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Dynamic Liquid Measurement Calculations

Scott Tanner Flow-Cal, Inc.

Chapter 12 - Calculation of Petroleum Quantities

• Section 1 – Calculation of Static Petroleum Quantities

• Section 2 – Calculation of Petroleum Quantities Using Dynamic Measurement Methods and Volumetric Correction Factors

• Section 3 – Calculation of Volumetric Shrinkage from Blending Light Hydrocarbons with Crude Oil

Chapter 12.2 Organization

• Part 1 – Introduction • Part 2 – Measurement Tickets • Part 3 – Proving Reports • Part 4 – Calculation of Base Prover

Volumes by the Waterdraw Method • Part 5 – Calculation of Base Prover

Volume by Master Meter Method

Chapter 12.2.x Applicable Liquids

• Hydrocarbon Liquids • Which are Considered to be Clean • Single-Phase • Homogeneous • Newtonian at Metering Conditions

Chapter 12.2.x Density Types

• Base or Standard Condition • Observed Condition • Alternate Conditions

Distinction Between “Base” and “Standard” Condition

• “Base” or “Standard” Condition – is a defined temperature and pressure at which liquid volumes are corrected for custody transfer purposes. – The terms Base and Standard are used

interchangeably.

Chapter 12.2.x Base Conditions • United States Customary (USC) Units:

– Temperature (Tb): 60.0°F (15.56°C) – Pressure (Pb): 14.696 psia (101.325 kPaa)

• International System (SI) Units: – Temperature (Tb): 15.0°C (59.0°F) or 20.0°C (68.0°F) – Pressure (Pb): 101.325 kPaa (14.696 psia)

• For Liquids with an Equilibrium Vapor Pressure (EVP) > Base Pressure (Pb), the (Pb) shall be the EVP at Base Temperature (Tb)

Distinction Between “Observed,” and “Alternate” Conditions

• “Observed” Condition – is the temperature and

pressure at which the density of a liquid is actually measured – Density Meter or Hydrometer Condition

• “Alternate” Conditions – are any other temperature and pressure conditions to which the observed or standard density can be corrected – Metering or Tank Condition

Commodity Types • A = Crude Oil • B = Refine Product • C = Special Application • D = Lubricating Oil

API Chapter 11.1 uses Three Distinct “Calculation Types”

• Type 1. Starts with “Base” density and corrects it to an alternate temperature and pressure condition using CTL & CPL – Procedures:

• 11.1.6.1 (USC) & 11.1.7.1 (SI) – Functions:

• densA11161API & densA1161RelDens • ctplB11161API & ctplB11161RelDens • fpC11161API & fpC11161RelDens • densD11171kPa & densD1171Bar • ctplA11171kPa & ctplA11171Bar • fpB11171kPa & fpB11171Bar


• Type 2. Starts with “Observed” density at its temperature & pressure and corrects it to base condition using CTL & CPL – Procedures:

• 11.1.6.2 (USC) & 11.1.7.2 (SI) – Functions:

• densB11162API & densB1162RelDens • ctplC11162API & ctplC11162RelDens • fpD11162API & fpD11162RelDens • densA11172kPa & densA1172Bar • ctplB11172kPa & ctplB11172Bar • fpC11172kPa & fpC11172Bar


• Type 3. Starts with “Observed” density at its temperature & pressure and corrects it to an “Alternate” temperature & pressure condition Procedures:

• 11.1.6.3 (USC) & 11.1.7.3 (SI) – Functions:

• densA11162API > ctplA11161API • densB11162RelDens > ctplB11161RelDens • dens1C1162API > fpC11161API • densD11172kPa > ctplD11171kPa • densA11172Bar > ctplA11171Bar • densC11172kPa > fpC11161kPa

Chapter 12.2.x Step 1 – Determine Base Density (RHOb)

• Use an API 11.1 – Type 2 Density Calculation – API 11.1 Procedure 11.1.6.2 for USC Unit – API 11.1 Procedure 11.1.7.2 for SI Units

• Enter “Observed” density at its observed temperature and pressure – RHOobs (XXX.x °API, X.xxx5 RD or XXXX.5 kg/m3) – Tobs ( XXX.x °F or XX.x5 °C) – Pobs (XXXX.0 psig or XX.xxx bar or XXXX.0 kPa) – Tb (15.0 or 20.0°C for SI Units only)

Determine Base Density (RHOb)

Chapter 12.2.x Step 2 – Are the Meter Readings Temperature Compensated?

• If “Yes” Go To Step 3a • If “No” Go To Step 3b

Chapter 12.2.x Step 3a – Determine Temperature Correction Factor (CTL) • Set CTL = 1.0000

Chapter 12.2.x Step 3b – Determine Temperature Correction Factor (CTL) • Use an API 11.1 – Type 1 Calculation

– API 11.1 Procedure 11.1.6.1 for USC Unit – API 11.1 Procedure 11.1.7.1 for SI Units

• Enter the base density at the meter’s flow weighted temperature and pressure – RHOb (XXX.x °API, X.xxxx RD or XXXX.x

kg/m3) from Step 1 – TWA ( XXX.x °F or XX.x5 °C) – PWA (XXXX.0 psig or XX.xxx bar or XXXX.0

kPa) – Tb (15.0 or 20.0°C for SI Units only)

Determine CTL

Chapter 12.2.x Step 4 – Are Meter Readings Pressure Compensated?

• If “Yes” – Step 5a • If “No” – Step 5b & 5c

Chapter 12.2.x Step 5a – Determine Pressure Correction Factor (CPL)

• Set CPL = 1.0000

Chapter 12.2.x Step 5b – Determine Scaled Compressibility Factor (Fp)

• Use an API 11.1 – Type 1 calculation – API 11.1 Procedure 11.1.6.1 for USC Unit – API 11.1 Procedure 11.1.7.1 for SI Units

• Enter the base density at the meter’s flow weighted temperature and pressure – RHOb (XXX.x °API, X.xxxx RD or XXXX.x kg/m3) – TWA ( XXX.x °F or XX.x5 °C) – PWA (XXXX.0 psig or XX.xxx bar or XXXX.0 kPa) – Tb (15.0 or 20.0°C for SI Units only)

Step 5b – Determine F

Where: • ρ = Base Density • T = Flow Weighted Temperature

( )2

79320.0 2326.0*exp 1.9947 0.00013427

TF

ρ

+ = − + +

Determine Fp

Chapter 12.2.x Step 5c – Determine CPL

• Use an API 11.1 – Type 1 calculation – API 11.1 Procedure 11.1.6.1 for USC Unit – API 11.1 Procedure 11.1.7.1 for SI Units

• Enter the base density at the meter’s flow weighted temperature and pressure – RHOb (XXX.x °API, X.xxxx RD or XXXX.x kg/m3) – TWA ( XXX.x °F or XX.x5 °C) from Step 1 – PWA (XXXX.0 psig or XX.xxx bar or XXXX.0 kPa) – Tb (15.0 or 20.0°C for SI Units only)

Step 5c – Determine CPL

Where: • F = Scaled Compressibility Factor • PWA = Flow Weighted Pressure • Pe = Equilibrium Vapor Pressure

( )5

11 10 * * e

CPLF PWA P−=

− −

Determine CPL

Chapter 12.2.x Step 6 – Determine Combined Correction Factor (CCF)

• CCF = (CTL) * (CPL) * (MF) X.xxxx – If a Meter Factor (MF) is Used

• CCF = (CTL) * (1.0000) * (CMF) X.xxxx – If a Composite Meter Factor (CMF) is Used

• CCF = (CTL) * (CPL) * (1.0000) X.xxxx – If an “Actual” K-Factor (KF) is used

• CCF = (CTL) * (1.0000) * (1.0000) X.xxxx – If a Composite K-Factor (CKF) is used

Determine CCF

Chapter 12.2.x Step 7 – Determine Indicated Volume (IV)

• IV = MRc – MRo – Barrels & Gallons = XXX.xx – Cubic Meter = XXX.xxx – Liter = XXX.0

where: – IV = Indicated Volume – MRc = Meter Reading Closed – MRo = Meter Reading Opened

Determine Indicated Volume (IV)

Chapter 12.2.x Step 8 – Determine Gross Standard Volume (GSV)

• GSV = IV * CCF – Barrels & Gallons = XXX.xx – Cubic Meter = XXX.xxx – Liter = XXX.0

where: – GSV = Gross Standard Volume – IV = Indicated Volume – (Step 7) – CCF = Combined Correction Factor – (Step 6)

Determine GSV

Chapter 12.2.x Step 9 – Determine Sediment & Water Correction Factor

where: – CSW = Correction for Sediment and Water – %S&W = Sediment and Water Percent

1 (% & /100)CSW S W= −

Determine CSW

Chapter 12.2.x Step 10 – Determine Net Standard Volume (NSV)

• NSV = GSV * CSW – Barrels & Gallons = XXX.xx – Cubic Meter = XXX.xxx – Liter = XXX.0

where: – NSV = Net Standard Volume – GSV = Gross Standard Volume – (Step 8) – CSW = Sediment & Water Correction Factor – (Step 9)

Determine NSV

Chapter 12.2.x Step 11 – Determine Sediment & Water Volume (SWV)

• SWV = GSV - NSW – Barrels & Gallons = XXX.xx – Cubic Meter = XXX.xxx – Liter = XXX.0

where: – SWV = Sediment and Water Volume – NSV = Net Standard Volume (Step 10) – GSV = Gross Standard Volume – (Step 8)

Determine SWV