Efficient and Accurate Calculation of High-consequence Areas
Figure 3: The Result List of High-consequence Area Analysis Based on Geographic Information System Technology
Figure 4: The Potential Impact Circle Analysis for a Gas Pipeline HCA PIR
Piping
Additional piping covered
I.S.
Additional piping covered
I.S. = Idenfied Site; HCA = high-consequence areas; PIR = potential impact radius.
Table 1: Comparison Between Field Identification and Adopting Geographic Information System Technology
Artificial Field Identification
Analysis time Participants
Analysis method Data preparation Analysis result format
Data sharing Objective
About one month GIS Technology About five hours
20 people from sites One person Field survey Nothing
Excel format
Hard Poor
Automatic calculation
Need pipeline land-base data Directly imported into pipeline database according to APDM Easy
Good APDM = ArcGIS pipeline data model; GIS = geographic information system.
In our pipeline database, identified sites are stored as either a point or polygon. We use GIS technology for HCA analysis based on the GIS point feature. For improving the efficiency of HCA analysis, we first perform the buffer analysis for the pipeline data, and the pre-defined buffer distance is equal to the potential impact radius (PIR). The December 15 2003 final rule defines the PIR (introduced as the C-FER equation) to be determined by the formula r = 0.69 x (square root of (p x d2)), where r is the radius of a circular area surrounding the point of failure (ft), p is the maximum allowable operating pressure (MAOP) in the pipeline segment (psi) and d is the diameter of the pipeline (inches). A potential impact circle means a circle with a radius equivalent to the PIR. Subsequently, we obtain the identified sites within the buffer polygon, and perform the circle buffer analysis around these sites. The intersection between the pipeline and the circles is acquired. Consequently, the HCA-affected segment is acquired as illustrated in Figure 5 (represented by the red line). With this algorithm, we have improved the efficiency of HCA analysis.
Conclusion and Suggestion
Using GIS technology for calculating HCAs along pipelines is more efficient and accurate. Based on this technology, we have developed a software named PipeHCATM for HCA analysis. The technology and software have been applied to several oil and gas pipelines. From a
1. 2. 40
Jia S, Feng Q, Zhou L, et al., Software uses GIS data to identify high consequence areas along pipelines, Pipeline & Gas Journal, 2009;236(8).
Federal Register, 49 CFR Parts 192, 2002. 3. 4. IS Pipeline Distance (equal to PIR)
Figure 5: The Efficient Potential Impact Circle Analysis PIR
HCA
IS = Idenfied Site; PIR = potential impact radius. The red line represents the high-consequence area (HCA)-affected segment.
pipeline integrity standpoint, it not only facilitates the identification of HCAs, but also assists in the implementation of the necessary integrity activities for those HCAs.
Furthermore, GIS has matured during recent years to become the logical repository for all pipeline facility, compliance and integrity data. These data can be shared across a pipeline-operating company and used for individual, departmental and specialised applications. One common centralised facility data set reduces the errors of redundant, often poorly maintained data sets. Costs associated with duplicated maintenance efforts are also reduced.4
Meanwhile, considering the high cost of integrity management, the time and expense required to research the GIS resource data behind the ‘could affect’ HCAs are negligible compared with the costs of mitigating areas where environmental resources have been depleted.5
It is noteworthy that the HCAs of pipelines do not remain unchanged; they change with changing population and environmental data along the pipeline. The historical GIS data requirements may not address current and future needs of HCA analysis. Optimising GIS data is a process that requires a thoughtful and well-planned team effort that will ensure that the data is up to date and meets the needs of the business. n
Brush R, Applying GIS To The New Gas HCA Rule, The GITA 27th Annual Conference Proceedings, 2004.
Jones BA, Using geographic information systems for pipeline integrity analysis and automated alignment sheet generation,
Exploration & Production: The Oil & Gas Review, 2003. 5.
Freeman B, Assessing ‘Could Affect’ High Consequence Areas with GIS, The 22nd Annual ESRI International User Conference Proceedings, 2002.
EXPLORATION & PRODUCTION – VOLUME 8 ISSUE 2
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