1) Pendahuluan Geologi Migas

Silabus Materi Kuliah Geologi Hidrokarbon (MGS325) Dosen : Ir. H.Taat Purwanto MT & Ir. Arista Muhartanto MT Kompetensi yang diharapkan dicapai oleh Peserta : Mahasiswa diharapkan mampu mengerti proses terakumulasinya minyak dan gas bumi dalam suatu cekungan dan mengetahui keterdapatan minyak dan gas bumi tersebut dengan menggunakan metode wireline-logging

Isi :  Mempelajari kualitas batuan induk yang berkaitan dengan kuantitas material organik dan tingkat kematangan, proses migrasi dan pengelompokannya, jenis-jenis batuan reservoar, tipe-tipe perangkap hidrokarbon, dan batuan penyekat/seal. Pola sedimentasi dan potensi hidrokarbon pada cekungan- cekungan sedimen di Indonesia.  Pembuatan peta net oil dan gas, penentuan parameter resistivity water (Rw), geologic correlation, pembacaan data wireline logging, meliputi : log gamma ray & spontaneous potensial untuk identifikasi litologi, log resistivity untuk identifikasi kandungan reservoar, log density & log neutron untuk identifikasi porositas. Perhitungan volumetric menggunakan metoda trapezoidal dan pyramidal. Daftar Pustaka :  North F.K., 1985, Petroleum Geology, British Library Catalog, 617 hal.  Waples D.W, 1985, Geochemistry in Petroleum in Exploration, IHRDC Publishers, 232 hal.  Welte & Tissot, 1984, Petroleum Formation and Occurrence, Springer-Verlag Berlin Heildelberg, 699 hal.  Schlumberger, 1989, Log Interpretation Principles/ Applications, Schlumberger Educational Services, 345 hal.  Asquith G., 1982, Basic Well Log Analysis for Geologist, APPG Publishers, 216 hal.

Pencaharian Migas

Industri MIGAS

Akumulasi MIGAS

Penuh Resiko

di tempat2 tertentu

Mencari tempat2 di dalam Kulit Bumi yang Keadaan Geologinya memungkinkan untuk dijumpainya MIGAS/HC

1. Source Rock (Batuan Induk) 2. Migration Path (Jalur Migrasi) 3. Reservoir Rock 4. Trap (Perangkap) 5. Seal (Lapisan Penutup)

Petroleoum Geology

1st

• SEDIMENTARY BASIN

• PETROLEUM SYSTEM 2nd 3rd

4th

• PLAY • PROSPECT

ECONOMICS NOT IMPORTANT

ECONOMICS VERY IMPORTANT

Magoon and Dow (1994)

Sedimentary basins, petroleum systems, plays, and prospect can be view as separate levels of investigation, all of which are needed to better understand the genesis and habitat of hydrocarbons.

Sedimentary basin investigations emphasize the stratigraphic sequence and structural style of sedimentary rocks.

Petroleum system study describe the genetic relationship between a pod of active source rock and the resulting oil and gas accumulations.

Investigation of play describe the present-day geologic similarity of a series of present-day traps.

Study of prospects describe the individual present-day trap

PETROLEUM SYSTEM

Petroleum System Definition Geologic components and processes necessary to generate and store hydrocarbons, including a mature source rock, migration pathway, reservoir rock, trap and seal. Appropriate relative timing of formation of these elements and the processes of generation, migration and accumulation are necessary for hydrocarbons to accumulate and be preserved. The components and critical timing relationships of a petroleum system can be displayed in a chart that shows geologic time along the horizontal axis and the petroleum system elements along the vertical axis. Exploration plays and prospects are typically developed in basins or regions in which a complete petroleum system has some likelihood of existing.

Elements Source Rock Migration Route

Processes Generation Migration

Reservoir Rock

Seal Rock Trap

Accumulation Preservation

Loss of carbon and related petroleum potential in the sedimentary cycle

Caprock/ Seal

Reservoar Rock

Source Rock

Stages of Hydrocarbon Generation

Migration Pathways

Characterizing Source Rocks To be a source rock, a rock must have three features: 1. Quantity of organic matter 2. Quantity capable of yielding moveable hydrocarbon 3. Thermal maturity The first two components are products of the depositional setting. The third is the function of the structural and tectonic history of the province.

Determining the Source Rock Potential The quantity of organic matter is commonly assessed by a measure of the total organic carbon (TOC) contained in the rock. Quality is measured by determining the types of kerogen contained in the organic matter. Thermal maturity is most often estimated by using vitrinite reflectance measurements and data from pyrolysis analysis. The table below shows the most common methods used to determined the potential of the source rock. To determine …. Quantity of source rock Quality of source rock Thermal maturity of source rock

Measure …… Total Organic Carbon (TOC), present in the source rock  

 

Proportions of individual kerogen Prevalence of long-chain hydrocarbons

Vitrinite reflectance Pyrolysis (Tmax), etc

Minyak & Gas Bumi  ditemukan ?

Batuan Sedimen

Fault and Other Traps

CEKUNGAN SEDIMEN (Sedimentary Basin) di Indonesia  berumur Tersier Jenis CEKUNGAN SEDIMEN di Indonesia, dibedakan berdasarkan : 1) Kedudukan terhadap jenis KERAK/LEMPENG (Plate) 2) Gerakan Relatif dari Lempeng (Koesoemadinata, 1978)

Bat. Beku & Metamorf

Plate Tectonics Basin Classification

Sumber : Koesoemadinata, 1978

AHLI GEOLOGI SEBAGAI INDIVIDU PASIF

Bekerja pada satu sistem 1. Berfikir Lateral

AKTIF 2. Mempromosikan ide baru 3. Membuat sistem baru

BERPIKIR LATERAL

Cadangan Migas Indonesia terbatas ? Batas tersebut ada di pikiran sendiri

“Oil is found in the mind of people” Find Oils

BERPIKIR LATERAL Baru 25% Cekungan di Indonesia dieksplorasi Jumlah Cekungan Hidrokarbon sebanyak 60 cekungan • 22 cekungan belum dieksplorasi • 38 cekungan sudah dieksplorasi • 15 cekungan produksi

• 11 cekungan belum produksi • 12 cekungan belum terbukti

Peta Cekungan Migas di Indonesia

CADANGAN MINYAK BUMI INDONESIA (Status 1 Januari 2003)

ACEH

NATUNA

176,40

291,81 NORTH 135,18 SUMATERA

MALUKU EAST KALIMANTAN

CENTRAL SUMATERA

7.47 110,62 IRIAN JAYA

1177,16

5075,70

132,43 SOUTH

673,7 5

SUMATERA 9,65

1112,82 WEST JAVA

235,87 EAST JAVA

TERBUKTI

CADANGAN MINYAK BUMI (MMSTB)

= 4,727,9 MMSTB

POTENSIAL = 4.403,5 MMSTB

TOTAL

= 9,131,4 MMSTB

CADANGAN GAS BUMI INDONESIA (Status 1 Januari 2003)

NATUNA

ACEH 9.75

55,30 NORTH EAST

SUMATERA

KALIMANTAN

1.06

SUMATERA

9.62

19.73

SOUTH SUMATERA

IRIAN JAYA

49,14

CENTRAL

SOUTH 21.43

SULAWESI 0.59

7.26 4.36

WEST JAVA

EAST JAVA

TERBUKTI

CADANGAN GAS BUMI (TSCF)

= 91.170,12 TSCF

POTENSIAL = 86.958,65 TSCF TOTAL

= 178.228,77 TSCF

Potensi Sumberdaya 5 Migas Indonesia 0

-5

Ind. Barat = 21 basin

Ind. Timur = 39 basin

TELAH DIPRODUKSI (15)

CADANGAN POTENSIAL BELUM -10 EKSPLORASI (22)

CADANGAN BELUM PRODUKSI (8)

BELUM TERBUKTI (15)

SEDIMENTASI & STRATIGRAFI CEKUNGAN2 DI INDONESIA Akhir Mesozoikum  Seluruh cekungan Terlipat, Diintrusi, Terangkat, dan Terdenudasi  menyebabkan seluruh Batuan pada umur tersebut (Beku atau Metamorfosa yang telah Tertetonikan) dianggap sebagai Batuan Dasar (Basement)  Batuan Pra-Tersier

Block Faulting (Pensesaran Bongkah) terjadi pada awal Tersier, dan setelahnya dimulai sedimentasi Non-Marin, biasanya terjadi pada Oligosen, tetapi pada Cekungan di P. Kalimantan terjadi pada Eosen Proses sedimentasi dimulai awal Tersier (umumnya Oligosen), tetapi di Cekungan di P. Kalimantan dimulai pada Eosen.

Perkembangan Sedimentasi Tersier  seluruh cekungan memperlihatkan Pola Yang Sama, dimulai dengan suatu Transgresi/Genang Laut, (Tersier Awal – Miosen Tengah), dan diakhiri dengan suatu Regresi/Susut Laut(Miosen Tengah – Plio/Plesitosen) Pola tsb terlihat jelas di Cekungan Sumatera Selatan, dengan kekecualian di Cekungan Jawa Timur

Diawali pengendapan yg merupakan suatu “Daur Terestrial”  Penghasil Minyak yg penting (source rock yg bagus) conto : Cekungan Sumatera Tengah & Cekungan Sunda Pengendapan “Transgresi/Genang Laut”  menghasilkan Reservoar Batupasir Ditandai gejala menyolok  Pembentukan ”Batugamping yg Luas” (terutama di L.Jawa)  menandai Periode mulai tergenangnya seluruh cekungan misal : Fm. Baturaja (Cek. Sumatera Selatan), Fm. Kujung & Berai (Cek. Jawa Timur Utara)

Pola/Daur Sedimentasi di Indonesia

Puncak “Maksimum Transgresi” ditandai oleh “Pengendapan Serpih Marine”  yg dianggap sebagai “Batuan Induk” antara lain : Formasi Gumai (Cek. Sumatera Selatan), Fm. Telisa (Cek. Sumatera Tengah) Sedimentasi berlangsung terus sewaktu Peg. Bukit Barisan (Sumatera) dan Peg. Selatan (Jawa) diangkat dan tererosi, di beberapa tempat ditandai oleh Unconformity Terjadi ”Regresi” yg berlangsung terus selama Pliosen, dan diikuti Perlipatan & Pensesaran pada Plio-Pleistosen “Regresi” yg menghasilkan “Reservoar Penting” yang bersifat Paralis/ Litoral misal : Fm. Air Benakat (Cek. Sumatera Selatan), Fm. Ngrayong (Cek. Jawa Timur Utara) & Fm. Balikpapan/Fm. Pulubalang (Cek. Kalimantan Timur)

Eksplorasi

Peta Topografi

Geologi Permukaan Tanah

Geologi Bawah Permukaan Tanah

Foto Udara / Foto Satelit

Kegiatan Survei Geofisika (seismik, gravity, magnet) dalam Eksplorasi Migas

KEGIATAN PENGEBORAN SUMUR EKSPLORASI

Peralatan survai well logging

Ahli Geologi meneliti sampel batuan dari inti pemboran (core)

Frequently used of geophysical methods for surface recording and typical application Geophysical method

Physical property measured

Typical applications

Comment on applicability

Seismology

Seismic wave velocity, seismic impedance contrast, attenuation, anisotropy

Delineation of stratigraphy and structures in petroleum exploration

Exploration seismology is the most widely used geophysical method in petroleum exploration.

Gravity Surveys

Rock density contrast

Reconnaissance of large-scale density anomalies in petroleum and mineral exploration

Gravity survey are generally less expensive but have less resolving power than seismic exploration.

Magnetic Surveys

Magnetic susceptibility or the rock’s intrinsic magnetization

Reconnaissance of the crustal magnetic properties, especially for determination of basement features

Aeromagnetic surveys are widely used in both petroleum and mining application for determining large, deep structure.

Electrical and electromagneti c surveys

Rock resistivity, capacitance, and inductance properties

Mineral exploration

These methods are used most frequently in mining exploration and well logging (resistivity, SP, and induction log)

(Lines and Newrick, 2004)

So…….. it is not that the resources of H/C basins in Indonesia limited, but …  there has to be another 42 basins (60% of the number of basins in Indonesia) yet to be explored in to prove that Indonesia still have lots of oil & gas to be found 

Major Events for Oil in Indonesia

Siklus-1

Siklus-2

Siklus-3

Year

Events

1890

Telaga Said production field sold to a company that later merged to form Royal Dutch Shell. First production was in 1892

1912

Standard oil of New Jersey through its Ducth subsidary received permission to explore for oil in South Sumatera

1921

The Talang Akar field discovered, which proved to be the biggest find before World War II

1942

Japanese took over most oil fields during World War II and slow production

1944

Caltex Minas field discovered. Largest oil field in Southeast Asia

1945

Indonesia declared independence from the Nederlands

1961

Government signs first PSC with Asamera for the Block A PSC in Aceh

1962

Pan America Oil Company signe the first contract of work with Pertamina

1962

Indonesia Joined OPEC

1968

National oil companies Permina and Pertamin merged to form Pertamina

1978

First LNG plant entered production

2001

The Government revised Oil and Gas Law

2002

Upstream/downstream bodies formed

2003

Pertamina becomes a limited liability company

BERPIKIR LATERAL

Konsep Siklus Eksplorasi Siklus eksplorasi migas Indonesia (I) * ) Siklus Pertama: minyak target dangkal, penemuan gas ditinggalkan, konsep dan teknologi sederhana, lokasi on-shore, reservoir batuan klastik, struktur-struktur PliosenPleistocene, endapan inversi/post-inversi.

Siklus Eksplorasi Migas Indonesia (I)

Siklus Eksplorasi Migas Indonesia (II)

Siklus Kedua: minyak target kedalaman menengah, gas dengan cadangan besar mulai dikelola, konsep dan teknologi lebih maju, lokasi on-shore dan off-shore, reservoir batuan karbonat maupun klastik, struktur-struktur Miocene, endapan-endapan post-rift.

Siklus Eksplorasi Migas Indonesia (III)

Siklus Ketiga: minyak dan gas target dalam, gas dengan cadangan menengah mulai dikelola, konsep dan teknologi mutakhir, lokasi on-shore, off-shore, dan laut dalam, reservoir batuan dasar (basement), karbonat, maupun klastik, struktur-struktur Paleogene, endapan-endapan synrift dan pre-rift.

Visualization of Exploration Drilling Sequence at Banyu-Urip

MENGUASAI TEKNIK KOMUNIKASI ALTERNATIF 1. Penguasaan Bahasa Inggris

2. Penguasaan Penggunaan Software (Perminyakan + Pertambangan) 3. Salesmenship

4. Net Working

Bisa dibentuk lewat kegiatan organisasi kemahasiswaan

MENGUASAI PORTOFOLIO EKONOMI

Cash Flow Analysis

Source: http://www.wtrg.com/oil_graphs/oilprice1947.gif

Note: Oil Prices from WTRG Economics (www.wtrg.com) and Graduate numbers from University of Arkansas 2004

2002

2000

1998

1996

1994

1992

1990

1988

1986

1984

1982

1980

1978

1976

1974

1972

1938 - 2005

70 $70

60 $60

50 $50

40 $40

30 $30

20 $20

10 $10

0 $0

World Oil Price Annual Average in 2004 US Dollars

80

1970

1968

1966

1964

1962

1960

1958

1956

1954

1952

1950

1948

1946

1944

1942

1940

1938

Number of "First Degree" Geoscience Graduates per Year

University of Arkansas

Geoscience Graduates vs Oil Price $80

PROSES PENCARIAN MINYAK DAN GAS BUMI ? Proses pencarian minyak dan gas bumi dimulai dari penelitian geologi → survei geologi permukaan dan survei geologi seismik.  Data yang didapat, berupa data seismik 2D ataupun seismik 3D → memberikan gambaran kondisi geologi mengenai lapisan batuan di bawah permukaan  Setelah dilakukan pemboran ujicoba (wild cat) dapat dilakukan penelitian yang lebih detail mengenai lapisan permukaan bumi → proses logging atau penilaian formasi. 

Evaluasi Formasi dalam Eksplorasi Minyak & Gas Bumi

Suryana Ino & Dono Nardio – Total E&P Indonesia Dn March, 2009Reference, date, place Universitas Trisakti - Jakarta - Mei 2009.

Offshore Seismic

Land Seismic

Hasil seismik 2D, 3D dan hasil logging

OPERASI PENGEBORAN (Drilling Operation) •

• •

• •

Pemboran → suatu cara untuk membuktikan apakah pada lapisan yang diduga, benar memiliki kandungan hidrokarbon. Proses pengeboran harus dilakukan secara aman, efektif dan efesien di lapisan permukaan bumi sampai menembus formasi yang diperkirakan terdapat cadangan minyak atau gas yg cukup potensial untuk dikelola dan ekonomis untuk diproduksikan. Pemboran sebagai jalan keluar masuknya fluida (dari reservoir ke permukaan, dan dari permukaan ke sumur injeksi) Pemboran untuk menyelidiki kandungan bawah tanah : • Isi kandungan batuan • Macam sifat batuan • Susunan perlapisan batuan • Umur dan sejarah pengendapan batuan tsb.

Tipe-tipe Pemboran   

Pemboran lurus (Vertical Drilling) Pemboran berarah (Directional Drilling) Pemboran horizontal (Horizontal Drilling)

Pemboran di : • darat (on-shore), • lepas pantai (off-shore) • anjungan lepas pantai (offshore)

Berbagai Perangkap Migas

PETROLEUM SYSTEM DIAGRAM

Caprock/ Seal

Reservoar Rock

Source Rock

HYDROCARBON KITCHEN

68

POOLS

Dn March, 2009- Reference, date, place

EVALUASI DEEP PROSPECT DIBAWAH EXISTING LAYER (1500 – 2000 MS), REF.GNK-81 TERDAPAT OIL 182 BPOD (LAPISAN GK24) SELATAN

UTARA GUNUNG KEMALA

EXISTING LIMAU

OBYEKTIF STUDY

??? INTERVAL 2366-2370 m: HASIL : 227.5/182 BOPD 8.21 MMcfgpd

???

B B A OIL WINDOW:

A

1200 m in Merbau Area 1500 m in Gunungkemala Area

MIGRATION: Late-Midle Miocene.... -VERTICAL: Fault Zones --LATERAL : along carrier beds LIMAU FIELD

A LEMATANG DEEP SOURCE ROCK

?

DRAG FOLD & SHEAR FRACTURE ZONE POTENTIAL PATH-WAY MIGRATION FROM LEMATANG DEEP TO UPPERLAYING LIMAU RESERVOIR

B

LEMBAK DEEP SOURCE ROCK

Mig. Path-way

GEOLOGICAL CROSSECTION WITH HC GENERATION

(Sarjono & Sardjito, 1989)

Petroleum System       

Source rock Maturity Kitchen area Migration pathway Reservoir Trap Seal

PETROLEUM SYSTEM DIAGRAM

PETROLEUM SYSTEM

PETROLEUM SYSTEM DIAGRAM

PETROLEUM SYSTEM DIAGRAM

SUMMARY        

Basin Geometry Basin Filling and Stratigraphic Architecture Source rocks distribution Maturity, time and distribution (kitchen area) Migration, time and framework Reservoir, distribution, geometry and Quality Trap formation, time and geometry Relative of, maturation, reservoir development and trap formation

Tahapan Eksplorasi Migas • Pemetaan Geologi permukaan dengan target struktur antiklin dimana sekitarnya banyak rembesan minyak atau gas. • Seismik digunakan untuk eksplorasi migas pertama kali di lepas pantai (offshore) – tahun 1960 an.

• Seismik 3D diperkenalkan (lebih detail dan akurat untuk “imaging subsurface”) – tahun 1980 an. • Simulasi 3D diperkenalkan untuk integrasi data reservoir, geofisika dan geologi – tahun 1990 an.

89

Dn March, 2009- Reference, date, place

Exploration review - Geophysical

90

Dn March, 2009- Reference, date, place

•Geologist

91

•Geophysicist

•Reservoir

Dn March, 2009Reference, date, place

Model from present Delta : Fluvial Channel Fill

FLUVIAL CHANNEL- FILL

POINT BAR

DIMENSIONS: - WIDTH: 1-2 KM - THICKNESS: 15-20 M

FLOW POINT BAR

CREVASSE SPLAY 92

Dn March, 2009Reference, date, place

•Geologist

93

•Geophysicist

•Reservoir

Dn March, 2009Reference, date, place

Mudlogging

• Peranan & Tanggungjawab geologist di operasi pemboran.

• Evaluasi data bor dan pembuatan MudLog

94

Dn March, 2009- Reference, date, place

95

Dn March, 2009- Reference, date, place

96

Dn March, 2009- Reference, date, place

97

Dn March, 2009- Reference, date, place

Rig system - Circulation (1)

98

Dn March, 2009- Reference, date, place

Rig system - Circulation (2) 1. Well head 2. Rotary table 3. Kelly 4. Rotary swivel 5. Derrick 6. Mud hose 7. Stand pipe 8. Mud pressure sensor 9. Weight under hook sensor 10. Wireline anchor 11. RPM sensor 12. Rotomatic

99

Dn March, 2009- Reference, date, place

13. Gamma densimeter 14. Electromagnetic flowmeter 15. Choke manifold 16. Thermometer (out) 17. GZ 11 gas trap 18. Mud ditch 19. Shale shakers 20. Restor pit level sensor 21. Pit no.1 22. Pit no.2 23. Pit no.3 24. Pit no.4

25. Thermometer (in) 26. Resistivity mud electrodes (in) 27. Mud suction 28. Pump 29. Expansion vessel 30. Electrical pumps 31. Dampener 32. Densimud 33. Disc gas trap 34. Settler-drier 35. Resistivity mud electrodes (out)

Rig Type

100

Dn March, 2009- Reference, date, place

101

Dn March, 2009- Reference, date, place

Rate Of Penetration (ROP)

105

Dn March, 2009- Reference, date, place

20 15 10 5

Cuttings Lithology

Hydrocarbon Analysis Chromotograph PPM

Continuous Total Analysis Methane--Gas in air % Propane---

Ethane--Butane---

Pentane---

1

10

PPM 1 K

Interpreted Lithology

Depth (m)

Drilling Rate M. per Hr.

Visual Porosity

Mudlog Example Remarks

10 K LS: wht, dk, br, vf, xin, cin, hd w tr foss SH: dk gy, gy, frm, occ sft, occ sity

SS: lt gy, cir, xin, sb ang, sb, rnd, m grn, oil stn, bri yel flour, bri gid stng cut

SH: dk gy, gy, frm, occ sft, occ sity SS: lt gy, cir, xin, sb ang, sb, rnd, m grn, oil stn, bri yel flour, bri gid stng cut SH: dk gy, gy, frm, occ sft, occ sity

106

Dn March, 2009- Reference, date, place

Wireline Logging • Cara kerja rekaman listrik dan data yg bisa dipakai untuk interpretasi batuan – tahun 1927 diperkenalkan oleh Schlumberger bersaudara. • Penentuan reservoir dan perhitungan porositas, kandungan lempung dan saturasi air. • Pemilihan reservoir yg berisi hidrokarbon atau air.

• Mempergunakan data rekaman listrik untuk perhitungan cadangan.

107

Dn March, 2009- Reference, date, place

Well Log SP

108

Resistivity

Dn March, 2009- Reference, date, place

Openhole Well Logs • Passive measurements • Gamma ray: Indicates lithology • Spontaneous potential: Indicates lithology • Caliper: Hole condition

Oil

Cap rock

• Active measurements • Resistivity: Fluid saturation, fluid type • Porosity: Rock properties, quantity of hydrocarbon • Density: Rock properties, seismic response • Sonic log: Rock properties, seismic response

Reservoir rock Source rock 109

Dn March, 2009- Reference, date, place

Wireline Logging cable

Tool system Cartridge

Cartridge

 electronic device  generator/power supply  telemetry system

Sonde :

 logging sensor(s)/receiver  transmitter

R Sonde T

110

Dn March, 2009- Reference, date, place

SP - Spontaneous Potential Log Principle : measurements

111

Dn March, 2009- Reference, date, place

SP - Spontaneous Potential Log Summary  measure the potential difference of formation fluid and drilling fluid  magnitude is measured from established shale-base line: negative to the left and positive to the right  SSP can be obtained from thick and clean sand, for shaly and thin sand it measures PSP that need to be corrected.  SSP reading can be used to calculate Rw and Vsh  SP defelection indicate the present of permeable bed

112

Dn March, 2009- Reference, date, place

GR - Gamma-ray Log Application      

Identify lithology Calculate shale content of a sand body (Vsh) Correlation purposes Provide a depth control/reference for other tools Definition of facies and depositional environment To ‘replace’ SP log when it can not be run : - Oil Based-Mud - salt Water Based-mud (no contrast) - carbonate formation - large borehole diameter - cased hole

NGS (Natural Gamma-ray Spectrometry)  Identify clay mineral type  Specific minerals identification: - Uranium Ores (uranium potential) - Evaporites (potassium potential)

113

Dn March, 2009- Reference, date, place

GR - Gamma-ray Log Vshale calculation

Possible error: - sand line is not clean enough - shale line is not pure shale - clay mineral in sand is not equivalent to the shale

114

Dn March, 2009- Reference, date, place

Density Log - Principle A radioactive source applied to the borehole, emits gamma rays into the formations These gamma rays collide with the electrons in the formations At each collision gamma ray loses some energy to the electrons, known as Compton scattering The scattered gamma rays reaching the detector are counted as an indication of formation density

115

Dn March, 2009- Reference, date, place

Neutron Log - Principle Neutron are neutral particles having a mass almost identical to the mass of a hydrogen atom. High energy (fast) neutrons are continuously emitted from a radioactive source in the sonde. These neutrons collide with nuclei of the formation material, including hydrogen atoms. At each collision the neutron loses some of its energy. The amount of energy lost depends on the relative mass of the nucleus with which the neutron collides. It loses more if it collides with hydrogen nucleus since this last one has practically the same mass. Therefore, if hydrogen concentration is large, most of the neutrons are slowed and captured within a short distance of the source. On the contrary, if the hydrogen concentration is small, the neutrons travel farther from the source. The neutron log is the counting of the rate of hydrogen concentration change. 116

Dn March, 2009- Reference, date, place

Sonic Log The sonic log is a recording time ‘t’ versus depth of a sound wave to traverse 1 foot of formation. Known as the interval transit time or transit time or t or slowness. It is the reciprocal of the velocity of the sound wave.

The interval transit time for a given formation depends upon its lithology and porosity. Therefore, if the lithology is known, its porosity can be determined.

117

Dn March, 2009- Reference, date, place

Summary

The use of Sonic - Litho-Density and Neutron logs • To determine the rock porosity • To determine the lithology • To identify reservoir fluids content particularly gas (Density - Neutron separation) • To determine the overpressured zone

118

Dn March, 2009- Reference, date, place

Neutron Log - Separation NPHI/Rhob

Gas or light hydrocarbons cause the apparent porosity from density log to increase (bulk density decrease) and porosity from neutron to decrease. It makes the density neutron logs separation over gas reservoir quite specific.

119

Dn March, 2009- Reference, date, place

High Resolution LDL/CNL logs

120

Dn March, 2009- Reference, date, place

Sonic Log Porosity - DT relationship (Raymer-Hunt) Empirical formula: t

= {[(1-F)2/tma] + (F/tf)} -1

Used tma :

121

sandstone limestone dolomite

Wyllie 55.5 47.5 43.5

Raymer-Hunt 56 49 44

fluid

189

189

Dn March, 2009- Reference, date, place

122

Dn March, 2009- Reference, date, place

Density Log - Principle Porosity - Density relationship

rb

Total mass =Fluid mass + Matrix mass Fluid

1*rb

= (F * rf ) + (1- F)* rma

F rf

F

= (rma- rb) / (rma- rf)

Matrix

Used rma sandstone limestone dolomite anhydrite

2.65 2.71 2.87 2.98

Note:

 Better model than sonic porosity  Possible error due to non-homogenous matrix compositions, e.g. Sst is not purely silica or Lst is not purely carbonate

123

Dn March, 2009- Reference, date, place

1-F rma

124

Dn March, 2009- Reference, date, place

125

Dn March, 2009- Reference, date, place

Archie’s Equation Empirical constant (usually near unity)

Sw = n

Water saturation, fraction Saturation

exponent (also usually near 2)

126

a Rw



m m

Porosity, fraction

Resistivity of formation water, -m

Rt

Cementation exponent (usually near 2)

Resistivity of uninvaded formation, -m Dn March, 2009Reference, date, place

Dn March, 2009- Reference, date, place

127

Resources = GRV * N/G * Ø * Shc *InFVF * RF Place volumes or Accumulations (OIP / GIP)      

GRV= Gross Rock Volume (saturated with HC) N/G = Net reservoir proportion within the GRV Ø = Porosity (average for the Net reservoir vol. saturated with HC) Shc = HC saturation (proportion of the Ø occupied by oil or gas – average for the Net reservoir vol.) FVF = Formation Volume Factor (ratio of HC vol. at atmospheric conditions vs Reservoir conditions) RF = Recovery Factor (proportion of the HC vol. contained in the reservoir that can be produced – based on Mode development scenario)

Probabilistic multiplication of independant parameters 128

Dn March, 2009- Reference, date, place

Evaluasi Gross Rock Volume Spill Point H gas

H oil

Rock Volume = Surface (km2) * H gas or H oil (m) * Geometrical factor

129

Dn March, 2009- Reference, date, place

Method Standard GRV: New Surface/ Depth graph (lebih akurat) Surface Depth Graph shows : • Volume of one layer including oil and / or gas fill • P95 Mode and P05 contacts

130

Dn March, 2009- Reference, date, place

Oil Resources : order of magnitude Associated Gas: 

Oil : 2 Mb

(0,3 Mm3)

30 Mm3 (GOR = 100)

RF = 0.3

1,75 Mm3

GRV: 10 Mm3

7 Mm3

0,8 Mm3

FVF = 1/Bo = 0.75

(1 km x 1 km x 10 m)

So = 0.75

PHI = 0.25 N/G = 0.7

131

1,3 Mm3

Dn March, 2009- Reference, date, place

Gas Resources (simplified) including

Wet Gas 0,25 (8,7 bcf)

0,24 Mb ( 0,04 Mm3 ) Condensate CGR = 300 g/m3 (GCR = 2600 m3/m3 ) RF = 0.4

Gm3

RF Gas = 0.75

Free Gas : 328 Mm3

1,75 Mm3

GRV: 10 Mm3

1,3 Mm3

7 Mm3

(1 km x 1 km x 10 m)

FVF = 1/Bg = 250 Sg = 0.75

PHI = 0.25 N/G = 0.7

Dn March, 2009- Reference, date, place

132

BAGAIMANA MEMPRODUKSIKAN MINYAK DAN GAS BUMI KE PERMUKAAN ?

1. TAHAP PRIMARY RECOVERY : a. Dengan tenaga dorong alamiah (natural flow).

b. Dengan tenaga dorong buatan (artificial lift).

a. TENAGA DORONG ALAMIAH (Natural Flow) Dengan tenaga dorong alamiah yang dimiliki oleh suatu reservoir untuk menggerakan minyak dan atau gas bumi yang dikandungnya, sehingga mampu mengalir sendiri melalui poripori batuan ke sumur-sumur penghasilnya.

NATURAL FLOW : DEPLETION DRIVE atau SOLUTION GAS DRIVE atau DISSOLVED GAS DRIVE

OIL

daya dorong oleh gas larut

NATURAL FLOW : GAS CAP DRIVE

GAS Initial GOC present GOC

OIL

daya dorong oleh gas dari tudung gas Selain juga dari gas larut

NATURAL FLOW : WATER DRIVE

GAS Initial GOC present GOC

OIL present OWC Initial OWC

WATER AQUIFER

daya dorong oleh air dari akuifer

selain juga gas dari larutan dan gas cap

NATURAL FLOW : DEPLETION DRIVE atau GAS DRIVE

GAS

daya dorong oleh gas itu sendiri

NATURAL FLOW : WATER DRIVE

GAS

present GWC Initial GWC

WATER AQUIFER

daya dorong oleh air dari akuifer

selain juga oleh gas itu sendiri

B. TENAGA DORONG BUATAN (Artificial LIft)

Artificial Lift dilakukan, jika tenaga dorong alamiah sudah tidak mampu atau tidak efektif lagi untuk mengangkat minyak dan gas bumi ke permukaan

Artificial Lift : Sucker Rod Pump

Artificial Lift : ESP

Artificial Lift : Gas Lift

2. TAHAP SECONDARY RECOVERY : Tahap Secondary Recovery, dilakukan jika proses primary recovery tidak efektif lagi mengangkat minyak dan gas bumi ke permukaan, maka dilakukan proses injeksi air atau injeksi gas.

3. TAHAP TERTIARY RECOVERY ATAU EOR: EOR atau Enhanced Oil Recovery, dilakukan jika proses secondary recovery kurang efektif lagi dalam proses pengangkatan minyak dan gas bumi ke permukaan

Prinsip Injeksi SUMUR INJEKSI

SUMUR PRODUKSI

RESERVOIR

FLUIDA ATAU FLUIDA + BAHAN KIMIA ATAU GAS

MINYAK

Skema Sistem Pendorong Reservoir PENGURASAN PRIMER (PRIMARY RECOVERY) atau PENGURASAN SECARA ALAMIAH

PENGURASAN TAHAP KE 2 (SECONDARY RECOVERY)

INJEKSI AIR (WATER FLOODING)

PENGURASAN TAHAP KE 3 (TERTIARY RECOVERY) atau ENHANCED OIL RECOVERY(EOR) atau TEKNIK PRODUKSI LANJUT

INJEKSI KIMIA (CHEMICAL FLOODING)

INJEKSI TERCAMPUR (MISCIBLE FLOODING)

INJEKSI PANAS (THERMAL FLOODING)

HYDRO CARBON MISCIBLE

STEAM FLOODING

POLYMER INJEKSI GAS IMMISCIBLE GAS INJECION)

CONVENTIONAL RECOVERY

SURFACTANT MICELLAR POLYMER

CARBON DIOXIDE (CO2)

ALKALINE

NITROGEN

IN SITU COMBUSTION

Memproduksi Minyak

Sumberdaya Migas Indonesia @ JUNI 2006

Basin Tarakan (Kalimantan) PA: 1 ( 13 MMBO + 16 BCFG) L: 3 ( 17 MMBO + 123 BCFG)

Basin Sumatra Utara PA : 5 ( 5 MMBO + 813 BCFG) PB : 23 (86 MMBO + 2459 BCFG) L : 14 (77 MMBO + 1546 BCFG) Basin Sumatra-Tengah PA : 8 ( 27 MMBO + 1387 BCFG) PB : 12 ( 104 MMBO + 1872 BCFG) L : 30 ( 260 MMBO + 929 BCFG)

Basin Banggai (Sulawesi) PA: 2 ( 0 MMBO + 161 BCFG) PB: 5 ( 0 MMBO + 1093 BCFG) L : 5 ( 0 MMBO + 787 BCFG) Basin Kutai (Kalimantan) L: 27 (288 MMBO + 355 BCFG)

Basin Salawati (Papua) PA: 1 ( 4 MMBO + - BCFG) L: 4( 13 MMBO + 19 BCFG)

Basin Barito (Kalimantan) L: 26 (227 MMBO + 0 BCFG) 5º E

Sumber PERTAMINA EP

6,6

5º S

U Basin Sumatra Selatan PA : 6 (180 MMBO + 244 BCFG) PB : 18 ( 152 MMBO + 996 BCFG) L : 82 ( 384 MMBO + 1210 BCFG) Scale 1 : 21,360,000

100º E Basin Jawa Barat Utara PA: 18 ( 292 MMBO + 733BCFG) PB: 68 ( 546 MMBO + 2255 BCFG) L : 18 ( 31.50 MMBO + 174 BCFG)

110º E Basin Jawa-Tengah Utara PB : 11 ( 164 MMBO + 712 BCFG) L : 39 ( 295 MMBO + 1340 BCFG)

130º E Basin Jawa-Timur Utara PA : 10 ( 162 MMBO + 350 BCFG) PB : 17 ( 183 MMBO + 1278 BCFG) L : 30 ( 502 MMBO + 1809 BCFG)

120º E

140º E Basin Bintuni (Papua) L: 4( - MMBO + 5067 BCFG)