0:00
primary causes of formation damage are
0:03
invasion of drilling mud solids or
0:07
formation expansion of water sensitive
0:11
Clays and the invasion of solids from
0:14
the completion fluid into the formation
0:17
research has shown that the solid
0:19
particles carried into the formation
0:21
pores are the main cause of permeability
0:23
impairment and such impairment is
0:25
dependent on the size of the particles
0:27
and the permeability of the formation
0:30
shallow invasion of these particles will
0:32
occur when their diameter is roughly 10
0:34
to 30% of the mean pore diameter of the
0:36
formation as indicated by this table it
0:40
is easier to damage higher permeability
0:42
reservoirs because fluid losses can
0:44
carry solids deeper into the
0:46
formation formation damage caused by
0:49
Drilling Fluids may be minimized by
0:51
properly sized mud solids which quickly
0:53
form a protective filter cake drilling
0:56
with clear filtered weighted fluids
0:59
underbalance Drilling and post- drilling
1:03
stimulation particularly when drilling
1:05
with freshwater muds mud filtrate
1:07
Invasion can cause permeability
1:09
reduction due to the swelling of native
1:11
Clays and their dispersion in the pores
1:14
of the formation low concentrations of
1:17
potassium or calcium chloride in
1:19
completion fluids have been found
1:21
helpful in preventing such damage
1:24
although the Perforating process itself
1:26
always causes some damage due to the
1:28
crushing of the rock surrounding the the
1:30
perforation the major causes of
1:32
Perforating damage are solids plugging
1:35
during overbalanced Perforating and
1:37
inadequate perforation density Andor
1:41
length underbalanced perating using
1:43
through tubing or tubing conveyed
1:45
techniques and the use of clear filtered
1:47
completion brins hold the greatest
1:50
promise for reducing such damage a
1:52
minimum of four shots per foot
1:54
preferably more properly sized charges
1:57
and centralized guns can also increase
2:00
the number of perforations contributing
2:02
flow the importance of clean completion
2:05
fluids cannot be overemphasized careful
2:08
rinsing of mud tanks removal of scale
2:11
rust and paint from drill pipe minimal
2:13
use of pipe dope on connections and
2:16
constant monitoring of filtering
2:17
elements are drilling procedures which
2:19
are becoming standard practice with many
2:22
companies the added cost of these
2:24
procedures is more than offset by the
2:26
Improvement in productivity
