Offshore installations in UK sectors of the North Sea are now well over 25 years old, there are around 90 fixed installations of this age. Although many have been decommissioned or are soon due to be decommissioned, however there still remains a large number of installations still in service. Furthermore, operators have indicated their intention to continue service of these installations for the foreseeable future.
The increased reliance and demand of oil and gas has made the process of extracting from the North Sea fields more inviting to oil corporations. Most production installations now have a continued requirement to produce oil or gas either from the original fields or to serve as a base for neighbouring subsea completions. The infrastructure is already existent, and the continued operation postpones the costs of decommissioning.
Over the course of time the structure and other facilities involving the installation are subject to ageing leading to deterioration of their condition, with a potential impact on functionality and safety in the longer term. Most process plants are designed with a typical life span of about 20 to 25 years, both for investment appraisal purposes, but also because this the approximate limit of current industry experience. We must also consider, where the effects of ageing are more gradual, can be managed through inspection, maintenance, and upgrading.
Many facilities and their infrastructure of offshore oil and gas reservoirs worldwide are approaching or have surpassed their original design life. However, the petroleum fields are still producing considerable levels of hydrocarbons which are both recoverable and profitable if the field’s lifetime is extended further.
Most offshore oil ; gas installations are in the life extension stage, because they have passed their original design life. Eventually an installed facility has to be closed down permanently as per the original design life. However, with certain specifications and processes put into place, the life of these facilities can be extended without compromising on safety.
There are many elements involved that influence the decision to extend the operation of a producing facility. They can range from; the reservoir produces more oil than estimated, any advancement in techniques that allows greater extraction, Commercial and economic issues.
Improved techniques to access seismic data provide more details about the reservoirs and the provision of processing capability at a nearby subsea or minimum facility platform.
In November 2007 the Offshore Division of the Health and Safety Executive (HSE) published a report based on its three-year long inspection initiative known as Key Programme 3 (KP3). This was a comprehensive appraisal of asset integrity management of offshore installations on the United Kingdom Continental Shelf. Some considerable issues were revealed regarding the maintenance of safety critical systems used in major accident hazard control in the industry. Although raising key concerns as well as setting new challenges, the KP3 report was accepted as instrumental by the UK offshore oil and gas industry.
The KP3 programme together with the long term view of the potential to extend the sustainable productive life of the North Sea, acted as a catalyst for driving the asset integrity management agenda to a more important level and has resulted in a better coordinated approach. Constructively working with HSE during the development and implementation of the KP3 programme resulted in significant improvements in physical integrity, together with considerable progress in effective asset integrity management, awareness and performance. Cross-industry acceptance of the need to raise the profile of effective asset integrity led to closer exploration of currant existing maintenance management systems that had in some cases developed irregularity, or where differences existed primarily as a result of mergers and acquisitions. The result was acknowledgment of a need for change as these systems were a barrier to effective and sustainable asset integrity management.
Between 2000 and 2004, the UK HSE’s Offshore Division ran a major programme (KP1) directed at reducing hydrocarbon releases focusing on the integrity of process plant. This resulted in a considerable reduction in the number of significant hydrocarbon releases. During this period, however, the Offshore Safety Division became concerned about an apparent general decline in the condition of the fabric and plant on installations and responded with Key Programme 3 (KP3) directed at evaluating asset integrity (Cutts, 2005), which ran between 2004 and 2007.
KP3 involved inspections of nearly 100 offshore installations representing about 40 per cent of the total. These included all types like fixed, manned and normally unattended installations, floating production (FP), floating production storage and offloading (FPSO) vessels and mobile drilling rigs. KP3 focused primarily on the maintenance management of SCEs (safety critical elements), the management systems and its processes which should ensure that SCEs are readily available when required.
In July 2010, the UK HSE’s launched Ageing ; Life Extension Inspection Programme
(KP4) to determine the extent to which asset integrity risks associated with ageing ; life extension are being managed effectively by duty holders. The HSE outlined specific objectives of KP4 as: raise awareness within the industry of the need for specific consideration of ageing issues, to inspect individual duty holder approaches to the management of ageing and life extension to ascertain the extent of compliance with the regulatory requirements, to identify shortcomings and enforce an appropriate programme of remedial action.