Can Gas Hydrates Provide a Solution to Gas Utilisation Challenges in Russian Oil Fields?

Abstract

The expanding demand for primary energy has pushed exploration and production activities towards more challenging environments, such as the north slope of Alaska, Siberia and deeper oceans. In many cases associated gas could be a limiting factor in the field developments. While stabilised oil could be transported by pipelines and/or tankers, the options for gas and associated gas is rather limited and/or not economical. There are strict limitations on flaring due to environmental/economical concerns, and most of the available options for gas utilisation (e.g. gas to liquid, gas to wire, compressed natural gas…) require considerable CAPEX. Recently, we have proposed HYDRAFLOW, which is a Cold Flow solution for avoiding gas hydrate problems. This could provide a solution for gas transportation. The concept of HYDRAFLOW is based on allowing/encouraging gas hydrate formation, but preventing their agglomeration and pipeline blockage by using chemicals and/or mechanical means. The aim is to eliminate/minimise the gas phase by converting it into hydrates and dispersing hydrates in oil and/or aqueous phase. Water could be added to maximise gas conversion into hydrates and/or adjusting the slurry viscosity. Furthermore, a loop concept has been developed where part of the liquid phase could be recycled, minimising chemical discharge to the environment. As HYDRAFLOW basically converts gas into hydrates and transport it as slurry in a liquid phase, it could provide a solution for gas utilisation for fields where the ambient temperature and pipeline pressure are inside the hydrate stability zone. In this communication, after introducing the HYDRAFLOW concept, the latest results of laboratory tests at subzero conditions are presented as well as an economical evaluation and a pipeline transportation simulation on one of the West Siberian oil fields. These simulations demonstrate that the concept is viable, and suggest that HYDRAFLOW technology could offer significant benefits over existing flow assurance strategies, providing a novel low CAPEX/OPEX solution for gas utilisation. Introduction The rising trend in global energy demand and high price of the oil has led to production from reserves previously considered uneconomic and/or less practical. There are many challenges in production from these reserves due to various reasons such as:–The field is remote and/or located in deepwater (e.g. stranded gas).–The gas field is too small to justify a gas pipeline for long-term production (marginal)–Ambient temperatures are very low such as the north slope of Alaska, Siberia and deeper oceans.–There are restrictions on flaring associated gas. In many cases associated gas could be the limiting factor in the field developments. While stabilised oil could be transferred by pipeline and/or tankers, the options for gas and associated gas are rather limited and/or uneconomic. Worldwide, governments are restricting/limiting flaring associated gas. In many cases these restrictions could limit oil production rates. According to statistics [1], approximately 113 billion m3 (4 trillion cubic feet) of natural gas is being flared annually and close to 142 trillion m3 (5,000 trillion cubic feet) of natural gas (either associated with crude oil, or non-associated) is stranded worldwide. However, there is a high demand for natural gas in global market and considerable effort is being made throughout the industry to reduce the costs for natural gas transportation. There are a number of methods of exporting gas energy from an isolated field for use elsewhere such as pipelines, liquefied natural gas (LNG), gas to liquid (GtL), Gas to commodity (GtC), gas to wire (GtW), compressed natural gas (CNG) and gas to solids (GtS), i.e. hydrate (NGH).