The petroleum resource account as of Dec. 31, 2001


The Article in Norwegian : Petroleumsressurser på norsk sokkel per 31.12.2001

The Norwegian Petroleum Directorate's (NPD's) resource account is an overview of the recoverable petroleum resources on the Norwegian continental shelf. Recoverable petroleum resources consist of both the original marketable and the remaining petroleum resources. The resource estimates are based on reports submitted annually by the operating companies, NPD evaluations for fields and discoveries and NPD estimates of undiscovered resources. The resources are on the Norwegian continental shelf classified according to maturity.

The NPD has revised it?s petroleum resource classification system, effective from July 1, 2001. Information about the classification system is available on the Internet at The intention of the revision has been to harmonize the classification with systems used within the oil companies and with recently adopted and acknowledged international systems (e.g. Society of Petroleum Engineers (SPE), World Petroleum Congress (WPC), and The American Association of Petroleum Geologists (AAPG)). The most important changes are that produced amounts of petroleum are separated as a specific class and that reserves now only consist of remaining recoverable reserves. The revised system also provides the possiblity to separate the quantities originally planned to be produced as described in the Plan for Development and Operation (PDO), and the quantities that originate from improved recovery projects.As of 31.12.2001 the total petroleum resources are estimated to 13,8 billion Sm3 oil equivalents (o.e.) with an uncertainty span of 12,.5 to 17,8 billion Sm3 o.e. This also includes the undiscovered resources. Compared to last year this is an increase of approximately 160 million Sm3 o.e. The remaining total recoverable resources are 10,6 billion Sm3 o.e. with an uncertainty span of 9,3 to 14,6 billion Sm3 o.e.

In the year 2001 181 million Sm3 oil, 53 billion Sm3 gas, 5 million tons of NGL and 7 million Sm3 of condensate, a total of 251 million Sm3 o.e. were sold and delivered. 12 new dicoveries were made in 2001 whereof seven are still not evaluated. However, it is assumed that the quantity of oil amounts to approximately 16 million Sm3 and the quantity of gas to approximately 28 billion Sm3. Evaluation of the discoveries is ongoing and there is a considerable uncertainty connected to these estimates. The petroleum quantity of last years discoveries is not sufficient to balance the production. Fig. GGG shows the annual increase of the amount of petroleum derived from the exploration activity.

As per 31.12.2001 a total of 61 fields have been granted a PDO. This includes 12 fields where production has ceased. By year?s end 42 fields on the Norwegian Continental Shelf were in production, thereof 37 fields in the North Sea and 5 fields in the Norwegian sea. In 2001 production started in the fields Tambar, Huldra, Glitne, and part of Ringhorne, all situated in the North Sea.

Remaining reserves in fields is 4033 million Sm3 o.e, distributed on 1501 million Sm3 oil, 2189 billion Sm3 gas, 131 million Sm3 condensate and 111 million tons of NGL. The remaining reserves also comprise reserves in the 7121/4-1 Snøhvit discovery, where development has been decided by the licensees, but for which the PDO at the end of the year still not was approved by the authorities. The reserves increased by 116 million Sm3 o.e. since last year. The comparison with last year is based upon a reclassified set of data.

Contingent resources (additional resources) connected to fields amount to 447 million Sm3 o.e., which constitute three per cent of the total recoverable resources. The distribution is 221 million Sm3 oil, 173 billion Sm3 gas, 16 million Sm3 condensate and 20 million tons of NGL. The total figure is a reduction of 163 million Sm3 o.e. compared to last year.

Recoverable resources contained in discoveries not yet approved for development constitue 292 million petroleum liquid and 972 billion Sm3 gas, a total of 1264 million Sm3 o.e. (nine per cent of total). This is a reduction of 198 million Sm3 o.e. related to last year. The quantity estimated for undiscovered resources is 1420 million Sm3 oil and 2510 billion Sm3 gas, totally 3939 million Sm3 o.e., an increase of 180 million Sm3 o.e. compared to last year. The increase is based upon a recent adjustment of the potential for undiscovered resources that shows an increase particularly for the Norwegian Sea.

Resources related to possible future changes for increased recovery is estimated to 400 million Sm3 oil and 500 billion Sm3 gas, totally 900 million Sm3 o.e. (6,5 per cent of the total).

78 discoveries are not yet approved for development (resource category 4F, 5F and 7F) and additionally there are 64 discoveries that are reported in other fields or discoveries.


Throughout the years of exploration, a number of so-called technical discoveries with very small recoverable resources has been made. Several discoveries are so difficult to produce, that it seems not very likely that any recovery will be made, even in the long run (resource category 6). As NPD has a low expectance for recovery from these finds, they are not included in this years resource account. This marks a change from previous years. As a consequence, direct comparison of the total number for recoverable resources with previous years, is not possible.

According to approved plans for production the expected average oil recovery at the Norwegian continental Shelf is 44 per cent. After several years with steady increase in recovery factor, it has levelled out the last four years. The major part of the recoverable petroleum resources (76 per cent) is connected to fields in production. The largest value creation related to improved recovery is therefore connected to the biggest fields currently in production.

The authorities have an objective to achieve an average recovery factor of 50 per cent for oil and 75 per cent for gas. This additional potential is called possible resources from future measures for increased recovery factor. As shown earlier this potential is estimated to 900 million Sm3 o.e. It is a considerable challenge both for the industry and the authorities in the coming years to increase the recovery factor.