Applications > Oil and Gas
In the oil and gas industry, numerous applications exist where operational and safety critical data is required from highly inhospitable measurement locations. Of the numerous advantages of FBG sensing listed on our technology pages, several key advantages are directly applicable to many of these oil and gas applications. These relevant advantages are: tolerance of harsh environments, electrical immunity, remote sensing capability, long-term measurement stability and dense multiplexing capability.
From these clear benefits, opportunity to exploit optical fibre sensing technology has emerged in the below areas:
Downhole Distributed Pressure Sensing (DPS)
For Reservoir Engineers and Petroleum Technicians, the challenge of maximising the recovery of existing reserves is becoming increasingly critical, particularly as new discoveries of readily accessible hydrocarbons are becoming fewer and farther between. The global oil and gas community has set itself a challenge of increasing total recovery of oil reserves from 30% to 50-60%, and gas reserves from 50% to 70-80%. A key tool to assist this enhanced recovery is information - engineers need to know as much as possible about the status of the reservoir and its dynamic changes as hydrocarbons are produced, particularly via complex well structures where multi-zone and multi-lateral configurations are employed. It is key for engineers to closely monitor the behaviour of the reservoir, and the distribution of contribution to the production flow from various producers in the well structure, so they are best able to produce the target hydrocarbons without encouraging, e.g. water coning.
Distributed temperature information is very helpful in indicating flow profiles in the well structure. Significantly added, and complimentary information can be gained through multi-point pressure measurements, pressure being considered the most valuable downhole measurement available by many industry experts. It is often impractical or impossible to run pressure-logging tools through these complex well structures, leaving permanently deployed gauges as the only available option. Also, where logging is feasible, it is often not economically viable to perform at the frequency required to give the engineers up to date information. To deploy the large number of gauges ideally required to fully monitor a complex well structure is prohibitively expensive with conventional electronic gauges, particularly since further gauges are needed for redundancy due to high failure rates of electronic gauges in temperature environments. Furthermore, the capability of wellbores to accommodate multiple electrical cables severely limits the quantity of installed gauges possible. Fibre optic sensors provide the solution. Dozens of fibre optic pressure gauges can be multiplexed on one miniature cable and, with no downhole electronics; the gauges offer a substantially upgraded reliability at very high reservoir temperatures.
Looking beyond existing reserves, where remaining production might be maintained for several decades, future hydrocarbon production will be primarily from unconventional reserves from deeper and hotter reservoirs, and from formations where chemical or thermal recovery techniques are needed to stimulate flow. From these unconventional reserves, the cost of extraction is very high, and the cost of operational failure is enormous. So, the need for monitoring will become greater still, and the unique benefits of optical fibre sensing will play a large role in delivering this need.
Pipeline integrity monitoring
Oil and gas pipelines, on land and on the seabed, represent some of the highest value and most critical assets of the midstream and downstream process sections of the industry. Risk of subsidence, fatigue, corrosion and malicious interference, all threaten the integrity of these assets. Consequently, the management of these enormous assets and their maintenance and repair regimes is complex, labour intensive and very expensive. The highly remote and extended distance sensing capabilities of fibre systems make them ideal technologies for automatic sensing of such integrity losses, either by way of strain or temperature measurements or both. The potential economic benefits of structural health monitoring could be of huge significance to the pipeline industry, and the availability of commercially viable means to monitor pipes over hundreds of kilometres with one single instrument brings these benefits a step closer to realisation.
Riser fatigue life assessment
The heaviest components which connect a floating platform to a subsea wellhead are steel catenary risers, used to inject water, export gas and bring production oil to the surface for offloading. Since these risers hang freely from the platform, there is much impetus towards reducing their weight, a process which can substantially affect the platform's size and cost, and help access deeper water reservoirs. Of course, this must not be at the expense of the riser structural integrity, so instrumentation of the risers is highly desirable in order to ascertain their loading histories and remaining service life, particularly at the top sections and seabed touchdown zones where fatigue damage is most likely. Fibre Bragg grating strain and temperature sensor arrays offer a perfect solution to this instrumentation challenge, due to their high multiplexing capability, zero power, remote deployment, and long-term stability.
|A case study summarising the development of such a system with NOV Flexibles is available via the link to the right|
Subsea machine condition monitoring
Producing deepwater reserves is a high value industry, and every component in the upstream process is of critical importance. Motorised pumps used to push hydrocarbons from subsea wellheads to floating production units are examples of such critical assets. The cost of the vessels required to bring these assets to the surface for maintenance and repair, and the expense of production downtime whilst such vessel availability is awaited, makes continuous health monitoring a highly valuable capability as part of a condition based maintenance regime.
However, the highly remote nature of subsea pumps makes monitoring with conventional sensor technologies impractical, expensive, and often impossible. Smart Fibres' technologies, and their relevant key performance benefits overcome many of these difficulties and offer the possibility of commercially viable monitoring systems with very high value propositions to asset owners.
|A datasheet showing the possibilities of a subsea rotating machine condition monitoring system is available via the link to the right|
A recording of a presentation made on Smart Fibres’ technology and its applications in the oil & gas industry, as seen in 2012, is shown below.