P RINCIPALES AMBIENTES DEL SISTEMA E STEROS DE F ARRAPOS

The volume of a product depends on pressure and temperature. The volume correction factor is the ratio of a unit volume at base pressure and temperature to a unit volume at the flowing pressure and temperature at the time of measurement. There are several volume correction factors depending on the product density, because the volume cor- rection factor varies with the product density and there is no universal equation to determine the factor. The volume correction method and applicable standards are for different products are described further in this section.

The petroleum industry has developed standardized calculation methods for deter- mining petroleum volumes at reference conditions which are expressed in the follow- ing API and ISO standards:

API MPMS Chapter 12.2.1

· — Calculation of Petroleum Quantities Using Dynamic Measurement Methods and Volume Correction Factors, Part 1 — Introduction

ISO 4267-2:1988

· — Petroleum and liquid petroleum products — Calculation of oil quantities — Part 2: Dynamic measurement

The reference (base) conditions for the measurement of liquids having a vapor pressure equal to or less than atmospheric at base temperature are as follows:

United States Customary (USC) Units: Temperature — 60.0°F

Pressure —14.696 psia International System (SI) Units: Temperature — 15.0°C Pressure — 101.325 kPa

For liquids having a vapor pressure greater than atmospheric at base temperature, the base pressure shall be the equilibrium vapor pressure at base temperature.

Base pressure and temperature can be different for different countries.

7.5.7 General Equations for Determining Liquid Volumes at

Base Conditions

Indicated Volume

IV = closing meter reading − opening meter reading or

IV = (closing pulses − opening pulses)/KF Gross Standard Volume

GSV = IV ´ CTL ´ CPL ´ MF or; GSV = IV ´ MF ´ DENobs/DENb or;

GSV = Mass/DENb Net Standard Volume

CSW = 1 — (%S&W/100) NSV = GSV ´ CSW ´ SF where

CPL — Correction for the effect of Pressure on Liquid — Correction for compress-

ibility of liquid at normal operating conditions. This factor is obtained from API MPMS or ISO Standards identified below.

CTL — Correction for the effect of Temperature on Liquid — Correction for effect

of temperature on liquid at normal operating conditions. This factor is obtained from API MPMS or ISO Standards identified below.

CSW — Correction for Sediment and Water — Correction for sediment and water

to adjust the gross standard volume of the liquid for these non-merchantable items.

DENb-Base Density — Liquid density at base pressure and temperature. DENobs — Observed Density — Liquid density at observed pressure and temperature. GSV — Gross Standard Volume — The volume at base conditions corrected also

for the meter’s performance (MF or CMF).

IV — Indicated Volume — The change in meter reading that occurs during a re-

ceipt or delivery.

KF — K-factor — A term in pulses per unit volume determined during a factory

or field proving. The number of pulses generated by a linear meter divided by the K-factor will determine the indicated volume.

MF — Meter Factor — A dimensionless term obtained by dividing the volume

of the liquid passed through the prover corrected to standard conditions during proving.

NSV — Net Standard Volume — The gross standard volume corrected for non-

merchantable quantities such as sediment and water. Pressure and Temperature Compensation

CTL and CPL must be calculated in accordance with the current Standards shown

below for the applicable density and temperature range.

API MPMS Chapter 11.1 — Temperature and Pressure Volume Correction Factors ·

for Generalized Crude Oils, Refined Products, and Lubricating Oils — provides the algorithm and implementation procedure for the correction of temperature and pressure effects on density and volume of liquid hydrocarbons which fall within the categories of crude oil, refined products, or lubricating oils; NGLs and LPGs are excluded from consideration in this Standard.

API MPMS Chapter 11.2.2 — Compressibility Factors for Hydrocarbons: ·

0.350–0.637 Relative Density (60 °F/60 °F) and –50 °F to 140 °F Metering Temperature — provides tables to correct hydrocarbon volumes metered under pressure for the metered temperature. Contains compressibility factors related to the meter temperature and relative density (60 °F/60 °F) of the metered ma- terial. 2nd Edition October 1986 Reaffirmed: December 1, 2007

API MPMS Chapter 11.2.2M — Compressibility Factors for Hydrocarbons: ·

350–637 Kilograms per Cubic Meter Density (15 °C) and –46 °C to 60 °C Metering Temperature — Provides tables to correct hydrocarbon volumes me- tered under pressure to corresponding volumes at equilibrium pressure for the metered temperature. The standard contains compressibility factors related to the meter temperature and density (15 °C) of the metered material. 1st Edition October 1986 Reaffirmed: December 1, 2007

API MPMS Chapter 11.2.4 — Temperature Correction for the Volume of NGL ·

and LPG Tables 23E, 24E, 53E, 54E, 59E, 60E — The Standard represented by this report consists of the explicit implementation procedures. Sample ta- bles, flow charts, and specific examples created from a computerized version of these implementation procedures are included. The examples are to pro- vide guides and checkpoints for those who wish to implement a computer- ized procedure to represent the Standard, however these are not part of the actual Standard. This standard covers a 60°F relative Density range of 0.3500 to 0.6880 which nominally equates to a density at 15°C of 351.7 to 687.8 kg/m3

and a density at 20 °C of 331.7 to 686.6 kg/m3_{. The temperature range of this}

Standard is –50.8 to 199.4 °F (–46 to 93 °C). At all conditions, the pressure is assumed to be at saturation conditions (also known as bubble point or saturation vapor pressure).

Or:

ASTM D1250 — Volume Correction Factors (Joint Standard with API MPMS Chapter 11.1)

ASTM D1250-04 — Standard Guide for Use of the Petroleum Measurement Ta- bles; 2000

Adjunct to D1250 — Temperature and pressure volume correction factors for gen- eralized crude oils, refined products, and lubricating oils. 01-May-2004, D1250 ADJ CD-2-10