FROZEN HEAT | Volume 2

A major consideration in estimating oil and gas resources is the difference between conventional and unconventional hy- drocarbons. The term unconventional lacks a standard defini- tion, but it generally refers to resources that require stimula- tion treatments or special recovery processes and technologies in order to economically produce oil and gas. Each unconven- tional type (e.g., oil shale, tar sands, coal bed methane, and gas hydrates) requires unique strategies, such as fracture stimulation in the case of shale oil and gas. Each also presents individual environmental challenges. The recoverability of un- conventional resources depends greatly on technological de- velopment. Combined with variations in demand and price, this means that the line between economically recoverable and uneconomical unconventional resources is constantly shifting. Estimates of gas reserves and resources are revised continuously as information, technology, and economics change. Many parts of the world currently lack the infrastructure for distribution or are too remote to make natural gas extraction economically viable at present. Because of this, exploration has often been limited in certain parts of the world. There still remains, how- ever, potential for discovery of new resources in these areas.

A large amount of the gas currently identified as uncon- ventional or not economically recoverable would need to be transferred into the reserves category to meet predicted fu- ture demand. The GEA (2012) estimates conventional gas reserves at 130 to 190 Tcm, or 5000 to 7000 EJ. According to the GEA, unconventional gas types include coal bed meth- ane, tight formation gas, and gas hydrates. The total global reserves and resources of this category are estimated to be in the range of 1600 to 5040 Tcm or 60 000 to 189 000 EJ. This represents, potentially, one of the largest reserves of all fossil fuels, exceeding even known coal reserves. Reviews of the literature indicate very substantial global gas hydrate occurrences. For example, WEA (2000) estimates the global in-place resource potential for gas hydrates at 350 000 EJ (9 400 Tcm). Moreover, gas hydrates appear to be widely distributed around the world in many marine and permafrost environments. This makes them very attractive to countries that are not naturally endowed with conventional domestic energy resources, as well as to the world’s largest and most-rapidly growing economies. Figure 1.1 shows the resource potential of gas hydrates by global region.

A GLOBAL OUTLOOK ON METHANE GAS HYDRATES 15