ALBERT

Beschreibung: Structural geometries, faults and their movement histories, together with the petrophysical properties of flow units, are some of the major controls on hydrocarbon migration pathways within sedimentary basins. Currently, structural restoration, fault-seal analysis and hydrocarbon migration are treated as separate approaches to investigating basin geohistory and petroleum systems. Each of these separate modelling approaches in their own fields is advanced and sophisticated but they are not compatible with each other. Lack of integration produces incorrect palaeogeometries in basin models and inaccurate migration pathways. A combined structural restoration and fault-seal analysis technique, integrated with fast hydrocarbon migration pathway modelling code based on invasion percolation (IP) methods, is described. These modelling methods are used to develop a 4D basin modelling workflow in which evolving basin geohistories and geometries form an integral part of the analysis of hydrocarbon migration and trapping. By combining structural restoration and 3D fault-seal analysis it is possible to investigate the evolution of structurally complex traps through time. Integration of these techniques with a numerically fast migration pathway modelling technique allows hydrocarbon migration pathways and accumulations to be modelled through the evolution of the basin with time. Additionally, the effects of uncertainties in structural geometry, fault seal or any of the model input parameters can be explored using a risk-driven approach to modelling. These methods are demonstrated using synthetic, computer generated, 3D models and a well-constrained model of the Moab Fault, Utah, USA. Comparison of modelled structural geometries, fault-seal properties and predicted trapped hydrocarbons with outcrop data is used to validate the integrated modelling approach. The validated techniques are then applied to a seismically derived, 3D model from the southern North Sea, UK, to demonstrate how an integrated, risk-driven approach to modelling allows the effects of uncertainties in the distribution of hydrocarbon accumulations to be investigated.

Beschreibung: Of all the fossil fuels, natural gas is environmentally the cleanest, having a lower carbon content with respect to energy output than either coal or oil. Global demand for gas has risen steadily over the last decade and forecast demand growth now outstrips all other major energy sources. These two factors should dictate that gas will remain the energy source of choice until renewable alternative energy sources become readily and economically available.The UK is set to face a shortage of proven indigenous gas reserves. However, the known conventional global resources of natural gas are very significant, with reserves projected to last for 60 years at current production levels, and expected un-discovered resources predicted to exceed this figure. In addition, huge volumes of ‘unconventional’ gas resources are trapped in hydrates on the seafloor, in coal beds, in low-permeability sandstone reservoirs (so-called ‘tight gas sands’) or in shale deposits. Whilst the global resource base is good, the UK is set become a net importer of gas as the scope for significant new conventional resources is small, UK gas production is already very efficient, and opportunities for unconventional resources are limited.Traditionally, natural gas has been viewed as a stranded asset when located far from markets. However, since natural gas can now be efficiently converted to a liquid by cooling to −160°C, and then economically transported in ships, gas is now a mobile commodity like oil. The bottleneck of the European Interconnector, once seen as the key to UK gas supply, has thus been circumvented. Liquified Natural Gas (LNG) is being transformed from a small volume, exotic trade into a sophisticated global spot market, opening global gas exploration and production to deep waters and plays far removed from markets.Additionally, the steady advance of technology has played and will continue to play an active role in developing new gas exploration plays, optimizing recovery factors and rapidly monetizing reserves. Unconventional sources of gas will undoubtedly provide additional significant reserves, but on a timescale of ten years and beyond. The future of natural gas looks assured for some time to come.

Beschreibung: Proven global reserves of conventional natural gas are immense, with some 5500 × 1012SCF recognized world-wide, sufficient for around 60 years supply at current global gas production rates. However, total global growth in demand for gas is expected to average 3.2% over the coming decade and is projected to double by 2025. Along with accelerating liberalization of gas markets, this growth in demand will generate huge opportunities for gas explorers and producers. The exploration and reservoir engineering challenges are to find and produce three times more gas over the next 20 years than the industry has found in cumulative total since 1970. Current estimates suggest that 50% of conventional gas resources have been discovered to date. These resources are well characterized and exploration will have to extend deeper into sedimentary basins, in deeper waters, and in new plays, as well as creatively re-evaluate current acreage, to discover additional conventional natural gas. Tertiary deltas will be a major exploration play over the next decade.In the future, unconventional gas resources will be used increasingly to supplement high volume demand in developed markets and as a major longer-term source of energy. Natural gas in low permeability sandstone reservoirs, coal beds and fractured shale already accounts for more than 25% of natural gas production in the USA. Additionally, enormous volumes of natural gas are generated by methanogenic bacteria during early burial in marine sediments, much of which then contributes to frozen methane hydrates on the continental slopes. At present, much of this unconventional natural gas is categorized as hypothetical and requires fundamental scientific research before it can be considered as an economic resource.Historically, the commercial imperative has been to find gas close to markets. Shipping of liquefied gas, liquid gas derivatives and potentially solid methane hydrates (LNG, GTL and GTS technologies) around the globe, are changing the traditional patterns of gas exploration, transportation and market supply as new producers and demand centres emerge. LNG has already been transformed from a small volume, exotic trade into a sophisticated global market and GTL is likely to follow, opening global gas exploration and production to deep waters and plays far removed from markets.