oleh Ir. Djoko Wintolo, DEAJurusan Teknik Geologi Fakultas TeknikUniversitas Gadjah Mada Slide kuliah Geofisika Eksplorasi Djoko Wintolo

LOGGING Suatu aktifitas merekam karakteristik bebatuan sebagai fungsi kedalaman.Rekaman selama pemboran dimana ada materail air dan lumpur dinamakan MUD LOGGING (lithological logging).Data yang terekam: Tipe bebatuan, Kekerasan/ kompaksi, Kandungan fluida. Rekaman setelah aktifitas pemboran dengan memakai alat yang berkabel (wire line tool /instrument) dinamakan WIRELINE LOGGING.Data terekam: Resistivitas bebatuan, densitas bebatuan, tebal Mud cake, Radioaktifitas bebatuan, sifat akustik, temperatur formasi, dsb.

Djoko Wintolo

WIRELINE LOGGINGOPENHOLE LOGGING (lubang terbuka)Logging pada suatu sumur bor sebelum fasa penyelesaian (sebelum konstruksi casing/ pipa selubung).Semua instrumen logging dapat dijalankan.CASEDHOLE LOGGING (lubang dengan pipa selubung)Logging setelah penyelesaian sumur (konstruksi pipa selubung) :Hanya untuk instrumen tertentu: - Gammaray-log- Caliper-log- NMR- CBL

Djoko Wintolo

Analisis Data dari Wireline LogObjective / Tujuan: Membuat interpretasi kuantitatif dan kualitatif dari data logging untuk identifikasi lapisan-lapisan produktiv / prospektiv. Djoko Wintolo

INTERPRETASI KUALITATIF Didasarkan pada pola-pola defleksi dalam kertas rekaman logging dimana kurva-kurva yang terbentuk dipengaruhi oleh litologi dan kandungan fluida formasi.Untuk memastikan litologi atau lapisan formasi bebatuan.Mendeteksi lapisan porous / permeable dan mengestimasi kandungan fluida pada batuan .- Estimasi formasi/lapisan minyak, gas dan air.- Estimasi posisi GOC / WOCSebagai suatu data dasar untuk interpretasi kualitatif.Djoko Wintolo

INTERPRETASI KUANTITATIF Dengan menggunakan persamaan atau tabel2 (charts) untuk menghitung parameter reservoar dari data log (Rw, Rt, b, f, m , dll) Porositas/ porosity () Tingkat kejenuhan air/Water Saturation (Sw) Saturation of Hydrocarbon remains (Shr) Saturation of Hydrocarbon mobile (Shm) Initial hydrocarbon reserve in volumetric form Original/ Initial Oil In Place (OOIP/IOIP)Djoko Wintolo

Djoko Wintolo

Tipe-tipe LOGLOG LITHOLOGILOG RESISTIVITYLOG POROSITYDjoko Wintolo

LOG LITHOLOGI Tipe Log (instrumen) yang dipakai untuk mengukur lithologi yang tertembus dalam operasional pemboran.- log - SP- log Sinar Gamma - log Caliper Djoko Wintolo

LOG RESISTIVITY Tipe log (instrument) yang dipakai untuk mengukur nilai resistivity batuan.- Log SP- Log Normal- Microlog- Microlaterolog- Laterolog- Induction Log- MSFDjoko Wintolo

LOG POROSITAS Tipe log (instrumen) yang mengukur atau mendeteksi porositas bebatuan.- Density - log- Neutron - log- Sonic - logDjoko Wintolo

Djoko Wintolo

Deskripsi litologi (mud-loggig) oleh seorang wellsite geologist sebagai bagian dari laporan pemboranDjoko Wintolo

Beberapa tipe wireline logging ( records)Djoko Wintolo

Image scanner loggingDjoko Wintolo

Djoko Wintolo

UGIS-11 housing, made by RusiaDjoko Wintolo

Logging for groundwater studyDjoko Wintolo

Geochemical loggingDjoko Wintolo

Djoko Wintolo

Djoko Wintolo

Djoko Wintolo

Djoko Wintolo

Proses Interpretasi

Mengidentifikasi interval reservoar potensial; membedakan non-permeable, interval non-reservoir dari interval potensial porous. Estimasi ketebalan dari reservoar berpotesi. Menentukan lithology (rock type) dari potential reservoirs. Menghitung porousity (). Menentukan resistivity of formation water (Rw). Menghitung water saturations (Sw, Sxo) dengan menggunakan resistivity (Rt, Rxo). Estimasi in-place and movable hydrocarbons.

Djoko Wintolo

Resistivity logs do not always measure resistivity directly. Some resistivity logs (actually induction logs) measures conductivity instead which is thereciprocal of resistivity. 1 x 1000resistivity (ohms /m) = ------------ (millimhos/m) conductivity

Induction logs are used in wells drilled with a relatively fresh-water mud (low salinity) to obtain more accurate value of true resistivity.Djoko Wintolo

Spontaneous Potential (SP log)

The SP log is a measurement of the natural potential difference or self potential between an electrode in the borehole and a reference electrode at the surface (problem with offshore wells, no ground). No artificial currents are applied.

Three factors are necessary to produce an SP current: 1. a conductive fluid in the borehole, 2. a porous and permeable bed surrounded by an impermeable formation, and 3. a difference in salinity (or pressure) between the borehole fluid and the formation fluid.Djoko Wintolo

Djoko Wintolo

Djoko Wintolo

Djoko Wintolo

Djoko Wintolo

Djoko Wintolo

Djoko Wintolo

Djoko Wintolo

Djoko Wintolo

Djoko Wintolo

Djoko Wintolo

Djoko Wintolo

Djoko Wintolo

Djoko Wintolo

Djoko Wintolo

Nuclear logs3 Principles:

Detection of radiation resulting from natural radioactivityMeasure absorption of -radiation emitted by controlled sourceMeasure penetration of -radiation emitted by controlled neutron source

Only -r adiation and neutrons have appreciable penetrating power

Djoko Wintolo

Djoko Wintolo

Djoko Wintolo

Djoko Wintolo

Djoko Wintolo

Djoko Wintolo

Djoko Wintolo

Thermal loggingMenentukan heat flow (geothermal)Menentukan letak thermal anomalies yang disebabkan oleh aliran fluidaAbnormal radioactivityOxidation regionsDjoko Wintolo

Djoko Wintolo

Well-logging in coal explorationDjoko Wintolo

Djoko Wintolo

Djoko Wintolo

Djoko Wintolo

Djoko Wintolo

Djoko Wintolo

Thanks YouDjoko Wintolo

Referensi1. Asquith, George B, Log Evaluation of Shaly Sandstone: A Practical Guide, The American Association of Petroleum Geologists, Tulsa Oklahoma. 2. Desbrandes, R, Encyclopedia of Well Logging, Gulf Publishing Company Book Division, Houston, Texas, 1985.3. Dewan, John T, Essential of Modern Open-Hole Log Interpretation, Penn Well Publishing Company, Tulsa Oklahoma, 1983.4. Harsono Adi, Evaluasi Formasi dan Aplikasi Log.5. Helander, Donald P, Fundamental of Formation Evaluation, OGCI Publications, Oil and Gas Consultants International Inc, Tulsa, 1983.6. Pirson, Sylvain J, Well Log Analysis for Oil and Gas Formation Evaluation, Prentice Hall, Inc Englewood Cliffs, New Jork, 1963. 7. Wyllie M.R.J, The Fundamental of Well Log Interpretation, 3th Edition Academic Press, Inc 1963.Djoko Wintolo