Global Trends
Global trends in energy consumption during the last 150 years have shown a transition from solid carbonbased sources of wood and coal to liquid carbonbased sources of oil and condensate and then to natural gas carbon-based sources of methane (see Figure 1). As the demand for natural gas continues to increase, we will continue to see a greater proportion of natural gas being produced from non-associated (with oil), disseminated or ‘unconventional’ sources. These sources include low permeability (‘tight’), very deep (> 5,000 metres), sub-salt, coal bed methane, shale and frozen gas (hydrates) resources. This trend towards a methane economy will have a positive impact on global economic stability, energy efficiency and the environment.
Figure 1: World Energy Consumption
Source: R A Hefner,III,"New Thinking About Natural Gas", USGS Professional Paper 1,570, 1993, pp.807-829
It has often been said that most of the easily accessible oil and gas has already been found and produced, therefore global oil and natural gas production will come from increasingly more complex reservoir systems (see Figure 2). As complex reservoirs require significant technological understanding and advanced reservoir management plans to make oil and gas recovery economic, the need for advanced reservoir characterisation will increase in the 21st century.
Figure 2: Recoverable Portion of In-place Gas Resources
Source: National Petroleum Council, "Natural Gas: Meeting the Challenges of the Nation's Growing Natural Gas Demand"
Vol.1, Summary Report, 1999. p.96
Unconventional gas, geopressured brines and hydrates not assessed by the National Petroleum Council.
The trend of producing from increasingly complex reservoirs has had an interesting impact on global reserve additions. Over the past two decades, a growing percentage of global reserve additions has come from enhanced recovery in known – and more complex – fields. In other words, we are discovering as many reserves in known fields as we are in new fields, and the ratio is increasing (see Figure 3). This phenomenon, known variously as inferred reserves, reserves appreciation and reserve growth, has been recognised as important for many years but has only recently been included in national reserve estimates and forecasts. Reserve growth (which includes reserves added as an extension of known fields), through reserve estimate revisions by new pool additions and as a function of the application of new technology to improved recovery, is expected to continue to play a major role in future reserve additions globally.
Figure 3: US Reserve Growth
Source: Energy Information Administration, 2002, "US Crude Oil, Natural Gas and Natural Gas Liquids Reserves". 2001 Annual
Report, DOE/EIA-0210, 2001, p. 160
Category:
Reservoir Engineering
|
Download PDF
References
