Oil reserves show the amount of technically recoverable crude oil at a financially feasible cost with current oil prices. Therefore reserves will change with prices, unlike oil resources , which includes all technically recoverable oil at any price. The reserves may be for wells, for reservoirs, for fields, for a nation, or for the world. Different classification of reserves is related to the degree of certainty.
The estimated total amount of oil in the oil reservoir, including the oil that can be produced and which can not be produced, is called oil in place . However, due to reservoir characteristics and limitations in petroleum extraction technology, only a small portion of this oil can be brought to the surface, and only this produced fraction is considered as reserve . The reserve ratio with the total amount of oil in a particular reservoir is called the recovery factor . Determining the recovery factor for a particular field depends on several features of operation, including the oil recovery methods used and technological developments.
Based on data from OPEC in early 2013, the highest proven oil reserves include non-conventional oil deposits in Venezuela (20% of global reserves), Saudi Arabia (18% of global reserves), Canada (13% of global reserves), and Iran (9%).
Because subsurface geology can not be checked directly, indirect techniques should be used to estimate resource size and recovery. While new technology has improved the accuracy of these techniques, significant uncertainty still persists. In general, the earliest estimates of oilfield reserves are conservative and tend to grow over time. This phenomenon is called growth reserve .
Many oil-producing countries do not disclose their field of reservoir engineering data and instead provide unaudited claims for their oil reserves. The figures revealed by some national governments are suspected of being manipulated for political reasons.
Video Oil reserves
Classification
All reserve estimates involve uncertainty, depending on the amount of geological data and available techniques and interpretation of the data. The degree of relative uncertainty can be expressed by dividing the reserves into two main classifications - "proven" (or "proven") and "unproven" (or "unproven"). Unproven reserves can be subdivided into two subcategories - "probable" and "possibly" - to indicate the relative degree of uncertainty about their existence. This most commonly accepted definition is based on those approved by the Society of Petroleum Engineers (SPE) and the World Petroleum Council (WPC) in 1997.
Proven backup
Proven is a reserve that is claimed to have reasonable certainty (usually at least 90% confidence) can be recovered under existing economic and political conditions, with existing technology. Industry specialists refer to this as "P90" (ie, have 90% certainty produced). Backup is also proven in the industry as " 1P ".
Backup is proven to be further subdivided into " proven to grow " (PD) and " proven undeveloped " (PUD). The PD backup is a reserve that can be produced with existing wells and perforations, or from additional reservoirs where minimal additional investment (operating costs) is required. PUD reserves require additional capital investment (eg, drilling of new wells) to bring oil to the surface.
As of December 2009, "1P" proven reserves are the only type of Securities and Exchange Commission that allows oil companies to report to investors. Companies listed on the US exchange must prove their claims, but many national government and oil companies do not disclose data verification to support their claims. Since January 2010, the SEC now allows companies to also provide optional additional information that states 2P (proven and probable) and 3P (proven plus plus possibilities) provided that evaluations are verified by qualified third-party consultants, although many companies choose to use 2P and 3P Estimates only for internal purposes.
Unsupported backup
Unproven reserves are based on geological and/or engineering data similar to those used in the estimated proven reserves, but technical uncertainties, contracts, or regulations impede such reserves are classified as proven. Unproven reserves can be used internally by oil companies and government agencies for future planning purposes but not routinely compiled. They are classified as possible and possibly .
Possible reserves are associated with a known accumulation and claim a 50% confidence level of recovery. Industry specialists refer to them as "P50" (ie, have 50% certainty generated). The amount of reserves is proven and possibly also referred to in the industry as " 2P " (proven plus possibilities).
The Possible backup is associated with a known accumulation that has less possibility to recover from a possible backup. This term is often used for reserves that are claimed to have at least 10% certainty produced ("P10"). The reasons for classifying the reserves may include various geological interpretations, reserves can not be produced at the commercial level, uncertainty due to reserves (seepage from adjacent areas) and projected reserves based on future recovery methods. The cumulative amount of the resource is proven, possibly and possibly referred to in the industry as " 3P " (proven plus plus possibility).
Russian backup category
In Russia, reserve categories A, B, and C1 correspond roughly to produce proven, proven undeveloped, and proven undeveloped, respectively; the designation of ABC1 in accordance with proven reserves. The Russian C2 category includes possible reserves and possibilities.
Strategic petroleum reserves
Many countries maintain government-controlled oil reserves for reasons of economic and national security. According to the US Energy Information Administration, about 4.1 billion barrels (650,000,000 m 3 ) of oil are held in strategic reserves, of which 1.4 billion are controlled by the government. This reserve is generally not calculated when calculating the state oil reserves.
Resources
A more sophisticated system for evaluating petroleum accumulation was adopted in 2007 by the Society of Petroleum Engineers (SPE), the World Petroleum Council (WPC), the American Association of Petroleum Geologists (AAPG), and the Society of Petroleum Evaluation Engineers (SPEE). It combines the 1997 reserve definition, but adds categories for contingent resources and prospective resources .
Contingent resources are estimated amount of petroleum, on a certain date, to be recovered from known accumulations, but the applied project has not been considered mature enough for commercial development because of one or more possibilities. Contingent resources may include, for example, projects with no viable market, or where commercial recovery depends on the technology being developed, or where the accumulated evaluation is insufficient to clearly assess the commercialities.
The prospective resource is the estimated amount of petroleum, on a certain date, to be recovered from the accumulations undiscovered by the application of future development projects. Prospective resources have opportunities related to discovery and development opportunities.
The United States Geological Survey uses technical terms and economically resources that can be recovered when making an assessment of its oil resources. Technically recoverable resources indicate that the proportion of refined petroleum is assessed in a recoverable place using current recovery technology, regardless of cost. Economically recoverable resources are technically recoverable oils where the costs of discovery, development, production, and transportation, including payback, can be recovered at certain market prices.
"Unconventional resources" exist in the accumulation of petroleum spreading across a wide area. Examples include extra heavy oils, oil sands, and oil shale deposits. Unlike "conventional resources", where petroleum is recovered through wellbores and usually requires minimal processing before being sold, unconventional resources require special extraction technology to be produced. For example, vapors and/or solvents are used to mobilize bitumen for in-situ recovery. In addition, extracted petroleum may require significant processing prior to sale (eg, bitumen processing). The total amount of non-conventional oil resources in the world far exceeds the amount of conventional oil reserves, but it is much more difficult and expensive to develop.
Maps Oil reserves
Estimation Techniques
The amount of oil in the subsurface reservoir is called on-site oil (OIP). Only a small part of this oil can be recovered from the reservoir. This fraction is called the recovery factor . Recoverable sections are considered reserves. The irreversible portion is excluded unless and until the method is applied to produce it.
Volumetric method
The volumetric method tries to determine the amount of oil available by using the reservoir size as well as the physical properties of the rock and liquid. Then the recovery factor is assumed, using the assumption of a field with similar characteristics. OIP multiplied by the recovery factor to achieve the amount of reserves. Current recovery factors for oil fields around the world typically range between 10 and 60 percent; some more than 80 percent. The wide variation is largely due to the diversity of liquid and reservoir characteristics for different deposits. This method is very useful in early life reservoir, before significant production occurs.
Material balance method
The material balance method for oilfields uses the corresponding equations of oil, water and gas volumes that have been generated from the reservoir and changes in reservoir pressure to calculate the remaining oil. This assumes that, when liquid from the reservoir is produced, there will be a change in the reservoir pressure depending on the volume of oil and gas remaining. This method requires extensive pressure-volume-temperature analysis and accurate field pressure history. This requires some production to occur (usually 5% to 10% of final recovery), unless a reliable pressure history can be used from the field with similar rock and liquid characteristics.
Method of production decrease curve
The method of curve decrease uses production data to adjust the downward curve and forecast future oil production. The three most common forms of decline curves are exponential, hyperbolic, and harmonic. It is assumed that production will decrease on a fairly smooth curve, so allowances should be made for closed wells and production restrictions. The curve can be expressed mathematically or plotted on the graph to predict future production. It has an (implicit) advantage including all reservoir characteristics. It takes enough history to form a statistically significant trend, ideally when production is not limited by rules or other artificial conditions.
Reserve Growth
Experience shows that the initial estimates of the size of newly discovered oilfields are usually too low. As the years progressed, consecutive estimates of the final recovery of the fields tended to increase. The term reserve growth refers to a typical increase in the estimated final recovery that occurs when oilfields are developed and produced.
Estimated backup by country
BBL = oil barrel
It is estimated that between 100 and 135 billion tonnes (equivalent between 133 and 180 billion mà oil) of world oil reserves have been used between 1850 and today.
OPEC countries
Since OPEC began to set production quotas based on reserve levels in the 1980s, many of its members have reported significant increases in their official reserves. There is doubt about the reliability of this forecast, which is not equipped with any form of verification that complies with external reporting standards. The following table illustrates this increase.
The sudden revision in OPEC reserves, which amounts to nearly 300 billion barrels, has been widely debated. Part of it is partially retained by a shift in reserve holdings from international oil companies, some of which are obliged to report reserves under the rules of the conservative US Securities and Exchange Commission. The clearest explanation of this revision was driven by changes in OPEC rules that set production quotas (in part) on reserves. However, revisions in official data have nothing to do with the discovery of new reserves.
Total reserves in many OPEC countries were almost unchanged in the 1990s. Official reserves in Kuwait, for example, do not change at 96.5 Gbbl (15.34 ÃÆ'â € " 10 9 m 3 ) (including parts of Neutral Zone) from 1991 to 2002, although the country generated over 8 Gbbl (1.3 ÃÆ'â € 10 9 m 3 ) and do not create anything important discovery during that period. The case of Saudi Arabia is also striking, with proven reserves estimated between 260 and 264 billion barrels (4,20 ÃÆ' - 10 10 m 3 ) in 18 last year, variations of less than 2%, while extraction of about 60 billion barrels (9.5 ÃÆ' - 10 9 m 3 ) during this period.
Sadad al-Huseini, former head of exploration and production at Saudi Aramco, estimates 300 Gbbl (48 ÃÆ'â € 10 9 m 3 ) of 1,200 Gbbl in the world (190 ÃÆ' - 10 ^ 9 m 3 ) proved reserves must be categorized as speculative resources, though it does not specify which countries increase reserves. Dr. Ali Samsam Bakhtiari, a former senior expert of Iran's National Oil Company, estimates that Iran, Iraq, Kuwait, Saudi Arabia and the United Arab Emirates have exaggerated reserves with a combined 320-390 billion barrels and said, "As for Iran, which is usually accepted officially 132 billion barrels (2.10 ÃÆ' - 10 10 m 3 ) is almost a hundred billion compared to any realistic test. " Petroleum Intelligence Weekly report that the official Kuwaiti secret document estimates Kuwait's reserves of only 48 billion barrels (7,6 ÃÆ'â € "span> 10 9 m 3 ), half as proven and half as possible. The combined value is proven and probably is half the official public estimate of proven reserves.
In July 2011, OPEC's Annual Statistical Overview showed Venezuela's reserves were larger than Saudi Arabia.
Prospective resources
Arctic prospective resources
A United States Geological Survey 2008 estimates that the area north of the Arctic Circle has 90 billion barrels (1,4 ÃÆ' - 10 10 m 3 ) from undiscovered oil, technically recoverable and 44 billion barrels (7,0 ÃÆ' - 10 9 Ã, m 3 ) natural gas liquids in 25 regions that are geologically defined as having petroleum potential. It represents 13% of the oil yet found in the world. Of the estimated total, more than half of the undiscovered oil resources are expected to occur only in three geological provinces - the Alaskan Arctic, the Amerasi Basin, and the East Greenland Rift Basins. More than 70% of undiscovered oil resources are expected to occur in five provinces: the Alaska Arctic, the Amerassas Basin, the East Greenland Rift Basins, the East Barents Basins, and West Greenland-East Canada. It is further estimated that about 84% of oil and gas will occur offshore. The USGS does not consider economic factors such as the impact of permanent sea ice or deepwater depth in the assessment of undiscovered oil and gas resources. This assessment is lower than the 2000 survey, which includes the land south of the Arctic Circle.
Unusual prospective resources
In October 2009, the USGS renewed the quantity of Orinoco tar sands, in Venezuela, to 513 billion barrels (8.16 ÃÆ' - 10 10 m 3 ).
In June 2013, the US Energy Information Administration publishes a global inventory of recoverable rigorous oil estimates and tight gas resources in shale rock formations, "Technically Restored Shale Oil Resources and Shale Gas Resources: An Assessment of 137 Shale Formations at 41 Country Outside the United States. " Inventories are incomplete as they exclude strict oil and gas from sources other than shale like sandstone or carbonate, formations that underlie large oil fields located in the Middle East and the Caspian region, offshore formations, or where there is little information. It is estimated that shaleable oil resources that can be technically recovered reach 335 to 345 billion barrels.
See also
- Curve analysis decreased
- Global strategic oil reserves
- Oil exploration
- Peak oil
- Petroleum Industry
- Strategic Petroleum Reserve
Energy and resources:
- Petro-aggression
- Energy security
- Resources and world energy consumption
- List of countries with proven natural gas reserves
References
External links
- OPEC Annual Statistics Bulletin
- Energy Supply Page on the Global Education Project website, including many charts and graphs on world energy supply and usage
- Oil reserves (most recent) by country
- Reviews of World Energy Considerations BP BP Energy Reviews 2013
Source of the article : Wikipedia
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