Malampaya work

Dr Cathy Hollis

Carbonate Depositional Systems – Malampaya, Philippines

EART 20020 Integrated Subsurface Description 2013-2014

Jahanzeb Ahsan 8529193

5-9-2014

TABLE OF CONTENTS

ASSIGNMENTS ........................................................................................................................................ 1-7

ASSIGNMENT 1 ............................................................................................................................................. 1

ASSIGNMENT 2 ............................................................................................................................................ 3

ASSIGNMENT 3 ............................................................................................................................................ 6

REPORT ON MALAMPAYA GAS FIELD .............................................................................................. 8

REFRENCES ...............................................................................................................................................10

Assignment 1

Land and Sea configuration for Miocene

Most of Asia, parts of American continents e.g. Florida and Europe were covered in sea water. This age was the initial step for cooling trend before the Earth’s

temperature dropped sharply (Middle Miocene Climate Transition). Antarctica was smaller than it is today. Most of the continents and land masses were covered in

water – Figure 1.

Black Sea, Mediterranean Sea and Persian Gulf were interconnected in Miocene age. The Red Sea was smaller than it is today and was blocked from Arabian Sea. The

sea level fluctuation is shown below.

Climate information for Miocene

Climate during this time was generally like today but relative to today it was warm. Western Asia was mostly

wet, and warm i.e. tropical climate. North and South poles were cold but not as it is today, as glacification

occurred from in Middle Miocene about 14.8 to 14.5 Ma. Region near equator were tropical. Further from

equator it became arid and warm before getting cool to cold towards North and South Pole as shown in

Figure 2.

Conclusion

The warm Tropical climate, relative low sea level (fluctuating), abundant sun light – closeness to equator,

and moderate to low clast input at the region of Malampaya field at that time were perfect for the carbonates

to form. The tectonic plate movement as can be seen by the attached pictures in this assignment suggest

optimum conditions for Malampaya/Nido carbonate reservoir to develop.

Relative sea level history of Malampaya field. From Grotsch

and Mecandier (1999)

1

Philippines

2

Assignment 2

Attach the work done scanned.

3

Pagasa clastic

Pre-Nido clastic

4

Low porosity – Black High porosity – red

5

Assignment 3

Ma-1 and Ma-5 share same lithofacies, but the time and space varies due to depositional processes and factors varied on both sides of the formation due to one being

on land-ward side and the other at sea-ward sides. Ma-2 do not have early Miocene deposit.

The Malampaya field consist of high porosity and low porosity zones subsiding each other, mainly carbonates.

All of the

samples

were

collected

from side

wall

No cores

recorded

Mixture of cores and side wall samples to identify the facies, for Ma-5 and Ma-2

Nido carbonates are divided into 11 units by Fournier, et al. 2005.

Intra-Nido

6

Pagasa clastics

Increase in water saturation: Sw

increasing downwards.

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Name: Jahanzeb Ahsan Integrated Subsurface techniques ID: 8529193

1. Cenozoic Carbonate Systems of Australasia edited by Andrew Morgan.

Carbonate Depositional Systems – Malampaya,

Philippines

Malampaya is carbonate based offshore gas field located north west of

Palawan Island, Philippines. The usual sea depth ranges from 850 to 900

meters, discovered in 1989 contains generous volume of gas of up to 650

meters. Under this is an oil border of about 56 meters1 which is primarily

Oligocene – Miocene. In past years many authors have discussed Malampaya

in detail e.g. Fournier et al. (2004, 2005). The architecture of the reservoir

is complex relative to other carbonate reservoirs. Gas from Malampaya is

used to generate electricity – pipelines covering a distance of 534 km from

wells to land. There are 23 contract areas covering an area of about

112,000 km2 of which 85 % is in deep water.

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Malampaya gas field is based on Nido limestone. The source

rock having deep-water lithofacies (marl and deep water

carbonates) is in South west Palawan are Cretaceous pre-rift

unit Paleocene to early Oligocene Synrift section. The average

total organic carbon is about 1.8 % TOC. The sync-rift unit (i.e.

Paleogene) is deep marine Shale and marl with average of 1.3

% TOC. Followed by source is reservoir which is Oligo-Miocene

carbonate at approx. 3000 m TVDSS (deep-water) as well

(average porosity of 25 %). The seal is provided by Bathyal shale

(Pagasa) and trap is stratiographic anticline.

Stochastic stratiographic well correlation method is used for

Malampaya build-up. Out of 10 wells seven are cored and a high

resolution 3D seismic survey (by shell in 2002 – increased the

vertical resolution from 80m to 50m and reduction in noise

within the reservoir). Correlation of well data is used to study

diagenetic units as previous studies emphasized rock properties

are controlled by diagenesis. Correlation rules – Stratigraphic

(Fourier & Borgomano, 2007):

1. Two units are correlated if they are of same diagenetic

type.

2. If they display a similar well log pattern.

In case of lithostratigraphic correlation there should be no

distortion in the signal and sedimentary record is presumed to

be complete that is, there no erosion on the considered

stratigraphic unit. Another method by Flang et al. (1992) is used

in which well logs are converted into simple patterns. Figure 2

shows section of diagenetic units made from stratigraphic

correlations computed by recommended algorithm.

Depostion of Nido limestone happened at the edge of sloped

block as a result of rifting phase of the China sea (Fournier et

al. (2005). The reservior is made from reef related Nido

carbonate and reefal Miocene reefal limestone.The Nido

carbonate was deposited during the drifting stage during

Oligocene-Early Miocene (Clyde H. Moore, William J.Wade, et

al. 2013). The north-west was oceanic margin and south-west

land margin – eastern basin. There is ample evidence of reef

debris where oceanic margin reside – reef environment

dominat. North-East to South-West reefal (Nido Limestone)

was controlled by the rift fault system under the Nido

Limestone.

Figure 1. (A) Trap (B) Seal (C) Reservoir (D) Basement – clastic. (Source: Department of Energy, Philippines). NOT TO SCALE.

C

A

B

Figure 2. Stratigraphic correlation. Reference well MA-1, 2 and 5. (Source: F. LALLIER et al.).

Mantinloc

Pagasa

Nido

Pre-Nido

D

Oceanward margin Drowning Succession Landward margin

Aggradation

Backstepping

Figure 3. Malampaya depositional model. (Source: Grötsch and Mercadier, et al.2009).

D

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According to Fournier & Borgomano (2007), the reservoir in

Malampaya was mainly controlled by diagenetic processes which

he classified into five types namely Ia, Ib, II, IIIa and IIIb – shown in

figure 4. Figure 4 shows well to seismic correlation, along with

diagenetic units, offering geobodies described by reservoir

properties and particular pore type. Porosity of each diagenetic

unit is shown below in figure 5.

The permeability of Malampaya gas field is reasonably well which

can be seen clearly in figure 6 below.

Carbonate reservoir are the most abundant and significant

hydrocarbon reservoirs in the world and many exist in South-

East Asia. Sometime many features are similar between the

reservoirs of same kind, but differences such as bio-marker and

content of individual gas/oil may vary. The summary of

comparison Malampaya with two other gas field by Fournier &

Borgomano, 2007) is shown in figure 8 on the next page. The

table suggest that the three fields share many common features

such as lithofacies, dominant biological components porosity

and etc. The petrophysical properties are controlled by

secondary porosity (Fournier & Borgomano, 2006). Difference

between the compared cases is acoustic contrast between the

lithological and diagenetic units.

It is difficult to categorize carbonate reservoir, mainly due to

heterogeneity. The recovery factor of all oil fields is about 35 %

but it’s a fact that recovery factor of carbonate gas reservoir is

lower than that of sandstone. Sand can travel a great distance

and deposit in another place far from its origin whereas

carbonate are locally formed close to their origin. Sand is less

reactive to chemical reactions whereas carbonates are bound

to react hence their initial porosity and permeability is high

(35% to 75%), but decrease sharply as sediments are altered

and depth of burial increase plus diagenesis. Heterogeneity in

Malampaya reservoir exist at all levels.

In most carbonate reservoir like Malampaya the rock matrix

holds the hydrocarbon, whilst fractures often provide main flow

paths. In fact the E11 offshore Malaysia share almost similar

shape, nearly shape porosity, age, constituents and

aggradational zones that leads to final drowning [William

Andrew Morgan, 2010]. More details for E11 and its comparison

is shown by Andrew Morgan et. al 2010.

Malampaya is one of the most studied and well documented

carbonate reservoir. Core analysis, seismic imaging, well

correlations, laboratory tests and use of analogues have been

performed on Malampaya to understand it better. Though

there is little that can be further done on Malampaya analysis

uncertainty at micro and macro level can still exist. Few other

types of tests that can be done may include: Soil sampling, in-

situ tests such as cone penetrometering and Electromagnetic.

Figure 4. Stratigraphic Model (Source: Fournier & Borgomano, 2007).

MA-3 MA-9 MA-4 MA-6 MA-7 MA-5 MA-8

Rudstone/reef debris or uppermost karst Rudstone-grainstone intermediate reef debris Grainstone-wackestone Cemented/dense layers “intra Nido” unit Cemented reef/slope Cemented slope

Figure 6. Source Shell

Figure 5. Histogram of acoustic impedance and porosity (Source: Fournier & Borgomano, 2007).

Quartz rich packestone Grainstone

Packestone to floatstone Wackestone to packstone

Packstone to floatstone

% Porosity

Figure 7. Porosity in depth v/s lateral distance (Source: Seismic imaging of carbonate reservoirs and systems: AAPG Memoir 81,

page 181).

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Figure 8. Comparison of Malampaya, Luihua and Luconia

References

Dancer, N. & B.V, S. P., n.d. Reservoir Characterisation of the Malampaya Field, a Carbonate ReefalBuild-up in the Philippines. s.l.:s.n.

Department of Energy, Philippines, n.d. Department of Energy. [Online]

Available at: http://www.doe.gov.ph/microsites/archives/win_opp/cd/SPEX/Malampaya%20Subsurface.pdf

[Accessed 11 April 2014].

Lallier, F. et al., 2012. Relevance of the stochastic stratigraphic well correlation approach for the study of complex carbonate settings:

Application to the Malampaya buildup (Offshore). In: Advances in Carbonate Exploration. s.l.:The Geological Society London.

Moore, C. H., 2001. In: CARBONATE RESERVOIRS: POROSITY, EVOLUTION & DIAGENESIS IN A SEQUENCE STRATIGRAPHIC FRAMEWORK:

Porosity Evolution and Diagenesis in a Sequence Stratigraphic Framework. s.l.:Elsevier, pp. 376-379.

Moore, C. H. & Wade, W. J., 20013. Carbonate Reservoirs: Porosity and diagenesis in a sequence stratigraphic framework. s.l.:Newnes.

Neuhaus, D. J. B., Jauffred, J.-C. & C. Mercadier, S. O. a. J. G., 2004. Quantitative seismic reservoir characterization of an Oligocene – Miocene.

Seismic imaging of carbonate reservoirs and systems: AAPG Memoir 81, pp. 169-183.

Otto Energy Limited, 2008. Offhore Philippines Farm-in Opportunities. [Online]

Available at: http://www.asx.com.au/asxpdf/20080407/pdf/318fp2f340flnx.pdf


PNOC Exploration Corporation, n.d. The South East Asia Petroleum Exploration Society. [Online]

Available at: http://www.seapex.org/farmout_files/9956_sc632011seapexfarm-out.pdf


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Engineering

Malampaya work