Pipeline integrity: Enhanced decision support with GIS

Pipeline integrity: Enhanced decision support with GIS

Todd R. Porter,John Parsons, Monty Martin
Tuboscope Pipeline Services
2835 Holmes Road
Houston, TX 77051
www.tuboscope.com

Abstract
The Pipeline industry is realizing the significant value that GIS adds to their integrity management programs. Programs are under development and refinement to improve the safety, efficiency, and profitability of this energy transportation infrastructure through effective data integration, analysis, and decision support methods. A case study is presented, showing such an implementation, using a large regional gas transmission system in Western Canada, complete with experience, benefits and examples.

Introduction
The pipeline industry has responded to the growing concern for public safety, and subsequent OPS Regulations and Rulemaking(s)1 that require integrity management programs. An integral part of these programs, is the use of internal inspection (ILI) devices or “smart pigs” that measure and map geometric and material anomalies. As well, given the large and diverse data sources available, a software platform is required that effectively integrates, manages, and provides analysis for decision support. The goal is to acquire, integrate, and analyze data in an efficient, comprehensive manner for informed decision making. This approach provides an enabling process for risk and consequence modeling tasks.

Using ILI data, numerous GIS map, profile, and pipe visualization views are constructed in a synchronized application framework. This approach provides a highly visual, multi-perspective presentation to assist in identification, location, and prioritization of potential pipeline defects. With the integration of spatial and attribute information via a GIS framework, consequence modeling and a more comprehensive interface to risk assessment systems can be provided. This facilitates the most efficient and effective means to address pipeline operational safety. Examples will be presented showing the benefits of an integrated approach.

Figure 1. Combination In Line Inspection Tool
ILI of pipelines involves the collection, processing, and analysis of a gigabytes of data. These data volumes consist of measurements from many sensor types on the tool, with multiple channels, and at close spatial interval and high frequency. Typical measurement resolution is at 1/10" (2.5mm) longitudinal and 0.3" (8mm) circumferential for corrosion and internal deformation sensors, with channel counts reaching into the thousands for large diameter lines. This data along with inertial measurements units (INS), velocity, and other internal detection sensors produces data sets approaching 100GB+ sizes, an enormous task to process, analyze, and prioritize without a streamlined and integrated system. Tuboscope provides a product line component called TruView GIS, built to provide GIS synchronized connectivity to the companion corrosion and mechanical damage analysis system TruView TM thus adding the geo-spatial element to the integrity management solution.

Technology integration
The location / geometry ILI tools used in pipelines utilize a combination of technologies: GPS, INS, and GIS Systems. These integrated geo-spatial capabilities take corrosion, deformation 3D geometry surveys to a new level of analysis and accuracy. A combined ILI tool (as shown in Figure 1) provides these component technologies in a single run, thus minimizing lost throughput, operator expense, and potential risk. As a result, analysts have a more complete information resource for:

Detecting and characterizing pipe anomalies,
Pinpointing locations of interest, and
Profiling the pipeline environment.

GPS (Global Positioning System) survey methods provide the means to accurately position key "sparse" points along the pipeline. This provides the absolute coordinate reference for the subsequent INS in-pipe inspection operation. These surface points are spaced at varying intervals along the pipeline and directly above the pipe, ranging from 1km to 5km separation. During the actual inspection run AGM's (above ground markers) are placed at these locations that record a precise synchronized time tag of the tool passage. Later correlation of these time events with survey position, provide calibration for the INS, and a means to control and minimize position errors computed from the INS.

The INS (Inertial Navigation System) is the main sensor unit comprised of precision rate gyros (ring laser or fibre optic) and accelerometers (Q-Flex) mounted on orthogonal 3-D axes and measuring at 100Hz rates and higher. This gives the much needed resolution described earlier. The inherent error characteristics, thus resultant accuracy of the INS are time based. These error sources, the most dominant being gyro drift, and accelerometer biases, must be corrected on a continual basis. This is done using continuous velocity derived from the odometer wheels that make contact with the inside pipe wall. Using advanced Kalman Filtering, and empirical / optimal smoothing techniques, the INS error sources are controlled and accurate position and attitude information produced. Thus, high resolution, accurate 3D position is produced, along with pipeline curvature, which could not otherwise be provided by conventional methods.

The GIS (Geographic Information System) provides spatial analysis and visualization of the pipeline and surrounding area. This spatial mechanism integrates inspection and positioning data with layers of spatial information about the pipeline and environment, such as topography, population densities and aerial photos, in both a planimetric map view, and profile view.

Data integration
By combining pipeline features, attributes, and anomalies (with precise coordinates) with other information the analyst has a more complete picture. Combining this information provides a comprehensive "prioritizing" tool for response, repairs / maintenance planning and risk-management decision-making. Information may include;

aerial photography
satellite imagery (multi-spectral)
landownership, easements, right
adjacent and intersecting pipelin
population centers,
public and private facilities (schools, hospitals, etc.),
transporation routes,
ground cover classification,
soil type surveys,
digital elevation models,
rivers, lakes, drainage, irrigation
environmental and special interest areas.

Data integration is now being used to assist with the development, implementation and maintenance of pipeline integrity programs. Tuboscope and Marr Associates 3 combined available data from a single valve section on a pipeline section to demonstrate the multiple capabilities of GIS and the PIMS2 database related to pipeline integrity management.

The valve section used for this was located along a mainline section located in southern British Columbia. This mainline was constructed in the late 1950’s and was coated in the field with asphalt. The diameter of the X52 pipe is 30 inches and the nominal wall thickness is 0.360 inches.

Between 1993 and the present, Marr Associates has been completing investigative excavations along the mainline system. These excavations were completed to investigate the severity of external corrosion, the presence of localized hard spot and SCC. The location of the external corrosion and hard spots was determined from the inline inspection of the line.

To integrate the data, site chainages identified along the pipeline were used to ensure the spatial location of the site within the TruView GIS system. The end result of this exercise illustrated the location of all past excavations, the terrain conditions associated with the sites and the documented results of the past programs as a layer within the GIS system. Based on the excavation results and severity of the integrity concern, the system easily highlighted where the past activity had taken place and the severity of the integrity concern. At each point, or location of an excavation the GIS system also stored in a tabular form, the investigative results.

The results of this initial study confirmed the following:

The TruView GIS system provides a visual representation of the history, results and mitigation of integrity concerns along the pipeline.
The integration of the two systems provides alternatives to traditional pipeline integrity program development, implementation and monitoring.
Within the IS group, there was no data conversion and program code rewriting required to either integrate the two independent sets of data and for presentation purposes, thus confirming the integration aspect and benefit thereof.

With the successful completion of this initial program, integrating the predictive models, historical ILI runs and other available data sources for integrity programs is possible. This systematic representation of data, in combination with the GIS system will provide the support mechanism for the long term use of the “direct assessment” process. The GIS system, with the supporting data will enable a pipeline integrity program to complete digital analyses for the continued assessment, evaluate and remediation of integrity concerns in a cost effective, iterative manner.

Application integration
In order to leverage these technologies, an effective integration is the key to successful implementation and utilization. Remember, the analyst must plow through possibly hundreds of miles of data at 1/10" resolution! Having the ability to detect, identify, and analyze only "anomalies", then prioritize them in an efficient and accurate manner is the objective. Therefore, these technologies must be tightly coupled and placed in an application framework that allows the user to configure for the optimal view perspective.

Figure 2. Pipeline MapView
Figure 2 presents a MapView within the application framework. This view is constructed using ESRI's MapObjects TM employing all theme, symbology, rendering, and display controls. As can be seen, the pipeline trajectory (at meter level position accuracy), along with multi-media themes, point themes, right-of- way theme, and backdrop aerial photography is presented for an effective location view. All direct assessment data is loaded with ILI data as shown.

Figure 3. Pipeline Profile View

The next view in Figure 3, shows the related elevation profile view of the pipeline. Any pipeline related them may be added to this view as in the MapView. A key aspect of the application integration is "synchronization". Any one of the views presented may be used as the navigation control. By clicking on a feature of interest, that pipeline "measure" (distance or stationing) is broadcast to all other applications which then update and display the exact location and view extents. This is a very powerful feature for the analyst; they can fly immediately to the next feature of interest. Note as well that other compliant applications, such as the corrosion analysis software are synchronized as well, providing a complete inspection view of the pipeline.

The system architecture has been designed to display any inspection related attribute as shown in the top panel of Figure 3. This includes geometry parameters such as; inside diameter, ovality, and curvature components. Shown above is the horizontal curvature and/or derived bending strain from the ILI INS unit.

Figures 4 show the color rendered perspective view of the pipeline deformation data from an open "slice" view and "axial" longitudinal view. The analyst has complete control of color classification of this internal shape data and controls to rotate, scale, and flip views to provide the best perspective on potential defects or anomalies. This view shows the internal geometry features of the pipeline.

Figure 4a. Slice Pipe View

Finally, the related and synchronized pipeline corrosion view is presented above in Figure 5. This application is the analysis tool used to identify and grade the internal and external defects of the pipe.

Figure 5. Pipeline Corrosion View

Conclusion
The integrated application framework presented utilizes GPS, INS, and GIS technologies to enable more comprehensive analysis of operating pipelines in the geo-spatial domain. An open architecture, and application synchronization provides ease of use for the analyst, and a resultant platform that provides interface to consequence modeling, risk analysis and integrity management. As discussed earlier, regulatory initiatives are underway that will require a geo-spatial reference frame for inspection, maintenance, and information dissemination. GIS provides an integral element in achieving that goal, and when coupled with materials inspection, direct assessment and other analysis tools, more efficient, informed, and rapid decision support is achieved.

Acknowledgements
The authors wish to acknowledge the support received from Westcoast Energy to present their data and integrity initiatives in part. As well, Mr. Jim Marr of MARR & Associates and their technical team for data contributions and analysis.

References

Federal Register / Volume 65, No. 79 / Monday, April 24, 2000 / Proposed Rules.
"Building Applications with MapObjects V2.0", ESRI, 1999, ESRI, Redlands, CA.
MARR & Associates, 7915 – 48 th Street SE Calgary, AB T2C-2Y6, Internal Technical Documents.