Keeping a check on production losses
2016 May 05, 14:00 CEST
In the face of lower oil prices and rising operating costs, the offshore oil and gas sector is looking for rapid productivity improvements. Smarter maintenance practices are a key part of the solution, says Mark Dunn, Reliability Engineering Manager at SKF.
Gothenburg, Sweden, 5 May, 2016: The oil and gas industry is struggling to adapt to a new economic environment. Price volatility remains high –but the combination of strong supply and slowing demand growth makes a rapid return to high prices unlikely.
Amid such prolonged, challenging conditions, offshore producers are under extraordinary pressure to reduce costs. In a sector where the long term cost trend has been upwards, turning the situation around requires wide ranging changes to operating practices. Many companies are recognising the need to innovate and are investing in long-term solutions.
Some of the drivers of lower productivity are inevitable, including tighter health, safety and environmental regulations, and more challenging technical conditions, but there is plenty that operators can improve, from better work scheduling to the introduction of leaner operating practices so personnel can spend more of their time on value adding activities.
Why maintenance matters
As offshore production assets age, the streamlining of maintenance and repair activities is becoming a key area of focus for operators seeking higher efficiency. Maintenance and reliability are critical to offshore productivity, because shutting down platforms for service or unscheduled repair is often the largest combined source of production losses.
Attempts to reduce reliability-related losses can put operators in a double bind, however. If they do not maintain equipment appropriately, they face the risk of costly and potentially dangerous unplanned stoppages. If inspection or replacement activities are scheduled too frequently, however, they produce their own sources of loss: driving up labour costs, extending the time required for maintenance turnarounds and increasing the chance that a maintenance intervention will inadvertently introduce new problems. Furthermore, plenty of in-service failures are random in nature, with assets as likely to fail early in life as to continue operating reliably into old age. That makes it difficult to plan meaningful time-based interventions.
Conditions for change
One way to resolve the maintenance challenge is the adoption of a condition-based approach. With advances in sensor and data analysis technology making the in-service monitoring of asset condition both more reliable and more affordable, it is no surprise that this is rapidly gaining ground as a preferred approach to drive up the reliability of offshore assets.
In general, the more sensitive and sophisticated the condition monitoring equipment used on an asset, the earlier it is able to warn of potential failures. Of course, with greater sophistication comes greater cost –- both in terms of the capital cost of sensors and analysis equipment and the effort required to configure, run and operate this equipment in the field. To achieve their goal of higher reliability at lower overall costs, therefore, offshore operators need to develop an appropriate strategy for individual assets, depending on the criticality of that equipment and the monitoring strategies available.
Basic asset care
The simplest condition-based strategies make use of handheld measuring devices to record asset characteristics and check for changes over time that could indicate potential failure. The SKF Microlog Analyzer CMXA 51-IS, for example, is an intrinsically safe, rugged and portable, hand-held instrument for the collection of vibration, process, and dynamic data in hazardous environments. The device can be connected to a variety of sensors including accelerometers, velocity transducers, displacement probes and infrared temperature sensors. The unit provides overall measurements and, when required, FFT spectrum analysis to allow the user to pinpoint problems such as bearing related issues, imbalance or misalignment. Data can also be transferred to a computer for trending and further analysis.
Better asset care
As assets become more critical, it becomes more important to identify potential problems earlier, allowing the operator to schedule an appropriate intervention, and ensure the required personnel, tools and equipment are brought together on site to minimise downtime or interference with other operations.
Operators work in close proximity to equipment, so they are usually the first to detect even the slightest changes in process conditions and machinery health; this can range from abnormal readings, odd noises, excessive heat and vibration, to leaks or pressure drops. The SKF Operator Driven Reliability (ODR) programme, enables this valuable source of data to be easily collected, analysed and acted upon. For example, operators can use handheld devices to capture data that is accurate and traceable. If abnormal conditions are detected, the operator is immediately prompted to take corrective action or initiate computerised maintenance management system (CMMS) work notification requests.
ODR empowers front-line operators to take a proactive role in communicating their findings and carry out early corrective action. In this way, operations teams become an integral part of a reliability-based asset management strategy, minimising unplanned downtime while increasing productivity and availability.
Monitoring critical assets
For larger and more critical assets where safety implications, production interruptions, difficult or dangerous access, and the costs of failure are significant, a permanent online monitoring system is more suitable and reliable than handheld data collection devices. In some instances, permanent on-line systems are used in conjunction with handheld or periodic data collection instruments, thus facilitating a more holistic approach to reliability and productivity, with round-the-clock monitoring of machinery.
The data itself is gathered and transmitted via permanently installed sensors, which can either be hardwired to junction boxes, or as is becoming more commonplace, connected wirelessly. The SKF Wireless Machine Condition Sensor, for example, which is an ATEX rated device, combines vibration and temperature sensors, a data logger and a radio into single compact unit that can be quickly and easily installed onto many types of rotating equipment. The sensor collects and transmits data on overall vibration levels and transient accelerations that can indicate problems with bearings and other common faults. The device uses the WirelessHART communication protocol, offering a simple, reliable and secure means of expanding condition based maintenance where it is difficult to install wired communication links. To overcome wireless communication obstacles, sensors can be configured to operate as router nodes, allowing them to relay data from other sensors.
Whatever type of sensors are in use, data is normally routed to a central computer system running an advanced management and data analysis tool such as the SKF @ptitude Monitoring Suite. The latest condition monitoring tools, such as the SKF Multilog On-line System IMx-M, can be configured to provide independent machine protection and surveillance capabilities, and can even provide automated advice for correcting existing or impending conditions, which can affect machine reliability, availability and performance.
Operators that have made the investment in advanced condition-based maintenance strategies have been able to capture significant cost savings and reliability improvements. When one oil major installed the technology across multiple items of machinery installed on its fleet of offshore service vessels, for example, it achieved a 20 percent drop in the number of machines requiring attention over a three-year period. The company estimates annual savings from the approach in the order of $1.2 million.
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