Oil reserves are the estimated quantities of crude oil that are claimed to be recoverable under existing economic and operating conditions.[1]
The total estimated amount of oil in an oil reservoir, including both producible and non-producible oil, is called oil in place. However, because of reservoir characteristics and limitations in petroleum extraction technologies, only a fraction of this oil can be brought to the surface, and it is only this producible fraction that is considered to be reserves. The ratio of producible oil reserves to total oil in place for a given field is often referred to as the recovery factor. Recovery factors vary greatly among oil fields. The recovery factor of any particular field may change over time based on operating history and in response to changes in technology and economics. The recovery factor may also rise over time if additional investment is made in enhanced oil recovery techniques such as gas injection, water-flooding[2], or microbial enhanced oil recovery.
Because the geology of the subsurface cannot be examined directly, indirect techniques must be used to estimate the size and recoverability of the resource. While new technologies have increased the accuracy of these techniques, significant uncertainties still remain. In general, most early estimates of the reserves of an oil field are conservative and tend to grow with time. This phenomenon is called reserves growth.[3]
Many oil producing nations do not reveal their reservoir engineering field data, and instead provide unaudited claims for their oil reserves. The numbers disclosed by some national governments are suspected of being manipulated for political reasons.
Sunday, August 30, 2009
Classifications
Reserves are those quantities of petroleum claimed to be commercially recoverable by application of development projects to known accumulations under defined conditions.[6] Reserves must satisfy four criteria: They must be:
discovered through one or more exploratory wells[6]
recoverable using existing technology[6]
commercially viable[6]
remaining in the ground[6]
All reserve estimates involve uncertainty, depending on the amount of reliable geologic and engineering data available and the interpretation of those data. The relative degree of uncertainty can be expressed by dividing reserves into two principal classifications - proved and unproved.[6] Unproved reserves can further be divided into two subcategories - probable and possible to indicate the relative degree of uncertainty about their existence.[6] The most commonly accepted definitions of these are based on those approved by the Society of Petroleum Engineers (SPE) and the World Petroleum Council (WPC) in 1997
discovered through one or more exploratory wells[6]
recoverable using existing technology[6]
commercially viable[6]
remaining in the ground[6]
All reserve estimates involve uncertainty, depending on the amount of reliable geologic and engineering data available and the interpretation of those data. The relative degree of uncertainty can be expressed by dividing reserves into two principal classifications - proved and unproved.[6] Unproved reserves can further be divided into two subcategories - probable and possible to indicate the relative degree of uncertainty about their existence.[6] The most commonly accepted definitions of these are based on those approved by the Society of Petroleum Engineers (SPE) and the World Petroleum Council (WPC) in 1997
Proved reserves
Proved reserves are those reserves claimed to have a reasonable certainty (normally at least 90% confidence) of being recoverable under existing economic and political conditions, with existing technology. Industry specialists refer to this as P90 (i.e. having a 90% certainty of being produced). Proved reserves are also known in the industry as 1P.[8][9]
Proved reserves are further subdivided into Proved Developed (PD) and Proved Undeveloped (PUD).[9][10] PD reserves are reserves that can be produced with existing wells and perforations, or from additional reservoirs where minimal additional investment (operating expense) is required.[10] PUD reserves require additional capital investment (e.g. drilling new wells) to bring the oil to the surface.[8][10]
Proved reserves are the only type the U.S. Securities and Exchange Commission allows oil companies to report to investors. Companies listed on U.S. stock exchanges must substantiate their claims, but many governments and national oil companies do not disclose verifying data to support their claims.
Proved reserves are further subdivided into Proved Developed (PD) and Proved Undeveloped (PUD).[9][10] PD reserves are reserves that can be produced with existing wells and perforations, or from additional reservoirs where minimal additional investment (operating expense) is required.[10] PUD reserves require additional capital investment (e.g. drilling new wells) to bring the oil to the surface.[8][10]
Proved reserves are the only type the U.S. Securities and Exchange Commission allows oil companies to report to investors. Companies listed on U.S. stock exchanges must substantiate their claims, but many governments and national oil companies do not disclose verifying data to support their claims.
Unproved reserves
Unproved reserves are based on geological and/or engineering data similar to that used in estimates of proved reserves, but technical, contractual, or regulatory uncertainties preclude such reserves being classified as proved. [11] Unproved reserves may be used internally by oil companies and government agencies for future planning purposes, but are not routinely compiled. They are sub classified as probable and possible [11]
Probable reserves are are attributed to known accumulations, and claim a 50% confidence level of recovery. Industry specialists refer to this as P50 (i.e. having a 50% certainty of being produced). Referred to in the industry as 2P (proved plus probable).[8]
Possible reserves are attributed to known accumulations which have a less likely chance of being recovered than probable reserves. This term is often used for reserves which are claimed to have at least a 10% certainty of being produced (P10). Reasons for classifying reserves as possible include varying interpretations of geology, reserves not producible at commercial rates, uncertainty due to reserve infill (seepage from adjacent areas), projected reserves based on future recovery methods. Referred to in the industry as 3P (proved plus probable plus possible).
Probable reserves are are attributed to known accumulations, and claim a 50% confidence level of recovery. Industry specialists refer to this as P50 (i.e. having a 50% certainty of being produced). Referred to in the industry as 2P (proved plus probable).[8]
Possible reserves are attributed to known accumulations which have a less likely chance of being recovered than probable reserves. This term is often used for reserves which are claimed to have at least a 10% certainty of being produced (P10). Reasons for classifying reserves as possible include varying interpretations of geology, reserves not producible at commercial rates, uncertainty due to reserve infill (seepage from adjacent areas), projected reserves based on future recovery methods. Referred to in the industry as 3P (proved plus probable plus possible).
Oil, gas reserves discovered
ISLAMABAD (APP) - The Oil and Gas Development Company Limited (OGDCL) as operator along with its joint venture partners Government Holdings (Pvt) Limited (GHPL) and Orient Petroleum International Inc. (OPII) has discovered oil and gas reserves in Sanghar City, Sindh Province.OGDCL sources told APP that the Company as operator along with its joint venture partners has discovered oil and gas reserves from its exploratory Well Baloch #01, in Sinjhoro Exploration License which is located at a distance of 22.5 km North West of Sanghar City, Sindh Province.The structure of Baloch Well # 01 was delineated drilled and tested by OGDCL’s in house expertise.The well was drilled down to the depth of 3463 meters, targeting to test the potential of sand body (Massive Sands) of Lower Goru formation of Cretaceous age.The significant reserves of hydrocarbons have been found at Baloch Well#01. The hydrocarbon bearing Zone comprising of 32.5 meters has tested 780 BBL of oil per day and about 3.5 MMCFD of gas through 32/64" choke, at well head flowing pressure of 880 Psi.
Oil refinery
An oil refinery is an industrial process plant where crude oil is processed and refined into more useful petroleum products, such as gasoline, diesel fuel, asphalt base, heating oil, kerosene, and liquefied petroleum gas. Oil refineries are typically large sprawling industrial complexes with extensive piping running throughout, carrying streams of fluids between large chemical processing units.
Exploration methods of Oil
Visible surface features such as oil seeps, natural gas seeps, pockmarks (underwater craters caused by escaping gas) provide basic evidence of hydrocarbon generation (be it shallow or deep in the Earth). However, most exploration depends on highly sophisticated technology to detect and determine the extent of these deposits using exploration geophysics. Areas thought to contain hydrocarbons are initially subjected to a gravity survey, magneic survey, passi seismicor regional seismic reflection surveys to detect large scale features of the sub-surface geology. Features of interest (known as leads) are subjected to more detailed seismic surveys which work on the principle of the time it takes for reflected sound waves to travel through matter (rock) of varying densities and using the process of depth conversion to create a profile of the substructure. Finally, when a prospect has been identified and evaluated and passes the oil company's selection criteria, an exploration well is drilled in an attempt to conclusively determine the presence or absence of oil or gas.Oil exploration is an expensive, high-risk operation. Offshore and remote area exploration is generally only undertaken by very large corporations or national governments. Typical Shallow shelf oil wells (e.g. North sea) cost USD$10 - 30 Million, while deep water wells can cost up to USD$100 million plus. Hundreds of smaller companies search for onshore hydrocarbon deposits worldwide, with some wells costing as little as USD$100,000.
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