SOCIEI'Y OF PETROLEUM ENGINEERS OF AIME
Fidelity Union Building
Dallas, Tex.
PNAUMPEBRER 1 0 5 1-
G
THIS IS
A PREPRINT --- SUBJECT TO CORRECTION
INCREASED SECONDARY RECOVERY
BY HYDRAULIC FRACTURING
By
J. R. Paul, Member AIME, Dowell, Inc., Evansville, Ind.
Lloyd C. Taylor, Dowell, Inc., Tulsa, Okla.
If an individual production well has begun
to produce large amounts of water it should not
be fractured. fracturing treatment would prob•
ably increase water production, rather than oil
production. However, a repair job [for example
using latex-cement or plastic] may successfully
shut off the water and make a fracturing treat•
ment feasible.
INTROIXTCTION
Fracturing has become an important stimula•
A
tion method both for production and injection
wells in secondary recovery operations. The in•
creased percentage of oil produced by secondary
recovery makes studies of the effect of fractur•
ing increasingly important.
REASONS FOR FRACTURING
In case of injection wells, fracturing
treatments are often performed simply because the
well does not accept water properly. This situa•
tion may occur when production wells are con•
There are several reasons why secondary re•
covery wells should be fractured. Fracturing
often makes possible recovering more oil from the verted to injection wells or when new injection
reservoir than could otherwise be produced.
reservoir's permeability is so greatly increased
that faster flow of fluid tprough the reservoir
A
wells are drilled.
a
MULTIPLE FRACTURES
can be obtained under given differential pres•
sures. This condition extends the reservoir's
productive life.
It is generally accepted that
a vertical
sweep is desirable in secondary recovery because
of its greater efficiency. For this reason,
fracturing treatments should be planned to pro•
vide multiple fractures, well spaced throughout
the vertical thickness of the formation.
In some cases fracturing reduces injection
well operating pressures, perhaps eliminating the
need for high pressure injection equipment.
Fracturing often makes profitable oil recovery
possible in
be considered commercial. Such a situation may
occur after prolonged waterflooding or early in
water flood project.
a reservoir which otherwise could not
In most cases,
bly more desirable than
If the upper or lower limits of the formation
have undesirable characteristics, as for example,
nearby water zones, vertical fractures would not
be preferred.
a
vertical fracture is proba•
horizontal fracture.
a
the life of
a
SELECTING WELLS TO BE FRACTURED
Several factors should be considered in se•
lecting wells to be fractured. After water in•
jection is started, several months may elapse
before the formation's void spaces are filled.
Several methods are used to control frac•
tures. The most common method is the use of tem•
porary plugging agents. Such agents include
naphthalines, gelled kerosines and rock salts.
Many operators use as
duction well should be fractured if it has not
responded satisfactorily after one and half
times the calculated fill-up volume has been in•
jected into off-set wells. This rule-of-thumb
has been used frequently, and, in most cases, the
fractured wells have responded immediately.
a
rule-of-thumb that
a
pro• They are removed by either dissolving in forma•
tion fluids or by internal chemical reactions
which cause them to break. recent development
a
A
in temporary plugging agents is the use of ball
sealers to close perforations. These work by
differential pressure and fall away from the per•
foration when the fluid flow is reversed.
Illustrations at end of paper
TABLE NO.1
CCMPLETED WATERFLOOD DATA
BARrLESVILLE SANDSTONE
Acres
Flooded
Thickness
Feet
Curve
No.
Bbl Oil Recovered bl Waterflood
Water Injected
Flood Life
Months
qtr.
Cum. Oil Prod.
Total
Per Acre
Per Ac-Ft
Bbl
0
1
2
2,140
2,189
08
30
30
18
20
25
26
15
25
40
30
30
30
40
25
30
30
22
25
12
28
40
6,623,000
2 7,536
71.3
73.0
32
II
21
20
97
37
139
ll9
100
140
100
40
0
80,975
9 7,360
60
2
0
ll6.0
156.0
2,681,325
1
5,1 9
2,
5
3
4
202
8
628,576
233,780
73,593
3,ll2
12,25 ,184
8
130
8,777,812
1,759,013
2,759,063
9,260,979
Unknown
1,79
71.9
5
6
38
60
1,227
2,241
1,631
7,000
2,472
47.2
24
0
150.0
65.2
3 2,549