Geological, isothermal, and isobaric 3-D model construction in early stage of geothermal exploration

5th ITB International Geothermal Workshop

Saputra, M.P.^1 ; Suryantini^1,2 ; Catigtig, D.^3 ; Regandara, R.^1 ; Asnin, S.N.^1 ; Pratama, A.B.^1

Graduate Program in Geothermal Technology, Faculty of Mining and Petroleum Engineering, Institut Teknologi Bandung, Bandung

40132, Indonesia^1

Engineering Geology Study Program, Faculty of Earth Sciences and Technology, Institut Teknologi Bandung, Bandung

40132, Indonesia^2

Emerging Power Inc., Philippines^3

关键词: 3-D model constructions;    Acceleration due to gravity;    Exploration and productions;    Geothermal exploration;    Geothermal gradients;    Reservoir temperatures;    Saturated liquid densities;    Surface manifestations;   

Others  :  https://iopscience.iop.org/article/10.1088/1755-1315/42/1/012009/pdf
DOI  :  10.1088/1755-1315/42/1/012009

来源: IOP

【 摘 要 】

Construction of geology, thermal anomaly and pressure distribution of a geothermal system in the early stage of exploration where data is limited is described using a 3-D software, Leapfrog Geothermal. The geological 3-D model was developed from a topographic map (derived from DEM data), geological map and literature studies reported in an early geological survey. The isothermal 3-D model was constructed using reservoir temperature estimation from geothermometry calculated from chemical analyses on surface manifestations, available shallow gradient temperature hole data and the normal gradient temperature (3°C/100m) for a nonthermal area. The isobaric 3-D model was built using hydrostatic pressure where the hydrostatic pressure is determined by the product of the fluid density, acceleration due to gravity, and depth. Fluid density is given by saturated liquid density as a function of temperature. There are some constraints on the modelling result such as (1) within the predicted reservoir, the geothermal gradient is not constant but continues to increase, thus, creating an anomalously high temperature at depth, and (2) the lithology model is made by interpolating and extrapolating cross-sections whereas usually only two to three geology sections were available for this study. Hence, the modeller must understand the geology. An additional cross section was developed by the modeller which may not be as suitable as the geologist constructed sections. The results of this study can be combined with geophysical data such as gravity, geomagnetic, micro-tremor and resistivity data. The combination of geological, geochemical, isothermal, isobaric and geophysical data could be used in (1) estimating the geometry and size of the geothermal reservoir, (2) predicting the depth of top reservoir, and (3) creating well prognosis for exploration and production wells.