well logging geology earth science

2. Sample log/Litho log

3. Principle;
 It based on the physical examining of the
rocks in well usually in well cuttings.

4. Well cuttings;
 Small rock chip that are cut by drilling bit.
 Well cuttings are washed to remove drilling mud &
examine under microscope.
 Rock type, texture, grain size, porosity, and
microfossil contents are noted.

5.  Well cuttings are sampled at regular interval
usually 5-10ft.
 Interval is short at reservoir is strike called
ditch sample.
 Core of drilling well is placed in sequence
usually right to left.

8.  All the observation are recorded & plotted
against depth.
Depth(ft) Lithology Description
10 shale Fine grained ,Greenish gray.
20 Sandston Coarse grained ,Reddish.
25 sandstone //
30 shale Fine grained , Greenish gray.
40 shale //

9.  When well is drilled at 1800ft it will take well
cuttings takes 3hours up to the surface.
 During this trip well cuttings from different
rocks are mixed and composition is changed.
 It often difficult to identified top and bottom
of the formation.