Potential Industry Applications Using Gas Hydrate Technology
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Abstract Over the past decade, gas hydrates have stimulated significant interest and triggered fundamental research. Primarily, the focus has been on hydrate blockage in pipelines, and on naturally occurring gas hydrates. However, gas hydrates can be useful in many different ways that can be pertinent to our industry, thanks to their unique structural packing where only certain molecules can enter the gas hydrate cavities. Among the several potential uses of gas hydrate technology are gas separation, transportation and storage of natural gas, desalination, and carbon dioxide disposal. In particular, it is possible to (i) separate the heavier components (pentane and higher) from natural gas, and (ii) capture, store and transport natural gas. This paper proposes a workflow for capturing, storing and transporting gas in the hydrate form, particularly for situations where there are infrastructural constraints such as lack of pipelines. These applications of gas hydrate technology can have potential benefits to the oil and gas industry. Introduction The need for new methods for gas transportation is the challenge that drives the development of hydrate technology for storing and transporting natural gas (Masoudi, et al, 2005). The ability of natural gas to form hydrate in combination with water is a very interesting and useful concept (Makagon, 1997) and can be widely utilized in the industry. An important feature of hydrates is their high storage capacity. 180 volume units of gas at standard conditions can potentially be packed into 1 volume unit gas hydrate crystals. Gas hydrates can be regarded as a safe and easy way of capturing gas, storing and transporting associated, stranded and flared gas (Berner et al, 2003). The objective of this work is to propose useful industrial applications that rely on gas hydrate technology, based on selected gas samples (Table1). These applications include situations when: (1) Gas storage is required, and so natural gas is converted to gas hydrate and stored for future use. (2) Natural gas hydrate technology provides an attractive method to capture and transport natural gas on a small scale. (3) In the hydrate process of capturing natural gas, heavy components (C5 and above) are separated out as Natural Gas Liquids (NGL), while C1 to C4 are stored in hydrate form. The proposed workflow will be discussed using two representative gas samples (Dry gas' and Sample 2'). The former is basically pure methane, whereas sample 2 has the heavier C5 and C6 components. It is assumed that these gases are produced from a given field, at a given rate. In this study, the PVTSim program (Calsep, 2008) was used for the evaluation of hydrate formation and expansion processes. Expansion of the gas from wellhead conditions is necessary to trigger hydrate formation, depending on the properties of the gas, as it will be shown in this analysis with the two selected samples.
