We have 3D density model and we perform a 3D stripping according to the observed Bouguer anomaly. We compute the gravity effect of the suitable layer (or several layers) and remove their effect from the real Bouguer anomaly
Stripped anomalies
The input model
The density model
Our density model have 6 layers. We need 5 steps to reach the end of the stripping. Note: hereafter, the remaining anomaly is the anomaly remaining after the stripping
Stripping step 1
Density model
Real Bouguer anomaly
Gravity effect
Remaining anomaly
The Bouguer anomaly is well reduced (see the remaining anomaly) compared to the initial Bouguer anomaly.
Stripping step 2
Density model
Real Bouguer anomaly
Gravity effect
Remaining anomaly
The Bouguer anomaly is interestingly more reduced indicating that the stripped first 2 layers (step 2) satisfy the observed data
Stripping step 3
Density model
Real Bouguer anomaly
Gravity effect
Remaining anomaly
We not reduce the anomaly compared to the previous step (i.e. step 2)
Stripping step 4
Density model
Real Bouguer anomaly
Gravity effect
Remaining anomaly
Again, the stripped anomaly is no more reduced, we doing completely the reverse
Stripping step 5
Density model
Real Bouguer anomaly
Gravity effect
Remaining anomaly
We are completely in the opposite of what we are expected.
Conclusion
From this stripping, we understand that our model is « correct » from the surface till the 3rd layer but down it’s not the case. As the model geometries comes from seismic, we understand that the densities of layers 4 and 5 are overestimated according to the observed data. The density decreases could more probably caused by the faults and fractures which are large in this area. This conclusion is so important for instance for exploration of deep geothermal target