Study of rheology of gas-to-liquid products, Alaska North Slope crude oil and their blends for transportation through the Trans Alaska Pipeline System

Abstract

In order to bring remote natural gas to market, conversion of natural gas to a liquid form (Gas-to-liquids (GTL)) may be an alternative to utilize this gas. Alaskan North Slope might prove as one of the first sites in the USA to commercialize this technology because of the huge natural gas resources it holds. The Trans Alaska Pipeline System (TAPS) will be the means of transportation of this GTL to the market. Thus it becomes major task to evaluate the technical and economic feasibility of transporting GTL products through the TAPS. One of the modes of transporting GTL products from ANS to Valdez is commingling them with Crude oil as a single phase before pumping through TAPS. This changes the properties of GTL as well as the Crude oil. Thus it becomes important to study the physical and chemical properties of not only the GTL but also its blends with the crude oil. Four blends of GTL/crude in the ratios of 1:1, 1:2, 1:3 and 1:4 were prepared for their rheological evaluation at different temperature conditions. Results show that flow behavior of the pure and GTL blends are temperature sensitive. Viscosity and density of the blends decrease with increasing amount of GTL and increasing temperature. Optimum blend ratio is between 1:2 and 1:3 GTL/Crude oil blends.