Geology Reference
In-Depth Information
varieties whose origin is associated with the Miocene Series (Inglewood,
Long Beach and Santa Fe Springs fields).
The formation's hydrochemical background is formed by alkaline waters
with salinity 40.4
−
46.8 mg.-equiv. (11.5
−
13.4 g/l), total alkalinity 9.6
−
10.6
mg.-equiv. and primary alkalinity factor 39.8
−
46.2%-equiv. (Potrero,
Inglewood, Long Beach, Wilmington fields).
The hydrocarbonate-sodium waters from productive zones have higher
salinity, 70.4
−
85.4 mg.-equiv. (20.1
−
24.4 g/l), lower total alkalinity (3.5
−
5.1
mg.-equiv.) and primary alkalinity factor 6.4
12.4%-equiv. (Wilmington,
Inglewood, Long Beach, Santa Fe Springs fields).
he
Pleistocene
intervals of the sediment cover in the region (Yorba-Linda
Field) and the Upper Pliocene rocks in some fields (West Coyote, Santa Fe
Springs and Long Beach) are saturated with low-salinity alkaline waters
of clearly meteoric origin. Their salinity does not exceed 6
−
−
16 mg.-equiv.
(1.6
−
4.6 g/l), the primary alkalinity factor 33.2
−
49.2%-equiv., the secondary
alkalinity factor 12.2
25.3%-equiv. A distinctive feature of these waters is
elevated sulphate content, to 1.5
−
2.5 mg.-equiv., which in some cases causes
the presence of sulphate-sodium varieties. The surface water penetration
depth into the section in strongly faulted and hydrodynamically open fields
(West Coyote, Long Beach) reaches in some fault-blocks 800
−
−
1,000 m. In
most other fields it does not exceed 200
300 m. In general the effect of the
present-day infiltration over the hydrochemical environment in the region's
sediment cover is insignificant and usually limited to local areas of the reser-
voirs exposed on the surface and the adjacent reservoir members.
A specific feature in the region's ground waters is a consistent, beginning
at some set depth (about 800
−
1,000 m), growth in the sulphate-ion content
down the section. Regardless of the water medium type and salinity, its
values are 0.1
−
4 mg.-equiv. in the most
subsided (heated) intervals (see Figures 2.22, 2.23). The correlation “SO
2
−
vs.
depth
” is SO
2
−
= 0.33
−
0.3 mg.-equiv. in the upper to 3
−
Н
1.939
, “SO
2
−
vs.
temperature
” is SO
2
−
= 2.76
⋅
10
-6
⋅
⋅
10
-6
t
2.735
.
The following conclusions can be made about the patterns in the ground
water spatial distribution by the component composition and salinity:
⋅
t
The regional hydrochemical background in the Lower- and
Upper Pliocene water complexes is formed by low-salinity
(11.5-17.5 g/l) hydrocarbonate-sodium waters with the
primary alkalinity factor 27.2-46.2%-equiv. The underly-
ing Jurassic, Upper Cretaceous, Middle and Upper Miocene
water complexes are regionally saturated with higher-salinity