geothermal potential of egypt
TRANSCRIPT
Tecronoph,sics. 96 (1983) 77-94
Elsevier Science Publishers B.V.. Amsterdam - Printed in The Netherlands
17
GEOTHERMAL POTENTIAL OF EGYPT
CHANDLER A. SWANBERG ‘, PAUL MORGAN 2 and F.K. BOULOS ’
’ Deparmwnts OJ Earrh Sciences and Physics, New Memco Stare lJniversrt_v, Las Cruces, N.M. 88003
(U.S.A.)
.’ Lunar and Planera? Instirure, 3303 NASA Road One, Housron, Tex. 77058 (U.S.A.)
’ Egrp!ian Geological Surq and Mmrng Aurhority, 3 Salah Salem Street, Cairo (Egvpt)
(Received August 24. 1982, revised version accepted December 2, 1982)
ABSTRACT
Swanberg. C.A.. Morgan, P. and Boulos. F.K., 1983. Geothermal potential of Egypt. Tectonoph_wcs. 96:
77-94.
One hundred and sixty samples of groundwater from nearly all parts of Egypt have been collected and
chemically analyzed in order to assess the country’s geothermal potential. The samples considered to be
thermal include 20 wells (T z 35’C). 4 springs (T > 30°C) and 1 spring not included in the present
inventory. The remaining samples. together with data from the literature. establish background chemistry.
The hottest springs are located along the east shore of the Gulf of Suez: Uyun Musa (48’C) and ‘Ain
Hammam Faraoun (70°C). Additional warm springs are located along both shores of the Gulf of Suez
and this region is the most promising for geothermal development. The Eastern Desert of Egypt.
particularly the coastal area adjacent to the Red Sea has above normal heat flow ( - 72.0 < mW mm’)
and therefore some geothermal potential although only one thermal well (Umm Kharga: 358°C) could be
located. In the major oases of the Western Desert (Kharga, Dakhla, Farafra and Bahariya). the regional
temperature gradient is low ( < 20°C/km), but many of the wells tap deep artesian aquifers and produce
large volumes of water in the 35-43’C range. Such wells constitute a low temperature geothermal
resource. None of our samples in northern Egypt can be considered thermal including several reported
“hot springs.” Application of the silica, NaKCa. and NaKCaMg geothermometers does not indicate the
presence of a high temperature geothermal resource at any area we visited.
INTRODUCTION
The present study is part of a much larger cooperative effort among scientists
from the Geological Survey of Egypt and several American universities to evaluate
the geophysical regime in Egypt, particularly the transition area between the active
spreading center of the Red Sea and the stable African platform. These studies have
included heat flow, microseismics, gravity, fission tracks, geothermal energy evalua-
tion, and the chemistry of groundwaters. In the present paper, we present the results
of our geothermal energy studies.
7x
To date we have sampled and chemically analyzed 160 samples of groundwater,
which when combined with another 50 samples taken from the literature. provide
reasonable coverage for the entire country. In most cases we sampled every available
groundwater, and in fact our data set includes a rather large percentage of all
available groundwaters in Egypt. Only along the Mediterranean coast were a
sufficient number of wells and springs available to permit selective sampling. The
only three areas not covered by the present study are the interior of Sinai (due to the
political situation), the Nile Delta (the abundance of surface water precludes the
need for wells), and the Great Sand Sea area of southwest Egypt (due to extreme
inaccessability and absence of wells for sampling).
Water chemistry studies of thermal waters are a rapid and inexpensive method of
geothermal appraisal. Such studies will provide information regarding the type of
geothermal reservoir (liquid or vapor dominated), its possible reservoir base temper-
ature, and any environmental problems that might result from the introduction of
geothermal fluids into the local environment. Such studies will also expand the
general body of hydrologic knowledge of a given area by providing an indication of
the water’s origin, subsurface flow patterns, and chemical quality.
The study of non-thermal waters is also an important factor in geochemical
exploration for geothermal resources. Such studies establish background chemistry,
for comparison with thermal water chemistry and this is required for application of
thermal water mixing models. Background geochemical studies also tend to reveal
the presence of factors that render the use of chemical geothermometers invalid.
Finally, it is also possible to utilize groundwater chemical data to detect the presence
of geothermal resources that are not represented by surface features such as hot
springs or hot wells (Swanberg and Alexander, 1979).
Several qualitative indicators of subsurface temperature have been proposed (see
Mariner and Willey, 1976), but only two quantitative geothermometers ha1.e been
demonstrated to have widespread application. The silica geothermometer (Foumier
and Rowe, 1966) is based on the temperature dependence of quartz solubilit>- in
water and the NaKCa geothermometer (Foumier and Truesdell. 1973) is based on
the temperature dependence of the ratios of sodium, potassium and calcium. A
magnesium correction to the NaKCa geothermometer has recently been published
by Fournier and Potter (1979). Both geothermometers attempt to determine the last
temperature of water-rock equilibrium within the geothermal resemoir and both are
subject to possible errors resulting from continued water-rock interactions as the
water migrates from the geothermal reservoir to the sampling point, mixing of waters
that have equilibrated at different temperatures. and precipitation of the ions
involved. Both geothermometers also require that the water chemistry be controlled
by temperature dependent reactions. The basic assumptions of chemical geother-
mometry and the equations are given by Truesdell (1975) and Foumier and Potter
(1979).
79
PROCEDURE
Field work has consisted of traveling to each site (well, spring. etc.) recording the
temperature and depth, and collecting a water sample for chemical analysis. Two
samples were collected at each site. For the 1976 data (numbers lP 111, Table I) we
collected one untreated sample and one sample which was diluted by a 10: 1 ratio
with deionized water. Each sample was placed in a 125-ml polyethelene bottle for
shipment to the chemical laboratory. For the 1979 data (sample numbers with letter
prefixes, Table I) we collected a filtered but otherwise untreated sample along with a
sample which has been filtered and treated with 2 ml of 1 : 1 HNO,. The purpose of
both the dilution and the acid treatment is to stabilize constituents such as SiO, and
25”s
Fig. 1. Location of sample points. The solid dots represent this inventory. The solid triangles represent
data taken from the literature as follows: “1” prefix from Ezzat (1974), “R” prefix from El Ramly (1969).
and the Gulf of Suez data from lssar et al. (1971). Well depth (m) for literature samples are shown in
brackets. Red Sea samples taken near shore.
TA
BL
E
1
Tem
pera
ture
, de
pth
and
geot
herm
al
data
fo
r sp
ring
s an
d w
ells
of
E
gypt
Not
es:
SS =
Sam
ple
Sour
ce,
DW
=
Dug
W
ell
(sam
ple
bale
d fr
om
top
of
wat
er
tabl
e),
PW =
Pum
ped
Wel
l (s
ampl
e fr
om
iron
ex
it pi
pe,
wel
l op
erat
ing
cont
inuo
usly
un
less
no
ted)
, S
= Sp
ring
(s
ampl
e fr
om
poin
t of
di
scha
rge)
, M
=
Min
e (s
tand
ing
wat
er
in
min
e),
AW
=
Art
esia
n W
ell
(sam
ple
from
ir
on
exit
pipe
),
SL =
Sal
t L
ake
or
salt
slou
gh
(sam
ple
from
sh
ore)
; D
=
Dep
th
(m);
T
=
in
situ
te
mpe
ratu
re;
TsI
oI
= te
mpe
ratu
re
estim
ated
by
th
e Si
O,
geot
herm
ome-
ter;
T
NaK
Ca
= te
mpe
ratu
re
estim
ated
by
th
e N
a-K
-Ca
geot
herm
omet
er;
TM
g =
tem
pera
ture
es
timat
ed
by
the
Na-
K-C
a-M
g ge
othe
rmom
eter
. (S
ee
Tru
esde
ll,
1975
an
d Fo
urni
er
and
Potte
r,
1979
, fo
r ge
othe
rmom
etry
eq
uatio
ns.)
So
urc
e Sa
mpl
e
no.
ss
Eas
tern
Deserr
Bar
ram
iya
Bar
ram
iya
(Dup
. no
. I)
Bar
ram
iya
Um
m
Kha
riga
G.
Sukk
ari
Bir
H
afaf
it
Bir
E
l Sh
adli
Bir
A
bu
Gha
laga
Bir
E
l R
anga
Bir
E
l R
anga
(D
up.
no.
8)
Bir
B
eiza
h
Bir
B
eiza
h (D
up.
no.
9)
Bir
‘A
sali
Bir
N
abi
Wum
m
Las
eifa
Bir
U
mm
G
heig
Bir
U
mm
G
heig
(D
up.
no.
56)
Bir
‘A
sal
Bir
Z
arei
b
Bir
A
wei
na
‘Ain
A
nbag
i
1 El7
2 3 4 6 8 El4
9 El6
IO
II
55
56
El
57
58
59
60
DW
DW
PW
DW
DW
DW
DW
DW
DW
S DW
DW
DW
DW
DW
DW
S
D
T
T s,
o*
T N
aKC
a TMg*
("C)
("(3
r-7
("C)
_ 27
.8
74
142
cold
_
46
150
cold
27.0
44
15
7 co
ld
_ 35
.8
85
37
37
_ 28
.0
73
40
40
_ 27
.0
105
148
cold
25.0
92
30
30
_ 29
.2
77
33
33
25.9
19
78
78
_ 26
.0
80
88
88
22.0
84
75
53
34.0
71
R
X
46
0 27
.7
94
88
88
_ 26
.0
92
69
69
_ 26
.7
85
69
69
25.0
83
76
71
30.0
79
80
67
26.7
56
X
8 45
26.7
63
15
2 11
2
26.7
57
96
59
0 29
.4
75
x3
77
Bir
B
eid
a 61
Bir
E
l S
id
62
Bir
U
mm
Fa
wak
hn
63
Bir
Se
iyal
a 64
Bir
Se
iyal
a (D
up.
no.
64)
E2
El
‘Ain
65
Bir
G
ahliy
a 66
Bir
Q
uei’
67
Um
m
Huw
eita
t 68
Um
m
Huw
eita
t 69
Mon
aste
ry
of
St.
Paul
71
Mon
aste
ry
of
St.
Ant
hony
72
Bir
E
l H
amm
amat
El
Laq
eita
Bir
E
l L
aqei
ta
Bir
A
mba
r
Bir
‘A
ras
Bir
Fa
ruqi
ya
Bir
A
bbad
Bir
K
anay
is
Mar
sa
Tun
daba
Bir
G
hadi
r
Bir
W
afi
E3
E4
E5
E6
E7
E8
E9
El0
El1
El2
El3
Kha
rga
Oam
Mah
ariq
Mah
ariq
Kha
rga
Gin
ah
Bal
ad
Gin
ah
Bal
ad
Bul
aq
5
Bul
aq
Bal
ad
Gar
mas
hin
5
Gar
mas
hin
5 *’
New
”
12
PW
160
29.0
45
19
6 33
13
PW
650
37.5
50
23
7 68
14
PW
642
38.0
52
24
5 59
15
PW
262
31.0
47
32
0 57
16
PW
504
33.2
50
30
0 75
17
AW
76
8 35
.0
48
268
48
18
AW
10
5 28
.8
47
242
49
19
AW
45
0 33
.3
47
23x
61
20
AW
50
0 34
.0
48
257
64
DW
DW
DW
DW
S DW
DW
DW
M
S S
15 0 _
150 0
0
DW
65
AW
45
0
DW
DW
DW
DW
DW
DW
DW
DW
4 18 2
51
28
27.X
70
26.1
79
26.7
x5
25.0
91
25.0
89
26.1
10
7
25.0
96
25.6
50
_ 66
29.4
63
_ 62
_ 58
25.0
x1
35.0
57
84
30.0
85
24.0
78
26.0
76
34.0
89
32.0
46
24.5
60
26.0
77
28.0
74
x2
x2
x4
66
79
79
x2
x2
84
x4
77
77
92
cold
136
27
70
59
IX7
19
57
57
56
56
86
86
89
65
152
19
191
44
16
76
51
51
159
cold
91
34
139
23
88
66
58
58
TAB
LE
I (c
on
tin
ued
)
So
urc
e S
amp
le
no.
Bar
is 9
-A
Bar
is 9
-B
Bar
is 1
4
EL
Qas
r
Buh
ariy
a O
asis
‘Ain
E
l W
adi
‘Aw
ein
a
‘Ain
E
l B
ase1
‘Ain
E
l G
edid
‘Ain
E
l G
edid
‘Ain
Y
ause
f
Bir
Sig
am
‘Ain
E
l B
ish
mu
‘Ain
E
t B
ish
mu
Hal
fa
Wel
l
Am
eric
an
Wel
l
El
Mae
sra
“New
”
Dok
hlu
Om
is
Bir
El
Om
da
Bir
El
Din
ariy
a
Bir
Eza
h E
l Q
asr
no
. 3
Bir
El
Mah
ub
no
. 4
Bir
El
Qas
r E
l B
alad
Bir
Eza
l E
l Q
asr
no
. I
Bir
Eza
b E
l Q
asr
no
. 1A
Bir
Bu
dkh
ula
no
. ?
Bir
Tin
cid
a n
o.
I B
ir B
alat
no
. IO
Bir
Bal
at n
o.
IOA
Bir
Ma’
xara
no
. 3
Bir
El
Gid
iba
Qib
ii n
o.
2A
21
AW
50
0 32
.9
45
22
AW
50
0 33
.9
49
23
PW
47
0 33
.5
45
24
PW
25
0 29
.0
44
81
AW
82
s
83
AW
84
S
85
S
86
S
87
AW
88
S
89
AW
90
AW
91
AW
92
AW
94
AW
95
AW
96
AW
97
AW
98
AW
99
AW
100
AW
101
AW
102
AW
103
AW
104
AW
LO
S
AW
106
AW
0 _ 0 _
650
250
330
250
200
820
755
246
305
640
500
400
642
x00
I 1
I N
uKC
‘.r
T
*
(W
,d”,
a,
c _~
.. ~
__._
25
2 66
253
68
124
IO
202
82
41.1
58
20
1 60
26.7
53
31
6 59
26.1
53
60
37
28.9
53
86
co
ld
28.3
53
80
52
28.9
53
91
co
ld
41.1
60
x2
co
ld
29.4
53
59
co
ld
31.7
54
66
co
ld
42.2
60
87
co
ld
29.4
53
82
co
ld
3x.1
55
79
co
ld
39.0
62
57
57
3x.3
60
57
57
42.x
60
69
69
42.8
60
59
59
38.3
58
so
50
33.9
52
43
43
37.8
55
62
62
33.9
49
33
33
32.X
49
61
61
38.9
56
73
41
37.2
54
6X
68
41.1
60
33
7 xx
31.7
52
86
50
Bir
E
l Q
alam
um
El
Bal
ad
Bir
M
ut
3
Bir
M
ut
3A
Bir
M
ut
I B
ir
MU
I E
l B
alad
IO7
AW
2x
0 32
.2
s.1
96
42
I OR
A
W
I220
42
.2
62
30x
77
109
AW
37
5 33
.9
53
69
69
I IO
A
W
70X
35
.0
54
77
62
III
AW
2x
2 33
.3
53
64
64
Siw
a O
asis
Gov
ernm
ent
Wel
l (N
. Si
wa)
Bir
E
l N
oss
(N.
Siw
a)
Bir
E
l D
ehab
a
Gua
r H
etat
R
ahm
on
‘Ain
C
amis
a
Gov
ernm
ent
Wel
l
‘Ain
M
eshe
ndit
‘Ain
E
l H
agal
i
‘Ain
A
bo
El
Gab
ba
Bir
ket
Siw
a
Bir
E
l H
ilw
(N.
Siw
a)
Bir
E
l G
ella
z (N
. Si
wa)
Aba
r E
l K
andy
is
(N.
Siw
a)
‘Ain
T
amus
i
‘Ain
K
halit
‘Ain
Z
eida
n
‘Ain
K
ures
het
‘Ain
A
bu
Shur
uf
‘Ain
D
eria
at
‘Ain
N
akb
‘Ain
Z
eitu
n
‘Ain
G
uba
‘Ain
D
akru
ri
Siw
al
Siw
a2
Siw
a3
Siw
a4
Siw
a5
Siw
a6
Siw
a7
Siw
a8
Siw
a9
Siw
alO
Siw
al
I
Siw
a I2
Siw
al3
Ali
1 A
li
Ah3
Ali
Ah5
Ali
Ah7
Ali
Ah9
Alil
O
DW
_ A
W
DW
AW
AW
AW
AW
AW
SL
DW
DW
DW
DW
PW
PW
DW
DW
DW
DW
DW
DW
DW
Cai
ro
Are
a
‘Ain
E
l Se
lein
(F
aiyu
m
Oas
is)
78
S
‘Ain
E
l Se
lein
(F
aiyu
m
Oas
is)
79
S
3 3 9 31 5
600 8 12
_ 7 5 _ 5 5 _ _ _ _ _ 0 0
23.0
22.0
27.0
26.0
29.0
_ 29.0
29.0
27.0
21.0
20.0
27.0
27.0
27.5
32.0
26.0
27.0
26.0
26.5
30.0
29.0
57
219
81
65
220
43
66
I61
24
64
164
24
68
166
31
58
205
56
66
159
23
67
161
27
68
158
30
90
234
cold
29
250
41
25
79
79
28
70
70
68
163
29
68
93
83
67
158
24
65
15x
cold
67
169
cold
65
156
cold
65
154
cold
64
168
23
67
I61
26
69
166
26
21.7
IO
1 51
51
22.2
10
0 29
co
ld
TA
BL
E
I (c
ontin
ued)
So
urc
e Sa
mpl
e
“0.
ss
D
Hel
wan
N
ew
Spri
ng
Hel
wan
Su
lphu
r Sp
ring
‘Ain
Su
khna
(G
ulf
of
Suez
)
‘Ain
Su
khna
(G
ulf
of
Suez
)
50
51
13
14
S
0
S
0
S
0
S
0
T Ll
, (“
0
(“C
) --
26.7
14
28.9
82
32.2
63
32.8
63
X6
38
120
21
130
25
129
26
Wa
di N
a~r
un
Mon
aste
ry
St.
Bis
hoy
Mon
aste
ry
St.
Bis
hoy
Mon
aste
ry
St.
Bis
hoy
Mon
aste
ry
St.
Bis
hoy
Nea
r St
. B
isho
y C
eram
ic
Pl,
Mon
aste
ry
Bar
amus
Bir
H
ooke
r
Mon
aste
ry
Mak
aryu
s
Ban
i Sa
lam
a B
irke
t
Siw
al4
DW
60
69
15
1 26
Siw
a 15
A
W
95
31.0
59
14
7 25
Siw
al6
AW
11
7 29
.0
60
136
28
Siw
al7
Ditc
h 2
32.0
71
12
3 28
Siw
alil
DW
IO
26
.0
116
145
22
Siw
af9
PW
55
69
141
24
Siw
a20
PW
25
30.0
71
x9
46
Siw
a2 I
PW
110
31.0
19
x0
47
Siw
a22
SL
23.0
13
4 84
33
Sin
ai
Uyu
n M
usa
76
AW
_
4X.3
75
6
3
63
‘Ain
H
amm
am
Fara
oun
CA
S30
S 0
70.0
94
1
53
85
Med
ifer
run
eun
El
Qas
r I
El Q
asr
2
El
Qas
r 3
El
Qas
r 4
Um
m
El
Rak
ham
Hes
sien
Sa
ad
Ang
iela
Mar
sa
Gar
guh
El
Aito
f
Sidi
B
arra
ni
Med
I
DW
5
Med
2 D
W
6
Med
3 D
W
4
Med
4 D
W
4
Med
5 D
W
4
Med
6 D
W
4
Med
7 I)
W
4
Med
X
IIW
4
Mcd
Y
f)W
26
Med
10
I>W
47
24.0
47
21 .o
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86
Fe. The samples were sent to the State Soil and Water Testing Laboratory, at New
Mexico State University for chemical analyses. The laboratory work was completed
within a few days of their shipment from Egypt so that most waters were analyzed
within three weeks of their collection in the field. The laboratory tests were
conducted by standard analytical methods. Table I gives the SiO,, NaKCa, and
NaKCa-Mg geotemperatures for each of our samples. The sample locations includ-
ing those taken from the literature are given in Fig. 1.
HOT SPRING DISTRIBUTION
Any discussion of hot springs must necessarily take into account the prevailing
mean air temperature of the area in question. At Cairo, the mean air temperature is
22°C and temperature depth data from the western desert oasis indicate that much
of Egypt may have a mean ground temperature as high as 26°C. If one accepts
87
Waring’s (1965) definition of a hot spring as one being 8.3”C (15°F) above mean air
temperature, then temperatures of Egyptian springs need to exceed 30-35°C in
order to be classified as thermal. Using this definition, many of the thermal springs
reported by El Ramly (1969) cannot be strictly classified as thermal, even though
their temperatures (25-35°C) may be sufficient for some geothermal applications.
Figure 2 shows the wells (T > 35°C) and springs (T > 30°C) that are considered to
be thermal. Representative thermal water chemistry is given in Table II. All the
thermal springs in Egypt are located along the shores of the Gulf of Suez. These
springs probably owe their existence to tectonic (or volcanic) heating associated with
the opening of the Red Sea-Gulf of Suez rift. Also shown in Fig. 2 is the Helwan
sulphur spring (sample 51). This spring is located just south of Cairo and has been
reported as having a temperature of 31.6”C (El Ramly, 1969). This spring exits into
a bathing pool where obtaining a reliable temperature measurement is difficult and
our measurement of 28.9”C may be slightly low. This spring probably represents
deeply circulating groundwater which has ascended to the surface along a fault zone.
In the Western Desert, there are no springs that can be strictly classified as
“ thermal.” All of the occurrences of thermal water are from deep wells. Figure 3 is a
plot of surface temperature against well depth for wells from the Kharga and
Bahariya oases. Since all these wells are either artesian or pumped continuously for
agricultural purposes, the surface temperature should adequately reflect the bottom-
24 - I1 I I1 I I I I , I I
0 200 400 600 000 1000 1200 1400 DEPTH (ml
Fig. 3. Plot of bottom hole temperature against depth for the deep artesian wells from the Kharga and
Bahariya oases.
TABLE II
Chemistry of representative thermal waters
Sample Temp. Ca
no. * (“C)
Mg Na K Cl co1
3 35.8 165.3 98.2 469.4 3.1 1038.4 0
E4 35 187.6 50.2 512.2 14.2 730.7 0
13 37.5 19.4 8.7 loo.5 30.1 20.6 0
14 38.0 25.8 Ii.7 66.0 26.6 5.3 0
17 35.0 35.7 21.3 57.2 35.2 102.1 0
87 41.1 15.6 15.3 45.1 6.6 73.4 0
90 42.2 13.8 14.3 48.3 7.0 81.5 0
94 39.0 14.2 6.8 22.3 3.5 1.8 0
96 42.8 9.2 7.0 13.6 4.7 0 0
103 38.9 Il.0 7.5 14.5 6.0 3.9 0
108 42.2 11.4 6.4 13.6 18.0 0 0
110 35.0 22.6 8. I 28.7 8.6 9.9 0
76 48.3 196.8 66.4 556.6 8.6 904.1 0
CAS 30 70.0 623.0 150.5 4272.9 151.3 7 176.4 0
74 32.8 479.4 255.0 1643.3 45.0 3442.3 0
51 28.9 282.0 151.5 1382.4 29.3 2302.1 0
24 - I, 8 / / I / / L 3 I I
0 200 400 600 800 1000 1200 I400 DEPTH (ml
Fig. 4. Plot of bottom hole temperature against depth for the deep artesian wells from the Dakhla oasis.
89
HCO, so4 TDS PH B F Fe SiO z
208.7 587.9 2692 7.42 1.07 0.48 < 0.1 34.0
222.3 557.6 2200 7.34 0.16 0.41 0.19 16.9
239.2 73.0 492 7.96 0.18 0.90 < 0.10 14.0
194.0 61.5 280 7.98 0.08 1.14 < 0.10 12.5
109.8 86.5 468 7.46 0.06 0.45 < 0.10 13.0
86.6 25.0 264 7.10 0.05 0.36 0.23 18.5
95.2 21.1 268 6.93 0.05 0.34 0.35 18.5
46.4 61.5 140 6.50 0.03 < 0.20 0.93 19.0
47.6 50.0 108 6.72 0 < 0.20 0.10 18.0
65.9 32.7 141 6.93 0.02 < 0.20 < 0.10 16.5
52.5 46.1 148 6.65 0 -c 0.20 0.16 19.0
52.5 71.1 190 6.4 0.03 < 0.20 0.31 15.5
104.9 614.8 2844 - 0.73 1.05 2.98 27.0
135.4 1400.0 13909 6.98 1.84 2.21 0.11 42.5
162.3 922.2 8992 7.04 1.25 2.34 -c 0.10 20.0
272.1 845.3 7048 7.11 1.65 4.02 -c 0.10 32.0
l Sample no. refer to Fig. 1.
hole temperature and can thus be used to estimate the geothermal gradient. A least
squares fit to these data yield a slope and intercept of 16.5 mK/m and 26.O”C
respectively. The former value is consistent with the gradient data reported by
Morgan et al. (1980) for northern Egypt. The latter value is consistent with the mean
annual ground temperature of Egypt (26.6’C) calculated on the basis of the
temperatures observed at the top of the water table for the hand-dug wells of the
Eastern Desert. Thus, it appears that the hot wells of these oases owe their thermal
nature to heating by a normal to low geothermal gradient and not to the presence of
exploitable geothermal reservoirs.
The situation at the Dakhla oasis is somewhat different. A least squares fit to the
temperature-depth data from wells at the Dakhla oasis (Fig. 4) yields a slope and
intercept of 11.8 mK/m and 29.4”C, respectively. Further, the wells that show
anomalously high temperatures are concentrated to the north (Fig. 5), near the
escarpment forming the northern boundary of the oasis. These data are most easily
reconciled by assuming that water, heated by a normal to low geothermal gradient, is
ascending along conduits at the north end of the oasis and migrating south through
the principal aquifers.
Finally, it is worth noting that two regions of Egypt have shown thermal activity
in the recent past. These are the extinct geysers on both sides of the Cairo-Suez
highway and the Jebel Uweinat area of southwest Egypt (El Ramly, 1969).
90
200 50’ 290 29010’ - 25O50’
25’50’
DAKHLA OASIS
- 25O40’ 25O40’ -4
. 106
Fig. 5. Sketh map of the Dakhla oasis showing the locations of the hottest wells with respect to the
escarpment at the north end of the oasis.
SUBSURFACE TEMPERATURE ESTIMATES
The silica, NaKCa, and NaKCaMg geothermometers have been applied to all the
samples collected as part of the present survey and the results are given in Table I. A
quick scan of these data fails to reveal any samples with abnormally high geotemper-
atures. Figure 6 shows the silica geotemperatures for the thermal waters plotted as a
subset histogram beneath a histogram showing the silica geotemperatures for all
waters included in this inventory. With the possible exception of ‘Ain Hammam
Faraoun (sample CAS 30) the thermal waters give results that are comparable to the
non-thermal waters for both the Eastern and Western Desert. Thus this geother-
mometer cannot be used to infer the presence of abnormally high subsurface
temperatures. A similar conclusion is reached by analysis of the NaKCa and
NaKCaMg geotemperatures. Figure 7 shows a plot (and least squares regression) of
the NaKCa temperatures against SiO, temperatures for the thermal and non-thermal
waters of the Eastern Desert. If the groundwater chemistry is being controlled by
temperature dependent reactions, this plot should show a positive correlation. The
data in Fig. 7 not only fail to show such a correlation but also fail to show elevated
91
WERN DESERT
j--L eii WdTERS
n= 88 40
i
meon = 55.2 z 11.WC
34.1
30 -
20 -
z e
z IO- z
g, p-y
L 0 20 w
.--I: THERMAL WTERS
” = 17
ITeD” = 57.314.i’C
23
I
80 100 120
2 EJ_STERN DESERT
“0 20 40 60 60 IO0 120
T6,02 V’C)
Fig. 6. Histogram of silica geotemperatures for all groundwaters from the western (top) and eastern
(bottom) deserts. Note that both the thermal and non thermal waters yield similar geotemperatures, and
that the values are more compatible with low temperature rather than high temperature hydrothermal
activity
EASTERN DESERT
l WELL OR SPRING 1, T”ERMIL WELL 0R SPRlW
,““I ” s ’ ) L s “1 0 20 40 60 80 100 120 I40
T&O2 (W
Fig. 7. Plot of NaKCa geotemperatures against silica geotemperatures for groundwaters of the Eastern
Desert. Note the lack of any obvious high temperature geothermal fluids.
92
01 I”“’ I’ I ( I ” 1 0 20 40 60 80 100 120 140
TS,02 VT)
Fig. 8. Plot of NaKCaMg geotemperatures against silica geotemperatures for groundwaters of the Eastern
Desert. Note the lack of any obvious high temperature geothermal fluids.
geotemperatures for the thermal waters relative to the non-thermal waters. A more
realistic plot is obtained by plotting (with a least squares regression) the NaKCaMg
temperatures against the SiO, temperatures (Fig. 8). This improvement underscores
the value of applying the magnesium correction, at least for this data set. Still.
however, there is no tendency for the thermal waters to give higher geotemperatures
than the non-thermal waters and we thus conclude that there is no evidence from the
geothermometry data to support the existence of a major geothermal anomaly
associated with any of the thermal springs of Egypt.
TABLE III
Heat flow estimates of Egypt based on the silica heat flow technique
Location Number of Ts,o, r, 4 Traditional q samples (“C) (“C) (mW m-‘) (mW mm’)
Eastern Desert 44
Kharga Oasis 13
Bahariya Oasis 12
Dakhla Oasis 18
Mediterranean Coast 21
Siwa Oasis 22
Wadi Natrun 7
Cairo Area 4
Sinai (West Coast) 4
75.4* 15.3 21.9 12.2 77.6 rl
47.55 2.4 26.0 32.1 40-45 .J
54.8* 2.8 26.0 43.0
55.1 k 4.2 24.4 46.1
55.4* 17.3 21.2 51.0
60.3 k 13.7 26.4 50.6
74.7 * 19.4 26.0 12.7
89.2 + 13.4 24.9 96.0
73.8 + 14.6 25 72.8 80-100 b
a Morgan et al. (1980).
’ Morgan et al. (1976).
93
SILICA HEAT FLOW
Swanberg and Morgan (1979, 1980) have shown that it is possible to use the silica
content of groundwaters to estimate regional heat flow. Normally, this technique is
used to supplement existing heat flow data by providing additional coverage in areas
where traditional data are sparse. The appropriate equation is q = (7”,o, - q;,)/m
where Ts,o is the quartz conductive silica geotemperature in “C, T, is the mean
annual ground temperature in “C, m is 670°C m2 W-’ and q is heat flow in mW
m -l. Table III gives the silica heat flow data for various parts of Egypt. In general
the agreement between the silica and the traditional heat flow data is good
(Swanberg and Morgan, 1980). Eastern Desert heat flow averages 72.2 mW mp2
which is higher than is normally observed in stable platform areas and implies a
major heat flow anomaly in the Precambrian of eastern Egypt. The heat flow
throughout the western desert oases and along the Mediterranean coast is low ( < 51
mW mm’). On the basis of a very scanty data set, it would appear that high heat
flow may exist from the Gulf of Suez area as far west as the Cairo-Faiyum-Wadi
Natrun area.
CONCLUSIONS
The use of silica geotemperatures of groundwater is a valuable technique for
estimating regional heat flow in Egypt. A relatively high heat flow zone (1.7 to 2.3
times normal) exists on the border of the Gulf of Suez and this area contains ‘Ain
Hammam Faraoun, the hottest spring in Egypt at 70°C. This zone, which is the most
favorable for geothermal exploration and development, could possibly extend as far
west as Cairo and the Faiyum oasis and Wadi Natrum areas based on the
groundwater silica data, extinct Geysers and the historic seismicity of these areas.
The Eastern Desert in general has a moderately high regional heat flow of about
75 mW rnp2 based on both the silica data and traditional measurements (Morgan et
al., 1980). This area should also be favorable for geothermal discovery although only
one thermal well was located during the present study.
The Western Desert has low regional heat flow ( < 50 mW me2) and correspond-
ingly low geothermal potential. However, many of these oases (perhaps all of them)
are underlain by deep artesian aquifers which produce high quality water in the
30-45°C temperature range. These aquifers may have low temperature geothermal
potential. A similar deep artesian aquifer has been observed at El Laqeita (sample
E4, Table I, Fig. 2) in the Eastern Desert between the River Nile and the Red Sea
hills. Therefore, it is possible that much of the area immediately east of the Nile may
also have low temperature geothermal potential. There is no geochemical evidence
that a major high temperature geothermal field underlies any area we visited.
94
ACKNOWLEDGEMENTS
The present study could not have been completed without the considerable
assistance of Dr. Rushdi Said, and Mr. Gala1 A. Moustafa, Consecutive Directors of
the Egyptian Survey and Mining Authority. We also acknowledge Mr. S.F. Hennin,
Mr. A.A. El-Sheriff, Mr. A.A. El-Sayed, Mr. N.Z. Basta, Mr. Y.S. Melic, Dr. P.H.
Daggett, and Mr. T. Roemer for their help with the data collection. The work was
funded by the U.S. National Science Foundation through grant numbers EAR77-
23354 and INT78-16649 from the Earth Sciences program and the Office of
International Programs, respectively.
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Ezzat, M.A.. 1974. Exploitation of groundwater in El-Wadi El-Gedid project area. Groundwater Series in
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Fournier. R.O. and Potter, R.W., 1979. Magnesium correction to the Na K Ca chemical geothermometer.
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