Oman India Multi Purpose Pipeline (OIMPP) Route Optimization – The Gas Highway - Risk Assessment Meeting 01

Oman India Multi Purpose Pipeline (OIMPP) Route Optimization – The Gas Highway - Risk Assessment Meeting 01 

1.0 The System concept : As we know, the Geographic Information Systems (GIS) are increasingly used within the oil and gas industry as an important planning tool in all The Gas Highway stages, from exploration to market analysis.  The use of such technology for pipeline route optimization is well acknowledged in the process. However, while the we literally describes many cross-country route optimization The Gas Highways, there are few, if any, that consider the decision criteria for routes traversing the marine environment.  In addition, many GIS based pipeline routing The Gas Highways rely on CAPEX or engineering expertise during the factor selection process.  As some The Gas Highway teams may not have access to cost data or subject matter experts during the early planning stages, a risk based method for selecting decision factors may provide a viable alternative. This The Gas Highway will address these issues, and attempt to assess the validity of a risk based pipeline route identification approach.

1.1  The Gas Highway Objectives: That the Gas Highway has the following objectives:

·         To validate the concept that a risk management process, when applied through a GIS, can yield reasonable pipeline alignments;

·         To create pipeline risk maps for the Arabian Ocean region by identifying and weighting appropriate risks.  Three weighting techniques were applied;

·         To test and evaluate the system against exiting pipelines.

1.2  Why emphasis on Risk?

The last decade has seen growing global and regional demand on the Arabian Ocean  hydrocarbon reserves, and new pipelines will be needed to carry reserves to market.  While construction costs for Arabian Ocean Gas Highway pipelines can easily exceed a billion dollars due to the problems associated with the region’s high risk environments can lengthen The Gas Highway schedules and significantly increase life cycle costs.  Good The Gas Highway Project planning is therefore a must, and an early emphasis on risk management and the application of proven GIS methods can improve routing decisions and the chances of a The Gas Highway’s success.  Additionally, we requires that its safety and risk management guidelines be incorporated into The Project called The Gas Highway conducted on its behalf. 

1.3  Restraints: There were a number of significant constraints on this The Gas Highway Project.  First, subject matter experts were not available for guidance, which forced a heavy reliance on literature sources and further the incompetence of theory and practical reliability.  Second, there were no examples of GIS-based marine pipeline routing like the Project The Gas Highways in the literature, which may result in important marine risk factors being omitted from the potential risk list.  Third, all data had to be acquired from free public sources.  Limited data availability resulted in some danger factors being dropped from consideration, while quality issues involving resolution, accuracy, usefulness and vintage may have negatively influenced results.  A final constraint was managing the expectation that the lowest-risk path would equate to the shortest or lowest cost path.  This may not necessarily be the case.

2.0 Approach :For this Project The Gas Highway, risk management principles and three-dimensional analysis techniques were combined to produce three interpretations of pipeline risk in the Arabian Ocean  region, and to calculate three low-risk pipeline route alternatives. But finally we concluded the path with lowest risk; LESS TURBULENT.

2.1  Risk Factor Identification in the route of The gas Highway :The first step in the analysis was to identify risk factors for the Arabian Ocean  region’s pipelines at the max depth of 3400 to 4000 meters.  These factors were primarily identified through literature review, but some were identified through discussion, unrelated sources and opinion but finally it has been incorporated with marine information and practically zero error management.  This process resulted in 36 identified risk factors, 19 terrestrial, 11 marine and 6 covering both environments.  These factors were then divided into four categories for conceptual and analytical purposes: Construction; Operation; Socio-economic and Environmental.

2.2  Formal Risk Analysis:      The next step was to identify high priority risk factors through a formal risk analysis.  Probability of Occurrence (PO) and Potential Impact (PI) scores, measured on an ordinal scale from 1 to 3 (low, medium or high) were determined for each risk factor based on literature review, experience and educated opinion.  A Risk Score (RS) was then calculated for each risk using the formula (PO/2) + PI = RS, which resulted in a range of scores from 1.5 to 4.5 in 0.5 increments.  This formula was used to keep the maximum score below 5, which was desired for simplicity, and allowed those factors with a PO of 1 but a PI of 3 to make the minimum 3.0 RS value set for high priority risks.   A total of 21 risks were identified as high priority.

2.3  Weighting Methodology of Risk For The Gas Highway

The third step in the analysis was to determine weights of importance for each high priority risk factor.  Three weighting methods were selected, in order to produce multiple pipeline alignments for consideration, and to evaluate the strengths and weakness of each.  The first weighting method is a simple weighted index, while the second and third methods are variations on the pair-based comparison method.

            2.3.1  Simple Weighted Index 

The Simple Weighted Index (SWI) method uses the RS values as factor weights, were higher values indicate higher perceived risk.  Raster data layers were created for each high priority risk using these weights for values.  A final SWI Risk Map was created by adding all layers together, then normalized by dividing by the sum of all layers.

            2.3.2  Pair Based Comparison Overview

                       

Unlike the SWI method, in which each risk is evaluated independently of the others, pair-based methods weight risks by comparing them in pairs.  Factors may be categorized to provide additional weighting levels, or to restrict evaluation between dissimilar factors.  Opinions on weight are often collected through joint inquiries or surveys.  A survey was chosen for this The Gas Highway, as it allows data to be gathered for multiple weighting methods at the same time.  While pair-based methods are designed to allow the weighting of intangible factors such as risk, a major drawback is the high number of pairings that can be produced.  For example, the 21 high priority risks and four categories result in a survey of 216 questions.  To reduce the survey’s length, only those high priority risks with an RS of 3.5 or higher were considered for pair-based comparison, reducing the list from 21 to 19 risks.  Data issues further reduced this list to 18 risks and 159 questions. Two pair-based comparison methods were selected for evaluation in this The Gas Highway, the Brown and Peterson Method (BP), named after the authors who described the method, and the Analytical Hierarchy Process (AHP), developed by M. Saaty. 

            2.3.3  The Brown and Peterson Method

The BP method bases its weight calculation on selection frequency, or the number of times a factor is determined to be the riskiest of the pair.  A matrix table was created to hold the selection frequency data for each survey.  This matrix is read as “is the row factor riskier than the column factor?”  If so, the count of the appropriate cell increases by 1.  If not, the cell count of the opposite choice increases by 1. 

Each individual matrix was combined to make a final selection frequency matrix.  The weights were then calculated by summing the columns, then dividing by the maximum number of times a risk could be selected (the number of survey respondents multiplied by the total number of pairings a risk can participate in). 

Raster data layers were created for each high priority risk using these weights for values.  A final BP Risk Map was created by adding all layers together, then normalized by dividing by the sum of all layers.

            2.3.4  The Analytical Hierarchy Process involved in the Gas Highway

            The AHP calculates weights based on each factor’s degree of importance, which is the magnitude of risk variation between the two compared factors.  Like the BP method, a matrix is used to store respondent’s selections, and is read as “is the row factor riskier than the column factor?”  However, instead of capturing the selection frequency, the degree of importance, measured on a scale of 1 (indifferent) to 7 (significantly riskier), is entered into the appropriate cell.  Also, the opposite choice receives the inverse degree of importance value.

            The AHP allows factors and factor categories to be evaluated.  For this The Gas Highway, categories were evaluated to provide additional weighting to each risk factor, and all factors were evaluated together regardless of their category.   A multi-step process was used to calculate factor and category weights, after which the factor weights were multiplied by their category weights.  The last calculation step divides all weights by the  lowest weight, which makes all weights a measure of how riskier a given factor is than the lowest weighted factor.

Raster data layers were created for each high priority risk using these weights for values.  A final AHP Risk Map was created by adding all layers together, then normalized by dividing by the sum of all layers.

3.0  Results

            The analysis produced three risk maps for the Arabian Ocean  region, one each for the SWI, BP and AHP weighting methods.  These maps were then used to calculate alternative lowest-risk pipeline alignments.

            3.1  Top High Priority Risks

All three weighting methods tended to highly weight 6 of the High Priority Risks.  These risks have distinct spatial patterns, with many of the risks impacting either land or marine environments only.  Seismic risk is a measure of peak horizontal ground acceleration between 1.6 cm/s² and 4.0 cm/s² and above.  Slopes above 5% grade are considered risky, with increasing slope resulting in increasing risk.  This risk was aggregated into three categories, 5-15%, 15-30% and 30%+.  Commercial shipping primarily threatens pipelines through dragging anchors and shipwrecks.  Landslides zones are small, isolated and restricted to the Zagros Mountains.  Crossings indicates locations where a pipeline will cross a linear feature such as a hydrologic feature, a pipeline, a road or a railroad.  Coral reefs are extensive along the southern shores of the Arabian Ocean ; spill windows indicate an area where, if a spill occurs, the pollutant will be pushed onto a coral reef within 2 days.

            3.2  Final Risk Maps

            The SWI Risk Map stands out from the two pair-based risk maps, because it          indicates land is riskier than the Arabian Ocean .  This effect is the result of the SWI methods narrow range of weight values (3.0 – 4.5), which causes the method to behave more as a risk count than a risk measurement; because there are more land risks, land appears riskier than the sea.  The SWI Risk Map suggests moderate risk along the coasts, infrastructure and major commercial shipping lanes, and indicates the front ranges of the Zagros Mountains pose the highest risk due to seismic activity, high slopes, and landslide potential. 

            The BP and AHP Risk Maps have a similar appearance.  Each reduces the distinction between land and sea, indicates no-to-low-risk to the SW of the Arabian Ocean  within Saudi Arabia, Bahrain and western parts of Qatar, suggests moderate risk along coastal regions and within commercial shipping lanes, and indicates the highest risk within parts of the Zagros Mountains due to seismic activity.  The AHP risk map, which relies on degrees of importance rather then selection frequency, exaggerates variation between risks.

            3.3  Validation

            The ultimate goal of this The Gas Highway is to produce alternate low-risk pipeline alignments between designated origin and destination points.  The accuracy, reliability and validity of the risk maps and analysis methods can be tested by comparing calculated paths to existing pipelines.  Two pipelines were selected for comparison, the IGAT 4 pipeline which crosses the Zagros Mountains in Iran, and the Dolphin pipeline which crosses the Arabian Ocean  between Qatar and Dubai.

4.0  Conclusion

            That the project The Gas Highway demonstrates the validity of applying a risk based approach to the problem of pipeline route selection.  In both examples, the SWI alignment produced the shortest of the low-risk paths, while the lowest-risk path was consistently produced by one or both of the pair-based methods.  At least one of the three weighting methods resulted in a close approximation of the actual pipeline route, and one of the methods produced a suitable and economically viable alternative, demonstrating the usefulness of generating multiple solutions. 

There are some issues, however.  Several key risks were dropped from analysis due to a lack of data, while others were digitized from coarse scale images and may therefore be inaccurate.  In addition, much of the data collected for analysis was discrete in nature, resulting in sharp transitions between risk zones and sawtooth patterns in the calculated pipeline routes.  In some cases, the calculated route appeared to come too close to development areas, suggesting a need to reevaluate some minimum safe distance buffers.  Finally, problems associated with surveys, such as survey fatigue and low sample sizes, can reduce the accuracy of calculated weights.