Failures do not just happen: there is almost always an identifiable- and so avoidable - cause. Roderick J. Allan, Vice President Engineering and Technical Services, R&B Falcon Drilling, believes a focused analysis of risk could not only improve offshore safety dramatically, but also save considerable sums of money.
Two years ago, DNV Houston developed its Failure Mode and Effects Analysis (FMEA) system. The project was launched to help offshore and process-plant operators improve safety and reliability management, by making it easier to identify why and how failures happen and so prevent them from recurring.
The system is now available and being used by, among others, Houston-based R&B Falcon Drilling, one of the worlds largest offshore drilling contractors serving the oil and gas industry.
Says Allan, Consequence of failure is the major risk we face today, especially regarding our deepwater activities. Typically, larger investments in this new generation of advanced vessels means greater consequences in the event of failure. One does not normally place an emphasis on such problems with proven technology units, since these risks have been well understood and the consequences can be remedied through experience.
One of R&B Falcons major goals for the year 2000 is to eliminate equipment failures, which can produce unacceptable results. As drilling moves into ultra-deep waters, the company is acutely aware of the fact that it may only take a small, seemingly inconsequential failure of a piece of equipment to cause a major incident. The companys intention this year is to expand the use of proven methodologies, such as FMEA, and to apply them to its critical systems to minimise the possibility of recurrence of such a failure that may cause major damage or system failure, such as that on the Deepwater Pathfinder last year.
Minimising risk
The Deepwater Pathfinder, a dynamically positioned drillship, suffered loss of braking capacity to its drawworks caused by contamination of the brakepads. DNV was called in to undertake a root cause analysis and FMEA. Allan explains, Through new design and maintenance processes, we have minimised the risk of this happening again. We have made presentations to other operators to show them what the problem was and how its not going to happen again. We intend to use this information to work with other operators and contractors who own or operate similar equipment. It makes a lot of sense to prevent it happening somewhere else, because we are all under the same microscope. Weve benefited from what weve done and learned from this exercise, and are willing to share the information with other interested parties who may benefit.
Isolating failure sources
People look at this as a way to create redundancy in a system, so that if a failure occurs, some of the human element is taken out of the equation. In many cases, one can go back and look at existing systems, even if the system and equipment are fairly new. Our approach is to identify the operations with the greatest risk of failure and analyse the systems, equipment and personnel to minimise the risk. This is very similar to assessments we have used in the North Sea. The process is nearly identical.
R&B Falcon is doing this at the moment on one of its DNV-classed rigs, Peregrine III, on which it has conducted an FMEA of the power and dynamic positioning systems. This rig has been in service for more than 25 years, and was classed at a time when the requirements were very different from todays - so it is obviously unpractical to replace an old system in its entirety with complete systems that meet the latest rules. However, by identifying the most likely potential failures, designers can minimise the consequences of those failures.
For example, explains Allan, if there are 20 single-point failures, and 18 of them can be eradicated for just a fraction of the cost of putting in a new system, then this is a wise, cost-effective decision. We believe the cost of conducting these analyses is very reasonable compared to the potential cost of the failure itself. The cost consequences of seemingly small item failures can easily run into tens of millions of dollars.
Allan points out that in many cases the issue to be remedied is not so much technical as procedural. Proper training and contingency for failures are also extremely important, so risk-based analysis leads us to adopt various philosophies within the company: maintenance and training, as well as the procedural aspects of the way we operate our rigs.