction during hydraulic fracturing (laminar flow)

Annulus pressure loss due to friction during hydraulic fracturing (turbulence flow)

Approximate ideal counterbalanced load

Average downstroke load (sucker-rod pump)

Average fracture width (acidizing)

Average permeability of a hydraulically fractured formation

Average specific weight of the formation (hydraulic fracturing)

Average upstroke load (sucker-rod pump)

Average wellbore fluid density (completion and workover fluids)

Capacity ratio of a hydraulically fractured surface

Choke discharge coefficient

Close-ended displacement volume of pipe

Convective mass transfer for laminar flow (acidizing)

Convective mass transfer for turbulent flow (acidizing)

Correct counterbalance (sucker-rod pump)

Corresponding reciprocal rate (post-fracture production-Constant Bottomhole flowing conditions)

Damaged/undamaged zone productivity comparison (acidizing)

Density of brine (completion and workover fluids)

Dimensionless fracture width for linear vertical fracture (Geertsma & Klerk)

Downhole operating pressure (hydraulic fracturing)

Entrance hole size (perforation)

Equivalent skin factor in fractured wells

Filter cake on the fracture (acidizing)

Flow coefficient during drawdown

Flow rate through orifice

Flow through fracture in response to pressure gradient

Formation fluid compressibility (acidizing)

Fracture area of a hydraulically fractured formation

Fracture coefficient of a hydraulically fractured reservoir

Fracture fluid coefficient for reservoir-controlled liquids

Fracture fluid coefficient for viscosity-controlled liquids

Fracture geometry (acidizing)

Fracture gradient (hydraulic fracturing)

Fracture-fluid invasion of the formation (acidizing)

Frictional pressure drop (Economides and Nolte)

Gas velocity under sonic flow conditions (through choke)

Hydraulic fracture efficiency

Hydraulic horse power for a hydraulic fracturing operation

Ideal fracture conductivity created by acid reaction (acidizing)

Incremental density in any wellbore interval (completion and workover fluids)

Initial rate following a hydraulic fracturing operation

Injection pressure for hydraulic fracturing

Lifetime of a hydraulically fractured well

Mass of rock dissolved per unit mass of acid (acidizing)

Mass transfer in acid solutions by Fick's law (acidizing)

Maximum treatment pressure (hydraulic fracturing)

Mechanical resistant torque (PCP)

Minimum polished rod load (sucker rod pump)

Peclet number for fluid loss (acidizing)

Perforation friction factor

Perforation friction pressure

Perforation hole size (perforation)

Perforation length in formation

Perforation penetration ratio (formation of interest/reference formation)

Perforation skin factor

Pore growth function (acidizing)

Pressure drop across perforations in gas wells

Pressure drop across perforations in oil wells

Pressure loss due to perforations during hydraulic fracturing

Pressure loss due to perforations during hydraulic fracturing - 2

Principal stress due to petro-static pressure (hydraulic fracturing)

Productivity index (for generating composite IPR curve)

Productivity ratio

Productivity ratio calculation of a hydraulically-fractured formation

Pseudo skin factor due to partial penetration (Brons and Marting method)

Pseudo-skin factor due to partial penetration (Yeh and Reynolds correlation)

Pseudo-skin factor due to partial penetration (Odeh correlation)

Pseudo-skin factor due to partial penetration (Papatzacos correlation)

Pseudo-skin factor due to perforations

Quantifying formation damage and improvement

Recommended underbalanced environment for perforation

Reynolds number for acid flow into the fracture (acidizing)

Reynolds number for fluid loss (acidizing)

Sand weight needed to refill a hydraulically fractured reservoir volume

Shape factor expressed as skin factor for vertical wells

Single-phase gas flow (subsonic)

Single-phase liquid flow through choke

Skin factor

Skin factor by Hawkins method

Skin factor due to partial penetration

Skin factor due to reduced crushed-zone permeability

Skin factor for a deviated well

Slope of Semilog plot for bottom-hole flowing pressure vs time for drawdown test

Sucker rod - Peak polished rod load

Suspension property of static fluids (completion and workover fluids)

Tangential annular flow of a power law fluid

Temperature at choke outlet

The z component of the force of the fluid on the wetted surface of the pipe

Total skin in partially depleted wells for a buildup test

Velocity distribution in the annular slit of a falling-cylinder viscometer

Velocity distribution in the narrow annular region in annular flow with inner cylinder moving axially

Velocity distribution of flow through an annulus

Velocity of fluid in annulus

Velocity of fluid in pipe

Viscous force acting on the rod over the narrow annular region

Volume capacity of pipe

Volume of fluid loss per unit area measured in a dynamic test (acidizing)

Volume of fluid loss per unit area measured in a static test (acidizing)

Volume of rock dissolved per unit volume of acid (acidizing)

Water quantity that dilutes the original brine with assumed density (two-salt systems)

Weight of crystalline CaCl2 and CaBr2 salt addition to brine (two-salt systems)

Well flowing pressure (line-source solution by including skin factor)

Well flowing pressure under Pseudo-steady state flow for non-circular reservoirs

Wellbore pressure loss due to friction during hydraulic fracturing (laminar flow)

Wellbore pressure loss due to friction during hydraulic fracturing (turbulence flow)

Wellbore storage

Wellbore storage due to fluid level

Wellhead pressure (multiphase flow across the choke)

Workover operations (maximum allowed tubing pressure)

Young Modulus by using sonic travel time (acidizing)

Archimedes number

Average number of collisions to reduce neutron energy

Average velocity of a falling film with variable viscosity

Average velocity of flow through a circular tube

Average velocity of flow through an annulus

Average velocity of fluids in flow of two adjacent immiscible fluids

Average velocity over the cross section of a falling film

Blowdown time in unsteady gas flow

Boltzmann equation

Boussinesq approximation-Buoyancy

Brinkman number

Buckingham Reiner equation

Calculation of mass flow rate

Calculation of momentum flux

Combined momentum flux tensor

Combined radiation and convection

Compressible flow in a horizontal circular tube

Compton scattering

Correction factor for stagnant film according to the penetration model

Darcy Weisbach equation (head loss form)

Darcy Weisbach equation (pressure loss form)

Dean number

Deborah number

Decay of thermal neutrons

Determination of the controlling resistance

Determination of the diameter of a falling sphere

Diffusion from an instantaneous point source

Diffusion in a moving film

Diffusion in polymers

Diffusion Into a falling liquid film (gas absorption)

Diffusion of low-density gases with equal mass

Diffusion potential

Diffusion through a non-isothermal spherical film

Diffusion through a stagnant film

Diffusion through a stagnant gas film

Diffusion through cleat spacing in coalbed methane reservoirs

Diffusion with a heterogeneous chemical reaction

Diffusion with a homogeneous chemical reaction

Diffusion, convection, and chemical reaction

Drag coefficient

Drag force

Draining of a cylindrical tank

Draining of a spherical tank

Eckert number

Effective emissivity of a hole

Effective thermal conductivity for a solid with spherical inclusions

Efflux time for draining a conical tank

Ekman number

Elimination of circulation in a rising gas bubble

Energy emitted from the surface of a black body

Estimation of diffusivity of liquids

Estimation of self diffusivity at high density

Estimation of the viscosity of a pure liquid

Euler number

Fanning friction factor (laminar flow)

Fanning's friction factor (turbulent flow)

Fick's law of binary diffusion

Film condensation on vertical pipes

Film condensation on vertical tubes

Film thickness of a falling film on a conical surface

Flow in a liquid-liquid ejector pump

Flow in a slit with uniform cross flow

Flow near a corner

Flow of power law fluid through a narrow slit

Fluid kinetic force in conduits

Fluid kinetic force in flow around submerged objects

Form drag

Free air correction-Gravity survey

Free batch expansion of a compressible fluid

Free convection heat transfer from a vertical plate

Friction drag

Friction factor for creeping flow around a sphere

Friction factor in flow around submerged objects

Friction factor in flow through conduits

Friction factor in packed column (laminar)

Friction factor in packed column (turbulant)

Galilei number

Gas absorption from rising bubbles for creeping flow

Gas absorption through bubbles

Gas absorption with chemical reaction in an agitated tank

Gas absorption with rapid reaction

Gas mass rate flow in compressible tube flow

Graetz number

Graham equation viscosity ratio

Grash of number

Hagen number

Hagen-Poiseuille equation (2)

Influence of changing interfacial area on mass transfer

Knudsen flow

Krieger Dougherty equation viscosity ratio

Laminar flow along a flat plate (approximate solution)

Laminar flow of an incompressible power-law fluid in a circular tube

Laplace number

Lewis number

Mach number

Manning formula

Marangoni number

Mass absorption (attenuation) coefficient

Mass flow rate as a function of the modified pressure drop in a network of tubes

Mass flow rate in a rotating cone pump

Mass rate of flow

Mass rate of flow in a squared duct

Mass rate of flow of a falling film

Mass rate of flow through a circular tube

Mass transfer for creeping flow around a gas bubble

Mass transfer to drops and bubbles

Maximum flow rate (Vogel's equation)

Maximum velocity of a falling film

Maximum velocity of flow through a circular tube

Maximum-velocity Vz-maximum of a falling film

Method for separating helium from natural gas

Modified capillary number

Modified Van Driest equation

Momentum flux distribution of flow through a circular tube

Momentum flux distribution of flow through an annulus

Momentum flux profile of fluids in flow of two adjacent immiscible fluids

Momentum fluxes for creeping flow into a slot

Mooney equation viscosity

Non-Newtonian flow in annulus

Nusselt number

Ohnesorge number

Potential flow around a cylinder

Prandtl number

Pressure distribution in a creeping flow around a sphere

Pressure drop per length of the adsorption unit

Pressure loss due to sudden enlargement

Reynolds number

Schmidt number

Sherwood number

Slit flow in Bingham fluid

Smoluchowski equation

Stanton number

Stefan number

Stokes number

Strouhal number

Taylor dispersion (axial dispersion coefficient)

Taylor equation viscosity

Taylor number

Theory of diffusion in colloidal suspensions

Toricelli equation

Total force of the fluid on the sphere in a creeping flow around a sphere

Velocity distribution in a creeping flow around a sphere

Velocity distribution of a falling film with variable viscosity

Velocity distribution of flow through a circular tube

Velocity profile of fluids in flow of two adjacent immiscible fluids

Viscosity by a falling-cylinder viscometer

Winsauer equation

Acoustic transit time

Amplitude transmission coefficient in seismic reflection and refraction

Apparent intensity reflected by recorder (gamma ray)

Apparent resistivity

Apparent sorption compressibility

Atlas wireline neutron lifetime log

Barenblatt-Chorin universal velocity distribution

Coefficient of reflection

Compaction correction factor for sonic logs in shale lithology

Composite capture cross section of the formation (Schlumberger thermal decay time tool)

Correlation of mud cake resistivity to mud resistivity

Correlation of mud filtrate resistivity to mud resistivity

Diffuse-layer thickness

Effect of clay on conductivity

Effective photoelectric absorption cross section index

Electric resistance to a radial current from a wellbore

Electrochemical potential (SP log)

Electrokinetic potential (developed across a mud cake)

Electron density index (GR absorbtion logging)

Epithermal neutron diffusion coefficient

Epithermal neutron distribution (epithermal neutron flux)

Fertl and Hammack equation

Formation conductivity in dual water model

Formation factor - Archie's equation

Formation factor (Archie's equation with resistivity logs)

Formation resistivity and permeability (Carothers) relation for limestones

Formation resistivity and permeability (Carothers) relation for sandstones

Formation resistivity and porosity relations for carbonate rocks

Formation resistivity and porosity relations from well log data based on Porter and Carothers data

Fraction of total porosity occupied by clays

Fresh water-filled porosity (fresh-water-bearing limestones)

Fxo / Fs approach

Gamma ray log shale index

General form of the Archie equation-Water saturation from resistivity logs

Generalized relationship between formation resistivity factor and porosity (Chevron formula)

Geometric coefficient for the electrode

Geometric coefficient for the lateral device

Geometric coefficient for the normal sonde

Half thickness value

Hingle nonlinear-resistivity/linear-porosity crossplot

Humble equation (formation resistivity factor vs porosity)

Integrated radial geometric factor

Lennard Jones potential

Linear absorption (attenuation) coefficient

Maximum potential for self-potential (SP) log

Mean free path (photon absorption)

Membrane potential

Neutron lethargy (logarithmic energy decrement)

Neutron porosity of shale zone

Oil saturation determination (IE and CDN logs)

Pair production (gamma ray interactions)

Phillips equation (sandstones)

Photoelectric absorption cross sectional area

Pickett crossplot

Poisson's ratio (seismic arrival time method)

Porosity by using density log data

Porosity corrected for gas effect

Porosity-neutron flux relationship

Rate of radioactive decay

Relation between concentration of K, Th, or U and recorded total gamma ray signal

Relationship between rock resistivity and water saturation

Relationship between SSP and Rw (NaCl predominant)

Relationship between SSP and Rw (non-ideal shale membrane)

Relationship between SSP and Rw for water containing salts (non-NaCl predominant)

Resistivity of a partially saturated shaly sand with hydrocarbons (Vsh models)

Resistivity of a water-saturated shaly sand (Vsh models)

Rock conductivity (relatively clean water bearing rocks)

Shale index from gamma ray spectrometry

Simandoux (total shale) equation

Sonic porosity (Raymer Hunt Gardner method)

Spacing between transmitter and receiver

Static self potential

Time between the initiation of the pulse and the first arrival acoustic energy at the receiver

Time-average relation in compacted formations (porosity/transit time relationships)

Time-average relation in uncompacted formations (porosity/transit time relationships)

Tortuosity (resistivity logs)

Total rock conductivity

True porosity from sonic log (corrected for compaction)

True resistivity - Archie

Volumetric photoelectric absorption cross section

Water salinity index ratio

Water saturation determination (IE and CDN logs)

Water saturation from neutron tools

Water saturation - Resistivity logs

Wavelength equation

Wellbore electric voltage generation

Acceptable reliability level

Additional production estimation with new wells

Annual gross revenue after royalties and wellhead taxes

Annuity from future value

Annuity from present value

Average annual rate of return method

Average book rate of return method

Calculation of unknown interest rate

Compound interest

Cost depletion

Cumulative interest on operational expenses during the lifetime of a well

Effective interest rate for periodic compounding

Exploration efficiency

Future value of an annuity

Future value of present sum

Generalized expected value calculation

Growth rate of return for continuous compounding

Hoskold method for annual rate of return prediction-1

Hoskold method for annual rate of return prediction-2

Initial capital needed to survive in a minimum chance scenario

Meterage model

Minimum number of jobs to survive in a minimum chance scenario

Minimum profit ratio per a risky job

Net cash flow

Net present value

Operating cash income

Payback Period

Present value of an annuity

Present value of a deferred annuity

Present value of future sum

Present value of profit/investment ratio for an oil well

Present value of uniform gradient series

Present worth expectation for a risky job

Probability of an oilfield discovery

Profitability index

Rate of growth per unit of exploration length

Simple interest

Total expected additional production discovery

Total expected additional production discovery in constant production per unit area

Total new production area estimation expected to be discovered

Amount of heat required to increase the temperature

Benedict-Webb-Rubin PVT equation

Critical pressure Cavett relation

Critical temperature Cavett method

Effective thermal conductivity of composite solids

Einstein equation effective viscosity

Equilibrium vaporization ratio

Equilibrium vaporization ratio of heptane

Evaporation loss from an oxygen tank

Expansion factor for diffuse layer

Flat-plate boundary layer model

Freezing of a spherical drop

General thermal conductivity

Heat conduction in a cooling fan

Heat flux distribution in a wall

Heat loss by free convection from a horizontal pipe

Heat released during in-situ combustion given by Burger & Sahuquet

Heat transfer coefficient for condensation - Pure vapors on solid surface

Heat transfer in packed bed

Heat transfer rate in laminar forced convection along heated flat plate

Jacoby aromaticity factor

Joule Thompson expansion

Latent heat of hydrocarbon mixture

Mixing fluids of different densities

Mole fraction of a component in liquid phase

Mole fraction of a component in vapor phase

Necessary inhibitor concentration required in liquid phase to reduce hydrate point

Peng Robinson characterization factor

Peng Robinson PVT equation

Pseudo-reduced conditions

Radiant heat transfer between disks

Radiated energy flux

Radiation across an annular gap

Radiation shields

Rayleigh number

Redlich-Kwong PVT equation

Reservoir gas density

Stefan-Boltzmann law

Surface temperature of a heating coil

Temperature due to free convection

Temperature increase due to forced convection

Temperature profile after viscous heat transfer

Temperature profile with a nuclear heat source

Thermal conductivity for pure metals

Thermal conductivity of polyatomic gases

Thermal conductivity of liquids

Thermal conductivity of solids with gas pockets

Thermal diffusivity

Thermal energy of a fissionable substance

Thermoelastic effect on stress

Unsteady evaporation of a liquid

Van Der Waals PVT equation

Wien displacement law

Absolute viscosity for Saybolt viscosimeter measurements

Absolute viscosity for Ubbelohde viscosimeter measurements

Adhesion tension

Amott-Harvey wettability index

Apparent facial tension (De Nouy ring method)

Average compressibility of oil

Average gas solubility

Characterization factor for oil distillation

Clasius-Clapeyron equation for water vapor

Clay concentration of drilling mud (methylene blue test)

Contact angle

Correction factor for facial tension (De Nouy ring method)

Drilling mud density (solid content analysis of drilling muds)

Effective porosity

Error percentage of porosity measurements

Facial tension (De Nouy ring method)

Filtration rate for API fluid loss measurement

Filtration volume without spurt loss

Filtration volume with spurt loss

Gas permeability measurement (lab measurement using Klinkenberg effect)

Kinematic viscosity for Saybolt viscosimeter measurements

Liquid permeability (permeameter lab measurement)

Permeability determination using porosity data (Kozeny-Carman equation)

Pycnometer volume correction

Relative centrifugal force

Relative permeability

Reservoir wettability characterization (rise in core method)

Resistance

Resistivity

Resistivity index-Archie's law

Solid content ratio of drilling mud

Specific gravity of air (upper phase) (De Nouy ring method)

Standard discharge time for Saybolt viscosimeter measurements

Total porosity

USBM wettability index

Yield of clays as drilling fluids

Areal extent of heated zone

Average reservoir temperature in a cyclical steam injection process

Bottomhole pressure in a static geothermal well

Chromatographic lag in polymer flooding

Cumulative heat injected for steam drive - Myhill and Stegemeier

Depth of carbon dioxide alteration front (Battlet-Gouedard, 2006)

Depth of carbon dioxide alteration front (Kutchko, 2008)

Dimensionless heat injection rate (Gringarten and Sauty)

Dimensionless injection rate of air for in-situ combustion

Dimensionless ratio of effective volumetric heat capacity of injected steam to that of the steam zone

Dimensionless time for semi-steady state flow in coal bed methane reservoirs

Dimensionless time in wet combustion by Kuo

Dykstra-Parsons coefficient

Effective (apparent) transmissivity

Effective oil transmissivity for thermal stimulation

Equivalent atomic H/C ratio of fuel for in-situ combustion

Equivalent volume of steam injected - Myhill and Stegemeier

Equivalent water saturation in burned zone in-situ combustion by Nelson

Estimates of cumulative oil displacement

Estimates of oil displacement rate

Estimating fraction of heat injected in latent form (steam-drive)

Estimating heat injection rate (steam-drive)

Estimating performance prediction of steam-drive reservoirs (cumulative oil produced)

Estimating recovery steam drive (volume of steam in reservoir)

Estimating steady-state five-spot injection rate (steam-drive)

Estimating volume of steam injection (steam-drive)

Fraction of heat injected in latent form - Myhill and Stegemeier

Fraction of injected heat remaining in reservoir

Fractional flow of water in hot floods dependent on temperature and saturation in hot water flood

Growth of steam-heated area - Marx-Langenheim

Heat loss over an incremental length of a well (two-phase flow)

Heat ratio of contents in a geothermal reservoir

Heat released during in-situ combustion - Burger & Sahuguet

Heat remaining in reservoir - Marx and Langenheim

Horizontal well breakthrough time in a bottom-water-drive reservoir

Ignition delay time in in-situ combustion

Injected air required to burn through unit bulk of reservoir for in-situ combustion by Nelson and McNiel

Mass of fuel burned per unit bulk reservoir volume combustion - Nelson and McNiel

Minimum air flux required for advance of fire front - Nelson and McNiel

Oil breakthrough newly swept zone

Oil recovery as a function of the fraction of oil displaced from heated zone

Oil solubilization factor

Oil volume at breakthrough by Craig, Geffen, and Morse

Oil-steam ratio - Marx and Langenheim

Proppant settlement in fracture

Rate of advancement of combustion front (in-situ combustion)

Rate of growth of heated zone in hot water heated reservoir

Rate of oxygen-reacted per unit mass of fuel

Relationship with real and dimensionless time in hot water floods

Reservoir flow for gas flow in a formation

Reservoir flow through the wellbore of a geothermal well

Saturation of layer under hot water flood

Slug size in polymer floods

Temperature increase with time during in-situ combustion process

Temperature of a producing geothermal well

Temperature of a single-phase liquid or gas injected geothermal well

Total heat loss of a geothermal well

Total oil production from in-situ combustion - Nelson and McNeil

Total oil production from wet in-situ combustion - Nelson and McNeil

Total water production from in-situ combustion - Nelson and McNeil

Volume of burned part of reservoir (in-situ combustion)

Volume of reservoir burnt by wet combustion

Volumetric heat capacity

Wet combustion design (in-situ combustion)

Axial stress around vertical wellbore

Axis of a deviated borehole from an arbitrary origin

Bulk modulus (using Lame)

Bulk modulus (using Poisson's ratio and Lame's constant)

Bulk modulus (using Poisson's ratio and shear modulus)

Change in pore volume due to initial water and rock expansion

Cohesive strength of rocks

Compressibility of a coalbed methane formation

Effect of pore pressure on stress

Effective stress on individual grains

Failure criteria (Mohr-Coulomb)

Formation compressibility by using hydrofrac data

Fracture conductivity

Fracture gradient (Eaton)

Fracture gradient (Holbrook)

Fracture gradient (Matthews and Kelly)

Fracture gradient (Zoback and Healy)

Fracture pressure (Hubert and Willis)

Fracture volume (GDK method)

Fracture volume (Perkins and Kern method)

Fracture width (GDK method)

Fracture width (Perkins and Kern method)

Hoek and Brown criteria for principal stress failure

Horizontal effective stress (assuming no lateral strain as per Lorenz and Teufel)

Horizontal maximum stress (Bredehoeft)

Induced fracture dip

Initial effective horizontal stress

Isothermal compressibility of limestones (Newman correlation)

Least principal stress as function of depth in Gulf of Mexico (Hubbert and Willis)

Least principal stress as function of depth in Gulf of Mexico (Matthew and Kelly)

Linearized Mohr failure line

Linearized Mohr coulomb criteria

M Modulus (using shear modulus and bulk modulus)

M Modulus (using Young's modulus and Poisson's ratio)

Maximum anisotropic failure stress

Maximum compression at vertical wellbore

Maximum normal stress in tangential direction at wellbore wall (hoop stress)

Maximum plane tangential stress acting on deviated wellbore (1)

Maximum principal stress failure (Hoek and Brown)

Maximum principal stress in normal faulting

Maximum principal stress in reverse faulting

Maximum principal stress in strike-slip faulting

Maximum principal stress calculation using breakout width

Minimum compression at vertical wellbore

Minimum normal stress in tangential direction at wellbore wall (hoop stress)

Maximum plane tangential stress acting on deviated wellbore (2)

Modified lade criterion

Normal stress in radial direction near wellbore

Normal stress in rock at failure

Normal stress in tangential direction at wellbore wall (hoop stress)

Normal stress in tangential direction near wellbore (hoop stress)

Pore pressure increase due to fluid activity (Mody and Hale)

Pore pressure increase due to given fluid activity contrast (Mody and Hale)

Pore pressure of shale (Flemings)

Pore pressure of shale (Traugott)

Porosity irreversible plastic deformation occurs

Pressure required to induce a tensile fracture (breakdown pressure)

Pressure to grow fractures (Abe, Mura, et al.)

Radial stress around vertical wellbore

Ratio of pore pressure change to original due to depletion

Rotation of maximum principal stress near wellbore

Rotation of maximum principal stress near wellbore (Zoback \ Day-Lewis)

Shale compaction

Shear modulus

Shear modulus from Young's modulus

Shear stress near vertical well

Slowness of the formation

Storativity of fractures

Stress at edge of wellbore breakout

Stress component near normal faulting in reservoir

Stress components in original coordinate system in depletion drive

Stress intensity at tip of mode I fracture

Stress path (induced normal faulting)

Stress path of reservoir with changes in production

Stress perturbation (Segall and Fitzgerald)

Subsidence due to uniform pore pressure reduction in free surfaces

Unconfined compressive strength of rock

Velocity of bulk compressional waves

Velocity of compression waves

Velocity of shear waves

Yield strength (Bingham plastic model)

Allowable gas velocity through gas separator

Allowable velocity in downcomer for tray type tower

Bed diameter of adsorption unit

Bed length of adsorption unit

Block efficiency factor

Bottom distillation column rate

Breakthrough time in an adsorption unit

Breathing loss of natural gas

Capacity coefficient of valves in gas processing

Column diameter of packed towers

Cooling of an ideal gas

Correction factor for foamless separation

Correlation factor for Benedict-Webb-Rubin equation

Critical pressure values for pressure in Van Der Waals equation

Downcomer velocity in tray type tower

Electrical heating of a pipe

Energy requirement of single-stage ideal compressor

Error in thermocouple temperature measurement

Eykman molecular refraction

Fenske's method for minimum theoretical plates

Gas capacity of separator

Gas mass velocity in an adsorption unit

Gas mass velocity in separator

Gas originally adsorbed

Gas pressure testing time for unsteady gas flow

Gravitational attraction of a layer (Bouguer correction)

Heating of a liquid in an agitated tank

Height of downcomer filling

Inhibitor injection rate required

Instrumentation noise control

Internal diameter of gas separator

Isostacy-Airy hypothesis

Lift coefficient

Mass of steel Shell in adsorption unit

Mass transfer zone length of adsorption unit

Modified Clapeyron criteria

Packed column actual height

Pan-Maddox equation for density

Pan-Maddox equation for molecular weight

Photoelectric effect

Power requirement for pumping a compressible flow fluid through a long pipe

Pressure criteria for separator by ASME (external radius)

Pressure criteria for separator by ASME (internal radius)

Pressure storage

Proportional band in pressure controller

Raoult's law in glycol dehydration unit

Refrigerator shaft speed

Relative humidity

Required oil length in separator

Required separator liquid section

Required water length in separator

Residence time of water in separator

Residence time oil in separator

Retention time in a liquid-liquid vessel

Safety relief valves sizing in vapor services

Steady-state temperature controller

Still column diameter in glycol dehydration unit

Stripping factor

Surface tension from density

Tarnishing of metal surfaces

TEG weight percent in glycol dehydration unit

Temperature after refrigeration

Temperature dependent source rate for flow reactor

Temperature distribution in a hot-wire anemometer

Terminal velocity in a separator

Thickness criteria of spherical shells in separator (ASME)

Top distillation column rate

Vapor mass velocity of tray type tower

Wall thickness criteria for separator by ASME (external radius)

Wall thickness criteria for separator by ASME (internal radius)

Water loading in adsorption unit

Weight of rich TEG in glycol dehydration unit

Wobbe index

Work done by expansion tube refrigerator

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