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SELF POTENTIAL (SP). Achmad Y oshi S atriady Muhamad Ha rfan Yusuf H adi. Self Potential Surveying. Introduction This method measures naturally occurring electrical potentials on the ground surface.
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SELFPOTENTIAL (SP) AchmadYoshiSatriady MuhamadHarfan Yusuf Hadi
Self Potential Surveying Introduction • This method measures naturally occurring electrical potentials on the ground surface. • The spontaneous or natural potentials developed in the earth by electrochemical actions between minerals and subsurface fluids or by electrokinetic processes involving the flow of ionic fluids.
Basic Concept • Electrofiltration Potential The flow of fluid through a capillary or porous medium may generate an electrical potential (called the streaming potential) along the flow path
Basic Concept • Mineralization Potential
Field Procedure • Fixed-Based Configuration • Dipole Configuration (Gradient Configuration)
Aplication of Self-Potential Method • Detection of Buried Tank • Self-potential signals associated with ground water flow
Jl.Siliwangi ITB Jl.Tamansari Lokasi Penelitian U Lokasi Pengukuran Anomali SP • Daerah survey dilakukan di Lebaksiliwangi Sabuga Bandung • Luas daerah pengukuran 14 x 9 m2 • Teknik pengukuran yang dipakai Metode Amplitudo Potensial
Pola pengukuran • Jumlah titik pengukuran 150 grid • Jarak tiap titik panjang maupun lebarnya sebesar 1 meter, dengan 1 titik acuan tetap
Hasilkurvaanomalikordinat -4 yang didapatsetelah data processing • daritabeldangrafikdisampingdiketahui : • V(0) = -2,5 mV • xo = -0,122 meter • L(xi) = hasilpengukuranpotensial yang dianggap anomaly • q (silinder) = 1 (sesuaireferensimenurutBhatacharyadan Roy) merupakanordinatposisi yang padakasusiniposisinyasedikitdigeser agar mempermudahperhitungan (denganmenambahkan 4,275)
Hasil kurva anomali kordinat -6 yang di dapat setelah data processing • V(0) = -4,3 mV • xo = -0,217 meter • L(xi) = hasilpengukuranpotensial yang dianggap anomaly • q (silinder) = 1 (sesuaireferensimenurutBhatacharyadan Roy) merupakanordinatposisi yang padakasusiniposisinyasedikitdigeser agar mempermudahperhitungan (denganmenambahkan 4,18)
Hasil survey Besar momen dipol yang didapat berupa minus, dalam hal ini dapat di asumsikan bahwa kedua anomali merupakan bahan mineral berbahan konduktor, diprediksiinimerupakansebuah drum.
Self-potential signals associated with ground water flow (infiltration test from a ditch) • Acquisition
Self Potential anomaly expected over water flowing into & out fracture zone • Self Potential anomaly expected over water flowing into fracture zone. Self Potential anomaly expected over water flowing into fracture zone.
The Measured Self-Potential Signal (measured along profile 3)
References • Sharma, Prem V., 2004, Environmental and Engineering Geophysics, Cambridge University Press, UK. • A. Boleve et al., A new formulation to compute self-potential signals associated with ground water flow, 2007, Hydrology and earth System Sciences Discussions. • Putri, Anggun K., Fenomena Self Potential danInterpretasinyaDenganMetoda least square, 2006, UniversitasNegeri Jakarta, Indonesia.