ALHBRANDT, THOMAS S., U.S. Geological Survey, Dnever, CO 80225, USA

Abstract: Conventional Natural Gas Provinces of the World

Non-associated natural gas reserves are known to occur in 296 provinces of the 954 geologic provinces identified by the U.S.Geological Survey throughout the world. By contrast, oil reserves are reported in 409 of these provinces. Natural gas reserves worldwide seem to be relatively under-reported compared to oil reserves and constitute about 50% of the latter on the basis of barrel of oil equivalent (BOE). In the U.S., reported oil and gas reserves are comparable in BOE. According to Petroconsultants' (1996) data allocated to all provinces, the total known reserves (cum. prod. plus remaining reserves) are 6,753.4 trillion cubic ft (TCF) of gas (5,844.7 TCF excluding the U.S.). There are notable geographic discrepancies between oil and gas provinces of the world. The largest natural gas province, West Siberian Basin, is also the third largest known petroleum province; whereas the second ranked gas province, Qatar Arch is the 91st ranked oil province. The top 135 natural gas provinces, representing 98% of all known natural gas reserves are geographically more widely distributed than the 135 top ranked oil provinces. North America province reserves rank relatively higher compared for gas than for their oil ranking. This may reflect better reporting and increased utilization of natural gas in North America. The top five North American gas provinces rank fifth, twelfth, sixteenth, eighteenth and nineteenth in world gas provinces. The top five oil provinces in North America conversely rank twelfth, fourteenth, twentieth, twenty-sixth, and sixty-seventh in the world oil provinces. Additionally, North America has considerable identified natural gas reserves that are considered unconventional. Such unconventional natural gas resources are known to occur elsewhere in the world, such as in the Middle East, Russia, China, South America, and Africa, but have been little developed. A ranked list of natural gas provinces of the world and their known product volumes are shown with volumes of gas in trillion cubic ft (TCF), and Oil and NGL in billion barrels (BB). The first number in the USGS province code refers to the region in which the province occurs. Region 1=Former Soviet Union, 2=Middle East / North Africa, 3= Asia Pacific, 4 = Europe, 5 =North America, 6 = Central and South America, 7 = Sub-Saharan Africa, 8= South Asia. Also shown for each province is the percent of total known gas (Gas %) and cumulative percent of known gas (Gas Cum%).