Copy of `Reid Geophysics - petroleum and mineral exploration info`

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Reid Geophysics - petroleum and mineral exploration info
Category: Earth and Environment > Geophysics
Date & country: 25/11/2007,
Words: 7


Depth ensemble filtering
or pseudo-depth slicing uses the grid power spectrum slopes from different source depths to produce grids emphasising the effects of sources at particular depths.

Euler deconvolution
uses a sliding window on profile or gridded gravity or magnetic data and a simple equation involving gradients. It estimates the location and depth of geological edges which show a density or magnetization contrast. A structural index distinguishes contacts, faults, dykes, sills, pipes and compact bodies. Enhanced Euler decon. estimates dips, strikes, structural index and body property contrasts. Commercially available through Intrepid.

Gamma ray multi-element imaging
employs the gamma ray channels associated with potassium, uranium and thorium to control red, blue and green virtual light sources and show local lithology. Noise Adjusted Singular Value Decomposition (NASVD) uses multichannel data to estimate elements optimally. Available through Intrepid.

Gravity isostatic residual
is the observed gravity after correction for the effects of meter drift, tides, latitude, altitude, topography and (in particular) variations in the depth to the crust/mantle boundary. Isostatic corrections usually remove a regional trend.

Horizontal gradient of gravity
or pseudo-gravity peaks over contacts between rocks of different density or magnetization.

Pseudo-gravity
is the gravity anomaly that would be observed if density contrast were proportional to magnetization contrast. It is calculated from magnetic observations and is used to compare gravity and magnetic observations to distinguish between the effects of different source rock types.

Tensor gradients
are the fully specified gradients of vector fields (like gravity or magnetic fields). They have 9 components of which 5 are typically independent and are sensitive to local detail. Gravity tensor gradients are currently measured commercially. Gradient-enhanced total magnetic field grids are offered by several contractors. They use the vector gradients of total field data.