spatial data integrity behind sis a #1 wild cat exploration discovery

8/20/2019 SPATIAL DATA INTEGRITY BEHIND SIS A #1 WILD CAT EXPLORATION DISCOVERY

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PROCEEDING OF THE INDONESIAN ASSOCIATION OF GEOLOGISTS CONVENTION JCB 2015

HAGI-IAGI Joint Convention, Balikpapan October 5-8, 2015

SPATIAL DATA INTEGRITY BEHIND SIS A #1 WILD CAT EXPLORATION DISCOVERY

Yudi Syahnur – Sr Geomatics Engineer, PT Saka Indonesia Sesulu

Keywords: Spatial Data, Geomatics, Exploration

ABSTRACT

Spatial Data, also known as geospatial data, is information about a physical object that can be

represented by numerical values in a geographic or projected coordinate system (Surve & Kathane,

2014). Conceptually, Spatial Data can be described as Points, Lines, Areas, Surfaces or Volumes thatare connected to a place in the Earth. It is estimated that more than 90% data and information used

in Energy Sector is spatially referenced. From Block concession to Seismic lines to Well data, they all

pertaining to specific geographic location.

Science and technology to collect, process, manage, analyze and display geospatial data and

information defined as Geomatics. It includes the tools and techniques used in land and marine

surveying, remote sensing, cartography, geographic information systems (GIS), global navigation

satellite systems (GNNS).

Since 1990's Oil and Gas companies have been using Global Positioning System (GPS), as well as

airborne and space observation remote sensing technologies to effectively find hydrocarbon. Marine

surveying techniques have been extensively used to perform comprehensive Geohazard study prior

to offshore drilling activities. Up until now, more and more oil and gas companies use Geographic

Information System (GIS) to help extracting hydrocarbon in a more efficient manner.

Since the PSC signing in May 2009 Geomatics have been integral part of South Sesulu Exploration

activites, located in the most southern part of Kutei Basin. From planning and execution of 550 km

square 3D Seismic Survey to Jackup Rig positioning activity, this paper will illustrate the importance

of Spatial Data Integrity behind the SIS A #1 Gas discovery.

Spatial Data Integrity ensure oil companies working in a safe and efficient manner. It allows people

from multi-discipline and different backgrounds to collaborate easily, and then contribute to the

success of South Sesulu Block PSC Exploration activities.



INTRODUCTION

Spatial Data can be describes as information that identifies the geographic location of features and

boundaries on Earth, such as natural or constructed features, oceans, and more. Conceptually,

Spatial Data can be described as Points, Lines, Areas, Surfaces or Volumes that are connected to a

place in the Earth. It is estimated that more than 90% data and information used in Energy Sector is

spatially referenced. From Block concession to Seismic lines to Well data, they all pertaining tospecific geographic location (Figure 1)

Figure 1. Typical spatial data and information related to Oil and Gas Industry (Chandrasekhar , 2013)

In recent years, Spatial Data representation have evolved from sets of hardcopy maps into layers of

thematic information stored in digital database. Based on the structure, they are divide into 2 type

namely Vector and Raster. Vector data have better location accuracy and also less voluminous. But

Raster data have more superior appearances and also ideal to represent continuous data over a largearea. Different types of description and Spatial Data is presented in Figure 2.

Figure 2. Different types and descriptions of Spatial Data



Sources of Spatial Data can be varied. The first option (and arguably cost-effective) is to extract

internally –owned existing Spatial Data. Most commonly source is from old hardcopy maps published

by Authorities/Mapping Agencies that area being scanned, georefferenced and then digitized using

specialized software. Other option is import georefferenced coordinate points from other thematic

tabular information or databases. But whenever Spatial Data is not yet exist, the last option is to

conduct new survey or acquire spatial data from external data provider.

Science and technology to collect, process, manage, analyze and display Spatial Data and information

is known as Geomatics (Figure 3). 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).

Figure 3. Science and technology to collect, process, manage, analyze and display Spatial Data

The added value of Geomatics to the E&P business lies in the assurance of the integrity of spatial

data and the mitigation of the associated risks resulting from potential Integrity violations. And

Spatial Data Integrity should be able to return reliable and accurate position, and retrieve all the

information required within 7-10 years’ time period of the E&P life circle (Figure 4).



Figure 4. Geomatics activities within Oil and Gas life-cycle (modified after Whitcombe, 2006)

Spatial Data is expressed explicitly via the use of Coordinate Reference System (CRS), but inadequate

control of these CRS can lead to potentially serious risks for business, reputation, and Health, Safety

& Environment (OGP, 2008). In most cases, spatial integrity failures arise from incorrect assumptions,

poor or non-existent labelling of coordinates or a lack of awareness of the geodetic complexities.

Many individuals are not aware for instance, that latitude and longitude are not unique.

Furthermore, International Association of Oil and Gas Producer in 2008 drawn a list consist of

implications of what can go wrong when geodetic issues are not given due diligence. The list is shown

on table 1 below.

Operation Scenario Root Cause Business Impact

Seismic Interpretation Whilst merging two separate

3D seismic datasets observed

on different CRS, a

cumulative error was made

of 250 m due to incorrect

and coordinate

transformations.

Lack of knowledge of the

proper transformation

method.

Use of different geology

and geophysics (G&G)

software packages that

did not handle CRS data

properly.

Lack of quality control

(QC).

• Resources spent on

investigating error.

• Expensive

reprocessing which

took 3 months.

•

Knock on effect on

subsequent

operations e.g well

planning or drilling

sequence.

Jack-up Rig Positioning During a rig move in theNorth Sea. The surveyor

went off shift, leaving his

engineer to look after the

navigation. The engineer did

familiarize himself with the

software, but didn’t realize

he had inadvertently

changed the reference

•

The projected gridcoordinates generated by

the navigation software

were incorrect.

• By selecting the wrong

ellipsoid, the software

generated incorrect

geographical and

•

Rig 1.5 km offlocation, in another

company’s block.

•

Anchor handling

vessels recalled to

site.

• Rig had to be

repositioned.

• Cost: $750,000.



ellipsoid. Surveyor arrived

back on shift whilst

approaching location,

navigation appeared fine so

rig was positioned and

moored up accordingly.

Radar checks on a localplatform revealed

inconsistent positions.

The wrong ellipsoid had been

used i.e Everest was applied

instead of International.

subsequently the wrong

grid coordinates.

•

No offshore survey

representative present

to perform relevant QC.

• Reputation issues.

• Government reviewed

license arrangements.

Facility Construction A proposed position for a

new subsea manifold was

issued via an E&P operator

on the ED50 datum. The

Subsea Installation

contractor wrongly assumed

that these coordinates wererelated to the WGS84 datum

and positioned accordingly.

The pile driven manifold was

therefore positioned 136

meters away from the

intended location.

Error only discovered when a

pre-lay survey vessel did not

find the manifold in the

expected position.

• Incorrect assumptions

were made (common

geodetic problem).

•

The CRS was not properly

identified.

• European Petroleum

Survey Group (EPSG)codes were not used to

identify the two CRS

systems.

• No offshore survey

representative present.

•

Staff not competent to

perform task i.e had not

received correct

awareness training

• Significant delay to

project.

• Re-routing of pipeline

approach.

• Reputation issues with

government &

environmental bodies.•

Contract dispute with

installation

contractor.

• Contract Variation

issued at as cost of

$500,000.

Table 1. List of implications of what can go wrong due to spatial integrity failures (modified after

International Association of Oil and Gas Producer , 2008)

Since the PSC signing in May 2009, Geomatics have been integral part of South Sesulu Exploration

activities. From basin and play assessment, planning and execution of 550 km square 3D Seismic

Survey to Jackup Rig positioning activity, this paper will illustrate the importance of Spatial Data

Integrity behind the SIS A #1 Gas discovery. This paper will also describe how Spatial Data Integrity

have played small but critical roles during exploration phases of South Sesulu PSC.

BASIN AND PLAY ASSESMENT

At the time when South Sesulu PSC was signed on May 2009 by previous operator, Play Based

Exploration (PBE) approach was extensively used to effectively and efficiently run its petroleum play

assessment. PBE is an evaluation process to arrive at an understanding of the fundamental logic of

Hidrocarbon plays, as a sound technical basis for ranking and prioritizing all exploration projects and

activities (de Jager , 2014).



PBE simply a method to build and leverage an understanding of the basins and petroleum systems

in which a company works, and the geological plays they contain. The benefits lie in providing better

early Focus to a range of exploration activities.

The PBE methodology is encapsulated in the “Exploration Pyramid: Basin-Play-Prospect”, where the

initial focus is on the basics - the determination and description of the regional context and the basinframework leading to an understanding of the working petroleum system(s). Petroleum system

understanding forms the basis for the subsequent play focus - quantifying the various aspects of the

system within each play, and using tools such as common risk segment mapping to highlight sweet

spots within each play.

Geographic Information System (GIS) tools was extensively used to create Charge, Reservoir and Seal

Common Risk Segment (CRS) maps using advance Spatial Analysis techniques (Exprodat , 2013). GIS

tools was also being deployed to validate play chance maps against post-well results (Figure 5),

analyses basin activity over time, analyze basin and play volume statistics, create creaming curves,

and estimate yet-to-find (YTF) or undiscovered reserves.

Figure 4. CRS Map of Mid Miocene Clastics Play (Putrohari , 2012)

When the plays have been mapped and where possible, quantified, then the focus shifts again to use

more detailed geological and geophysical analysis to define prospects within each play, and build the

portfolio. It’s including making estimates of volumetrics, risk and uncertainty. It was concluded that

the main risk for generated prospects at South Sesulu PSC was Source (Charging), while

Reservoir/Trap deemed as moderate risk.

3D SEISMIC SURVEY

3D seismic mapping is crucial to better understand the lead structures and analogues to adjacent

discovery fields, as well as reduce risk and uncertainty for drilling. 3D seismic inversion and sequence

stratigraphy may also help in further understanding of the reservoir distribution.



Previous operator conducted 3D seismic survey for a duration of 3 weeks in October 2010. It’s

covered a 580 km2 area on a relatively shallow water depth between 32 to 65 meters below MSL

(Figure 5), with shallow target around 1200ms. The survey using 6 streamers @ 4 km long each, with

75 m streamer separation lowered to 6 meters below sea line. Common Mid-Point (CMP) Bin size is

18.75 x 6 m.

Figure 5. South Sesulu 3D Seismic Area of Interest (Setiawan, 2010)

From Spatial Data Integrity point of view, Seismic Survey is arguably the most important one as the

Navigation Data will be used as main spatial reference for further Exploration and Production

activities within South Sesulu PSC. The quality and reliability of the seismic navigation data will

directly impact on the ability to accurately relate the physical of a well location to the geophysical

interpretation.

Surveys that have been poorly specified, inadequately quality controlled or where there is

insufficient information available to quantify the accuracy of the data, are all potential error sources

and may not be suitable to support detailed well planning (OGP, 2006). The verification of Coordinate

Reference System (CRS), geodetic parameters, bin grid definition and so on should always be by

comparison to original source material, for example: acquisition, QC and processing report; UKOOA

P1, P2 and P6 format files.

All navigation data acquired during South Sesulu 3D Seismic survey was using Real Time Differential

Global Positioning System (DGPS), thus WGS 1984 datum was chosen as geodetic reference.

Meanwhile Universal Transverse Mercator (UTM) Zone 50 South was defined as projected

coordinate system.

Prior to loading seismic data to a workstation, the following check should be made to ensure Spatial

Data Integrity of seismic interpretation (OGP, 2006):

•

Verify the CRS of the data to be loaded against the acquisition parameters, and ensure that

this is identical to the project, license or country data that the data relates to.

• Verify the CRS definition in the input project database is correct.



•

For 3D surveys; verify the bin grid definition against the acquisition parameters.

•

If transformation of geodetic datum is required; verify that the coordinates have been

correctly transformed.

• If the positioning data is to be loaded from SEG Y header; verify that the positions and extent

of the lines correspond exactly to the UKOOA P1 data.

•

Verify the geographic location and inter-relationships of the seismic data after loading (e.g.by comparison with SP base maps, remote sensing images, etc.)

ACREAGE RELINQUISHMENT

As part of PSC agreement, at the end of 3rd year, 25% of working area should be relinquished. Due to

delays on SIS A #1 drilling (initial program was scheduled in Q1 2013), Saka should bear penalty of

another 15% relinquishment of working area on May 5th 2013. Final 40% relinquishment was

commenced on May 5th 2015, at the end of 6th year since PSC signing. This final relinquishment is

mandatory for additional 4 years of “Penambahan Jangka waktu Eksplorasi” (PJWE). The history of

South Sesulu PSC acreage is shown in Figure 6.

Figure 6. South Sesulu PSC relinquishment history 2009-2015 (Syahnur , 2015)

Relinquishment should be done as accurate as possible, as Ditjen Migas required relinquishment

points to be presented in degree-minute unit. Use of 1’x1’ grid would be very helpful to accurately

locate the points and to optimize retained acreage. Coordinate transformation from Geographic

(Longitude, Latitude) to Projected UTM zone 50 S vice-versa should be done with extra cautions, sothat acreage calculation result is consistent with PSC contract document. Use of GIS software that

support on-the-fly projection and transformation is highly recommended to ensure the spatial

integrity of all relinquishment points.



DRILLING PREPARATION

Offshore drilling activity have been relies heavily on spatial data integrity for decades. Offshore

drilling site preparation requires hazard site surveys consist of geophysical and hydrographic site

surveys of proposed offshore well locations. And later on Real-time Differential Global Positioning

System (DGPS) technology will be utilized to accurately guide Mobile Offshore Drilling Units (MODUs)

to the intended drilling location.

Site surveys are performed to minimize the risk of harm to personnel and equipment, and to protect

the natural environment. The objective of any site survey is to identify all possible constraints and

hazards from man-made, natural and geological features which may affect the operational or

environmental integrity of a proposed drilling operation, and to allow appropriate operational

practices to be put in place to mitigate any risks identified (OGP, 2011).

Any site survey must include a review of all seafloor conditions and geology to a depth at least 200m

below the preferred setting depth of the first pressure containment string, or to a depth of 1000m

below seabed, whichever is greater. In addition, the proposed site survey area should be of adequatecoverage to plan any potential relief well locations, and provide sufficient data to fully assess

potential top-hole drilling hazards at these locations.

The site survey report should include a discussion of all relevant geological and/or man-made

features that have a direct bearing on operational risk. Table 2 consist of a list of conditions to be

addressed by a marine site survey, composed by International Association of Oil and Gas Producer

in 20011.

Man-made features Natural seabed features Subsurface geological features

•Platforms: active, abandoned,

or toppled

• Pipelines: on or buried below

the seabed

• Power and umbilical lines

• Communications cables

• Wellheads and abandoned

well locations

• Manifolds and templates

• Pipeline terminations, valvesand protection frames

• Subsea isolation valves

• Rock dumps

• Scour protection material

• Jack-up rig footprints

• Seabed topography and relief

• Seafloor sediments

•Sand: banks, waves, and

mega-ripples

•Mud:flows, gullies, volcanoes,

lumps, lobes

• Fault escarpments

• Diapiric structures

• Gas vents and pockmarks

• Unstable slopes • Slumps

• Collapse features

• Fluid expulsion features

•Chemosynthetic communities

• Gas hydrate mounds

• Sedimentary sequences

• Stratigraphy

• Shallow gas charged intervals

• Gas chimneys

• Shallow water flow zones

• Over-pressure zones

• Buried infilled channels

• Boulder beds

•Buried slumps and mass

transport complexes•Gas Hydrate zones and

hydrated soils

• Faults

•Erosion and truncation

surfaces



• Non-oil & gas infrastructure

such as navigation buoys,

wind turbines etc.

• Shipwrecks

•Ordnance and chemical

dumping grounds

• Archaeological remains

• Miscellaneous debris

• Rock outcrops, pinnacles and

boulders

• Reefs

• Hard grounds

• Seabed channels and scours

•Salt or mud diapirs and

diatremes

Table 2. Examples of site survey results, presented in thematic spatial data (modified after

International Association of Oil and Gas Producer , 2011)

Saka conducted South Sesulu SIS-A site surveys survey for a duration of 10 days in August 2014. It’s

covered a 12 km2 area on a relatively shallow water depth between 34 to 62 meters below MSL. The

site survey consist of analog geophysical survey (Sub Botttom Profiler, Multibeam Echo Sounder and

Side Scan Sonar) and digital geophysical survey also known as 2D High Resolution seismic for a total120 km long using 600 m long streamer and 48 channel receiver (Figure 7).

Figure 7. Illustration of SIS-A Site Survey activities in 2014 (MGS, 2014)

The survey successfully provided Saka with valuable information regarding Seabed features aroundSIS-A prospects, as well as the latest Shallow and Intermediate Zone Geology, Anchoring and Top

Hole conditions (Figure 8). Detailed bathymetry data also confirm the water depth of SIS-A #1

location is more than 50 meter, thus ex-situ dumping permit would not be needed.



Figure 8. Results of SIS-A Site Survey: Seabed features (top-left); Shallow geology profile (top-right);

bathymetry (bottom-right); shallow gas hazard potential (bottom-left) (MGS, 2014)

Based on site survey assessment and soil boring investigation, the proposed SIS-A #1 drilling location

was then considered safe. With regards to water depth, Jack Up drilling rig was deemed suitable for

drilling operation. Once again Real Time Differential Global Positioning System (DGPS) method was

employed in the rig positioning.

DGPS result was subsequently displayed on monitor, overlaid with the proposed SIS-A #1 drilling

location and the intended rig heading. This system allows rig mover to adjust direction and speed of

tug boats in order to positioned drill stem as close as possible to the intended SIS-A #1 drilling

location (Figure 9). Rowan Gorilla II was finally well positioned for drilling operation, with accuracy

of 1.8 meter to intended location and rig heading of 122° 28’.

Figure 9. DGPS provide rig mover with real time rig position and heading



CONCLUTION AND RECOMMENDATION

Spatial Data Integrity have been well established during South Sesulu Exploration activities,

culminated by SIS-A #1 gas discovery. From 3D seismic to rig positioning, Spatial Data Integrity have

played small but critical roles to South Sesulu Exploration activities. It may not be the key factor to

the finding of a working petroleum system, but it certainly help to eliminate uncertainty with regards

to spatial aspect in every phase of exploration activities.

Geographic Information System (GIS) have been widely used as main tools to maintain Spatial Data

Integrity. It is time to leveraging the capabilities of GIS system owned by companies by implementing

industry standard for storing and managing oil and gas spatial data such as OGP P6/11 for seismic

bin grid exchange format or OGP SSDM (Seabed Survey Data Model) for site survey data. By

implement this industry standard, spatial data integrity within company can be managed in more

consistent and easy manner.

REFERENCES

Chandrasekhar, T. 2013. Geospatial Data Management BP North America Gas. DMS Presentation

Material. Not Published.

De Jager, J. 2014. Play-based Exploration. Course Material. PetroEdge Singapore.

Exprodat. 2013. Petroleum Play Assessment and Play Based Exploration. Available at:

http://www.exprodat.com/Software/TGEA/ (accessed 15 December 2013)

International Organization of Oil and Gas Producer (OGP), 2006. Surveying & PositioningGuidance note 16- Quality Control of Proposed Well Co-ordinates. Available at:

http://info.ogp.org.uk/geodesy/ (accessed 28 November 2014)

International Organization of Oil and Gas Producer (OGP), 2008. Surveying & Positioning Guidance

note 1-Geodetic awareness guidance note. Available at:


International Organization of Oil and Gas Producer (OGP), 2011. Surveying & Positioning

Guidance note 18-

Guidelines for the conduct of offshore drilling hazard site surveys. Available at:


Putrohari, R.D. 2012. Hess ELT South Sesulu. Presentation Material. Not Published.

Setiawan, D. 2010. 3D Seismic Survey Hess (Indonesia -South Sesulu) Ltd & Western Geco.

Presentation Material. Not Published.



Surve & Kathane. 2014. “Disparity of Spatial and Non Spatial Data”. International Journal of Advance

Foundation and Research in Computer (IJAFRC) Volume 1, Issue 8, August2014. ISSN 2348 - 4853 35

(3): 262.

PT Mahakarya Geo Survey, 2014. Analogue and Digital Geophysical Site Survey For Proposed SIS-A

Well Location, South Sesulu Makassar Strait Indonesia. Report Number: MGS-R/228/14/SS-01, Dated

13th September 2014. Not Published.

Whitcombe, D. 2006. An Overview of Geomatics Involvement in the Offshore Oil & Gas Industry.

Hydro Fest Presentation Material. Not Published.

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