Scope of Applicability
- Depth Matching between cased-hole and open-hole logs
- Pick up radioactive anomalies caused by saline water invasion
- Pick up radioactive anomalies caused by water invasion or radioactive tracers
Mathematical Model
GR = (1-\phi_e) \cdot GR_{m} + \phi_e \cdot s_w \cdot GR_w |
where GR_w is natural gamma radioactivity of formation water and GR_m is natural gamma radioactivity of rocks:
GR_m = \sum_i GR_{mi} |
where GR_{mi} natural gamma radioactivity of i-th mineral.