HOVIK, NORWAY The global oil and gas industry is now facing the reality that many of its on- and off-shore wells are being used beyond their original lifespans.

This presents significant uncertainty around the integrity, safety and productivity of the remaining service life. DNV GL has established a Joint Industry Project (JIP) to develop guidelines for a decision support framework for corrosion assessment and integrity management of ageing wells.

Many wells are reaching an age of upwards of 30 or 40 years and operators are facing a growing challenge to predict output, mitigate against risk and ultimately decide whether to retire or rejuvenate ageing wells. Life extension of ageing wells is moving up the agenda for oil and gas operators in many regions. Factors driving this include high oil prices, technology advances and regulatory requirements.

“As well as dealing with the operational changes in the well’s lifetime, such as long-term degradation effects, there can also be difficulties caused by uncertainty over the integrity of the well and access to design documentation. Corrosion, in particular, poses a major threat to these wells,” said Shamik Chowdhury, project manager at DNV GL. “The JIP aims to close the existing gap in well integrity management and introduce proper corrosion assessments, as well as provide estimates on the remaining life of individual wells. The outcome will help operators to squeeze the remaining life out of their wells safely and cost effectively, as well as to plan for decommissioning.

“The proposed guideline resulting from the JIP will provide a clear method to evaluate and manage corrosion for wells. This can be used on a field or company-wide level to ensure the HSE and economical performance is balanced and that corrosion risks are sufficiently managed,” he continued.

DNV GL is inviting participants to take part in the JIP, which will deliver a corrosion threat and integrity well screening assessment method as well as guidelines for a decision-making tool on corrosion evaluation, monitoring, maintenance and inspection.

“There are many risks to consider at the well level," Chowdhury said. "External casings deteriorate over time at different depths for a variety of different corrosion mechanisms and can result in a loss of structural integrity. The risk of well collapse is therefore higher. Ageing wells also tend to have more aggressive conditions, normally being higher water cut, and potentially with H2S arising from reservoir changes or microbial activity, which may accelerate attack or introduce corrosion damage where it was considered ‘not to happen’ before.”

The JIP will involve the review of corrosion inspection techniques, prediction and modelling tools, as well as the impact from other interfacing aspects such as pipelines and process equipment. Investigative data will be gathered from participants’ own experiences in this field and the operational history of selected operators’ wells. The project will also carry out a pilot study to test the methodology on selected wells.

The JIP will kick off later this year and will commence through to the end of 2015, with the development of a guideline for corrosion management in wells.

For more information, visit www.dnvgl.com.