Bakken Crude Properties

In the past year, considerable attention has been focused on transportation and quality issues related to

Bakken crude oil. As a result of several high profile railcar incidents in the U.S. and Canada, various investigations have been launched by governmental and industry groups to better understand the safety aspects of moving Bakken crude by rail. Questions as to whether Bakken is materially different from other crude oils and if the current railroad materials classification is appropriate have been raised.

Investigations are ongoing as to the cause of the railcar accidents and potential hazards to the public associated with crude oil rail movements in general. In response to these concerns, the North Dakota Petroleum Council (NDPC) commissioned a comprehensive sampling and testing program to answer questions regarding the chemical and physical composition of Bakken, issues regarding proper classification and establish a Bakken quality baseline.

The key findings were as follows:

• Bakken crude is a light sweet crude oil with an API gravity generally between 40° and 43° and a sulfur content <0.2 wt.%. As such, it is similar to many other light sweet crude oils produced and transported in the United States.

• Bakken crude had an average vapor pressure of 11.5 and 11.8 psi, which is more than 60% below the vapor pressure threshold limit for liquids under the Hazardous Materials Regulations (43.5 psi).

• Bakken crude has a flashpoint of less than 73 degrees Fahrenheit, which is within normal range;

• The Initial Boiling Point (IBP) generally averaged between 95 degrees and 100 degrees Fahrenheit, which is within normal range for a light crude oil. (using ASTM D86).

• The light ends concentration of Bakken crude was between three and nine percent, with five percent being the typical concentration.

• The qualities of Bakken were very consistent within the sample population and throughout the supply chain – from wellhead to rail terminal to refining destination. Test results showed no evidence of “spiking” with Natural Gas Liquids (NGLs) before rail shipment.

• These specifications demonstrate Bakken crude meets the standards to be transported by DOT-111 cars and newer design railcars, the type of car used in the same for both Packing Group I and Packing Group II material transport.

Bakken Field Operations Recommended Best Practices

In addition to reinforcing the preliminary findings presented in May, the final report also outlined Field Operations Recommended Best Practices to ensure consistent operation of field treating equipment, Bakken crude oil quality and testing procedures and shipping classification:

Field Treating Equipment (in an effort to standardize light ends in crude oil presented for market):

• Design and operate all equipment within manufacturers recommended operating limits.

• Operate Gas/Liquid Separator (if utilized) at the lowest pressure to accommodate gas sales and fluid delivery to the Emulsion Separator/Heater Treater.

• Operate Emulsion Separator/Heater Treater pressure to the lowest operating pressure to safely accommodate gas sales and fluid delivery to the production tank battery.

• Maintain all fired treating equipment (Emulsion Heater Treater, etc.) temperature between 90° and 120° F+ year round.

• Provide maximum tank settling time possible prior to shipment.

• Reduce stock tank pressure to lowest pressure possible to maintain vapor collection equipment (engineered flare, vapor recovery, etc.) operational integrity.

Established Typical Bakken (BKN*) Specifications (ranges reflect expected seasonality):

*BKN refers to light sweet crude aggregated at rail and pipeline terminals within the Williston Basin. This crude is predominantly sourced from the Bakken common source of supply, but also includes legacy production from various other producing formations located within the proximity of the Bakken field. BKN does not include nonstabilized condensate recovered from wet gas gathering pipelines or from product derived outside the U.S. Williston Basin. Individual well values may be higher or lower than the aggregated values observed at the rail terminals.

Testing Procedures:

• Well Site Operators/Purchasers – Prior to each custody transfer or LACT EOM

  • API gravity corrected to 60° F using hydrometer

  • Basic Sediment & Water (BS&W) by field centrifugal grind-out

  • Spot test vapor pressure pending available field testing equipment

• Rail/Pipeline Terminal Operators

  • Test each unit train loading or tank shipment batch

    • API gravity corrected to 60° F using hydrometer

    • BS&W by field centrifugal grind-out

  • Test at least midmonth and EOM

    • ASTM D6377 @100° F vapor pressure using certified laboratory

• DOT PHMSA Hazmat Shipping Category

  • Flammable Liquid Category 3

  • Packing Group I**

** PG I is recommended even though the majority of samples tested for the study would fall within specifications for PG II. The margin of error for the test methodology can result in different labs testing the same sample with values meeting both PGs. PG I has the more stringent standards and is therefore recommended to avoid further confusion.

Other recommended procedures:

• DO NOT deliver fluid recovered from gas pipe lines (a.k.a. “pigging operations”) to crude oil sales system unless processed by stabilization unit capable of lowering vapor pressure below 10 psi at 100° F.

• DO NOT blend non-Williston Basin crude oils into the BKN common stream.

• DO NOT blend plant liquids (plant condensates, pentanes, butanes or propane) into the BKN common stream.

This study provides the most thorough and comprehensive analysis of crude oil quality from a tight oil production basin to date. The report provides conclusive and consistent scientific data about Bakken crude that will help regulators, operators, shippers and other key stakeholders properly classify and monitor Bakken crude in the future. The NDPC will be committed to using and sharing this information with key stakeholders to develop and implement standards that will ensure the safe transportation of all commodities, goods and cargoes on our rail system

To read the Full Report, click here.

Other links:

News Release: NDPC Releases Final Bakken Crude Characteristics Study

News Release: NDPC Study Shows Bakken Consistent with Other Light, Sweet Crudes

Preliminary Findings summary (May 2014)

BKN Quality & Safety Initiative: NDPC Bakken Crude Characterization Task Force Presentation of Preliminary Results (presentation from Williston Basin Petroleum Conference, May 2014)