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A well equipment reliability database

Thursday, December 11, 2014

Wood Group Intetech has put together a database of the reliability of different well barrier components. By Ged Lunt, Technology Manager at Wood Group Intetech

Wood Group Intetech has launched a global database of well component performance data.

Known as 'iQRA', this online quantitative reliability analysis tool provides operators with access to global well and oilfield component performance information.

Subscribers can identify the highest performing well components, benchmark reliability figures, and extract statistical and mean-time-to failure (MTTF) data to support cost-saving decisions.

Choosing well components
Making the correct selection of well equipment is far from simple.

Different equipment models may be more suited to certain operating conditions.

When conditions are very challenging, well designs may need to be adjusted to allow for lower achievable reliability of particular equipment.

A lot of considerations lie behind the selection of well designs and the selection of replacement components during well workovers.

The performance of installed well components must be totally predictable.

Should a problem arise at any given point in time, operators must be confident that they know how their well barrier components will respond.

For example, if they shut a subsurface safety valve (SSSV), then they know with certainty that it's going to close and contain the well fluids in the specified time.

Getting accurate reliability figures for well barrier components requires access to a statistically significant database. Whilst the industry recognises this need, a key challenge has been the reticence of operators to make data such as component reliability and failure rates available externally.

In addition to concerns over data confidentiality, efforts to build such a database have tended to be limited to single regions such as the North Sea, or focussed strongly on specific components such as the SSSV. Previous systems have also been badly structured and suffered from poor quality of data or difficulty of use or access.

Most operators accept that certain well barrier component failures are inevitable and operational constraints may mean that they cannot be repaired immediately. It can be necessary for wells with individual components not in full working order to continue to operate, provided risk assessment indicates the risk level is acceptable.

Of course, some types of failure call for the well to be shut-in and repaired immediately, but for the majority of non-critical failures, repairs are scheduled to take place within a designated timeframe, or when the opportunity arises.
Testing can actually reduce the lifetime of the equipment - especially an active component that is opened and shut, each cycle causing some amount of wear and fatigue.

Given that it is necessary to close valves in order to test the leak rate across them, using risk-based analysis to determine that testing can be safely performed less frequently, should extend the lifetime of valves, as well as reducing operating costs.

Access to this kind of reliability information makes it possible for operators to identify where they have low reliability equipment or potentially a faulty component installed.

They can pre-empt potential failures on other wells by taking the opportunity to replace a questionable piece of equipment if another well intervention is taking place.

The quality and volume of data upon which iQRA is based means that operators can make independent and impartial assessments of reliability performance.

For example, decisions on well components for new well designs or replacement during workovers can be made based on the highest performing and most reliable equipment.

Selecting high reliability components is a must to reduce well entries, establish optimum maintenance levels, and justify plugging and abandonment decisions.

The development of iQRA was driven by operators.

Following the ISO-14224 standard, iQRA's functionality also includes failure data analysis such as critical failures versus degraded failures. These features have been designed to accelerate the industry shift to risk-based assessment and performance-led decision-making for maintenance scheduling.

These capabilities are already enshrined in UK health, safety and environmental practices, and in Norway, where the Petroleum Safety Authority stipulates that each well workover case be assessed per well and based on reliability data.

The iQRA reliability information service allows an independent and impartial assessment of well component reliability performance. The scope of data incorporated includes all well environments: onshore; platform; and subsea.

iQRA can be accessed from anywhere via a standard web browser.

Users can build data queries based on Individual Xmas tree, wellhead valve and seal components as well as SSSV; Global regions and well location (land, platform, subsea); Equipment manufacturers; Operating environment characteristics; Time period of data to interrogate Results reported include statistical evaluation of the failure data and the mean-time-to failure (MTTF) report, while a 'saved searches' option allows users to quickly run further reports according to their specific requirements, as new data becomes available.



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» Wood Group Integrity Management
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