Effective resource management in mature areas

Improving the recovery rate on fields in production can further add to value creation on the Norwegian shelf. Declining production from a field also releases infrastructure capacity, which can be used by tying in new resources to the same infrastructure. In some cases, new smaller deposits can only be profitably developed and produced by using existing infrastructure.
Improving the recovery rate on fields in production can further add to value creation on the Norwegian shelf. Declining production from a field also releases infrastructure capacity, which can be used by tying in new resources to the same infrastructure. In some cases, new smaller deposits can only be profitably developed and produced by using existing infrastructure.
Improved recovery Third-party access and development of discoveries Decommissioning

To ensure sound long-term management of petroleum resources and consideration of other important public interests, the authorities have established a clear and predictable framework for development and operation. This includes requirements for operators to seek long-term, integrated and effective solutions at all stages from field development to decommissioning.

Major investments are being made to improve recovery from fields in production on the Norwegian shelf. This, combined with favourable geological conditions, means that the recovery rate on the Norwegian shelf is high compared with rates in other petroleum provinces. Moreover, new satellite discoveries are being tied in to infrastructure on existing fields, ensuring that the infrastructure is used efficiently and that the lifetime of the fields can be extended.

When operations have been closed down, the area must be cleared and the installations disposed of (made safe in place or removed).

Improved recovery

The average oil recovery rate for oil fields on the Norwegian shelf is currently about 47 %, and the aim is to increase this further. However, recovery rates differ greatly from field to field, partly because reservoir conditions vary and different technical solutions are applied.

There is great potential for improving recovery on the Norwegian shelf. An increase of only one percentage point in the average recovery rate from the 25 biggest producing oil fields equals about NOK 60 billion in sales revenues (based on 50 USD/boe and 8 NOK/USD). However, this would require considerable effort and new investment decisions by the licensees.

Distribution of oil reserves and resources for the largest oil fields as of 31 December 2016

Source: Norwegian Petroleum Directorate

Print illustration Download data Distribution of oil reserves and resources for the largest oil fields as of 31 December 2016 Download PDF Download as image (PNG)

Distribution of oil reserves and resources for the largest oil fields as of 31 December 2016

The process of ensuring the highest possible recovery rate from a field starts when development is being planned and the facilities are being designed. Most oil fields on the Norwegian shelf incorporate pressure support in the form of water and/or gas injection from the time they come on stream. Constant improvements in technology for and knowledge about reservoir monitoring are making it possible to design better recovery strategies for the fields.

Systematic data acquisition and use of production and reservoir data increase understanding of reservoir properties throughout the production phase. An improved understanding of where oil and gas are located and their flow paths makes it possible to place wells more effectively. As new drilling targets are identified in this way, additional wells need to be drilled.

The steady improvement in understanding of reservoir properties throughout the production phase tends to result in considerable differences between the production forecast used in the original plan for development and operation (PDO) for a field and the volumes actually produced. The figure below shows the differences for selected fields on the Norwegian shelf.

Extended lifetime - production trends for Ekofisk, Varg, Oseberg and Ula

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Source: The Norwegian Petroleum Directorate

Production trends for Ekofisk, Varg, Oseberg and Ula
Source: The Norwegian Petroleum Directorate

The amount of oil that can be produced from a field is a function of factors including reservoir conditions, the development solution chosen, the production strategy and the available technology. It may be possible to extract oil not included in current production plans by using improved recovery methods. This oil can be divided into two categories – mobile and immobile.

Mobile oil can in principle be recovered using conventional production wells and techniques, by drilling additional wells and increasing the duration of water and/or gas injection.

Immobile oil adheres to the pore walls in the reservoir, and cannot be forced out of the pores and produced by water or gas injection. More advanced methods, known as enhanced recovery techniques, are needed to mobilise a proportion of the immobile oil.

Third-party access and development of discoveries near existing infrastructure

According the the National Accounts, more than NOK 4 000 billion at the current monetary value has been invested on the Norwegian continental shelf. The infrastructure financed by these investments is used to produce and transport oil and gas and can also be used to produce further resources more cost effectively.

Exploration and development of resources close to existing infrastructure can result in substantial value creation for the Norwegian society. Declining production from a field releases infrastructure capacity, which can be used efficiently by tying in new resources to the same infrastructure.

In some cases, new smaller and surrounding deposits can only be profitably developed and produced by using existing infrastructure. These are sometimes known as time-critical resources, because they need to be produced before the existing infrastructure is phased out.

In some cases, new smaller deposits can only be profitably developed and produced by using existing infrastructure
Risers at Kvitebjørn
Risers on the Kvitebjørn platform (Photo: Harald Pettersen - Statoil)

In order to promote the effective use of existing infrastructure, including platforms and pipelines, the Ministry of Petroleum and Energy adopted regulations relating to the use of facilities by others (the Third-party Access Regulations), which entered into force in 2006.

The objective of the regulations is to promote the efficient use of facilities and thereby provide incentives for licensees to conduct exploration and production activities close to existing infrastructure. To this end, they set out a framework for negotiations and for tariffs and conditions in agreements on the use of facilities by others. The regulations do not alter the principle that negotiating good solutions is the task of the commercial actors themselves.

Decommissioning

Throughout all phases of petroleum activities, the industry is amongst other things required to take environmental concerns into account and show consideration for other users of the sea. After operations have been closed down, the area must therefore be cleared and the installations disposed of (made safe in place or removed).

As a general rule, the Petroleum Act requires licensees to submit a decommissioning plan to the Ministry between two and five years before the production licence expires or is relinquished, or use of a petroleum installation will be terminated permanently. A decommissioning plan consists of an impact assessment and plans for disposing of the installations.

Throughout all phases, the industry is required to take environmental concerns into account and show consideration for other users of the sea

The impact assessment must provide an overview of the possible environmental and other impacts of the shut-down process. The disposal part must contain detailed plans for closing down operations and decommissioning installations in the best possible way. Cessation of petroleum activities and decommissioning are governed by Chapter 5 of the Petroleum Act and Chapter 6 of the Petroleum Regulations.

In addition, Norway is bound by international law and decisions and guidelines. Decision 98/3 under the OSPAR Convention is particularly important to the Norwegian authorities. The decision generally prohibits leaving disused offshore installations in place, with very limited exceptions.

Bilde tatt fra Ekofisk Sør
Picture from the Ekofisk field (Photo: MPE)

The Ministry of Petroleum and Energy has so far processed more than 20 decommissioning plans. In most cases, it has been decided that disused facilities must be removed for decommissioning onshore: examples include Odin, Nordøst Frigg, Øst Frigg, Lille Frigg and Frøy. During processing of the decommissioning plans for Ekofisk I and Frigg, permission was given to leave in place the Ekofisk tank with its protective concrete barrier and the TCP2 concrete substructure on the Frigg field.

New discoveries and improved recovery techniques have extended the lifetime of a number of fields, including Statfjord A and Gullfaks, and the submission of decommissioning plans has therefore been postponed.

The lifetime for the fields are extended - change in estimated lifetime for selected fields

Source: Norwegian Petroleum Directorate

Print illustration Download data The lifetime for the fields are extended - change in estimated lifetime for selected fields Download PDF Download as image (PNG)

The lifetime for the fields are extended - change in estimated lifetime for selected fields
Decommissioning after production ends
Decommissioning after production ends (Photo: NPD)
Updated: 15.03.2017