This paper presents specialized simulation techniques addressing some of the unique challenges related to modeling of heavy crude (dilbit) pipeline systems. These techniques were developed to improve the accuracy and effectiveness of modeling efforts associated with simulation of seasonal operation and product blending, and include methods to modify fluid properties and other characteristics with simulation coding.
Heavy crude generally refers to oil of density higher than 900 kg/m3. Pipelines shipping products from oil sands production sites typically transport fluids heavier than those servicing conventional oil fields. The bitumen produced either by open mining or SAGD method is often mixed with light condensate ("diluent") to meet pipeline specifications. The mixture of bitumen and diluent is called "dilbit".
The dilbit system discussed in this paper can be viewed in Figure 1. This system originates at the SAGD facilities in northern Alberta and terminates in Edmonton. It includes:
LACT (Lease-Automatic Custody Transfer) facilities at each of the SAGD sites.
300 km (186 mile) of NPS42 pipeline ("Upstream Pipeline")
50 km (31 mile) of NPS30 pipeline ("Delivery Pipeline")
Trim blending (diluent injection) and product quality monitoring facilities located between the Upstream Pipeline and the Delivery Pipeline.
Mainline block valve stations
Pig launchers and receivers for each pipeline
This paper will discuss the major considerations and simulation techniques in connection with the unique challenges associated with modelling dilbit systems.