Controlling factor in Pliocene carbonate reservoir quality as key to - - PowerPoint PPT Presentation

Controlling factor in Pliocene carbonate reservoir quality as key to evaluate play chances: Case study from Mundu carbonate from South Madura strait - East Java

Maradona Mansyur*

AAPG GTW Bandung, September 2017

Today’s Agenda

• Studied area
• Mundu play in East Java
• Data, observation, and result
• Comparison to Miocene carbonate from East java
• Factors controlling reservoir porosity and Permeability
• Conclusions and recommendation

• Surface geology map combined with isopach of

tertiary sediment

• East – West trend of low and high

Studied area

Map edited from: Smyth, 2008; Waltham, 2008

Studied area

• North – South seismic transects from the studied

area

• Simplified wheeler reconstruction diagram
• Definition of Randublatung low and Kendeng

Studied area

Studied area

• Definition of Mundu
• Discussed interval, limitation and assumption

Discussed interval

Madura Bali/Lombok

Mundu play

• Documented Mundu discoveries
• Cumulative > 3.2 Trillion cubic feet discovered gas
• TER commercial

discovery made

• n 1983

followed by MD and SIRA

• Drilled on 2D

seismic

• Aggressive

exploration post 2001 after 3D seismic technology application

Data, observation, and result

• Mundu consist of > 85% foraminifera bioclasts
• Previously said to be pelagic rain deposit and

product of contourite

SANTOS 2017 8 |

• Compilation of

sedimentary structure found wave-tidal hydrodynamic association

• Collection of bioturbation

indicating shore-shelf likelihood

• Multi-grains composition:

swamp pollen/paly, lagoonal benthic forams, deepwater buliminids, encrusted coral and algae grains

SANTOS 2017 9 |

Data, observation, and result

• Excellent reservoir

consist of granules clast with sand-silt carbonate matrix

• Very-good reservoir

composed of granules- coarse sand grain with silt carbonate matrix

• Less quality reservoir

made by finer grain sand grain with silt carbonate matrix, cemented

1 mm 1 mm 1 mm

Field close to Madura Field close to shelf-slope break

Data, observation, and result

• Macro –meso and

micro pore connection supporting the permeability

• Enabled due to the

intraparticle- interparticle porosity connection through foraminifera test open punctae

• Clogged punctae

associated with cement development and clay appearances

Data, observation, and result

• Compiled porosity versus permeability data from 12

field producing from Mundu

• Total 1008 core plug data and 257 thin section slides

The best Mundu limestone reservoir belong to coarse grainstone, with minor cementation, minor clay minerals, and less bioturbated

Data, observation, and result

Modern day foram data from: Mahyar Mohtadi et.al., 2008 Ancient carbonate data from: Dicky Hehakaya, 2017

• Stable isotopes plot modern day foraminifera vs

ancient carbonate

• Modern day data indicate tropical seawater
• Contrast Carbon-

Oxygen isotopes signature

• Modern day data

indicate carbonate grains not yet through diagenesis process

• Ancient carbonate from

Kujung indicate an extensively karstified carbonate grains

Modern day foram data from: Mahyar Mohtadi et.al., 2008 Ancient carbonate data from: Dicky Hehakaya, 2017 Data from this study from: OY ( R.Tampubolon, 2016) & ME field

Mundu Vs. Oligocene/Miocene Carbonate

• Stable isotopes from Mundu occupy the same field

with modern day foraminifera from Indonesia water

• Variation on oxygen indicate water temperature
• Mundu Carbon-Oxygen

isotopes indicate no/minor diagenesis takes place at the reservoir zone.

• Diagenesis shutdown

due to no diagenesis cross-fluid exchange during burial.

• Indicating very early

hydrocarbon filling to reservoir.

Depositional mechanism

Depositional setup during deposition

A A’

• East-West 3D seismic

transect from studied area controlled with borehole biostratigraphy

• Mundu deposited

during an extensive transgressive time

• Deposition from time to

time always associated with shelf-slope topography

Susanto, Mitnik & Zhang, 2005

Depositional setup during deposition

• Internal wave from Bali – Lombok strait
• Occur due to densely stratified water flowing

through rough and shallow barier

• Internal waves occur

within subsurface layer

• f ocean with dense

stratification

• Disturbance occur

when the dense water flow passing over shallow underwater

• bstacles such; sill

(guyot) or shallow ridge

• The disturbance

causing body of water with shore wave and tidal attitude

Observed internal wave locality from Java to Flores

Echogram image SAR image

Depositional model: process and product

Mixed layer interval Deeper water interval

• Internal waves flow hit the shelf break and

depositing the high density plankton in water.

• Tide and waves generated by the interlayer

disturbance winnowed the deposited sediment.

• Disturbance also generate canyon/buttress zone,

where the un-winnowed sediment flow following gravity differences (canyon-subsea channel features

• Mundu reservoir quality is strongly controlled by the sorting process and the

diagenesis shutdown

• New term : Internalites deposit differ from conventional contourites
• New exploration paradigm where unexplored area waiting for new 3D seismic

and further exploration drilling aiming at internalites deposit off-shore Bali Flores

Conclusion and recommendation

Observed internal wave locality from Java to Flores

Acknowledgement

• Santos (Sampang) Pty.Ltd, colleagues, and managements
• Prof. John Keith Warren, Ricky Tampubolon, and Dicky Hehakaya from

Chulalongkorn University

• Prof. Ian Cartwright from Monash University

THANK YOU