Making the best possible use of offshore assets and ensuring they continue to operate safely, reliably and cost effectively as they increasingly go beyond their anticipated working life is one of the major challenges faced by the oil and gas industry today.
One tool capable of significantly enhancing the integrity of apparatus is condition based maintenance (CBM), the science of determining the optimum time for machinery to be repaired or replaced. Although the benefits of such programmes are well known, it can often be the case that the sector does not make the most of the advantages such a system can provide. Being able to identify, through the use of data collection and analysis, the required actions to keep equipment performing at their most efficient level is an important aspect of making certain that production continues at its desired rate.
CBM became recognised as an effective form of monitoring the integrity of oil and gas assets during the 1980s. The technology used and the resulting benefits have come on leaps and bounds in the period since with diagnosis and recommendations being far quicker than 30 years ago.
A range of condition monitoring techniques, such as vibration analysis, lube oil analysis, thermography, and performance monitoring and acoustic emissions, form part of most CBM programmes. The data can be gathered in a variety of ways, such as automatically by online systems, by deploying technicians from the condition monitoring team offshore or it can also be recorded by an operator’s staff members already on board. In all cases the data is then analysed before a report of the remedial work required and timescales to complete is produced.
The key to success is to make sure that the CBM programme is focused on risk reduction and applied consistently. The reasons to choose CBM over other methods such as planned maintenance are compelling. In comparison to CBM, planned maintenance can be more expensive as remedial work that is not required will be carried out due to being part of a schedule of repairs. Conversely it can also leave machinery vulnerable to earlier than expected breakdowns as the ongoing status of the item and any deteriorations are not taken into account.
While there is an array of products one can use as part of a CBM regime it does not need to cost a fortune getting started. Effective systems can be set up without having to purchase the latest kit on the market, often one just needs to make the best use of the programme and systems that are already in place.
CBM is often targeted at production critical machines to ensure that the platform is able to operate efficiently. Such machines will regularly have inbuilt spare capacity in the form of a second backup machine sitting alongside the working appliance because of the potentially large revenue losses if the platform is unable to operate.
In the case of a gas turbine generator (GTG) being unavailable the spare capacity will prevent long term losses. However if the duty GTG fails without warning, then the likeliest outcome in such a situation would still be a production upset caused by the switch over. Typically this will equate to a loss of production for anything from 24 - 48 hours.
One can avoid unnecessary downtime as CBM provides sufficient warning through the data gathered that can highlight potential machinery failures. This will enable the spare capacity machinery to begin operating and gradually take the strain completely from the failing machine. This changeover in a controlled manner can eliminate any downtime or disruption to proceedings and is considerably more cost effective than the lost time and repairs that would otherwise occur.
CBM also has obvious safety benefits, as well as ensuring that turbo machinery such as turbines and compressors are operating within a safe range of vibration, CBM can be used to prove that safety critical equipment is operating as desired. For example, ultrasonic flow meters have been used for some time to determine the performance of firewater pumps. XPD8 Solutions, has recently extended these tests for a number of our clients, to take into account not only the performance of the pump but also the demand of the fire ring main. The tests are conducted using the worst case deluge conditions. This can then be used to determine how far an individual pump can deteriorate before remedial action is required. In some instances the safety case has subsequently been updated, with a reduced number of pumps required to be available at any one time making planned maintenance outage easier to manage.
There are environmental benefits to CBM as well, it is obviously better if we have a large lube oil inventory in the machine that is only changed when required rather than on a periodic time basis. The time to change is identified by a simple and inexpensive test requiring minimal oil quantity.
One obstacle that can potentially impact upon an effective maintenance programme can be arranging for a person to physically be on a platform to gather the required data. Limited spaces on helicopters and a fixed capacity for the number of people allowed on board a platform from a safety aspect mean it can be logistically difficult and financially prohibitive to send someone offshore to gather the data.
This issue, however, can be overcome relatively easily by training staff already on board to gather the data and through online monitoring, so getting the information back to base onshore is not a problem. The widespread use of WiFi offshore means apparatus can be monitored 24 hours a day in real time and acted upon just as promptly. Even in a situation where the link between offshore and onshore is lost the information would still be recorded and could be monitored by the trained staff offshore until communication was reestablished.
Whilst the data gathering and subsequent reports are extremely effective, it can be the case that actually acting on the information and repairing or replacing parts is something that the operators choose not to do. The prime reason for this is the cost to the business of taking the machinery out of service to perform the required repairs.
While the balance sheet is critical to business, it is probably worth remembering that the oil will still be in the ground once the maintenance work is complete. Carrying on beyond the recommended timescale leaves an operator vulnerable to unplanned downtime and higher costs. Repair work will invariably be more expensive than scheduled maintenance.
At XPD8, we do recognise that there are times when a piece of kit just ‘has to work’. With this in mind, the company will follow through on recommendations with an operator and look for a compromise to buy time for repair work. Whether it is performing a temporary fix or amending the way or frequency of the machinery’s use, the company can find a solution that minimises the potential of a breakdown.
Operators need to avoid potentially damaging, time consuming and, ultimately, expensive breakdowns. CBM makes it possible to minimise unscheduled downtime and ensures the oil and gas industry can continue to operate effectively and safely regardless of the age of its assets. Making this into a reality will be a valuable success for the sector and will play an important role in securing its future for years to come.
Gordon Ellis is operations director at XPD8 Solutions. XPD8 is recognised as a leader in maintenance engineering, condition monitoring and integrity services for the oil & gas sector. Formed in 2003, XPD8 is a privately owned company which provides skilled engineers for all areas of the data development process.
Edited by Claira Lloyd
Read the article online at: https://www.oilfieldtechnology.com/special-reports/03032015/oil-gas-asset-security/