Gng Report

7/25/2019 Gng Report

1/16

2.1 SUMMARY OF THE GELAMA MERAH FIELD

Geological Area : Sabah Basin

Area : Offshore Sabah

Country : Malaysia

Reservoir Structure : Anticlines

Coordinate : Longitude 114 !"# $%&'4#(

: Latitude $! ''# 4"&")#*

+y,e of -ield : Oil and gas

2.2 INTRODUCTION

2.2.1 REGIONAL SETTING

Gela.a Merah field is located in the offshore of Sabah Basin& /t 0as believed that the

field is located nearby the Se.arang Asa. aya roduction Sharing Contract 0hich in (ast

Malaysia at Sabah offshore& +his field 0hich is about 4! .iles 235.6 north0est of theLabuan Gas +er.inal is surrounded by shallo0 reed 0ith the 0ater de,th of '$ feet 2".6&

+he location of the Gela.a Merah field is sho0n in the figure belo0& Sabah7 located in the

northern ,art of Borneo7 lies at an i.,ortant 8unction bet0een the (urasian7 /ndo9Australian7

acific and hili,,ines Sea ,lates& +he Sabah Basin7 0hich is located in *orth est of Sabah7

is .ainly offshore 0hile the other t0o basins cover so.e areas in the *orth (ast and South

(ast of onshore Sabah& +he Sabah Basin contains 195. thic5 *eogene sedi.ents that 0ere

de,osited 0ithin the dee, .arine and ,rogradational shelf slo,e environ.ent& +here are si;

tectonostratigra,hic ,rovinces are identified in Sabah Basin 0hich is Ra8ang Grou, -old9

+hrust Belt7 /nboard Belt7 Bara.


2/16

-igure 1&1 = Location of Gela.a Merah field

+he Geogra,hical Coordinate of Gela.a Merah is $! ''# 4"&") *7 114 !"# $%&'4(&

+here are three 0ell on Gela.a Merah field 0hich is Gela.a Merah 17 Gela.a Merah S+91

and finally Gela.a utih& +he last and .ost recent tie9in to Sa.arang Asa. aya SC is

fro. the nearby Su.anda5 field& +he fault that is occurred in Gela.a Merah is regional

0rench fault&

&1&1 late +ectonic Syste.

+here are four .a8or tectonics event occurred in Sabah Basin that contribute to the

fault align.ent> 16 develo,.ent and de,ositional during syn9riff ,hase2(ocene =Oligocene67

6transgression of deltaic de,osits of during late syn9riff ,hase2Late Oligocene9(arly

Miocene67 '6 .ar5ed by tectonic ?uiescence during Middle Miocene7 and 46 /nversion and

folding of tectonics during Middle Miocene9leistocene&

+he tectonic setting and basin evolution of the Sabah Basin is very .uch related to

the closing of the ,roto9South China Sea@ Ra8ang Sea& +he o,ening of the South China Sea

since Oligocene causing .icrocontinents of


3/16

-igure &1& = +ectonic (vent of Sabah Basin

2.1.2 Exploration Opportuniti!

+he e;,loration of Sabah Basin 0as carried out by nu.erous ty,e of oil co.,anies& A

nu.ber of initiatives by (+RO*AS and SC contractors to test ne0 ,lay9ty,es and

continuous studies to .ature ,lays have resulted in recent discoveries& +he success story

begins 0ith the discovery of Gela.a Merah by Gela.a Merah 1 0ere drilled in Se,te.ber

$$1& +hen7 seven .ore e;,loration 0ell 0ere drilled on the sa.e ,lay in the area bet0een

$$1 until $$'&

+o date7 t0enty9eight 2)6 develo,.ent 0ells have been drilled on Gela.a Merah

area and the fields are currently on ,roduction& /n order to further e;,lore the hydrocarbon

,otential of this area7 a regional study 0ith se?uence stratigra,hic a,,roach 0as carried out in

$$)& +he .ain ob8ective of this study is to generate stratigra,hic fra.e0or5 of Su.anda5

that can be correlated to the Sabah regional chronostratigra,hic fra.e0or5&

+he generated stratigra,hic fra.e0or5 0ill hel, to facilitate inter,retation in the

Bloc5 SB'1$ and surrounding areas& /n addition7 the study 0as also ai.ed to identify any

u,side hydrocarbon ,otential for further e;,loration& +he a,,roach ado,ted in this study 0as

based on (;;on#s techni?ues 2an agoner et& al& 1""$6 0hich defined Se?uence Boundary

2SB6 as a ,roduct of relative falls is sea level&


4/16

Seis.ic data and 0ell data 2logs7 cores biostratigra,hic data 0ere used to identify

.a8or bounding surfaces in order to establish a fra.e0or5 in 0hich genetically related facies

can be studied and a realistic de,ositional .odel can be constructed&

2.2 2"DIMENSIONAL CROSS IMAGING

Contour line that is in surface .a, indicate the de,th of the area fro. to, vie0&

Contour lines connect all the sa.e elevation ,oint and are used to illustrate relief on a .a,&

Contour .a,s for e;,loration .ay de,ict geologic structure as 0ell as thic5ness of

for.ations& By this contour7 the angle of a fault and 0here it intersects 0ith the for.ations

and other faults as 0ell as 0here the for.ations ta,er off or sto, abru,tly can be sho0n&

Basically7 geologist used iso,ach .a,s to assist in e;,loration 0or5 0hich is to calculate ho0

.uch ,etroleu. re.ains in a for.ation and to ,lan 0ays to recover it& +he range of de,th

that ,lotted on to, of .a, is 0ithin 1'$$91)$$.& +here are a total of " layers of surface .a,

0hich are '&7 4&$7 !&$7 %&$7 3&$7 )&$7 "&$7 "&1 and "&& +he .a,s 0ere scaled

as 1:!$. 0hich is in A' siDes& An identical scale of horiDontal and vertical are

reco..ended for conventional cross section i.aging as sho0n belo0&

ertical (;aggeration 2(6 E value of one unit .easure.ent on the ForiDontal 2MA6scale

value of the sa.e unit of .easure.ent on the ertical D

E 1:!$ E 1

1:!$


5/16

Fi#ur 2.1= Surface .a, for nit '&

+he de,th of cross section 0as dra0n to visualiDe the contour line in t0o di.ensional

vie0s that is obtained fro. the surface .a,& +he vertical and horiDontal cross sections 0ere

both ,lotted using Microsoft (;cel& +he ;9a;is re,resents the horiDontal line 0hile the y9a;is

re,resent the thic5ness of each Done&

+he ater Oil Contact 2OC6 is found to be at 1!'!. +


6/16

2.$ %ETROLEUM SYSTEMS

&'&1 Source Roc5

Success in the ,reservation of organic .atter in the * Sabah Basin see.s to be

related to the high ,ri.ary terrigenous ,roductivity7 high sedi.ent accu.ulation rates and the

resistant nature of the +y,e /// higher land ,lant 0a;es to o;idation and biodegradation&

/nterestingly7 as .uch of the Sabah shelf tended to be o;ic during Middle Miocene7 it a,,ears

that ano;ic de,ositional conditions 0ere not essential for organic .atter ,reservation& /n

origin7 de,osited in generally o;ic environ.ents such as deltaic@,eat s0a.,s7 brac5ish

.angrove s0a.,s and lagoons&


7/16

&'& Migration

+he ti.ing of .aturation varies fro. Middle Miocene to the ,resent& Most of the area is still

undergoing subsidence& Migration along faults is ,robably a .a8or .ethod of .igration

though .any faults act as seals& So.e .igration through sedi.entary facies has ,resu.ably

occurred7 es,ecially in an u, di, direction fro. condensed intervals&

&'&' Reservoir Roc5

Reservoir roc5s for Gela.a Merah field consist of interbedded sandstone 0ith thin shales

layer of non9reservoir& ,,er shoreface sandstones of regressive ,arase?uence sets and

fluvial and tidal sandstones filling incised valleys cut during lo0stands& +he de,ositional

environ.ents for each sandstone reservoir differ 0ith the stratigra,hy& +he ,ri.ary

de,ositional environ.ent7 burial diagenesis and .ineralogical contents of the reservoirsandstone ,lay an i.,ortant role in the ?uality of the reservoir in Sabah Basin& -or.ation that

0as de,osited during .iddle to u,,er Miocene contains reservoir roc5s that are de,osited in

fluvial9deltaic7 coastal ,lain and shallo0 .arine environ.ent 2Madon M&7 1""46& +hese strata

contains .ediu. to very fine grained sandstone 0ith ,orosity value that .ore than '$H and

1$$$.< ,er.eability value 2Bisho,7 $$6&

&'&4 +ra, Seals

Most ,roducing reservoirs are anticlinal features& +his can be sho0n through the horiDontal

cross of the contour .a, in -igure &'& Based on the location of basin it is either rollover

anticlines ,roduced by gro0th faulting or anticlinal features associated 0ith .orris faults&

So.e reservoirs are related entirely to sealing against faults& +he seals are either .arine

flooding surfaces or faults 0ithin reservoirs& -urther.ore7 there are also stratigra,hic tra,s

unrelated to anticlinal features according to the basin 0here the Gela.a Merah located&


8/16

-igure &' = ForiDontal Cross Section

2.& Strati#rap'( an) Corrlation

+he correlation is done across 0ell Gela.a Merah91 2GM916 to 0ell Gela.a Merah91 S+1

2GM91 S+16& +o, and base sand unit correlation data are given for GM91 and GM91 S+1&

Iuality chec5 of ga..a ray log res,onse is being used in order to identify the lithology of

the for.ation& Sand and shale unit identification is done using ?uic5 loo5 .ethod& -igure &4

illustrates the stratigra,hic correlation fro. sand and shale distribution fro. the log res,onse&


9/16

GR: Lo0 2clean

for.ation6 9

indicate sand

for.ation&

GR: Figh

2radioactive

for.ation69indicate

shale

GR: /rregular readings 2lo0

high69indicate sand

for.ation

interbedding 0ith

shale layers

GR: /rregular readings

2lo0 high69indicate sand

for.ation interbedding0ith shale layers

GR: Lo0 2clean for.ation6

9 indicate sand for.ation&

GR: /rregular readings

2lo0 high6 9 indicatesand for.ation

interbedding 0ith shale

GR: Figh 2radioactive

for.ation69indicate shale


10/16

-igure &4 : ell to, correlations using Ga..a ray log for GM91 and GM91 S+91

/t can be seen that the oil accu.ulation are distributed at a thic5 layer at Done "&$7 "&1 and

"& as sho0n in the .ulti9layered reservoir in -igure &'& +he thin oil layered are sho0ed

above the GOC is at Done '&7 !&$ and "&$ above the GOC level& tectonic .ight have

caused another ,ossible u,lift that gives the Gela.a Merah the current anticlinal sha,e it has

no0& +he hydrocarbon bearing reservoirs in Gela.a Merah area are re,resented by to,set

Documents

Gng Report