5. Seismic Interpretation Ganjil 2015-2016 TG

8/19/2019 5. Seismic Interpretation Ganjil 2015-2016 TG

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EXPLORATIONGEOPHYSICSSeismic Data Interpretation

5

Program Studi Teknik Geologi Fakultas Teknologi Kebumian

dan Energi Universitas Trisakti

Ir. Al an Usman!"T! "#

Semester Gan$il%&'()* &'(+


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2


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1. Objectives2. Structural Interpretation

a. Data Preparationb. Well Seismic Ties

c. Horizon Picking. Horizon Tracing an !ault I enti"ication

e. Horizon #ea ing an Posting". !ault #econstruction

g. $ontouring%. #eporting

&. Pit"alls in Seismic Interpretation'. Direct H( rocarbon In icator

SEISMIC INTERPRETATION


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OBJECTIVES1. Interpreting t%e geological

structure) t%e elementsan t%e processes o"occurrence as *ell as t%e"actors t%at in"luencet%em.

2. Provi e recommen ationo" prospective area anrisk containe t%erein.


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F S !" L # $ O%er%ie&Co(r'esy of E))on*o+i,

Re-ainder of 'his Co(rse

Seismic Interpretation and Beyond … .e%e,op a Geo,ogi/ Fra-e&or0

App,y 'he Geo,ogi/ Fra-e&or0 'oProspe/'ing 1E)p,ora'ion2

Given our time constraints, we will only be able tolook at a subset of the concepts, procedures andtools that geologist and geophysicists use in theexploration phase of the oil & gas industry


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E)p,ora'ion3s Tas0

Success Uneconomic

.ri,,

i,d/a's

Assess

Prospe/'s

.rop

Prospe/'

Con4r-a'ion

e,,

Success Failure In'erpre'

Seis-i/ .a'a

Pro/essSeis-i/ .a'a

A/ (ireSeis-i/ .a'a

Cap'(rePri-e Areas

Iden'ifyOppor'(ni'ie

s

To .e%e,op-en'Or Prod(/'ion

From Lecture 1


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Geo,ogi/ Fra-e&or0

S'r(/'(ra, In'erpre'a'ion• Fa(,'s 6 Fo,ds• S(+siden/e 6 7p,if'• S'r(/'(ra, Trends• S'r(/'(ra, Fea'(res

S'ra'igraphi/In'erpre'a'ion

• 7n/onfor-i'ies• S'ra'a, Pa/0ages

• En%iron-en's 8 Fa/ies 8Li'ho,ogies

• Ages

7sing a,, a%ai,a+,e da'a 1&e,,s9 seis-i/9 o('/rop9

regiona, s'(dies9 gra%i'y9 -agne'i/s9 e'/:2 +(i,da fra-e&or0 of presen';day s'r(/'(re ands'ra'igraphy


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F S !"


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App,ying 'he Fra-e&or0 forProspe/'ing


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• StructuralI enti"ication

• Stratigrap%icI enti"ication

• !aciesInterpretation

+eolog(,o el

• Source #ock• #eservoir • Traps an Seals• ,igration

PetroleumS(stem • +eological

#isk• Project

-conomic

Prospects

SEIS*IC INTERPRETATIONAN. PETROLE7* SYSTE*ANALYSIS


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SeismicSections

GeologyModelInterpretation

Seismic section Well log S(nt%etic !acies mo el+eolog( ,o el Structure !acies map

SEISMIC INTERPRETATIONStructural and Stratigraphic Interpretations

Seismic Modeling


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• Seismic section• /ase map• Well 0og• elocit( Data• ,istie nal(sis

DataPreparation

• Well Seismic Tie• Horizon Picking• Horizon Tracing• !aults I enti"ication an

reconstruction• Horizon rea ing an

posting• $ontouring

Interpretation • Prospects rea

• Project-conomic

#eport

STR7CT7RAL SEIS*ICINTERPRETATION OR? FLO


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ATA PREPARATION


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Persiapan

/eberapa ta%apan alam interpretasi ata seismic (ang %arus iikuti 3Peta asar dan Penampang seismi!Peta asar mencakup 3

• Posisi ara% lintasan seismic an perpotongan antar lintasan seismic.• 4oor inat) sistim koor inat (g igunakan• 5ama lintasan an nomer s%ot point 6titik tembak7.• Skala peta 6tegantung tujuan7) ara% utara8mata angin• Posisi sumur• $ulture an legen 8 keterangan.

Penampang Seismi! 3• bentuk stack migrasi an umumn(a a ala% PST, .• Skala umumn(a %orisontal 1 3 29 999 an vertikal 1 cm : 199 msec.•

Pa a penampang seismik juga memuat in"ormasi tentang 3bagian atas 3 ata kecepatan) nomer SP) Trace ) posisi crossing line) topogra"i)s%ot %ole ept% bagian samping (kanan) 3 nama lintasan) nomer SP an status processing)in"ormasi ata ac;uisition) in"ormasi processing an sekuenn(a) peta in eks


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ata S"m"r

• !inal log) untuk mengeta%ui puncak "ormasi atau lapisan tertentu sebagaimarker atau zona


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Veri#i!asi

• ata navigasi)•

ata sumur an ata lainn(a (ang terkait. 6 apatikerjakanpa a saat loa ing ata ke *orkstation7

• kesesuaian penempatan lintasan


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F S/hroeder @!

L B $ e,,;Seis-i/


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F S/hroeder @!

L B $ e,,;Seis-i/


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F S/hroeder @!

L B $ e,,;Seis-i/


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F S/hroeder @!

L B $ e,,;Seis-i/ =!Co(r'esy of E))on*o+i,

Co-parison of Seis-i/ and e,, .a'a

Seis-i/ .a'a•

Sa-p,es area and %o,(-e• Lo& fre (en/y 5 ; ! H• er'i/a, reso,('ion

• Ti-e -eas(re-en'

e,, .a'a•

Sa-p,es poin' a,ong &e,, +ore• High fre (en/y9

H• er'i/a, reso,('ion = /- ; = -• Hori on'a, reso,('ion !:5 /- ;

-• *eas(res %er'i/a, %e,o/i'y9

densi'y9 resis'i%i'y9radioa/'i%i'y9 SP9 ro/0 and (idproper'ies fro- /ores

•.ep'h -eas(re-en'

. / / m

. / / m


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F S/hroeder @!

L B $ e,,;Seis-i/ =


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F S/hroeder @!

L B $ e,,;Seis-i/ ==Co(r'esy of E))on*o+i,

Seismic S%ot

/ore%ole+eop%one

e p

t $

C$ec! s$ots meas"re t$e 'erticalone&%ay time #rom s"r#ace to'ario"s dept$s 2geop$onepositions3 %it$in t$e %ell

>*sed to determine start time o#top o# %ell&log c"r'es

> *sed to cali4rate t$erelations$ip 4et%een %ell

dept$s and times calc"lated#rom a sonic log

Che/0 Sho' .a'a


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F S/hroeder @!

L B $ e,,;Seis-i/ =>Co(r'esy of E))on*o+i,

The *ode,ing Pro/ess

• +e /#loc(0 the velocity 1sonic and density logs and compute animpedance /log0

Velocity ensity Impedance

50S$ale

Sand

S$ale

Sand

S$ale

+it$ologyRe#lection

Coe##icients

• +e calculate the re.ection coe3cients at the step-changes inimpedance

6

(a'elet

• +e convolve our pulse with the ) series to get individual wavelets• 4ach ) generates a wavelet whose amplitude is proportional to the

)

Synt$etic

• +e sum the individual wavelets to get the synthetic seismic trace


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S7NT,ETIC SEISMOGRAM


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F S/hroeder @!

L B $ e,,;Seis-i/ =5Co(r'esy of E))on*o+i,

O(r E)a-p,e

Well A


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F S/hroeder @!

L B $ e,,;Seis-i/ =Co(r'esy of E))on*o+i,

Tying Syn'he'i/ 'o Seis-i/ .a'a

Position synt$etic trace on seismic line8

> Pro9ect synt$etic along str"ct"ral orstratigrap$ic stri!e i# %ell is o## line

Re#erence dat"m o# synt$etic to seismicdata 2"s"ally gro"nd le'el or seismicdat"m3

> (it$o"t c$ec! s$ots estimate start timeo# #irst 4ed

S$i#t synt$etic in time to get t$e 4estc$aracter tie

> *se stratigrap$ic in#o on detailed plotto $elp

> determine t$e 4est #it8

T i m e ( m s )

Syn'he'i/Tra/e


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ATA INTERPRETATION


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Ta$ap = Penari!an $ori;on 1pic!ing

Setela% selesai persiapan) berikutn(a a ala%• ,ema ukan ata (ang terse ia.• ,embuat looping 8composite line untuk memastikan kon isi ata

tersebut an memeriksa a a ti akn(a mistie.

Pemili%an %orizon 3i asarkan pa a 3 kontinuitas re"leksi) amplitu e (ang mu a% ikenal)

si"at


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Pemetaan

Persiapan Pemetaan

Sebelum memetakan) cek ulang 3• lintasan (ang mele*ati sumur apaka% korelasi seismic an ata sumur sesuai

6matc%ing7)• pastikan pa a perpotongan antar lintasan) %orizon ataupun sesarn(a su a% ?tie@.• /ase map8peta asar su a% ilengkapi lintasan an nomer SPn(a.•

4*alitas mapping tergantung pa a ketelitian interpretasi

Pem4acaan 1 Gridding

• Pembacaan 8gri ing untuk mengeta%ui %arga an posisi %orizon atau "ault (angakan ipetakan ) engan s(arat seluru% ata seismic su a% cocok 6tie7.

• Hasil pembacaan kemu ian i plot pa a peta asar . Dalam beberapa kasusapabila lintasan seismic (ang ter apat pa a peta asar masi% jarang 6jarak antarlintasann(a jau%7 maka %arga pa a posisi antar lintasan akan iinterpolasi .


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Conto"ring

Sebelum penggambaran garis kontur)

• Plotting posisi sesar 6"ault7) pola sesar an

simboln(a %arus ilakukan terlibi% ulu.B Pemetaan ini a ala% contouring (aitu titik titik

%arga tersebut apat ikontur engan interval

atau jarak antar kontur (ang isesuaikanengan skala peta 6182999 C skala peta7 atauisesuaikan engan kebutu%an


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F S !" L

Structural Analysis

,or8 >

,or8 .

,or8 ?


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F S !" L

So-e *aDor E,e-en's• Jasin For-a'ion• Fa(,' Ne'&or0 *apping• S'ra'igraphi/ .efor-a'ion• Presen';.ay Trap .e4ni'ion• Ti-ing of Trap .e%e,op-en'


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• Iden'ify and -ap fa(,'s9 fo,ds9 (p,if's9and o'her s'r(/'(ra, e,e-en's

• In'erpre' s'r(/'(ra, se''ings ands'r(/'(ra, s'y,es

• Ins(re >. geo-e'ri/ /onsis'en/y in anin'erpre'a'ion ; is i' s'r(/'(ra,,y%a,id

• .e'er-ine 'i-ing re,a'ionships9espe/ia,,y 'he 'i-ing of 'rap for-a'ion

• Che/0 if 'he in'erpre'a'ion isad-issi+i,i'y


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• Inheren',y >;. 1e%en if a =;. grid2• A+,e 'o i-age 'rap;s/a,e s'r(/'(res• A+,e 'o i-age s'ra'igraphy9 'o iden'ify

reser%oir9 sea,9 and for (se as

s'r(/'(ra, -ar0ers9 e: g: 'o /ons'rainfa(,' oKse's

• Pro%ides a >;. /on'e)' for(nders'anding o'her da'a – s(rfa/e geo,ogy – &e,, da'a – po'en'ia, 4e,d da'a


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• Li-i'ed reso,('ion /an3' reso,%e s-a,,M

fea'(res• S'eep dips /an +e di /(,' 'o i-age• A/ (isi'ion /an +e di /(,'9 e: g: in areas

of %aria+,e 'opography9 %aria+,e s(rfa/e

geo,ogy9 or hardM &a'er +o''o-• er'i/a, a)is is 'ypi/a,,y 1-igra'ed2 'i-e9

no' dep'h – e,o/i'y %aria'ions dis'or' geo-e'ries

• .isp,ay s/a,es are /o--on,y no'H <


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F S !" L

A

JC

'ie

EN S

A J C

Fa(,'s -(s' 'ie on,ines 'ha' in'erse/'

or 'he in'erpre'a'ionis no' in'erna,,y

/onsis'en'


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Structural Observations

Structural Concepts


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Structural Observations

• Fa(,' seg-en's on seis-i/ ,ines• Fa(,' p,ane orien'a'ion• Sense of -o'ion• *agni'(de of oKse'• Range of dep'hs• Re,a'i%e 'i-ing

– &hen fa(,'s -o%ed

– &hen s'r(/'(res gre&

Structural Concepts

• Te/'oni/ Se''ing – .i%ergen' ones – Con%ergen' ones – S'ri0e;s,ip ones – *o+i,e s(+s'ra'e

• Ho& S'r(/'(res E%o,%e – Fa(,';+end fo,ds – Fa(,';propaga'ion fo,ds – Sa,' -o%e-en' – e'/:


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F S !" L


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F S !" L

1 mile


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$akupan pemba%asan struktur

• Pemba%asan struktur geologi pa a eksplorasi %i rokarbonmeng%aruskan kita untuk menganalisa %al


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Pembentukan graben

• +raben menja i unsur (ang sangat penting alampembentukan aera% apur %i rokarbon. Isolate se imentbiasan(a sangat bagus sebagai apur %i rokarbon sebagaipro uk en apan lacustrine.

• Dalam mo el (ang ibuat ari material lumpur (angilengkungkan seperti busur menunjukkan e"ormasi engan

membentuk graben.• ,o el lain menunjukkan ba%*a graben apat terbentuk akibat

ga(a tensional atau terja in(a ri"ting.• S(ntesa lainn(a a ala% a an(a akibat arus konveksi ari

alam bumi (ang men(ebabkan terja in(a seri sesar listrikmembentuk graben.


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4arakter regime tensional• Sesar normal engan su ut

kemiringan besar 6 E9 9 7• Domino st(le• 0istric normal "aulting•

Sesar utama biasan(a iikuti sesarantitetik


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4arakter regime kompresi

• T%rust "ault engan /asement involve• T%in skin e"ormation• Inconsistenc( e"ormation) perbe aan

pertumbu%an pensesaran.• /entuk t%rust i pengaru%i ole% kemiringan

bi ang pergeseran) ke alaman sesar) stratigra"i


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#$D<

/4P<

,#T<

SPT


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,o el Penampang seismik pa a sesar naik


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!"

#! M!C !"T#RPR#TAT!$"

P!T%A&&


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In doing seismic interpretation, it must be remembered, it still contains noiseswhich is any reflection unrelated to geology objects.Common noises which are multiples, diffraction and velocity anomaly . Thisnoises can act as pitfalls for interpreter, and thus need to be recognized.

1.Multiple

Multiple occurs when the wavefront is reflected more than one time.

ata ac!uisition parameters can be designed to minimize multiple, mainly byusing stac"ing and deconvolution techni!ue#owever, multiple still often appear in the record even though the data have

been intensively processed

Pit&alls in Seismic Interpretation


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!igure A. -Camples o" multiple 3 W/ > *ater bottom multiple) I/,


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$. iffraction

iffraction occurs due to the sharp change of reflector plane geometry, fore%amples due to the faults, instrusion, "arst, etc &'igure (). The sharp planerefract energy to all direction and recorded as hyperbolic trace with diffractionsource as its ape%. The position of fault plane can be estimated by joining the

ape%es &'igure 1*).

+ven though diffraction can be minimized using migration techni!ue, theystill appear in seismic records and interfere interpretation.


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☼

Sketch showing a diffraction from a fault.The h perbolic form of diffractions arises

from the assumption made b the C!"method that reflections arise from mid#point locations between the source andgeophone

ig"re D 8 Ill"stration o# di##raction e##ect d"e to #a"lt plane 2Badley .D 3

+eop%one Source

Diffraction from fault

Assumed mid-point locationst


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!igure 19 . Seismic eCamples o" a burrie "ocus. 6a7 Stacke section s%o*ing t%e bo*


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3.Velocity Efect

Changes of rock properties, for instances due to formation thickness and faciescan create velocity change. The change can give distortion between the stackedtime section and the real thickness and depth.

own!dip apparent thinning occurs due to the increasing interval velocity withdepth for a constant thickness bed. This makes the bed become thinner to thedepth in time section "#igure $$%. &pparent thinning can also accur along fault

plane due to the change of rock velocity across the fault plane "#igure $'%.Velocity anomaly also often occurs beneath low!angle dip fault plane like in thecase of thrust and lystric normal fault because of the lateral velocity change dueto the faulting "#igure $3!$(%

)ull!up velocity anomaly will also develop under salt structure, and high!velocity carbonate or channel "#ig.$*!$+%. n the contrary, push down velocityanomaly can occur beneath shale diapir or carbonates with lower velocity thanthe surroundings "#igure $-%. E treme change of water depth can also causesevere velocity anomaly "#igure $/%.


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ig"re . 8 Velocity anomaly 4eneat$ car4onate ree#8 2a3 and 243 P"ll&"p8 2c3 and 2d3 p"ll&do%n 2Badley .D 3

SEISMIC SECTION SEISMIC SECTION

SEISMIC SECTION SEISMIC SECTION


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The effect of increasing velocifty withdepth on the seismic expression of adipping unit.

(a) Geological model of a thick dippingsandstone unit. The sandstone sinterval velocity increases with depthdue to diagenesis, but its thicknessremains constant.

(b) !eismic expression " The sandstoneunit appears to thin. #t takes lesstime for the seismic signal to travelthrough the sandstone as its intervalvelocity increase.

!igure 11. pparent be t%inning ue to velocit( e""ect 6/a le() 1 A7

I n t e r v a l v e l o c i t ( i n c r e a s e s

Interval t%ins in timeTime6b7

Dept%6a7

sur"ace


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irect ,ydrocar4on Indicator

2 ,I3


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5. Seismic Interpretation Ganjil 2015-2016 TG