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* Saka Indonesia Pangkah, Ltd ** ConocoPhillips Indonesia

IPA15-E-143

PROCEEDINGS, INDONESIAN PETROLEUM ASSOCIATION Thirty-Ninth Annual Convention & Exhibition, May 2015

GEOMATICS BEST PRACTICES IN SAKA INDONESIA PANGKAH LIMITED (CASE STUDY:

UJUNG PANGKAH PIPELINE INTEGRITY)

Yudi Syahnur* Khostarosa Andhika Jaya*

I Putu Ariseputra** ABSTRACT Pangkah Block PSC is located in Offshore East Java. It’s a highly sensitive area due to massive fishing activity on and around 700 square kilometer area, as well as thousand hectares of fishpond located adjacent to the south of block’s boundary. Ujung Pangkah Field is the only producing field in Pangkah PSC block so far, located in active delta branches of the Bengawan Solo River. Large amounts of sediment materials are being transported from the land outflow to the sea by the Bengawan Solo River. It is estimated Bengawan Solo river delta has a huge mud sedimentation flow that deposited 17 million tons of mud per year.

Operating in such harsh condition, Pipeline Integrity in Ujung Pangkah is critical to company’s success. Loss of pipeline integrity can result in leaks of crude oil or natural gas, which can negatively impact the safety of community, environment, and Pangkah Field operability. Pipeline integrity should be maintained through proper design, proper installation and robust maintenance program that consist of proper monitoring, proper inspection and proper intervention when required.

Geomatics can be described as science and technology to collect, process, manage, analyze and display geospatial data and information. It includes the tools and techniques used in land and marine surveying, remote sensing, cartography, geographic information systems (GIS), global navigation satellite systems (GPS, GLONASS, Galileo, Compass). Geomatics have played an important role to promote Pipeline Integrity in Saka Indonesia Pangkah Limited (SIPL). This paper will describe how seabed stability and geomorphology survey helped SIPL operation team finding the root caused of 6” Gas Injection Pipeline

Rupture in April 2011. The use of Geographic Information System, High Resolution Satellite Imagery and Intelligent Pigging data to identify and monitor construction activities around 20” Sales Gas Pipeline from OPF to PLN will also be discussed. INTRODUCTION Scientific term of Geomatics is defined and proposed for the first time by Michel Paradis, in an article published by Canadian Surveyor in 1981. It can be described as science and technology to collect, process, manage, analyze and display geospatial data and information. It is estimated that more than 90% data and information used in Energy Sector is spatially referenced or pertaining to specific geographic location. Oil and Gas industry considered as early adopter of Geomatics, which rapid progress and increased visibility has been made possible by advances in computer hardware, computer science, and software engineering. Since 1990's Oil and Gas companies have been using Global Positioning System to improve land and marine seismic acquisitions process, as well as airborne and space observation remote sensing technologies to effectively find hydrocarbon prospects. Up until now, more and more oil and gas companies use Geographic Information System to help extracting hydrocarbon in a more efficient manner. Geomatics includes the tools and techniques used in land and marine surveying, remote sensing, cartography, geographic information systems (GIS), and global navigation satellite systems (GPS, GLONASS, Galileo, Compass). The use of these tools and technologies in Saka Indonesia Pangkah Limited (SIPL) have been well established. Comprised from Exploration activities, Drilling preparation, Field Development to Operation and Maintenance, Geomatics have played small but important contribution to company’s success so far.

© IPA, 2015 – 39th Annual Convention Proceedings, 2015

One of the notable application of Geomatics’ marine surveying techniques was shown during identification of plausible root cause(s) for the 2011 rupture of a 6 inch Gas injection pipeline in September 2011, in vicinity of Ujung Pangkah field. The infield pipeline connects existing platforms WHP-A and WHP-B, surpassing a sedimentologically active subaqueous ‘branch’ of the Ujung Pangkah Delta formed at the mouth of the Bengawan Solo River in Eastern Java. (Figure 1). Further investigations on site (excavation, visual inspection by divers and recovery of ruptured section) indicated that the line was ruptured at a distance of approximately 1.4 km from platform WHP-B. Pipeline Integrity means that the pipeline and all its related components are running properly. When pipelines are not operating properly, it poses a risk to public safety as well as company employees and other workers. Loss of pipeline integrity can result in leaks of crude oil or natural gas, which can negatively impact the public and the natural environment. (Canadian Energy Pipeline Association, CEPA, 2014). Maintaining Pipeline Integrity requiring proper design, proper installation and robust maintenance program. Design phase had been considered critical, where pipeline routes are chosen to minimize potential negative impacts in the future. It should be based on detailed bathymetry map and seabed stability survey, which can be obtained from marine surveying using multibeam echosounder. By comparing multi-temporal marine survey result (2008 and 2012 data), SIPL’s Operation team gaining valuable knowledge about the character of subaqueous delta between WHP-A and WHP-B. The area is subject to frequent mud flows forming a system of gullies and lobes. Sediment-laden flows relevant to the area involve pulsed mudflows caused by submarine slope failures and sustained turbidity flows caused by suspended sediment delivery from the Bengawan Solo River system (Fugro GeoConsulting Belgium, 2012). This knowledge will also be useful to evaluate the proposed design of pipeline replacement to connect gas lift from platform WHP B to WHP A. Maintenance program should include monitoring activities on and around pipelines, including social activity driven by economic growth of Ujung Pangkah and Gresik region. Problem was arise in 2014 when part of SIPL’s 9 kilometers long 20” Offshore Sales Gas Pipeline from OPF to PLN was

being subject to reclamation activity by local petrochemical firm (Figure 2). The reclamation activity soon will be followed by construction activity, so Pipeline’s Right of Way definition should be defined as soon as possible with external stake holders. SIPL’s Operations team reacted quickly by installing above-ground warning signs to clearly mark estimated pipeline rights of way to avoid worst possibility of active gas pipeline being piled during construction activities. Next task was to coordinate with Geomatics Group based in Jakarta to conduct land survey using Geo Penetrating Radar (GPR) technique to accurately locate the newly buried “Onshore” Sales Gas Pipeline to determine definitive right of way for the 1.40 km segment pipeline. The exact location of 20” Sales Gas Pipeline from OPF to PLN will be used as technical reference for further Right of Way definition with external stakeholders.

METHOD Marine surveying method using side scan sonar, sub-bottom profiler, multi beam echosounder (MBES) and single beam echosounder (SBES) was applied to capture seabed stability and geomorphology conditions at Ujung Pangkah site. The survey was done in 2008 and 2012 by PT Fugro Indonesia, using dedicated survey vessel equipped with differential global positioning system (DGPS). The site covers an area of seabed at between water depths of approximately 1 m and 30 m reduced to Lowest Astronomical Tide (LAT). The extent of 2008 and 2012 surveys is shown in (Figure 3). The MBES bathymetric data is resolute to a 1 m grid and covers the main delta front only, with acquisition of bathymetric data on the shallow delta shelf (less than 5 m bLAT water depth) carried out using low resolution SBES.

Spatial analysis method (overlay and subtraction) then applied to the high resolution gridded bathymetric data of 2008 and 2012, resulting new gridded information of net sediment deposition as result of seabed changes from 2008 to 2012 as describe in (Figure 4).

Land surveying technique using DGPS equipment, total station and GPR sensor was applied to determine exact location of buried 20” Sales Gas Pipeline (Figure 5). DGPS will be used to accurately measure the location of Bench Mark 1 (BM 1), BM 2 and BM 3 as reference stations. Total station will

be sit above each Bench Marks to accurately measure the beginning and ending point of GPR tracks. GPR works by sending a tiny pulse of energy into a material and recording the strength and the time required for the return of any reflected signal. A series of pulses over a single area make up what is called a scan. Reflections are produced whenever the energy pulse enters into a material with different electrical conduction properties or dielectric permittivity from the material it left (Figure 6). Exact surface location (Easting and Northing) of buried pipeline will be determined by interpolating the beginning and ending location of GPR tracks, while Depth of buried pipeline will be calculated using (Equation 1). Along with Intelligent Pigging Data, a recent high resolution World View Imagery, and relevant CAD drawing from surrounding firms, the result was subsequently plotted on a map. These critical information will be used for further Right of Way definition with local petrochemical firm and other external stakeholders around the Sales Gas Pipeline. A web-based Geographic Information System (GIS) was then used to visualize all relevant data gained from the above marine and land surveying activities. This tools was intended to be single source of information within SIPL internal stakeholder, and then used as technical reference for Ujung Pangkah Pipeline Integrity activities such as design and maintenance. RESULT Based on measured bathymetric data, the deltaic morphology between WHP B and WHP A is split into four zones as defined in (Figure 7). 2D image of 2012 combined MBES-SBES bathymetry color-coded according to seabed changes from 2008 to 2012, showing areas of net sediment deposition (green to yellow to red) and erosion (light to dark blue). The color map shows deposition thickness in meters. Existing and proposed pipeline routes are overlaid as black lines with markers at Kilometer Posts. Location of the 6”line rupture at KP 1.4 is indicated as a black arrow (Figure 8). The present-day seabed morphology of the site is dominated by the submarine delta that is prograding northward in a semi-radial manner at a rapid rate. In the shallowest section of the site (approximately 1.0 m to 5.0 m LAT), the Delta Shelf is present as an apparently flat, featureless subaqueous plateau,

defined by the slope break and incision of gullies at its northern periphery where the pro-delta begins. The slope of the pro-delta is gentle with an average slope gradient of 1.0° to 2.0° encompassing water depths down to approximately 30.0 m LAT where a transition is seen to the flat and mostly featureless outer delta. Between water depths of approximately 5 m and 15 m LAT, the pro-delta is apparently incised by six main gullies up to approximately 100.0 m wide and 3.0 m deep. Between water depths of approximately 15.0 m and 30.0 m LAT, many overlapping depositional sediment lobes are observed with relatively flat tops and steep angled sides. In between the gullies and lobes (Figure 9), areas of relatively smooth and flat seabed are present. Thalwegs of the various gullies have been mapped (Figure 10). A typical longitudinal profile along gully 3 (Figure 11, top-left panel) highlights a succession of relatively flat gully bases separated by short but steep steps in elevation, which are considered remnants of past failure events. The corresponding cross-sectional profiles (shown in (Figure 11), other panels) highlight three stages of gully development: the upper regions of the gullies (cross-section 3a) show a negative relief (relative incision) with respect to the inter-gully areas; the middle regions of gullies (cross-section 3b) also show a negative relief, but feature ribbons of positive relief on both side of the gully, characteristic of levees emplaced by mudflows overflowing the main gully and depositing sediments on the sides. The lower portions of the gullies (cross-section 3c) are associated with flat-topped depositional lobes emplaced by freezing of the decelerating mudflows The size of individual lobes varies substantially. Average surface area of individual lobes varies in the range of 11,000 to 48,000 m². Individual volumes averaged over each gully system are in the range of 42,000 to 131,000 m³. This corresponds to an average lobe deposit thickness in the order of 2 to 4 m (Table 1). Exact location plot of buried 20” Sales Gas Pipeline overlayed with Intelligent Pigging Data, a recent high resolution World View Imagery, and relevant CAD drawing of surrounding area is presented in (Figure 12). This web-based GIS application is published and accessible throughout SIPL intranet. CONCLUSION The assessment of the geomorphological conditions

at the Ujung Pangkah site highlights the large mobility of seabed sediment over the region of gullies and lobes, with a high level of activity observed within the inter survey period from 2008 to 2012. This fact confirming that the observed morphological features are associated with relatively frequent events occurring at present. The main conditioning and triggering factors for the slope instability that give rise to the slope failures is the rapid sediment accumulation rate across the delta, resulting in oversteepening and underconsolidation of very soft clay sediments. The proposed route for the new pipeline, which is shown to cross several active gullies near a region where they may be most active, is consequently considered highly risky in terms of geohazards. Rather than ultradeep (>5m) trenching which might be considered unpractical, alternative solutions for risk reduction strategies of the new line should consider rerouting. Two rerouting options that are considered worth a more detailed analysis, i.e. (1) rerouting to the North in deeper areas not subject to gully and lobe activity, (2) rerouting to the very shallow shelf area which is associated with milder seabed gradients and is not subject to gully incision. SIPL’s Operation team exercised the 1st option. The replacement pipeline have been built and operate safely since November 2012 (Figure 13). Pipeline integrity fails can result in leaks of crude oil or natural gas, which can negatively impact natural environment, public safety and company’s reputation. Harsh seabed condition combined with massive construction activities above certain

segment pose a real threat to Ujung Pangkah pipeline operability. Implementation of good Geomatics practices provide SIPL with better data to promote design and monitoring of Ujung Pangkah pipeline integrity. REFERENCES Canadian Energy Pipeline Association, 2014. Available at: http://www.cepa.com/about-pipelines/maintaining-safe-pipelines/pipeline-integrity (accessed 28 November 2014) Fugro Geoconsulting Belgium, 20012. 6”OD Gas Injection Pipeline Rupture Study, Ujung Pangkah, Indonesia. Report Number: C811, Dated 29th June 2012. Not Published. Paradis, Michel. 1981. "De l'arpentage à la géomatique". Le géomètre Canadien 35 (3): 262.

PT Fugro Indonesia, 2012. Seabed Stability and Geomorphology Survey at Ujung Pangkah Block, East Java Sea, Indonesia. Report Number: S2747, Dated 29th August 2012. Not Published.

PT Fugro Indonesia, 2008. Survey for Infield Flowline Routing From Proposed WHP-B Platform to Existing WHP-A Platform. Report Number: S2061-01 (03), Dated 21st July 2008. Not Published.

PT Mustika Paruh Anggang, 2014. Sales Gas Pipeline (SGP) As-Built Survey. Report Number: P083-SAE-GPR-MPA, Dated 4th December 2014. Not Published.

TABLE 1

THE SIZE OF INDIVIDUAL LOBES IN WESTERN PRO DELTA

Equation 1 - Formula to calculate Pipeline Depth using GPR data

Figure 1 - Location of Ujung Pangkah Delta, Gresik East Java

Figure 2 - Location of Sales Gas Pipeline, Gresik East Java

Figure 3 - Extent of 2008 and 2012 Marine Surveys

Figure 4 - Multi temporal data subtraction to calculate Net Sedimentation from 2008 to 2012

Figure 5 - Illustration of Land Surveying using GPS, Total Station and GPR instruments

Figure 6 - Sample of GPR Track cross line data interpretation

Figure 7 - Deltaic morphology between WHP B and WHP A

Figure 8 - Seabed changes from 2008 to 2012, showing areas of net sediment deposition (green to yellow to

red) and erosion (light to dark blue) in meters.

Figure 9 - Six main gullies up to approximately 100.0 m wide and 3.0 m deep

Figure 10 - Black lines indicate Thalwegs of the six gullies

Figure 11 - Cross section and longitudinal profile along gully 3

Figure 12 - Web-based GIS application accessible throughout SIPL intranet, showing plot of buried 20”

Sales Gas Pipeline overlayed with Intelligent Pigging Data, a recent high resolution World View Imagery, and relevant CAD drawing.

Figure 13 - As-built-drawing of the replacement Gas lift Pipelines from WHP B to WHP A, shown in yellow-

dotted symbol.