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well logging
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PENGANTAR
MPF-232 INTERPRETASI
WELL LOGGING
(KELAS-D)
OLEH : L. WIHARDJO
SELASA - 19.03.2013
JURUSAN PEMINYAKAN
FAKULTAS ENERGI & TEKNIK KEBUMIAN
Pengantar
Proses Penilaian Formasi
Input
Output
Mengapa bisa tidak akurat?
Penyelesaian Problema Penilaian Formasi
Kuliah Interpretasi Logging
Penutup
ACARA HARI INI
Proses Interpretasi Well Logging (Umum)
Formasi Evaluasi
Lubang Terbuka
Lithologi,
porositas &
Sw
Faktor-faktor penyebab “ketidakakuratan” interpretasi :
• Kondisi lubang sumur (terutama lubang sumur yang kurang bagus washout, rugous, breakout, oval)
• Pengaruh invasi mud-filtrate ke dalam lubang formasi
• Ketidakakuratan alat : Kondisi optimum lingkungan tidak terpenuhi
(resolusi vertikal alat yang dipakai)
Alat yang tidak sesuai dengan lingkungannya
• Kalau rumus Archie tidak bekerja secara
akurat?
Log Lubang
Terbuka
INTERPRETASI LOGGING
CONTOH IDEAL
C
RESISTIVITY
DENSITY (RED)
NEUTRON
(BLUE)
CALIPER
1
2 GOC
OWC Perfo
A
B
OPEN HOLE LOGGING
CONTOH IDEAL
C
1
2
Zone C-2 : Berubah menjadi minyak, GAS sudah terproduksi
Zone C-1 : Masih ada
gas, terlihat ada GWC (Gas Water Contact)
Apakah saudara
puas dgn
kesimpulan ini?
Arsiran Merah &
Kuning menun-
jukkan efek
Gas/Light HC
CASED HOLE LOGGING
CONTOH IDEAL
Arsiran Merah &
Kuning menun-
jukkan efek Gas /
LIGHT H.C.
GAS
OIL
GAS
WATER
OIL
OIL
GAS
GAS
OIL
WATER
GAS
WATER
OIL
WATER
CASED HOLE LOGGING
BEYOND THE TOOL SPECS LIMITATION : THIN BEDS
The summary : • No HC contrast
on both resistivity and porosity reading
• WHERE IS THE
HYDROCARBON RESERVOIR ?
OUT OF SPECS
> 100
ohmm
No-
XOver
HIGHEST VERTICAL RESOLUTION TOOL IS REQUIRED TO IDENTIFY THIN BEDS
OUT OF SPECS
> 100
ohmm
No-
XOver
THIN BEDS : WHAT SHOULD WE DO?
In Summary :
• None of the logs shows reservoir (all shale zone?)
• None of the reservoir shows hydrocarbon signature
• No Density – Porosity X-over • Low Resistivity (non-hydrocarbon signature of resistivity)
OUT OF SPECS
0.5 – 0.7
ohmm
No-
XOver
Highest Vertical Resolution Tool Must be Used
Tested interval xx875’ - xx960’ 3742 BOPD (30.2’)
OUT OF SPECS
0.5 – 0.7
ohmm
No-
XOver
Interpretasi Logging
Minggu 1 – 5 : Bahan UTS
1. BASIC LOGGING • Physical Measurements
• Tool Tech. Specification
• DOI
• Vertical Resolution
2. LOGGING ENVIRONMENTS • Borehole environments
• Borehole Geometri
• Invasion Effects
• Temperature Log
3. INTRODUCTION TO OPEN HOLE
FORMATION EVALUATION, STEP-1 • Lithology identification
• SP, GR & Dens – Neutron
• Limitation of each measurements for
lithology identification
1 SEMESTER BAHAN KULIAH MAHASISWA : INTERPRETASI LOGGING
Interpretasi Logging
Minggu 1 – 5 : Bahan UTS
1. BASIC LOGGING • Physical Measurements
• Tool Tech. Specification
• DOI
• Vertical Resolution
2. LOGGING ENVIRONMENTS • Borehole environments
• Borehole Geometri
• Invasion Effects
• Temperature Log
3. INTRODUCTION TO OPEN HOLE
FORMATION EVALUATION, STEP-1 • Lithology identification
• SP, GR & Dens – Neutron
• Limitation of each measurements for
lithology identification
Minggu 8 – 14 : s/d UAS
1 SEMESTER BAHAN KULIAH MAHASISWA : INTERPRETASI LOGGING
4. RESISTIVITY MEASUREMENTS • Resistivity vs. Induction
• Why do we need 3 DOI resistivity
• Deep Invasion vs. No Invasion
• Induction for water based mud
• RT vs Rxo : What does it mean?
• OH form. Eval. Step-2 : hydrocarbon vs.
Water Identification
5. 3 – POROSITIES MEASUREMENTS • Lithology dependent porosity
• Why do we need 2 or 3
measurements?
• Compatible scale
• Fluid typing from porosity
• OH form. Eval. Step-3 : porosity
determination
6. ARCHIE EQUATION • What is the requirement for Archie to work?
• How if Vshale .neq. 0%?
• Clay corrected Archie Equation
• Computing Formation water resistivity
• Step-4 : Saturation computation by Archie’s
equation
• The impact of a, m and n for Sw Calculation
Apa yang ingin saya berikan pada mata kuliah Interpretasi Well logging :
PENUTUP
• Interpretasi well logging pada kondisi lubang
terbuka, sangat dipengaruhi oleh banyak hal : • Paling Utama : keakuratan pembacaan data karena
kondisi lubang
• Kedua : keakuratan pembacaan data karena pengaruh
dari fluida lain (invasi mud filtrat atau filtrasi mud ke dalam
formasi)
• Ketiga : pengaruh mineral-mineral lain, sehingga
pembacaan kurva tidak mengindikasikan adanya
hidrokarbon
• Jika “rumus Archie” tidak bisa memberikan
hasil “terbaik” karena ada masalah-masalah di
dalam formasi yang “tidak diperkenankan”