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Making more from well data

Thursday, March 7, 2013

How do you do more with the data you have, to help manage the safety and integrity of your wells? By Dr Liane Smith of Intetech

Oil and gas operators are sitting on vast reserves of data that has the potential to transform the way they manage the integrity of their wells.

But many lack visibility at field or enterprise level because information relating to well production, barrier equipment and design is held in different departments in various formats and under different timelines.

These silos make it difficult for senior executives and management teams to collate, compare and report on well integrity data.

And the length of time this can take impacts on their ability to identify problem wells, make informed decisions and take remedial action.

With around half of all well work-overs and shut-ins in mature fields caused by well integrity problems, this lack of visibility presents a significant risk and cost to the business.

The challenge is compounded by the fact many oil and gas operators have grown by acquisition, which means certain asset information is stored or reported in different systems and is not always readily available to the right decision makers.

Knowing your wells

The integrity of well barrier components is continuously threatened by the corrosive nature of the well fluids.
Scaling, corrosion and failed well barrier equipment are all common issues.

Managing well integrity is much more than ensuring safety during a current activity. It is also about the sustainability of the equipment to operate safely for the full design life of the well.

Information on the status of safety-critical well barrier components must be completely dependable, and the performance of these components must be totally predictable, should a problem arise at any given point in time.

An operator must be confident that they know how their well barrier safety equipment is going to respond.

For example, if the operator shuts a subsurface safety valve, the operator must know with certainty that it is going to shut in the several seconds it is supposed to.

Sustained annulus pressure, where casing pressure rebuilds after being released, is the number one killer of wells.
It can lead to an external leak or, at worst, result in a blowout.

Even if no leakage occurs, the risk is that when pressure within the well rises above the design limit at which it is safe to operate, a failure of well barrier equipment can be too risky to repair and therefore the well has to be abandoned.

Poor quality information about annulus pressure creates a real possibility that incorrect and perhaps dangerous decisions might be made.

Disconnected information

Silos of well integrity information make it difficult to collate information for analysis and review, which in turns makes it hard to identify inaccuracies that would otherwise allow operators to pinpoint barrier components at risk of failure.

The large volumes of information collected automatically from instruments on a well using Supervisory Control And Data Acquisition (SCADA) systems is in essence 'dumb' or 'grey' data, because it is simply a set of readings that in many cases, is rarely interrogated or validated.

When compared against readings acquired manually (which tend to be more reliable, though less frequent), anomalies are often found.

Management dashboard

A cost efficient and flexible approach to viewing the data is to interface with third party systems such as production data management and other types of database, e.g. WellView, SAP, Maximo.

You can extract the required information for presentation in a management dashboard.

This is effectively a graphical user interface providing a simple overview of key operating well and production data, but allowing users to drill through to more detailed engineering data as required.

This type of system allows operators to build on their existing investments and legacy data, by starting out with their basic information and then scaling the system accordingly.

For example, initial set-up might see the translation of well design data from various electronic and paper formats into an audited well design database that is accessible per well for managing and generating well handover documentation.

It might collate the results of routine and specialised leak testing of safety critical elements (SCEs) for monitoring and review.

Once basic functionality has been established, more sophisticated applications can be introduced, such as using production data to estimate corrosion damage to the tubing in a well, automatically identifying the presence of
sustained annuli pressures and notifying users with warning traffic lights and email alerts, or risk-ranking wells failing to meet safe operational limits.

A traffic light warning system provides a simple device for highlighting wells at risk.

These can be configured against a wide range of operating parameters and conditions that are to be pro-actively monitored on an ongoing basis.

A green, amber or red light provides a view of well status, whether it is being operated within its safe operating envelope and whether all well barrier components are intact.

Reports can provide a standardised format for the well integrity data being monitored to ensure better efficiency and clearer communication of well integrity issues across the enterprise.

Repairing wells

Most operators accept that certain well barrier component failures are inevitable.

Operational constraints may mean that they cannot be repaired immediately.

It can be necessary for wells with individual pieces of equipment not in full working order to continue to operate, provided risk assessment indicates the risk level is ac ceptable.

For the majority of non-critical failures, repairs are scheduled to take place within a designated timeframe, or when the opportunity arises.

Testing and preventative repairs have an associated cost and an impact on the operator's short-term productivity, whilst equipment failures have different costs and perhaps an impact on long-term productivity, or potential safety and environmental consequences.

Having the capability to evaluate, in real time, the mean time to failure of a selection of equipment can help to reduce operating costs substantially by adopting risk-based inspection frequencies, and feed-back of the performance experience to well designers can result in more reliable equipment selection for new wells.

It is important to have the complete history of a well and the integrity status of its near neighbours in order to make an informed decision when it comes to correcting an issue with a well.

Otherwise there a risk that they might not solve a problem, they could make it worse.

Also while sustained annulus pressure or individual well issues can be controlled and addressed in isolation, the danger is that a combination of issues occurring in offset wells simultaneously can lead to unexpected escalation of consequences if the full picture is not visible.

Different users

There can be tens, if not hundreds of potential users requiring access to well integrity data and all will have slightly different aims and requirements.

A well integrity engineer will need access to well component reliability data.

An operations supervisor would be more interested in being able to access a schedule of tasks and receive notification of due dates.

Drilling engineers might use a well integrity system to check for details of the well design to select an optimum workover program.

Reservoir engineers concerned with optimising production will confirm that wells are operating within the defined well operating window and check whether impending well integrity issues will interfere with production or reservoir drainage plans.

Other information needed for decision making includes:

Production information, to confirm that all fluids in the well are within their safe operating limits for flow rates, pressures and temperatures

Barrier tests, to check that safety-critical equipment is leak-free

Well design data, to support informed well workover plans

Well history, to track all actions on the well and handover events

Having all necessary data readily available via a management dashboard provides executives with an accurate picture of the company's exposure at all levels, enabling them to measure performance against any given set of key performance indicators.

Views are customisable at a company level, enabling users to tailor fields, views and outputs to suit their well integrity philosophy and help ensure regulatory compliance and mitigate risk.



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» Intetech
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