# Susceptibility and Remanent Magnetization Estimates from Orientation Tools in Borehole Imaging Logs
## 4 Conclusions  
Results achieved with this research lead to the conclusion that both magnetic susceptibility and remanent magnetic field can be satisfactorily estimated for forward magnetic  
Figure 14: Magnetic susceptibility estimates for well 1-RJS-755-RJ and the result of 58 susceptibility laboratory measurements made in rock samples. The lithologic log along the well is exhibited in the base of the chart for illustration. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Interval (m)** & \(\mathbf{I_{R}}\) (\({}^{\circ}\)) & \(\mathbf{D_{R}}\) (\({}^{\circ}\)) \\ \hline
6211–6300 & \(-\)29.98 & 114.63 \\ \hline
6305–6495 & \(-\)29.14 & 115.96 \\ \hline
6500–6535 & \(-\)29.43 & 112.05 \\ \hline
6540–6570 & \(-\)28.20 & 117.68 \\ \hline
6585–6605 & \(-\)27.53 & 116.66 \\ \hline
6620–6681 & \(-\)26.96 & 116.32 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Inclination \(I_{R}\) and declination \(D_{R}\) estimates for remanence of the six igneous intervals in well 1-RJS-755-RJ. modeling purposes from the magnetic field acquired by orientation tools in borehole imaging logs. The methodology can also be applied in mining boreholes if they have acquired the magnetic field. The use for magnetostriagraphy, however, depends on a resolution improvement in the acquired magnetic data. When applied to real data the proposed methodology has estimated magnetic susceptibility values inside the range of values published in the literature for igneous rocks, and very close to laboratory measurements taken from rock samples collected in the well. The methodology can be improved by doing adjustments in the correction of the rotation tool effect, the most important correction. The choice of the Earth's magnetic field model can also be improved by taking always the most complete model. Finally, the use of a base magnetometer near the well may provide better data to the correction of diurnal field variation. Although measurements of intensity, inclination and declination for magnetic remanence were not available to validate our estimates, the small values dispersion of each variable and the consistence of the results in terms of what we would expect for a magnetic field, gives confidence to the process. The promising results achieved here has proved that the proposed methodology is able to provide reliable susceptibility values for magnetic forward modeling and inversion, specially in the case of hydrocarbon exploration where direct measures are rare. Applications in mining and magnetostriagraphy may also be possible but require further investigations. Conceptualization, J.C.S.O.L., A.P.C.C.L. and J.C.J. ; methodology, J.C.S.O.L. ; software, J.C.S.O.L. ; validation, A.P.C.C.L. and J.C.J. ; formal analysis, A.N.G.R. ; investigation, J.C.S.O.L. ; resources, A.P.C.C.L., J.C.J. and L.d.S.M. ; writing--original draft preparation, J.C.S.O.L. ; writing--review and editing, J.C.S.O.L. ; visualization, A.N.G.R. ; supervision, L.d.S.M. ; project administration, L.d.S.M. All authors have read and agreed to the published version of the manuscript. This research received no external funding. Not applicable. The data used in this research may be requested to the Brazilian National Petroleum Agency-ANP. Instructions to request data can be found at [[https://www.gov.br/anp/pt-br/assuntos/exploraco-e-producao-de-oleo-e-gas/dados-tecnicos/acesso-aos-dados-tecnicos](https://www.gov.br/anp/pt-br/assuntos/exploraco-e-producao-de-oleo-e-gas/dados-tecnicos/acesso-aos-dados-tecnicos)]([https://www.gov.br/anp/pt-br/assuntos/exploraco-e-producao-de-oleo-e-gas/dados-tecnicos/acesso-aos-dados-tecnicos](https://www.gov.br/anp/pt-br/assuntos/exploraco-e-producao-de-oleo-e-gas/dados-tecnicos/acesso-aos-dados-tecnicos)), accessed on 31 January 2025. The authors are thankful to the colleague [PERSON] for the valuable suggestions. We also would like to thank others colleagues from PETROBRAS for the encouragement and for many useful discussions. We thank PETROBRAS for permission to publish this work.