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Simulation of Time-Lapse Resistivity Method on Sandbox Model to Determine Fluid Changes and Desaturation Rizka Rizka; Beta Arroma Piskora; Soni Satiawan; Hendra Saputra
Journal of Geoscience, Engineering, Environment, and Technology Vol. 5 No. 4 (2020): JGEET Vol 05 No 04: December 2020
Publisher : UIR PRESS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.25299/jgeet.2020.5.4.4266

Abstract

Time-lapse resistivity method is an implementation of the resistivity method that is executed exactly at the same spot but with various in time. In this study, the technique uses to identify the dynamics of groundwater fluids. The application of the time-lapse resistivity method was carried out by performing a sandbox model simulation that contains layers of rocks with a fault structure. The rock layers consist of tuff, fine sandstone, shale, coarse sandstone, gravel that represents confined and unconfined aquifers. The simulation was achieved by applying the Electrical Resistivity Tomography (ERT) dipole-dipole configuration at the same place, and measurements with 3 different conditions, namely dry, wet conditions filled with 2.5% water and wet conditions filled with 5% water. Data acquisition uses Naniura resistivity meters with a track length of 96 cm. The first measurement results (dry conditions) obtained a range of resistivity values ​​from 3.7 to 168.1 Ω.m, the second measurement (wet conditions filled 2.5% water) obtained the range of resistivity values ​​from 3.3 to 110.8 Ω.m and the third measurement (wet conditions) filled with 5% water the resistivity values ​​range from 1.7 to 91.2 Ω.m. Following the results of time-lapse inversion processing, a larger percentage change in the amount of 5.6% due to water absorption by the surface which then migrates into the inner layer. Whereas the percentage of desaturation ranges is from -3.11 to 0.217 %, refer to Archie’s Law assumes conduction is caused by water content.
Investigasi Lapisan Akuifer Berdasarkan Data Vertical Electrical Sounding (VES) dan Data Electrical Logging; Studi Kasus Kampus ITERA Rizka, .; Satiawan, Soni
Bulletin of Scientific Contribution Vol 17, No 2 (2019): Bulletin of Scientific Contribution : GEOLOGY
Publisher : Fakultas Teknik Geologi Universitas Padjadjaran

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (1143.222 KB) | DOI: 10.24198/bsc.v17i2.22393

Abstract

ABSTRAKTelah dilakukan pengukuran geolistrik Vertical Electrical Sounding (VES) dengan 33 titik sounding untuk mengidentifikasi geometri akuifer yang terdapat di kampus ITERA. Konfigurasi yang digunakan pada pengukuran Vertical Electrical Sounding (VES) adalah konfigurasi Schlumberger. Karena target penelitian ini adalah akuifer dengan variasi kedalaman dari permukaan hingga lebih dari 100 meter di bawah permukaan sehingga panjang garis pengukuran dibuat bervariasi, nilai minimum dan maksimum AB / 2 masing-masing adalah 2 dan 150 meter. Sedangkan perubahan MN / 2 dilakukan tiga (3) kali (0.5, 2, dan 10 meter). Hasil pengolahan data geolistrik Vertical Electrical Sounding (VES) dikorelasikan dengan data sekunder berupa data sumur electrical logging resistivity dan Spontanous Potential (SP). Berdasarkan hasil pengolahan data Vertical Electrical Sounding (VES) yang dikorelasikan dengan data sumur electrical logging resistivity dan Spontanous Potential (SP), daerah kampus ITERA memiliki potensi akuifer bebas (unconfined aquifer) dan akuifer tertekan (confined aquifer). Akuifer bebas diduga merupakan batuan tuff dengan nilai resistivitas tinggi (>80 Ωm) yang ditemukan pada kedalaman dangkal (< 5 meter dari permukaan). Akuifer tertekan diduga merupakan pasir tuffan dengan nilai resistivitas menengah (20 – 80 Ωm) ditemukan pada kedalaman dalam (>75 m dari permukaan).Kata kunci: Akuifer, VES, Electrical Logging, ITERAABSTRACTGeoelectric measurements of Vertical Electrical Sounding (VES) have been carried out with 33 sounding points to identify the geometry of aquifers at the ITERA campus. Sounding technique with Schlumberger configuration is applied to collect the data. Since the target of this study is aquifers with variations of depth from surface up to more than 100 meters beneath the surface therefor the length of the line measurement was made varied, the minimum and maximum of AB / 2 are 2 and 150 meters respectively. The changes of MN / 2 are carried out three (3) times (0.5, 2 and 10 meters). The results of processing Vertical Electrical Sounding (VES) data were correlated with secondary data in the form of electrical well data logging resistivity and Spontanous Potential (SP). Based on the results of Vertical Electrical Sounding (VES) data processing correlated with electrical well logging data on resistivity and Spontanous Potential (SP), the ITERA campus area has the potential of unconfined aquifers and confined aquifers. Unconfined aquifers are thought to be tuff with a high resistivity value (> 80 Ωm) which are found at shallow depths (<5 meters above the surface). The confined aquifer is thought to be tuffaceous sandstone with an intermediate resistivity value (20 - 80 Ωm) found at deep depth (> 75 m from the surface).Keyword: Aquifer, VES, Electrical Logging, ITERA