| Title | Integration of Geoscience, Geomechanics, And Geostatistics Method To Model The Fracture Distribution And Permeability In Naturally Fractured Geothermal Reservoir |
|---|---|
| Authors | M. Ikhwan, S. Suryanto, R.M. Tofan |
| Year | 2022 |
| Conference | New Zealand Geothermal Workshop |
| Keywords | geothermal, fracture, DFN, reservoir, modelling |
| Abstract | It is well-known that geothermal reservoirs are mostly controlled by secondary permeability, for instance, natural fractures zone and fault, as the natural conduit for geothermal fluid flow. However, not all natural fractures contribute to the fluid flow. In this paper, we attempt to identify the contributed-natural fractures to hydrothermal flow by using the geoscience data, geomechanics and geostatistics method in the naturally fractured reservoir characterization through the discrete fracture network (DFN) model. A geomechanics method is used to filter the fractures along the borehole so the fractures input in the modelling only uses the critically-stressed fractures as the possible permeable fractures. This driver is converted into an intensity log and mainly controls the vertical spacing fracture distribution in the 3D model. In the horizontal dimension, we utilize the deterministic surface fault model and microearthquake (MEQ) events distribution, which is interpreted as an indication of fluid flow through fault or fracture to give us geologically reasonable spatial control in modelling the DFN. To confirm the modelled flowing natural fractures distribution, we upscale the DFN model into the permeable zone model. The permeability calculation parameter is derived from the assumption that we generate from image log data such as aperture and modelled fracture length. This permeability model will compare with the actual feedzone or depth of sweet spots in the well which has been proved to contribute to the fluid flow. The discrete fracture network model derived from this method gives a fit permeability model with the actual flow condition in the well-scale. The reason is that the permeability control, in this case, is mostly associated with fracture intensity. In other words, a highintensity fracture zone with a certain orientation penetrated by the well will give high permeability magnitude, thus characterizing the reservoir through the DFN model will be a benefit. |