Study of natural gas hydrates for hydrocarbon transportation

Abstract

Indonesia ranks third in terms of gas reserves in the Asia Pacific region after Australia and China, contributing 1.4 percent of total global gas reserves. Despite high demand for natural gas, there are over 169.90 trillion cubic meters of undeveloped natural gas reserves, referred as stranded gas (BP, 2013). The primary reason for a gas field being undeveloped is the gas transportation, which includes the reserves are too small to justify the investment, and the distant markets require expensive pipelines, etc. The gas transportation technology that includes pipelines, CNG (Compressed Natural Gas) and Liquefied Natural Gas (LNG) are variously limited by distance, and capacity. In some situations natural gas hydrates (NGH) could be a better option in terms of effectiveness in distance, capacity and CAPEX due to its lower pressure requirements than CNG and moderate temperatures compared to cooling requirements for LNG (approximately −162 °C) . NGH is a curious kind of chemical compound called clathrate, which consists of two dissimilar molecules mechanically intermingled but not chemically bonded. That is, one molecule forms a framework that traps the other molecule, providing high stability (Dutch, 2003). In this paper, the NGH application will be evaluated technically and economically. It will be compared with other methods such as LNG and CNG, on operation challenges like high pressure and low temperature. The study was supported by a numerical simulation using HYSYS V7.3 to analyze the probable operating conditions of NGH. The energy requirements then will be compared to determine the most efficient option for longdistance gas transportation. * University of Indonesia INTRODUCTION With 241 million people, Indonesia is the most populous country in Southeast Asia and the fourth populous country in the world. Formerly as a net oil exporter in the Organization of the Petroleum Exporting Countries (OPEC), Indonesia exported about 70 percent of Indonesia’s annual oil production in the late 1980s, but domestic consumption increased steadily and reached half of annual oil production by 1990 (Frederick & Worden, 2011). By the end of 2011, the energy consumption of Indonesia was supported by oil production (30%), biomass and renewables, coal, natural gas and imports. With 7% yearly increase in Indonesian energy consumption, the declined oil production has not been able to meet the demand since 2004 (Figure 1). This situation has resulted in the conversion of BBM (fuel based oil) to BBG (fuel based gas). The high energy demand along with the depleted oil supplies drives Indonesian government and industry to focus on the large reserves of natural gas. Currently, Indonesia contains the third-largest gas reserves of the Asia Pacific region (after Australia and China), accounting for 1.4 percent of total global gas reserves. The Indonesian major gas producers such as Arun, Bontang, Tangguh and Natuna Island have been supporting the Indonesian energy demand. Unlike oil production, fortunately, gas production can always fulfill the national consumption in Indonesia. Figure 2 shows that Indonesia has large gas reserve, but most of it is stranded. The main reason for gas fields being undeveloped is the gas transportation because some reserves are far from markets and some of them are too small to justify the investment. The idea of natural gas hydrate (NGH) for gas transportation was advocated by Dr. Gudmundsson of Norwegian University of Science and Technology in 1996. © IPA, 2014 – 38th Annual Convention Proceedings, 2014