PETE 411
Well Drilling
Lesson 32
Cementing - Salt Solutions
1
Cementing - Salt Solutions
 Use of salt in Cement Slurries
 Unsaturated Salt Solutions
 Saturated Salt Solutions
 Types Cements
 Cement Additives
 Examples
2
Read:
Applied Drilling Engineering, Ch. 3
HW #17
Cementing of Liner
due November 27, 2002
3
Salt in Cement Slurries
Salt Zones
 Salt-saturated cements were originally used for
cementing casing strings through salt zones.
 Fresh or unsaturated salt cement slurries will
not bond satisfactorily to salt formations
because the slurry tends to dissolve or leach
away the salt at the wall of the hole.
 Salt-saturated cements will not dissolve any
more salt so a good bond can be achieved
4
Salt in Cement Slurries
Shale Zones
 Many shales are sensitive to fresh
water.
 Salt helps to protect these shales in
that they tend to prevent
excessive sloughing or heaving
of the shales.
5
Salt in Cement Slurries
Accelerator
 In low concentrations salt tends to
accelerate the setting of cement.
Retarder
 In high concentrations ( >5% by wt. of
water) the salt will tend to retard the
setting of the cement.
6
Salt in Cement Slurries
7
Salt in Cement Slurries
Expansion
 Salt results in a more expansive
cement.
Freezing
 Salt reduces the freezing
temperature of cement slurries.
8
mg/L
ppm
EXAMPLE:
200,000 mg of NaCl
800,000 mg of H2O
1,000,000 mg of solution
< 1 litre of solution
of solution
9
Volume of Sodium Chloride Solution
EXAMPLE:
Adding 30 lbs of NaCl
to 100 lbs of H2O
increases the volume of
solution by ~10.7%
30% by weight =
13.8% by volume
(SG = 2.17)
10
Density of Sodium Chloride Solution
11
12
13
14
15
16
17
Example: Salt Solutions
30% NaCl (by weight of water) is added to
one gallon of fresh water.
Calculate the density of the mixture:
(i) Before the salt goes into solution
(ii) Using the solubility charts shown above.
18
Problem : Salt Solutions
(i) Assuming that
ρ1V1  ρ2 V2  ...  ρmix Vmix
ρmix
ρ W VW  ρS VS  ρmix Vmix
ρ w Vw  ρ S VS

Vmix
8.33 * 1  0.30 * 8.33 x 1

1  (0.30 * 8.33) / (2.17 * 8.33)
mix  9.51 lb/gal
19
Problem : Salt Solutions
(ii) From the chart,
 mix  9.8 lb/gal
{ 9.51 lb/gal vs. 9.8 lb/gal !! }
{ what if we had 60% salt? }
20
21
22
23
24
Problem
Calculate the density and yield of a
cement slurry consisting of:
65% Class “A” cement
35% Pozmix cement,
6% bentonite BWOC and
10.9 gal/sk of water.
25
Problem
(i) Initial tabulations and calculations:
Weight Specific
Density
Component
lbs/sk Gravity
lbs/gal
Class “A”
94
3.14
8.33*3.14 = 26.16
Pozmix
74
2.46
8.33*2.46 = 20.49
Bentonite
2.65
8.33*2.65 = 22.07
Water
1.00
8.33*1.00 = 8.33
26
Problem
(ii) Determine the properties of one sack of dry
cement mixture; 65% Class “A” and 35%
Pozmix:
Cement
Class A, 0.65 sk
Pozmix, 0.35 sk
Weig ht (lbs)
0.65 * 94  61.1
0.35 * 74  25.9
87.0
Vol. (gal)
61.1
 2.336
26.16
25.9
 1.264
20.49
3.600
27
Problem
(iii) Determine density and yield of final slurry:
Component
Cmt. mix, 1 sk
Weight (lbs)
87.0
Bentonite, 6%
0.06 * 87  5.22
Water, 10.9 gal
10.9 * 8.33  90.80
183.02
Vol. (gal)
3.600
5.22
 0.2365
22.07
10.9
14.7365
28
Problem
mix
183.02

 12.42 lb/gal
14.74

14.74 gal/sk
Yield 
3
7.48 gal/ft
 1.97 ft / sk
3

29