Description
The Formation MicroScanner sonde (FMS) consists of four orthogonal
imaging pads each containing 16 microelectrodes which are in direct
contact with the borehole wall during the recording. The button
current intensity is sampled every 0.1 in (2.5 mm). The tool works
by emitting a focused current from the four pads into the formation.
The current intensity variations are measured by the array of
buttons on each of the pads.
Processing transforms the current intensity measurements, which
reflect the microresistivity variations of the formation, into
high resolution gray or color images of variable intensity. Black
and white (darkest or lightest color) indicate low and high microresistivity,
respectively. The tool also includes a General Purpose Inclinometry
Cartridge (GPIT) which provides accelerometer and magnetometer
data in order to allow one to define the tool position and spatial
orientation of the data.
In smooth boreholes with very homogeneous bedding the depth of
investigation is about 10 in (25 cm). The vertical resolution
is 0.2 in (5 mm).
 |
<---- Sixteen-electrode arrangement for the four-pad
tool. |
Applications
- Mapping of bedding planes, fractures, faults, foliations,
and other formation structures and dip determination.
- Detailed correlation of coring and logging depths.
- Precise positioning of core sections where core recovery
is less than 100%.
- Analysis of depositional environments.
Log Presentation
FMS images can be plotted with identical vertical and horizontal
scales to see features without exaggeration. However, due to
physical constraints, different vertical and horizontal scales
are commonly used. The images are displayed on an oriented
plot, also called an azimuthal plot, because the images are
positioned according to their orientation in the borehole with
N in the center and S on both edges. Images from two passes
of the tool can be merged and plotted together. The calipers
or other curves can be plotted alongside the images as well.
With an additional processing step, dipmeter
calculations can be made. Standard dipmeter plots consist of
borehole drift, calipers, dip angle and direction (tadpoles),
azimuth frequency plots, and pad traces.
Tool Specifications
Temperature rating: |
350° F (175° C) |
Pressure rating: |
20 kpsi (13.8 kPa) |
Diameter: |
3.625 in (9.2 cm) |
Length: |
25.3 ft (7.72 m) |
| Weight: |
537 lbs (243.8 Kg) |
Sampling interval: |
0.1 in (2.5 mm) |
Maximum logging speed |
1,800 ft/hr (549 m/hr) |
Measurement Specifications
Vertical resolution: |
0.2 in (5 mm) |
Depth of investigation: |
10 in (25 cm) |
Deployment Notes
* ®trademark of Schlumberger
|
