Determination of the strike and dip of fracture in cores (Fig.4-1) is an important task to estimate the geological structure of the geothermal field, as well as to estimate the path of geothermal fluids (Fig.4-2).
The measurement of the dip in a core fracture is simple, but not the measurement of its strike because the orientation of the core is hardly defined. This is the reason why measurements of both, dip and strike, is not included in the core fracture analysis.
Recently, sampling techniques of fixed core orientation have been developed, but because of their high cost, these sampling techniques are not of general use.

To fill this gap, West JEC in collaboration with NEDO, developed a system to analyze both, dip and strike of fractures in cores using thermo-remnant magnetization (Fig.4-3).
This system has been useful to estimate, during geothermal development surveys, the strike and dip of the faults playing the role of reservoirs (Fig.4-4). Especially, in the case of all coring well, this technique is useful to assess the location and extent of the reservoir.

Click to image
Fig.4-1 Fracture in core samples
Fig.4-2 Image of the relation between a geothermal well and fault( fracture )
Fig.4-3 Flow chart for the analysis of orientation in a core fracture
Fig.4-4 Example of fracture orientation analysis

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