Mounting regulatory pressures and rising service and supply costs are pushing the pipeline industry toward a more preemptive approach in ensuring pipeline integrity.
The idea is avoid or minimize the need for intervention in order to cut operating and maintence (O&M) expenses and reduce costly downtime. Accordingly, much of industry’s focus is on developing or enhancing new inline inspection (ILI), real-time monitoring, and corrosion-detection capabilities:
Two new standards are emerging around that vision:
- Building in integrity monitoring and assessment capabilities at the design stage.
- Developing a broader array of methods to provide constant vigilance with minimum manpower.
Industry is busily advancing the state of the art in a number of technologies to achieve these standards, but it’s difficult to see a true game-changing new technology emerging as a dominant solution.
A key hurdle may be the lingering disinclination by operators to invest in the technologies that would address these goals because of short-term financial concerns, say some service/supply companies.
Dietmar Neidhardt, vice-president and general manager of pipeline operations for Tuboscope Pipeline Services, a division of National Oilwell Varco, Houston, contends the wave of mergers in the industry has driven operators away from long-term research and development investments at the same time that government R&D funding has fallen dramatically.
“As in the E&P industry, this gap ultimately will have to be closed by the service providers,” he says. “However, the present financial environment offers little attractions for the service industry to take on this challenge within the foreseeable future.
“In consequence, we will most likely witness over the coming years a series of improved existing systems, rather than breakthrough technology providing a new and previously unavailable concept to the ILI industry.”
It’s also crucial to remember that no single technology can anticipate integrity threats across a broad variety of pipelines. That means it’s important to develop a broad-based integrity management program from the outset.
“The fundamental importance of proper line preparation and assessment is becoming better understood by the industry,” says Phillip Morrison, vice-president, pipeline integrity products and services, T.D. Williamson Inc., Tulsa. “Because of this elevated level of realization, pipeline operators are finding that programs can be more accurately budgeted and executed through findings revealed by detailed assessment procedures.”
But gaps in assessment and analysis remain a concern due to technologies that are capable only of providing a partial examination of existing pipeline problems, he contends.
“Historically, pipeline assessment technology has focused on singular threats even though every pipeline represents its own unique collection of symptoms, which include dents, cracks, corrosion, and intrusions/constrictions. Reinspection with other available technologies aimed at different threats may be called for to detect significant situations that previously used technologies were not capable of revealing.
“Overall, the industry has gained significant experience with the identification and quantification of dents and corrosion. Long-seam cracks, gouges, and stress corrosion cracking (SCC) may now become the issue for pipeline operators. Continuing to adequately understand all threats being faced by a pipeline will remain an ongoing issue for all operators.”
Accordingly, more pipeline operators are looking to incorporate pipeline integrity solutions at the design stage.
Claudi Santiago, president of GE Oil & Gas, Florence, Italy, notes that trend with new work for his company’s Pipeline Integrity & Inspection Services unit.
“We are being asked more and more to assist in the engineering phase to help ‘design-in’ integrity and, furthermore, to provide technologies such as third-party damage monitoring and data management software, that if implemented during construction, provide very cost-effective, long-term integrity management support,” he says.
ILI advances
New technology is needed to stretch ILI capabilities to address the industry’s current limitations.
The deepwater pipeline industry needs to develop new internal inspection tools and systems that will widen the design range and reliable performance of multidiameter pipelines and thick-walled pipes, says John Stearns, vice-president, marine pipeline systems for Houston-based Intec Engineering.
“These technology enhancements would increase industry confidence that pipelines with varying geometries and high-wall thickness can be effectively inspected and operate safely and efficiently for the life of the associated fields,” he says. “Development of such tools, however, requires extensive testing programs using pipeline test loops to document inspection pig passage through complex subsea pipeline configurations.”
Steve Schroder, general manager of Houston-based Baker Hughes’s pipeline management group, notes that the current state of the art for mechanical damage evaluation with magnetic flux leakage (MFL) technology is limited to being able to detect metal loss associated with deformations.
“The next step forward will be when the industry develops the technology to assess mechanical damage with the level of accuracy and repeatability that is now routinely available for corrosion,” he says.
That limitation for MFL is felt most keenly in the burgeoning new deepwater pipeline construction industry, according to Stearns.
“Industry requires the development of suitable tools that can reliably inspect thick-wall risers and pipelines, as most steel catenary risers and many deepwater pipelines are currently outside the range of conventional MFL inspection tools. Emerging technologies, such as ultrasonic inspection, although useful, still have limitations.”
Corrosion detection
One of the most critical issues in the area of pipeline integrity is the lack of accurate and reliable nonintrusive monitoring technologies that continuously assess the damage due to corrosion in a cost-effective way, says Gary Jolly, president and CEO of Fox-Tek, Toronto. He cites a recent study that put the annual cost of corrosion detection within the oil and gas industry alone at $18 billion annually.
Neal Prescott, director, subsea/deepwater technology, for Fluor Corp.’s Upstream SBL, Energy & Chemicals group based in Sugar Land, Tex., contends that predicting future corrosion defect growth must take into account the various factors influencing the dynamics of the growth pattern.
“For example, a corrosion defect under a sulfate-reducing bacteria colony can experience accelerated growth, whereas a corrosion defect initiated by a galvanic cell may in fact decelerate with time as concentration resistance of the cell increases,” he says. “Therefore, an assumption of a linear progression of a corrosion defect dimensions with time may not result in an accurate prediction of a defect size at a certain point in the future.”
Prescott also cites direct-assessment external corrosion detection surveys as another area ripe for improvement. These techniques include close interval survey, direct-current voltage gradient surveys (DCVG), and pipeline current mapping.
Real-time monitoring
Sensor systems allow continuous pipeline monitoring to be built in at the design stage so that high-consequence areas can be tracked for corrosion growth or damaging ground movements, notes Jolly.
“By making this standard practice, pipeline companies achieve significant cost savings by reducing unplanned maintenance activities,” he says.
Fox-Tek has developed a highly sensitive fiber optic technology capable of monitoring subtle changes in wall thickness related to corrosion with resolution that can exceed 0.5%. Through a fiber optic sensor applied to the exterior of a pipeline, the system precisely, continuously, and non-intrusively monitors the rate of corrosion.
“The role that internal pressure fluctuations play in the growth of SCC is not well understood, yet may be a very important one,” says Jolly. “A continuous crack growth monitoring capability…can help to correlate changes in SCC with the pressure fluctuations.”
Recent advances in fiber-optic sensing technology have resulted in an increasing acceptance with operators for remote leak detection, says Prescott.
“Distributed temperature sensing, which allows a continuous measurement in real time of changes to the pipeline or surrounding environment, has provided a new tool to the industry and has allowed more advances in remote leak detection not only on onshore pipelines, but also for offshore and deepwater applications.”
Critical to tying together fiber-optic sensing and SCADA systems is new software. Here, too, advances are needed, according to Prescott.
“A software platform that integrates operational and integrity data is becoming central to regulatory compliance, but opportunities for improvement still exist in the software’s workflow functionality,” he says. “I still think there is significant value that can be delivered through better integration of the data and the corresponding work processes.”
These new technology advances won’t come cheaply, say service companies, who nevertheless contend that they not only are needed in a more stringent regulatory environment today but also can be cost-effective.
“Operators should view pipeline integrity expense as an investment in either sustaining or extending the asset life,” Santiago says. “Benchmark studies worldwide have confirmed that prudent investment in pipeline integrity management best practices lowers O&M cost over time, while improving overall system reliability.”
