Processing Magnetic Data

Under supervision of :

Dr. / Maher A.Mesbah

Done by / Mahmoud Emad Abdel-Fattah MohammedB.No. / 8144

Presentation Layouts

Data Processing Major Definitions Filtering , A ) Derivatives B ) Downward & Upward

Continuation C ) Reduction To Pole (RTP) D ) Pseudo Gravity &Pseudo

Magnetic

Data Processing

• Required to remove ‘noise’ and other errors in

data, and correct for other survey parameters.

• Can be broken into ‘corrections’ and ‘data

enhancements’

Major definitions

The angle between the direction of the magnetic and geographic north poles, called the magnetic declination, varies at different points on the Earth's surface.

The angle that the magnetic field vector makes with the horizontal plane at any point on the Earth's surface is called the magnetic inclination.

processes to get the regional formula (like gravity).

Filtering

The sediments have low susceptibility and the basement high susceptibility.

• Emphasizing shorter wavelength features.• First vertical derivative emphasizes near surface features. It can be measured with gradiometer, or derived from corrected data• Second vertical derivative emphasizes boundaries of target zones.

Derivatives

First Vertical Derivative :This enhancement sharpens up anomalies over bodies and tends to reduce anomaly complexity,allowing a clearer imaging of the causative structures.secondVertical Derivative :removes the effects of large anomalies or regional influences.

Total Horizontal Derivative :It usually produces a more exact location for faults than the first vertical derivative, but for magnetic data it must be used in conjunction with the other transformations e.g. reduction to pole (RTP) or pseudo-gravity.

Downward/Upward Continuation

The purpose of the downward continuation filter is to calculate the magnetic/gravity field with the measurement plane closer to the sources. This process also increases the amplitude of the anomalies.Care must be taken because in addition to the amplitude of the anomalies increasing the amplitude of any noise present will also increase.A similar effect is achieved using the upward continuation, except that the measurement plane is further from the sources

• Process by which effects of inclination and declination areremoved from the data.• The data are mathematically transformed to measurements overthe same geologic structure, but at the magnetic pole where theinducing field is vertical.

Reduction to Pole

The process requires pole reduction, but adds a further procedure which converts the essentially dipolar nature of a magnetic field to its equivalent monopolar form.

Pseudo-Gravity and Pseudo-Magnetic Fields

Comparison of gravity and pseudo-gravity maps can reveal a good deal about the local geology. Where anomalies coincide, the source of the gravity and magnetic disturbances is likely to be the same geological structure.

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