Measures Reference

A measure is the physical dimension of a value: a pressure, a rate, a permeability. Every numeric value handled by KAPPA-Automate (a data channel, a well property, a plot axis) has a measure, and the measure decides which units that value can be expressed in. The SDK exposes the measures as kappa_sdk.MeasureEnum values, and the units accepted by each measure are listed in the Units Reference.

Internal units

Values are read from and written to KAPPA-Automate in the internal unit of their measure, whatever the unit system of the field. The internal unit of a measure is the unit that converts with a = 1 and b = 0 (see Units Reference).

Warning

Internal units are close to SI units but not exactly SI: time is in hours, not seconds. Always check the Internal unit column of the table below rather than assuming the SI unit.

For instance, a pressure is internally in Pascals, a temperature in Kelvin, a surface rate in standard cubic meters per second, an elapsed time in hours.

To work in another unit, either pass the unit parameter that most read/write methods accept (kappa_sdk.Data.read(), kappa_sdk.Data.append(), kappa_sdk.WellPropertyContainer.get_well_property_values(), …) or convert explicitly with the Unit Converter.

Unit systems

A unit system maps each measure to the unit it is displayed in. KAPPA-Automate ships four of them – SI, Oil Field, Hydro and French – and additional ones can be defined from the KAPPA-Automate web interface. A field is bound to a unit system at creation time, through the unit_system_name parameter of kappa_sdk.Connection.create_field().

Note

A unit system only drives what the user interface displays. It never changes the unit of the values exchanged through the SDK, which are always the internal units.

Available measures

The table below lists the measures of a stock KAPPA-Automate catalog, with their internal unit and the unit each shipped unit system displays them in.

• Measure id is the identifier used by the REST API, and the string to use where a measure can be given as a raw string (the measure of a kappa_sdk.DataType, for instance).

• MeasureEnum is the matching SDK member. Every measure of the shipped catalog has one; a measure created on your own instance has none, in which case pass the measure id string where a kappa_sdk.MeasureEnum is expected.

• Units is the number of units the measure accepts, all listed in the Units Reference.

• Composed marks a measure built from other measures, such as Pressure/Time. Composed measures can also be created by users, so your instance may expose more of them than this table.

• Internal unit shows several units when they coincide – a difference of 1 K is a difference of 1 °C, so both are internal units of the DeltaTemperature measure.

Measure	Measure id	MeasureEnum	Internal unit	Units	Composed	SI	Oil Field	Hydro	French
[Pressure**4.Temperature**8]/Time	[Pressure**4.Temperature**8]/Time	MeasureEnum._pressure__4_temperature__8_time	[Pa**4.K**8]/hr	3	yes	[Pa**4.K**8]/hr	[psia**4.°R**8]/hr	[bara**4.K**8]/hr	[bara**4.K**8]/hr
A.√k	AreaPermeabilitySquareRoot	MeasureEnum.a_sqrt_k	m³	5		m³	ft².√md	m³	m³
Absolute Roughness	RoughnessAbsolute	MeasureEnum.absolute_roughness	m	7		m	in	cm	m
Acoustic impedance	AcousticImpedance	MeasureEnum.acoustic_impedance	Mrayls	1		Mrayls	Mrayls	Mrayls	Mrayls
Acoustic noise	AcousticNoise	MeasureEnum.acoustic_noise	dB / n / n.u.	3		n.u.	n.u.	n.u.	n.u.
Angle	Angle	MeasureEnum.angle	radian	2		radian	°	°	°
Angle/Depth	Angle/Depth	MeasureEnum.angle_depth	radian/m	3	yes	radian/m	°/ft	°/m	°/m
Angle/Time	Angle/Time	MeasureEnum.angle_time	radian/hr	2	yes	radian/hr	°/hr	°/hr	°/hr
Angle/Time²	Angle/Time²	MeasureEnum.angle_time__2	radian/hr²	2	yes	radian/hr²	°/hr²	°/hr²	°/hr²
Area	Area	MeasureEnum.area	m²	5		m²	acre	m²	m²
Attenuation	Attenuation	MeasureEnum.attenuation	dB/m	2		dB/m	dB/ft	dB/m	dB/m
Capacitance	Capacitance	MeasureEnum.capacitance	cps / Norm / Hz	5		cps	cps	cps	cps
Capture cross section	CaptureCrossSection	MeasureEnum.capture_cross_section	c.u.	1		c.u.	c.u.	c.u.	c.u.
Compressibility	Compressibility	MeasureEnum.compressibility	Pa⁻¹	8		Pa⁻¹	psi⁻¹	bar⁻¹	bar⁻¹
Critical volume	CriticalVolume	MeasureEnum.critical_volume	m³/mol	4		m³/mol	ft³/lb-mol	l/mol	l/mol
Current	Current	MeasureEnum.current	A	3		A	A	A	A
Density	Density	MeasureEnum.density	kg/m³	4		kg/m³	g/cc	g/cc	kg/m³
Density/Time	Density/Time	MeasureEnum.density_time	[kg/m³]/hr	2	yes	[kg/m³]/hr	[g/cc]/hr	[g/cc]/hr	[kg/m³]/hr
Depth	Depth	MeasureEnum.depth	m	4		m	ft	m	m
File size	FileSize	MeasureEnum.file_size	Byte	4		MB	MB	MB	MB
Force	Force	MeasureEnum.force	N	7		N	lb	N	N
Frequency	Frequency	MeasureEnum.frequency	1/s / cps / Hz	6		Hz	Hz	Hz	Hz
Gamma ray	GammaRay	MeasureEnum.gamma_ray	cps	2		cps	GAPI	GAPI	GAPI
Gas liquid ratio	GasLiquidRatio	MeasureEnum.gas_liquid_ratio	stm³/stm³	3		stm³/stm³	scf/stb	stm³/stm³	stm³/stm³
Gas liquid ratio 2	GasLiquidRatio2	MeasureEnum.gas_liquid_ratio_2	stm³/m³	3		stm³/m³	scf/b	stm³/m³	stm³/m³
Gas mass rate	MassRateGas	MeasureEnum.gas_mass_rate	kg/sec	13		kg/sec	lb/sec	kg/sec	kg/sec
Gas potential	GasPotential	MeasureEnum.gas_potential	Pa/sec	7		Pa/sec	psi²/cp	Pa/sec	Pa/sec
Gas productivity index	GasProductivityIndex	MeasureEnum.gas_productivity_index	m³/s/Pa	8		m³/s/Pa	Mscf/D/psi	m³/D/bar	m³/D/bar
Gas rate	GasRateSurface	MeasureEnum.gas_rate	stm³/sec	16		stm³/sec	Mscf/D	l/min	stm³/D
Gas rate downhole	GasRateDownhole	MeasureEnum.gas_rate_downhole	m³/sec	17		m³/sec	Mcf/D	l/min	m³/D
Gas rate/Pressure	Gas rate/Pressure	MeasureEnum.gas_rate_pressure	[stm³/sec]/Pa	4	yes	[stm³/sec]/Pa	[Mscf/D]/psia	[l/min]/bara	[stm³/D]/bara
Gas volume	GasVolumeSurface	MeasureEnum.gas_volume	stm³	9		stm³	Mscf	stm³	stm³
Gas volume downhole	GasVolumeDownhole	MeasureEnum.gas_volume_downhole	m³	13		m³	Mcf	m³	m³
Heat Capacity	HeatCapacity	MeasureEnum.heat_capacity	J/kg/°C	7		J/kg/°C	Btu/lbm/°F	J/kg/°C	J/kg/°C
Heat transfer coefficient	HeatTransfertCoef	MeasureEnum.heat_transfer_coefficient	W/m²/°C	3		W/m²/°C	Btu/D/ft²/°F	Cal/s/m²/°C	Cal/s/m²/°C
Interfacial tension	InterfacialTension	MeasureEnum.interfacial_tension	N/m	4		N/m	dyn/cm	N/m	N/m
Internal diameter	InternalDiameter	MeasureEnum.internal_diameter	m	5		m	in	cm	m
Inverse gas productivity index	InverseGasProductivityIndex	MeasureEnum.inverse_gas_productivity_index	Pa/m³/s	8		Pa/m³/s	psi/Mscf/D	bar/m³/D	bar/m³/D
Inverse length	InverseLength	MeasureEnum.inverse_length	1/m	7		1/m	1/ft	1/m	1/m
Inverse liquid productivity index	InverseLiquidProductivityIndex	MeasureEnum.inverse_liquid_productivity_index	Pa/m³/s	6		Pa/m³/s	psi/stb/D	bar/m³/D	bar/m³/D
Inverse pressure	InversePressure	MeasureEnum.inverse_pressure	1/Pa	8		1/Pa	1/psia	1/bara	1/bara
Inverse rate downhole	InverseRateDownhole	MeasureEnum.inverse_rate_downhole	sec/m³	18		sec/m³	D/STDB	min/l	D/m³
Inverse rate surface	InverseRateSurface	MeasureEnum.inverse_rate_surface	sec/m³	18		sec/m³	D/STDB	min/l	D/m³
Inverse time	InverseTime	MeasureEnum.inverse_time	1/hr	7		1/hr	1/hr	1/hr	1/hr
k.Xmf²	PermeabilityLengthSquare	MeasureEnum.k_xmf__2	m⁴	5		m⁴	md.ft²	m⁴	m⁴
Large distance	LargeDistance	MeasureEnum.large_distance	m	4		m	ft	m	m
Large gas volume	LargeGasVolumeSurface	MeasureEnum.large_gas_volume	stm³	8		MMstm³	bscf	MMstm³	MMstm³
Large gas volume downhole	LargeGasVolumeDownhole	MeasureEnum.large_gas_volume_downhole	m³	8		MMm³	bcf	MMm³	MMm³
Large liquid volume	LargeLiquidVolumeSurface	MeasureEnum.large_liquid_volume	stm³	6		MMstm³	MMstb	MMstm³	MMstm³
Large liquid volume downhole	LargeLiquidVolumeDownhole	MeasureEnum.large_liquid_volume_downhole	m³	6		MMm³	MMB	MMm³	MMm³
Large time	LargeTime	MeasureEnum.large_time	hr	7		day	day	day	day
Large volume	LargeVolumeSurface	MeasureEnum.large_volume	stm³	10		MMstm³	bscf	MMstm³	MMstm³
Large volume downhole	LargeVolumeDownhole	MeasureEnum.large_volume_downhole	m³	10		MMm³	bcf	MMm³	MMm³
Latitude	Latitude	MeasureEnum.latitude	°	1		°	°	°	°
Length	Length	MeasureEnum.length	m	7		m	ft	m	m
Liquid gas ratio	LiquidGasRatio	MeasureEnum.liquid_gas_ratio	stm³/stm³	4		stm³/stm³	stb/MMscf	stm³/stm³	stm³/stm³
Liquid gravity	LiquidGravity	MeasureEnum.liquid_gravity	sp. gr.	3		sp. gr.	sp. gr.	sp. gr.	sp. gr.
Liquid mass rate	MassRateLiquid	MeasureEnum.liquid_mass_rate	kg/sec	13		kg/sec	lb/sec	kg/sec	kg/sec
Liquid productivity index	LiquidProductivityIndex	MeasureEnum.liquid_productivity_index	m³/s/Pa	9		m³/s/Pa	stb/D/psi	m³/D/bar	m³/D/bar
Liquid rate	LiquidRateSurface	MeasureEnum.liquid_rate	stm³/sec	15		stm³/sec	stb/D	l/min	stm³/D
Liquid rate downhole	LiquidRateDownhole	MeasureEnum.liquid_rate_downhole	m³/sec	17		m³/sec	B/D	l/min	m³/D
Liquid rate/[Pressure**0.5]	Liquid rate/[Pressure**0.5]	MeasureEnum.liquid_rate__pressure__0_5	[stm³/sec]/[Pa**0.5]	4	yes	[stm³/sec]/[Pa**0.5]	[stb/D]/[psia**0.5]	[l/min]/[bara**0.5]	[stm³/D]/[bara**0.5]
Liquid volume	LiquidVolumeSurface	MeasureEnum.liquid_volume	stm³	8		stm³	stb	stm³	stm³
Liquid volume downhole	LiquidVolumeDownhole	MeasureEnum.liquid_volume_downhole	m³	13		m³	barrels	m³	m³
Logical	Logical	MeasureEnum.logical	Identity	1		Identity	Identity	Identity	Identity
Longitude	Longitude	MeasureEnum.longitude	°	1		°	°	°	°
Margins	Margins	MeasureEnum.margins	m	8		cm	cm	cm	cm
Mass	Mass	MeasureEnum.mass	kg	6		kg	kg	kg	kg
Mass rate	MassRate	MeasureEnum.mass_rate	kg/sec	13		kg/sec	lb/sec	kg/sec	kg/sec
Mass/Length	Mass/Length	MeasureEnum.mass_length	kg/m	2	yes	kg/m	kg/ft	kg/m	kg/m
Mobility	Mobility	MeasureEnum.mobility	m²/Pa.s	10		m²/Pa.s	md/cp	m²/cp	m²/cp
Molar weight	MolarWeight	MeasureEnum.molar_weight	kg/mol	3		kg/mol	lb/lb-mol	g/mol	g/mol
Motor speed	MotorSpeed	MeasureEnum.motor_speed	rps	3		rpm	rpm	rpm	rpm
No unit	NoUnit	MeasureEnum.no_unit	Identity	1		Identity	Identity	Identity	Identity
Noise	Noise	MeasureEnum.noise	n.u.	1		n.u.	n.u.	n.u.	n.u.
Parachor	Parachor	MeasureEnum.parachor	(N/m)^¼·m³/mol	2		(N/m)^¼·m³/mol	(dyn/cm)^¼·cm³/mol	(dyn/cm)^¼·cm³/mol	(dyn/cm)^¼·cm³/mol
Perm thickness product	PermeabilityThicknessProduct	MeasureEnum.perm_thickness_product	m³	3		m³	md.ft	m³	m³
Permeability	Permeability	MeasureEnum.permeability	m²	5		m²	md	m²	m²
Permeability hydro	PermeabilityHydro	MeasureEnum.permeability_hydro	m/s	2		m/s	m/s	m/s	m/s
Pipe weight	PipeWeight	MeasureEnum.pipe_weight	kg/m	5		kg/m	lb/ft	kg/m	daN/m
Power	Power	MeasureEnum.power	W	9		W	Hp	W	W
Power per length	PowerPerLength	MeasureEnum.power_per_length	W/m	7		W/m	Btu/s/ft	W/m	W/m
Pressure	Pressure	MeasureEnum.pressure	Pa	13		Pa	psia	bara	bara
Pressure derivative	PressureDerivative	MeasureEnum.pressure_derivative	Pa/hr	5		Pa/hr	psi/hr	bar/hr	bar/hr
Pressure difference	DeltaPressure	MeasureEnum.pressure_difference	Pa	9		Pa	psi	bar	bar
Pressure gradient	PressureGradient	MeasureEnum.pressure_gradient	Pa/m	9		Pa/m	psi/ft	Pa/m	Pa/m
Pressure.Temperature	Pressure.Temperature	MeasureEnum.pressure_temperature	Pa.K	3		Pa.K	psia.°R	bara.K	bara.K
Pressure/Area	Pressure/Area	MeasureEnum.pressure_area	Pa/m²	4	yes	Pa/m²	psia/acre	bara/m²	bara/m²
Pressure/Current	Pressure/Current	MeasureEnum.pressure_current	Pa/A	3	yes	Pa/A	psia/A	bara/A	bara/A
Pressure/Density	Pressure/Density	MeasureEnum.pressure_density	Pa/[kg/m³]	4	yes	Pa/[kg/m³]	psia/[g/cc]	bara/[g/cc]	bara/[kg/m³]
Pressure/Depth	Pressure/Depth	MeasureEnum.pressure_depth	Pa/m	3	yes	Pa/m	psia/ft	bara/m	bara/m
Pressure/Time	Pressure/Time	MeasureEnum.pressure_time	Pa/hr	3	yes	Pa/hr	psia/hr	bara/hr	bara/hr
Pressure/Time²	Pressure/Time²	MeasureEnum.pressure_time__2	Pa/hr²	3	yes	Pa/hr²	psia/hr²	bara/hr²	bara/hr²
Pressure/Time³	Pressure/Time³	MeasureEnum.pressure_time__3	Pa/hr³	3	yes	Pa/hr³	psia/hr³	bara/hr³	bara/hr³
Pressure².Temperature**4	Pressure².Temperature**4	MeasureEnum.pressure__2_temperature__4	Pa².K**4	4	yes	Pa².K**4	psia².°R**4	bara².K**4	bara².K**4
Pressure³.Temperature**5	Pressure³.Temperature**5	MeasureEnum.pressure__3_temperature__5	Pa³.K**5	4	yes	Pa³.K**5	psia³.°R**5	bara³.K**5	bara³.K**5
Productivity index	ProductivityIndex	MeasureEnum.productivity_index	m³/s/Pa	6		m³/s/Pa	B/D/psi	m³/s/Pa	m³/D/bar
Ratio	PercentOrFraction	MeasureEnum.ratio	Fraction	2		Fraction	Fraction	Fraction	Fraction
Reservoir to SC Gas Volume Ratio	ReservoirToScGas	MeasureEnum.reservoir_to_s_c_gas_volume_ratio	m³/stm³ / cf/scf	4		m³/stm³	cf/scf	cf/scf	m³/stm³
Reservoir to SC Liquid Volume Ratio	ReservoirToScLiquid	MeasureEnum.reservoir_to_s_c_liquid_volume_ratio	m³/stm³ / rb/stb	3		m³/stm³	rb/stb	rb/stb	m³/stm³
Resistance	Resistance	MeasureEnum.resistance	Ohm	3		Ohm	Ohm	Ohm	Ohm
Resistivity	Resistivity	MeasureEnum.resistivity	Ohm.m	1		Ohm.m	Ohm.m	Ohm.m	Ohm.m
Roughness	Roughness	MeasureEnum.roughness	Identity	1		Identity	Identity	Identity	Identity
Salinity	Salinity	MeasureEnum.salinity	ppm	2		ppm	ppm	ppm	ppm
Slowness	Slowness	MeasureEnum.slowness	s/m	15		ms/cm	µs/ft	ms/cm	ms/cm
Specific enthalpy	SpecificEnthalpy	MeasureEnum.specific_enthalpy	J/kg	3		J/kg	Btu/lbm	Cal/g	Cal/g
Spinner	Spinner	MeasureEnum.spinner	rps	3		rps	rps	rps	rps
Square root of time	SquareRootTime	MeasureEnum.square_root_of_time	√(hr)	7		√(hr)	√(hr)	√(hr)	√(hr)
Storage	Storage	MeasureEnum.storage	m³/Pa	8		m³/Pa	stb/psi	m³/Pa	m³/bar
Strain rate	StrainRate	MeasureEnum.strain_rate	1/s	2		nm/m/s	nm/m/s	nm/m/s	nm/m/s
Temperature	Temperature	MeasureEnum.temperature	K	4		K	°F	°C	°C
Temperature difference	DeltaTemperature	MeasureEnum.temperature_difference	K / °C	4		°C	°R	K	K
Temperature gradient	TemperatureGradient	MeasureEnum.temperature_gradient	°C/m	8		°C/m	°F/ft	°C/m	°C/m
Thermal Conductivity	ThermalConductivity	MeasureEnum.thermal_conductivity	W/m/°C	3		W/m/°C	Btu/D/ft/°F	Cal/s/m/°C	Cal/s/m/°C
Time	Time	MeasureEnum.time	hr	8		hr	hr	hr	hr
Total rate	TotalRateSurface	MeasureEnum.total_rate	stm³/sec	18		stm³/sec	stb/D	l/min	stm³/D
Total rate downhole	TotalRateDownhole	MeasureEnum.total_rate_downhole	m³/sec	17		m³/sec	B/D	l/min	m³/D
Transmissibility	Transmissibility	MeasureEnum.transmissibility	m³/Pa.sec	4		m³/Pa.sec	md.ft/cp	m³/Pa.sec	m³/Pa.sec
Transmissivity Hydro	TransmissivityHydro	MeasureEnum.transmissivity_hydro	m²/s	2		m²/s	m²/s	m²/s	m²/s
Velocity	Velocity	MeasureEnum.velocity	m/sec	9		m/sec	ft/min	m/min	m/min
Viscosity	Viscosity	MeasureEnum.viscosity	Pa.sec	3		Pa.sec	cp	cp	cp
Voltage	Voltage	MeasureEnum.voltage	v	2		v	v	v	v
Volume	VolumeSurface	MeasureEnum.volume	stm³	12		stm³	stb	stm³	stm³
Volume downhole	VolumeDownhole	MeasureEnum.volume_downhole	m³	13		m³	barrels	m³	m³

Reading the catalog from the REST API

Measures, units and unit systems all come from a single endpoint, GET /v3/field/unitSystems, which the SDK calls once per kappa_sdk.Connection to build its kappa_sdk.UnitConverter:

https://your-ka-instance.com/v3/field/unitSystems

Its response has three sections:

{
  "unitSystems": [
    {
      "id": "585745ca-0391-42ba-80d1-28be03059316",
      "wellKnownUnitSystem": "SI",
      "name": "SI",
      "measures": [
        { "id": "Pressure", "unit": "PressurePascalUnit" },
        { "id": "Temperature", "unit": "TempKelvinDegUnit" }
      ]
    }
  ],
  "userMeasures": [
    {
      "id": "Pressure",
      "name": "Pressure",
      "isDelta": false,
      "units": ["PressurePascalUnit", "PressureBarUnit", "PressurePsiaUnit"]
    }
  ],
  "units": [
    {
      "id": "PressureBarUnit",
      "isNonLinear": false,
      "name": "bara",
      "longName": "Bar absolute",
      "a": 100000,
      "b": 0
    }
  ]
}

unitSystems

One entry per unit system. wellKnownUnitSystem is SI, OilField, Hydro, French or Custom for a user-defined system; measures gives the unit displayed for every measure of the catalog. Only the four well-known systems are documented here, since custom systems are specific to an instance.

userMeasures

One entry per measure, despite the name: these are the measures of the catalog, built-in ones included. id is the measure id, name its display name, units the ids of the units it accepts, and isDelta tells whether the measure expresses a difference rather than an absolute value. Delta measures (DeltaPressure, DeltaTemperature) have their own units, identical to the absolute ones but without the offset: TempCelsiusDegUnit has b = 273.15 while DeltaTempCelsiusDegUnit has b = 0.

units

One entry per unit, with the conversion coefficients described in the Units Reference. The same unit can be shared by several measures – LengthMeterUnit serves Length, Depth and Absolute Roughness.

Note

The SDK does not expose this catalog as a public object; it is only used internally to build the kappa_sdk.UnitConverter. Call the endpoint directly to get the exact catalog of an instance, including its user-defined measures and unit systems.