Phase Behavior Measurement and Modeling of Gas-to-Liquids and Alaska North Slope Crude Oil Blends

The feasibility of transporting gas-to-liquids (GTL) products (natural gas chemically converted to liquid hydrocarbons) through an existing oil pipeline—the Trans Alaska Pipeline System (TAPS)—for bringing value to Alaska's vast stranded natural gas resources is currently being investigated. As part of this major project, the phase behavior measurement and modeling of GTL and Alaska North Slope crude (ANSC) oil blends have been carried out. The saturation pressures for various types of GTL and ANSC oil blends were measured in a conventional windows based PVT apparatus. The phase behavior of GTL and ANSC oil blends were also modeled by the Peng-Robinson and Soave-Redlich-Kwong equations-of-state. The measured and modeled saturation pressures were found to be in close agreement. The results also indicated that the GTL and ANSC oil blends would always exist as single-phase liquid under the current TAPS operating conditions.