PAC
Even when refineries utilize cryogenics to ease the quenching effect, it can still occur and skew the data.
FIGURE 2: HT SIMDIS report from the AC Analytical Controls SIMDIS analyzer.
With traditional crude that normally only consists of a small percentage of light distillates, this didn’t present much of an issue since HT SIMDIS works well with the heavier hydrocarbons found in traditional crude. Since these light distillates weren’t as prominent in traditional crudes, most refineries did not even process them. However, with Bakken light crude, there are a higher percentage of light distillates, which include everything from C1 to C9. Due to the increased presence of these light distillates, refineries have found them to be a profitable part of their business and now need accurate measurement for the full hydrocarbon range. The HT SIMDIS technique, as discussed, is not enough by itself to measure the full boiling point range of Bakken crude. The report shown in Figure 2 has been generated by a HT SIMDIS analyzer. From the report, we can clearly see that the sample has an initial boiling point of 36°C, which is the boiling point of the first N-Paraffin calibrating the system. It also determines a recovery of 96.3 percent. At the same time, in the front portion of the Chromatogram, it appears there is some sample eluting below C5, but it is hard to analyze with just HT SIMDIS. To accurately measure these lightend distillates, a technique known as DHA Front-End (DHA-FE) is used. With DHA-FE, the entire crude is injected into a gas chromatography unit with a pre-fractionator. The role of the prefractionator is to retain the heavies and allow the light compounds to pass through and be subsequently analyzed into a 50-meter-long capillary column, where all the light components are separated and individually identified and quantified using a flame ionization 144
BAKKEN OIL REPORT – FALL 2014
FIGURE 3: Merged Report – HT SIMDIS and DHA-FE – from the AC Analytical Controls Crude Oil Analyzer.