PETROLOGICAL AND WATER GEOCHEMISTRY STUDY TO DETERMINE SCALING POTENTIAL AT MUARALABOH GEOTHERMAL FIELD

• Main Author: Anjani Suwanto , Saphira
• Format: Final Project
• Language: Indonesia
• Subjects: Geologi, hidrologi & meteorologi
• Online Access: https://digilib.itb.ac.id/gdl/view/30811
• Institution: Institut Teknologi Bandung

<p align="justify">Muaralaboh Geothermal Field is located at Solok Selatan, 150 km southeast of Padang City, West Sumatera. Muaralaboh Geothermal Field is a high enthalphy volcanic hydrothermal system (reservoirs temperature ~246°C) and liquid dominated reservoir. Scaling potential at Muaralaboh Geothermal Field was determined by analyzing fluid geochemistry data, litology and alteration of the reservoir rocks, and scaling samples of wells X1 and Y1. Fluid geochemistry data is taken from water at separators (pressure of 17,5 and 6 atmospheric bar (b.a.)) and weirbox (pressure of 1 b.a.). Litology and alteration of the reservoir rocks are analyzed from petrography analysis from cutting samples of well X1 on depths of 800 until 996 m, and well Y1 on depths of 1.265 until 1.610 m. The study shows that well X1’s reservoir rock is made of dacite lava, meanwhile well Y1’s reservoir rock, which is located deeper, is made of andesite lava. Propilitic and silicification alterations were observed on both wells with the appearance of calcite, epidote, chlorite, secondary quartz, illite, and opaque minerals (pyrite). These hydrothermal alteration types show that hydrothermal fluid is rich of silica (SiO2) and carbondioxide (CO2) therefore allowing silica and calcite scaling to occur on wells X1 and Y1. The result of reservoir fluid’s chemical elements’ concentrations calculations shows that, the minerals with a scaling potential are silica (amorf silica) on production pipelines, surface equipments on wells X1 and Y1, and also the injection well. Anhydrite scaling is also predicted to form on the production pipelines on wells X1 and Y1, but calcite and halite scaling will not form. Based on the calculations of the temperature and pH of reservoir fluids there is no corrosion potential on both wells. In reality, scaling is found on production pipelines, surface equipments, and as deposits on Y1’s reservoir fluid’s pond. Scanning Electron MicroscopeEnergy Dispersive Spectroscopy (SEM-EDS) and X-Ray Diffraction (XRD) analysis on scaling samples shows the appearance of amorf silica, anhydrite, and halite. <p align="justify"> <br />