(547e) Crude Oil Compositional Analysis Methods and Their Impact on Thermophysical Properties

Crude oil composition can be useful when extracting, transporting, or refining crude oils since the chemical makeup affects properties linked to the safety, transportation requirements, and value of the material. Determining composition requires a combination of several analysis methods due to the wide range of constituents, from dissolved gases (N₂, CH₄, CO₂) to light- and mid-range hydrocarbons to heavy ends (C₃₀+). These analytical methods, each optimized to a fraction or boiling range cut of the original sample, must be followed by a numerical or physical recombination step to recreate a “whole oil” composition in which each constituent is quantified on the basis of its mass, volume, or mole percentage of the whole sample. In some cases, the limitations of the individual analytical methods propagate to the recombined whole oil. These limitations become clearer as Equation of State (EOS) model calculations are compared to direct property measurements, eliciting the need to carefully select analysis methods. The analysis presented here was performed on tight crude oils sampled mid-stream in North Dakota and Texas as part of the Crude Oil Characterization Research Study.

The Crude Oil Characterization Research Study (funded by US DOE, DOT, and Transport Canada: http://energy.gov/fe/articles/crude-oil-characteristics-research, https://www.theatlantic.com/technology/archive/2018/02/the-great-crude-oil-fireball-test/552029/), seeks to understand the crude oil property differences between conventionally produced and tight oils. Recent activities analyzed the effects of sampling containers/techniques (ASTM D3700, GPA 2174, ASTM D8009, ASTM 4057) and sampling locations (Texas vs. North Dakota) on crude oil thermophysical property measurements. Different compositional measurement techniques (GPA 2103, GPA 2177, ASTM D7900, ASTM D7169, ASTM D8003, GOR flash gas) have been used to calculate these properties as well, providing insight into the features and limitations of the methodologies.

Sandia National Laboratories is a multimission laboratory managed and operated by National Technology & Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525.