Standard Practice for Preparing an Equilibrium Liquid/Vapor Sample of Live Crude Oil, Condensates, or Liquid Petroleum Products Using a Manual Piston Cylinder for Subsequent Liquid Analysis or Gas Analysis

Importancia y uso:

5.1 This practice allows for compositional analysis of the gases in equilibrium with crude oil, condensate, and liquid petroleum products at a 4:1 vapor/liquid ratio at ambient temperature for analysis using typical instrumentation (RGA) already available in typical refinery laboratories. These highly volatile components can result in vapor pressure conditions above atmospheric pressure, so this mechanically simple system is easily adaptable to day-to-day application at low cost/effort using existing analytical equipment.

5.2 This practice allows for compositional analysis and day-to-day tracking or trending of the light hydrocarbons in crude oil for the purpose of identifying unusual blending of NGL, LPG, butane etc. into individual crude oil batch receipts.

5.3 This practice allows identification of gases: including: CO, CO₂, H₂, H₂S, N₂, O₂, CH₄, C₂H₆, C₃H₈, etc. that can contribute to vapor pressure by Test Method D6377, but are not identified using Test Method D8003 (see Note 1). These components can originate from production or can be the result of the use of pad gas and may not be native to the original product. Significant difference in Test Method D6377 vapor pressure measurements at low V/L (for example, 0.1:1) versus high V/L (for example, 4:1) indicate the contribution of high vapor pressure gases such as those in 5.2.

Note 1: Test Method D8003 does identify: CH₄, C₂H₆, and C₃H₈. Test Method D8003 does not identify: CO, CO₂, H₂, H₂S, N₂, and O₂.

5.4 Nitrogen and combustion gases (mostly nitrogen and CO₂ with minor concentrations of air) at positive pressures up to 2500 mm water column (nominal 4 psig) is required by International Marine Organization (IMO) Marine Pollution (MARPOL) and Safety of Life at Sea (SOLAS) regulations for the marine transport of crude oil. Analysis of the equilibrium vapor may be required to determine the contribution of inert gases to the total vapor pressure of the crude oil on receipt at the discharge port or refinery.

Subcomité:

D02.08

Volúmen:

05.05

Número ICS:

75.080 (Petroleum products in general)

Palabras clave:

condensate; equilibrium vapor; gas analysis; live crude oil; manual piston cylinder; refinery gas analysis;