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SANDIA REPORT
SAND90-0224 •
UC-126
Unlimited Release
Printed December 1991
DE92 9885
III
11/11111111111111 1111
Strategic Petroleum Reserve SPR
Additional
e o ~ o g i ite
Characterization Studies
est
Hackberry Salt Dome, Louisiana
, Thomas
R.
Magorian, James
T.
Neal, Stephen Perkins,
, Qiang
J.
Xiao, Kathleen
O.
Byrne
_ ~ : : ~ -
c _::_
- - ~ ~ ; ~ A
REPRODUCED BY
NTIS.],
u.s.
Department of Commerce
National
Technicallnronnation
Service
I
I Springfielcl Virginia 22161
.
l
~
SF290QO(B,Bl
Prepared by
- Sandia Nat ional Laboratories
Albuquerque,
New
Mexico
87185
and Livermore, California
94550
fo r the United States Department
of
Energy
under Contract DE-AC04-76DP00789
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Issued by Sandia Kational Laboratories, operated for the United States
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SAND90-0224
Unlimited Release
December 1991
Strategic Petroleum Reserve SPR
Additional
Geologic
Site
Characterization
Studies
West Hackberry
Sal t
Dome
Louisiana
Thomas R Magorian
Amherst New York
James T.
Neal
Sandia
National Laboratories
Albuquerque
New
Mexico
Stephen
Perkins Qiang
J Xiao Kathleen
O
Byrne
Acres International
Corporation
Amherst New York
Prepared by Sandia
National
Laboratories
Albuquerque 87185 and Livermore
CA
94550
for the U S. DOE
under
Contract DE-AC04-76DP00789
UC-126
ABSTRACT
This report is a revision
and
update of
th e original geologic
s i te
characterization
report
that
was published
in 1980 Many
of
the topics
addressed in
th e
earl ier
report were predictive in nature
and
i t
is now
possible
to
reexamine them some 12
years la te r using
the data from 17 new
caverns
and more than ten years
of SPR
storage
experience
Revised maps of the sa l t configuration show
an
overhang
and faults on
the n orth sid e
of
th e
dome, defining more
clear ly
th e
edge
relationships
with
respect
to th e SPR
caverns
Caprock faults may locally i nf luence the
p atte rn o f subsidence which is occurring primarily as
a
result
of
cavern
creep closure
The
greater subsidence
rate
occurring at
West
Hackberry
w ill lik ely
require
mitiga tive act ion
within
a few
years
Seismicity
of
low intensi ty recurs inf requently at West Hackberry but a
small
earthquake in
1983 caused dish rat t l ing
in th e
immediate
vicini ty
i i i
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•
4.
•
i
q
~ ~ ~ - : ~ ~ r : c c ~ -- .c• ., : ~ ~ ; - ~ : : - - : ~ ; ; ~ - ; - ,
1
West Cove
1
_ .
. ::_ -
. . - l
l
:,t
l
- .
< .:
.
:
.
, .
.
.
I: ·
{BlackLakej
.
IC alcasieu Lake ~ ; ~
z::
._, .
,
F ront is pi ec e: H igh- al ti tu de view of West Hackberry SPR s i te
shoWing
th e -20 f t is land over th e
dome
surrounded by
coastal
mars hla nd s. G ulf
of
Mexico i s 5 mi from
to p
of photo, due
south
of West Cove.
.
.
C
0
a
e
CD
a.
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TABLE
OF
CONTENTS
Strategic Petroleum Reserve SPR)
Additional Geologic
Site
Characterization Studies
West
Hackberry
Salt Dome Louisiana
INTRODUCTION
N
PURPOSE .
1
New
or Revised
I n f o rma t i o n
1
GEOLOGIC
ASPECTS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Hydrology.
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Caprock
. , .
. . . .
7
Salt ; .
. .
.
. .
21
Salt
on t o u r s
28
Struc tural In te rpre ta t ions 33
SPR
SYSTEM CONSIDERATIONS.
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. .
.
33
Cavern Configurations 33
Subsidence 42
Hurricane Storm Surge Levels 48
Seismici
ty.
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 48
Environmental Considerations 50
Summary o f S igni fi cant
Features Affecting
SPR 52
Acknowledgments. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
53
References . . . . . . . . . . . . . . 54
Appendices
A Yest
Hackberry Regional Geologic History
A-1
B
Projected
Loss
of
Coastal
Marshlands B-1·
C Prediction
of
Subsidence Resulting from Creep Closure
of Solutioned-mined Caverns in Salt Domes C-1
D Yell Log Data D-1
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LIST OF
TABLES
Table
1
Stratigraphic Correlation Chart
10
Table
2 West Hackberry
Cavern
Geotechnical Parameters 34
Table
3
Oxy
USA
Cavern Data.
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
Table 4 Projected Elevations for
Selected
West Hackberry
Stations
. . . . . . . . . . . . . . . . . . . . . . . . 47
LIST OF FIGURES
Front-
piece
Figure 1
Figure
2
Figure
3
Figure
4
Figure 5
Figure
6
Figure
7
Figure 8
Figure 9
High
Altitude
View
of
West Hackberry SPR Site
i i i iv
Depth to Anahuac Shale
3-4
Depth to Hackberry Shale
5-6
West Hackberry Brine
Disposal
Well 2-C 8,9
Depth
to Top of
Caprock 11-12
Base with Site Boundaries, Caverns, and Flood
Contours 5-16
North-South Cross Section 17-18
Depth to
Top
of Salt 19-20
East-West
Cross Section 25-26
Conceptual
Diagram West Hackberry Structural Features. 27
Figure
10
Westernmost
North-South Cross
Section
29-30
Figure
11 Easternmost North-South Cross
Section
. .
31-32
Figure 12 Composite of Generalized SPR Cavern Configurations. . . . . 35
Figure 13
Air Photo,
West
Hackberry SPR Site . ,
37-38
Figure 14 Olin Brine Caverns ; October 1989 Sonar Surveys . . . . . . . . . 41
Figure 15 Oxy
USA
Cavern Configurations.. . . 43
Figure 16 Isoseismal
Map
16 Oct 83 Lake Charles
Earthquake
. . .
. .
49
Figure
17 Earthquake
Acceleration
Probability Map... 51
vi
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INTRODUCTION N PURPOSE
The
in i t i a l
geologic
s i te charac te r iza tion repor t
[Ref.
1]
was
completed
in
1980, when
only the five caverns that were acquired
from
th e
Olin
Corporation
s
6,7,8,9,
and 11) existed.
Since that
time 18
cavern
wells were
dril led
and
17 new caverns were leached
and
are now some
90
f i l led
with
crude
oi l
toward
the
currently
authorized
si te
c apac it y o f
219 million barrels MMB). The
construction
of
the
new
caverns ha s
significantly enhanced our confidence
in understanding
the
sa l t
dome
features.
I n add it io n
to
information that has become available during more
than
10
years
of
SPR
operation, new data are
also
available from numerous
commercial wel ls adj acen t
to the
s i te
This report
is a revision
and update of th e ear l ier
si te
characterization
r p o r ~ placing
t he geo logi c
understanding
in better
perspective. Several aspects a re
given
special attention in
the
report:
sa l t
contours
and structural interpretations
as
they relate to
cavern
integri ty;
subsidence
history
over
SPR
caverns;
and
potent ial
flooding
during future operations. In
numerous
cases, the original
maps
are
re
interpreted
in
l igh t of the
new
information,
and with reference
to
current
1991)
concepts
of Gulf Coas t geology.
New or
Revised
Information
The 18 new
cavern wells provided detailed information
on
th e character
of th e
sa l t mass
and
also the sa l t
contours
on top of
the
dome A new
sa l t map
is
presented, along with new interpretations of the structural
geological
configuration. These
have been
aided by o i l
company
interpretations and data, especially
on
th e north side adja cent to Black
Lake.
Configurations of the 22 caverns are discussed, along with the
.ten
year operating
history
a t th e s i te
Few
i f any , problems exis t although
Cavern I I I has
behaved
in
an
atypical manner.
The
3-dimensional
computer
model shows
that
Cavern
I I I
is
approximately
200
f t
further from th e
edge
of
the
sa l t than previously
estimated.
However a
faul t
and
shear zone
have been found in i t s
vicini ty.
Subsidence occurring over the cavern f ield
has
been resurveyed
annually for
some
eight years a t
more
than
eighty survey points, and
suff icient
data
exis t
to
make definitive
judgments
on
future direction.
The data show that West Hackberry is
subsiding
a t a greater rate than
the
other SPR
s i tes
and
that
th e
areas
on
the
s i te
with
low
elevation
will
eventually requ i re pro tec tion from permanent inundation. The adjacent
coastal marshlands are
also
subsiding and some 35 sq mi/yr of south
Louisiana is becoming open
water
and part of th e Gulf of Mexico Present
conditions and future
trends
suggest
that
the
higher por ti on s o f
the
West
Hackberry
s i te
are
effect ively an island in the
marsh
see frontispiece),
and
that eventually i t wil l
be a
small
island
in
open
water with direct
connections to
th e Gulf.
1
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Hurricane
surge
heights have been rev ise d to a higher va lu e than
previous ly indica ted ;
current 100 yr
flood stage heights are about
10 f t
above
mean
sea level amsl a t the s i te
The
eye
of
Hurricane
Audrey
in
1957
passed
about 12 mi west of
th e
s i te and produced high
water
marks of
10 f t above mean sea level
a t
that location.
National
seismic
zonation
maps
have
been refined in
the past ten
years bu t
the
Gulf Coast
interpretat ion
is
l i t t l e changed,
th e area being
essentia l ly aseismic.
Nonetheless; new data and a
small ear thquake
1983
near the
s i te a re d is cuss ed .
GEOLOGI SPE TS
The geologic discussion presented in Appendix A complements
that given
in th e ear l ie r
report [Ref. 1]
and is
not intended to dup lic at e
i t
The
geologic information
base
is needed to help maintain
th e integri ty
of th e
o il
storage
caverns
and
in clude s th e
extent
and
cha ra ct er o f
the
sa l t
dome
in i t s regional set t ing.
The
sa l t
mass containing
th e o il is in
turn
held
and
s tabil ized by th e
regional
sediments
into
which th e
sa l t
dome is
intruded. The low-permeability muds,
part icularly those a t geopressure
forming the shale
sheath,
form add it io na l p ro te ct ion for any
o il
stored in
the dome
[Ref.
2].
Figures
1 and 2
are
s tructural contour maps showing
depth to
Anahuac
and Hackberry
shale
units ,
respectively.
Figure
2
also
shows
the
locat ion o f c ro ss -s ec tions used
in subsequent
figures. Table 1
explains th e
abbreviated
s tr a ti g raph ic un it s
shown
on
th e sections.
Hydrology
Fresh
water
is
found
on
th e
is land in
th e
upper
glacial-equivalent
sands of the
Chicot
aquifer. The Wisconsin is freshest and most potable,
although the I l l inoian
is
also
suitable
for industrial use. The lower
Wisconsin or
Alton
is referred to
as
the 200 f t aquifer.
The
water in the caprock may contain quantit ies
of
hydrogen sulfide.
At
th e
base
i t is saturated
brine
in equi libr ium with
th e
sa l t that i t is
dissolving.
Deeper waters in hydrocarbon-bearing
sands around the
dome
vary
from fully saturated brines
in the
more massive Miocene sands
mineralized
close
to
the sal t to
anomalously-fresh
carbonate-saturated
brines r ich in boron, vanadium and
other ocean-floor
concentrates in
isolated sands in
contact
with
geopressured
shales.
The
DOE
injection
well
f ield
is
located
on
the opposite south
side
of
th e
dome from
th e o il
storage caverns. Directionally
dr i l led
from a
central
pad on the
steep
southeast
flank of
th e dome, a l l th e wells
were
completed in
the
RL
zone
at th e top of
th e
lower Miocene see Table
1 .
This
well-sorted marine bar sand exhibits good permeability
a t the top
and dips 30 degrees south-southeast. All of
the
wells took brine at
relatively good rates
in i t i a l ly
2
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-
o
o
o
o
Z 1t 8Sl lW III WZ O I
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\
~ ; : : J ~
I
1MI I
1 1
i O
I :
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8/19/2019 Additional Geologic Site Characterization Studies West Hackberry Salt Dome
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8/19/2019 Additional Geologic Site Characterization Studies West Hackberry Salt Dome
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~
' ,[
.
.
II
I 80 ..= ....
N:...
....
.
_
: . . -
••••••••
l I I
••
••• •••
•.• I .
,
• • •
I
.....
....... .
_
• ••
11.11.
• • •
WEST HACKBERRY
DOE BRINE DISPOSAL WELL
NO. 2-C
u
:E
>
0
>
:::
.....
a
0 gI =11
~
. lJ
0
.lJCI
l:lIE
a
:5
0
CI :
>0
ll
::J
iii
C1
. . . . .
25
Recent
MUCK
•
CLAY
••
••
71
••
III
II
·: :·: ::: : ::e
100 Wisconsin SANe •
: : :.: :.: :.:.: : GRAVEL
:8::::::6:
100 ppm
sooo
6000
ppm
8
1310 Kansan
SANe
•
GRAVEL
2
27: :
Figure 3
SHEET
1
OF
2
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WEST HACKBERRY
DOE
BRINE DISPOS L
WELL
NO 2 C
5 30
1
In .
I
n
••
1
••••
noo
. .
to
..0
E
9
.
CL Y
~
: : :0: : : : 1660 Nebraskan/Lafayette
S ND
GR VEL
: :·0
·0:· ;;;
~
1 = = ~ 1
. . . . . . .
1860 Pliocene -
SILT
with
:
thin S ND
laye,..
TITr
IIII
Trn
TITr
IIII
TITr
TITr
TITr
TITr
IIII
IIII
TITr
Figure 3 cont.
SHEET
2
OF
2
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TABLE 1 - VEST
H CK ERRY
STRATIGRAPHIC CORRELATION
CH RT
Unit
Recent: Beaumont clay
Q
Pleistocene
U
Wisconsin
A
Alton Peorian:
Prairie
Fm
T Sangamon: Ifontgomery Fm
E I l l inoian
R
Yarmouthian: n ~ l y Fm
N Kansan
A
Aftonian:
Williana
Fm
R Nebraskan
Y Lafayette
Symbol
a
s
i
p
ka ks
ne
Lithology
peat muck
mud
sand
and
gravel
mud
sand and gravel
mud
sand and
gravel
mud
sand
and gravel
gravel
T
E
R
T
I
A
R
Y
Pliocene
Miocene
Upper
Bigenerina f loridana
Textularia
Bigenerina
nodosaria
Textularia
stapperi
PL
MI
L
2
s i l t
mud,
and
sa
mud
sand
sand and gravel
mud
sand and gravel
mud
marine
sand
delta ic
sand
mud
delta ic sand
mud
Middle
Bigenerina humblei H
Cristel laria
CI
Cibicides
carstensi
op m CO
Amphistegina
Lower
Robulus RL
Operculinoides OP
Cibicides
C
Ifarginulina ascensionensis M
Siphonina
davisi
- - - U NCO N F O R M I T Y .
Anahuac
Discorbis) R
Oligocene
Heterostegina
H
Harginulina howei
MH
Frio
F
Cibicides hazzardi
-
CH
U NCO N ORM IT Y -
Hackberry
facies
H
Vicksburg VX
:10
unconformity
shale
thin
sands
sand
shale
m arin e sand
bituminous l imest
sand
and shale
sand
shale
thin sand
shale
coral reef
sand
shale
sands
marine·sands
geopressured
sha
b la ck s ha le
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LEGEND
COX: on
l
=
OLIN
CONST
OIA
1= O O E
OF CAVERN
W LL
NO
.
-
X S
• 20.016
CENTER OF L,..-J
CAVERN L-CAPROQ(
n
O O E_ PROPERTY
LINE
CAPRoa<
CONTOUR
-5000
CONTOURS
IN fEET
BELOW
£A N SEA
LEYUI
\
®
\
o
o
8
B LAC K
L A
KIE
IT
6
_ 5 3000 FEET
i
fiGURE 4
WEST
HACKBERR
CAPROCK
p lI U
\
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I t
l ies
on
top of
f la t
sa l t
across
th e
dome as a resul t of the
leaching of
sa l t to a
f l a t surface by
groundwater
as
the
dome r ises
through t he ove rlying sediments.
The
relat ively
insoluble
anhydrite
accumulates as
a cap and,
in
the
presence of
methane gas
seeping
up
th e
face of the
dome
is part ly
converted to carbona te .
The
continued
upward
movement
of
the
sa l t with l each ing to
a
f l a t surface creates
a complexly
faulted
and
fractured
domal-
to flat-topped
cap
containing extensive
interconnected voids ranging
from
small
vugs
to
caves.
The
caprock a t
West Hackberry
is
relat ively
thin -400
f t and l imited
in aerial extent. I t does not
overdrape the
stee p s id es of
th e
dome as
occurring a t th e next dome north, Sulphur
Mines
--
a
small, round conical
dome.
Most
of
the
S caverns
are loc ated near
the
middle
of
th e
dome
where
caprock
condi ti on s a re relat ively uniform. However Cavern I I I
is
located
near the
steep
outer edge
of
the sal t a t th e feather edge of the caprock
Figures 5,
6 . The
subsurface
control near
Cavern
I I I
is
l imited. The
closest wells dri l led into th e solid sa l t
face
are
in
Section
19
to th e
west
and
Section
16
to
the
northeast.
The
in tervening contro l
includes
one well
that included salt-mineralized
sands a t a
depth
of
approximately
3000
f t indicating that i t is
close to the sal t
face, as
shown
on the
cross-section
Figure 6 . The resul tant
interpretat ion
as shown on th e
sa l t map Figure 7
is
suf fic ien tly s t ra ight , except for the radial
fault
bel ieved to be
related
to a possible
shear
zone, to make the cavern quite
secure despite th e evidence
for an
overhang.
The
se ismic su rv ey s, while
incomplete, support
this
interpretation, as does gravity
data.
I f
o i l leakage
from
th e storage caverns
were to
occur i t
would
migrate
into
the
caprock
and join
th e
much
larger
volume of o il which
has
migrated
up
the face
of
the sal t
dome. Although no
commercial wells
have
been
completed
in
th e
caprock
at
th is dome
due
to
i ts
relat ively
low
porosity,
the thin overlying sands are o il
productive
and adequately sealed from the
surface by more
than
200
f t of
mud. However
gas may
leak
through these
muds,The gas accumulation under the brine
pond
l iner i s apparently
biogenic, originating
possibly from
unscarified decaying grass
[Ref. 15],
but a t other
domes
is indicative
of
escaping hydrocarbons.
h l l o ~
domestic water
wells
nearby also
make
gas.
Thus,
the r isk of
environmental
contamination through migra ti on path s a lr eady naturally
f i l led with hydrocarbons may be
moot.
Lost circulat ion:
The
hydrology
of
caprock i s controlled by th e large
voids
crea te d in
the
solution process.
Although the
water
is
s at ur at ed i n
carbonate
throughout,
in sulfate
half-way down and is
saturated
brine at
the
base, th e
flow
is
suff icient
to
keep
the
top
of
the
sa l t
very
nearly
f la t Hydrologic calculations
of the
rate of
sa l t
solution
which must
be
close to
that
of
intrusion
inside the
dome
were
made
a t
Bayou Choctaw
and
found to be
in
agreement with the geologic data
of
upl i f t on th e
flanks.
Thus,
lost circulat ion is
to be expected while
dri l l ing caprock,
although th e
problem
is less in thin caprock here than, for example, a t
Big
Hill where
the
caprock i s
one
of
th e
thickest
known
in
the
Gulf Coast.
13-14
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- ~ . \
,
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II
108
lOS
101
03
115 109
••
•
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1m
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.
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r
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Fl ••
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.
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.
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.
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ir.
•
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I
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SALT
•
•
NOTE:
REFER
TO
TABLE
I FOR
STRATIGRAPHIC
SYMBOlS
p.17.18
F IGURE
SECTIO
ON FIGU
WEST H
SECTIO
V:H
= I
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31
>
.p.19 20
fiGURE
7
WEST
H CK ERR
SALT
oX OXY
= OL 1N
CONST 1
1=
o.o .
Of CAVERN
r
WELL
NO
OX S
crNT[R
Of
l r J
CAVERN L SALT a n
0.0 . [ .
PROPERTY _ ••_ _
LiNt
SALT
CONTOUR
5
CONTOURS
IN
r[[T
BELa. Io£AN SO
[V [U
LEGEND
o 1500 3000
FEET
SCALE i
17
K
18
®
.\
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The most cost-effective method of pene trat ing
the
caprock
has
clearly been
demonstrated to
be
dri l l ing without returns.
By using
water
instead
of
mud to cool the bi t
hole
can
be
made in
this
br i t t l e rock without
cementing
every few feet , once casing is se t in the
hard
carbonate
caprock.
Hydrogen
Sulfide: ~ t Hackberry
may
have
signif icant
concentrations
of hydrogen sulfide. This
toxic
gas, commonly known in oi l f ie ld
terminology as sour gas; is formed in the re ac ti on o f hydrocarbons with
anhydrite to form carbonate caprock and sulphur.
Although
sulphur
exploration was not commercially
success fu l, t he re
are abundant shows of
sulphur
a t
the
top
of
the
anhydrite cap,
part icularly
in th e usual
location
near
th e
rim of
th e dome West
Hackberry
has
been
prospected
and
i s
close to
many domes that have produced commercial
sulphur,
including
High Island,
Fannett
and Spindletop [Ref. 4].
As
a result hydrogen
sulfide is
detectable
in most sal t-dome caprocks
[Ref.
5].
The
presence
of hydrogen
sulfide complicates
dri l l ing
through
th e
hard
caprock because
everything
in
th e
hole, including
th e
dr i l l
str ing, t urn s b la ck and corrodes. Any pipe harder than API American
Petroleum Ins t i tu te) Class E is
subject
to brl t t le fai lure under
normal
fatigue loads,
part icularly when corrosive saturated
brine must also be
used to
dr i l l
into sal t . Nickel
and
manganese, used to harden the
steel are more subject to sulfide corrosion
and
c rack ing than even
iron.
Faults: Caprock
is characterist ical ly fau lted in
most of
the cores
that are recovered,
so much so
as to
be
a
permeable jumble of
broken
blocks
with
secondary
calcite
cementation. Some of these faults
extend to
th e
surface, and
may
control
subsidence as
well as
localize small,
natural
shallow
o il
accumulations.
The
faults
are
further
suggested by th e shape
of
the tr iangular subsidence trough [Ref.
18], and by
the producing
wells
on
higher
blocks
across
the
top
of
th e
dome
The active shallow faults origina ti ng in th e caprock or sa l t
shear
zones have
only displaced th e
Recent
sediments a few
feet .
They do not
pose
any
apparent r isk to th e storage caverns by themselves, but
subsidence
along them
could
conceivably damage surface faci l i t ies or well
casing, as has occurred at
other
domes used
for
storage o f LPG) products,
e. go ,
Stratton
Ridge, [Ref.
]
Salt
The general shape of
the
combined
East
and West Hackberry domes a
flat-topped and
sl ight ly- t i l ted el l ipsoidal
cylinder,
is
similar to that
of
most
elongated
sa l t
domes
In
the
case
of
Hackberry,
th e
t i l t
is
northward.
The
west
end
is relat ively
blunt and
the
east end,
a t
th e
saddle to
East Hackberry, sharply
poin ted F ig .
7).
This disagrees
signif icant ly
with
the ear l ie r interpretations [Ref. I ]
which
included a
deep
valley
on the no rth side and an
elongate
conical dome As a result ,
several
signif icant
revisions
in the
external geometry of
the
sal t stock
were required in revising the dome contours.
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Commercial
exploratory dr i l l ing
was
very
l imited in
the
area f rom 1986
to
1991
because of the decline in o il prices so l i t t l e
new data
has been
available although
a few
old
wells
have been twinned to keep
up
production.
The
steep
southeast face
along
with
the sharp
east end
suggests
that a transform
or
wrench fault
separates the
domes.
Study
Method:
Sediment
structure
around
th e
dome
is
used
in
this
study to he lp de fin e
the
sa l t face. Methods of
determining th e
sa l t
face
include
dip and convergence or thinning
of the
beds
uplif ted
by
the sa l t
intrusion.
Asymptotic Dip: . From f la t beds
in the
bottom
of th e
rim
syncline the
dips
of
the sediments
around
the
sa l t
increase
65
degrees in
many places
against the near-vertical face. This
asymptote
allows the horizontal
posit ion of the sa l t face
to
be calculated
from
the observed
change
in
dip.
Convergence: In
addition to
structure as discussed below
s tr a tig raph ic vari a tion
is
used
in
this
study
to
help
define
the
edge
of
the sa l t That i s th e intersection
point
a t which
projected beds meet
is
a good
estimate of th e sa l t face. There is extreme
convergence
in th e
Oligocene with i t s thick shales but very l i t t l e convergence
in
th e
overlying Miocene Sands. The resul tant thinning is
part icularly
apparent
in th e oil-productive
Frio
sands.
Rate
Of
Uplift :
The
overal l average intrusive r ise of the dome
as
a
whole
can be calculated
from
the upl i f t
of dated marker
beds
that are
asymptotic to
th e face
of th e sa l t
The
deepest penetrated
Hackberry
shale
sheath
HB , some 40
million years old
my ,
has been uplif ted
some
7000
f t the top of the Oligocene DR,
30
my
6000
f t
middle Miocene
AB,
15
my
3000
f t
Miocene
10 my
2000
f t Pliocene 2
my
500
f t and
Peorian
p
0.5
my
100
f t
These
value s a re
a ll
very
close to
a
rate
of
0.1
mm/yr,
which is the
same
as that observed a t
Bayou Choctaw
and Big
Hill .
This
rate
is exceeded only
by
th e Five Island Chain including
Weeks
Island which has an apparent
upl i f t
rate
as
high as
4 mm/yr.
Spines:
The
spine theo ry
of
sa l t intrusion
and i t s
validation
in
mines
is reviewed in the
Weeks Island
SPR Geological
Characterization
Report
[Ref.
7].
The
well log data and
their
correlation a t
Weeks shows
two
spines separa ted by
a
shear zone in the south half of the dome used by
SPR. The
spines
are
interpreted as anticl inal
features or.domes
in the
anhydrite correlation data
a t
Big Hill
[Ref. 8].
In
east-west domes
l ike
West
Hackberry th e sa l t
flow
l ikely occurs in
widely-separated spines .
However,
there is·
insufficient
control within
the
sa l t
to define
the se spine s by their shear
zones
i
e areas of
more
anhydrite which
separate them. The
holes that were dr i l led to
leach
th e
new DOE caverns were
only
part ia l ly logged and a few cores cut. Only one
hole per cavern was dr i l led except 117
which has
two and logged through
the
sa l t so tha t i t was not possible to use th e methodology developed a t
Big Hill
for mapping anhydrite bands and
th ereby th e in ternal structure of
the
sa l t
intrusion. Consequently
any
additional cavern development should
22
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requi re exploratory dri l l ing
and
logging
to
delineate such features within
the sa l t
mass, even
though
speci fi c e ff ec ts on cavern construction
may
be
speculative.
Core samples show that
the sa l t is relat ively
dark
with considerable
disseminated anhydrite, even in the middle
of
apparent spines. The sa l t
crystals
are
t ightly
interlocked,
as
a result
of
the
compaction
due
to
the
weight of th e caprock. This dark sa l t beli ev ed t o be
l es s r ec ry s ta ll iz ed
since
upl i f t i s typical
of slower-moving domes
Shear
Zones: All sa l t domes
that
have
been
studied have their shear
zones
centered
on
and
paral le l to the
underlying sa l t ridges. The
shear
zones are a lways between th e spines. They are observed
as
a
high
concentration
of near-vert ical anhydrite
and
o th er i nc lu si on
bands,
usually
ref lected as
a
sharp
trough
or
low on the surface of the sal t
Sediment trapped between the spines
in an
overhang could
be
incorporated
into
the sa l t dome
by
continued
int ru sion , c reat ing
potent ial
prryblems i f
cavern leaching is attempted
acro ss s hear z o s ~
The
postulated
nor theast -southwest shear zone correlates very closely
with the faul t running
into
th e overhang Figures
8,
9 . A secondary shear
zone
normal to
this appears to cross i t
over the
center of th e
dome
somewhat l ike Weeks Island. This
complication
may be related to the
apparent
steep
dips
in
Miocene sediments near
the nor thwest corner
where a
radial
faul t
t ies
in with the
apparent
shear. This shear zone also
represents th e axis of th e sa l t ridge upon which th e dome s i t s
The par t ia l near-vert ical overhang on th e north side adjacent to the
s i te is a
much-less
complete seal, requiring la te ra l
sealing
along
th e
shear zone which has acted as a fault beyond the edge of the sa l t stock.
I t is
unlikely,
however, that a l l
th e
o i l and gas trapped against this
sa l t
dome
have
been
found.
Well Control
Significant dri l l ing has
been
done
close
to
th e sa l t face
around the
dome
since the
original geologic
characterization.
moco
has dr i l led two
additional wells downdip in the product ive
sa l ien t a t th e
southwest
corner
of the
dome which
do not
change
the
interpretat ion
of
th e sa l t
face. All
of
the available well data are included in th e appended Well Tables
Appendix
D . A long
overhang may l imit the depth
and extent of
caverns
in a broad arc
across
the north s id e of the OE property. This overhang
is very nearly ver t ica l l ike the
north
side of Weeks
Island and
the West
side of
Bayou Choctaw and
unlike
the 60
degree
overhang on the south side
of
Big
Hill .
Seismic Data
The
original
seismic data from 1983 was obtained under contract by
Woodward
Clyde Consu lt an ts , Inc.
However th e
l ines
were
not extended
out
into Black Lake
far
enough
to
get good
ref lect ions
from th e steep
sa l t
3 4
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-
-
--
.
SALT
-
-
-
-
-
:
:
:
-
--
:
:
•
·
.
:::
.
.
.. :,
.
.
I
•
,
CAPROCIC
1
I
, I
D
D 7
8
U
V
U
114
107
1011
•
.-
--
m
:
NOTE: R EFER TO
TABLE I FOR
SmA TI
GRAPH
IC S n8OlS
FIGURE
SECTIO
ON
FIGU
p.
25 26
l T H
SECTIO
V,H =
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22
27
LEGEND
SAL
T
CONTOUR 5
D O Eo PROPERTY _ ••
LINE
PROBABLE
SP IHE CENTER
21
20
H
..
o. s o. J
l _
I
PROBABLE
SPINE
CENTER
2 500
1
8/19/2019 Additional Geologic Site Characterization Studies West Hackberry Salt Dome
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face
and i t s flanking sediments. The only data
is
from the top of the
cap
and
sa l t
Amoco data is available, possibly
indicating
an
overhang. The
cr i t i ca l
l ine ,
closest to
Cavern 111, was to have been
reprocessed
in
early
1991
to help resolve the
overhang uncer ta in ty , but
with
lower
o il
prices
apparently
has been delayed
indefini tely.
Amoco g ravi ty d ata was
examined to
improve
the
interpretation of
shallow
faults , sal t spines, and possibly
subsidence.
The
data
support
th e overal l i n te rpret a ti ons reported
on
here.
Sal t
Contours
The sa l t contours
Figure
7 were f i t ted to the digitized database
using
more
than
50
cross-sections, smoothed both horizontally and
ver t ica l ly between
the
faults found
in well
cuts in th e
oil-bearing
and
overlying sediments near the sa l t The most
important
changes in th e
shape
of
the
dome
from
previous
maps
are
th e overhang and
faults
on the
north side, next to the SPR storage s i te
Most
of
the
shape of the
rest of
the
dome
connecting to
East
Hackberry in a neck
protected
by shale, is smoother than previously mapped
since
we have shown that
the shallow
solution topography
on th e top
of
the
dome
is
unrelated
to
th e s t ~
flanks which
have never been systematically
contoured via
computer
graphics with
a
digi ta l database.
An
east-west and th ree north-south cross-sections Figures 6, 8, 10,
and
11 ;
located
on Fig.
2
have
been prepared from the
digi t ized
database
for this report . The two westernmost north-south
sections
show clearly
the
overhang
jus t
north of
the
SPR
s i te
The
westernmost section Figure
10 shows
th e northwest corner of th e
dome
where the
complex
near-ver t ical
Frio sands have been dragged up to
a lmos t cover
th e shou lder of th e
dome. The
o i l has leaked
up
into th e
basal Miocene sand, and
probably
from here into
the
sands above the
caprock.
A
similar
complex area is found
in the
same posit ion a t Weeks
Island where the n e r ~ v e r t i l sands are basal Miocene age.
The middle north-south section
Figure
6 through
th e
SPR
caverns
shows the normal 60 degree dips
extending
nearly
a
mile
out from the sa l t
overhang,
providing
most of
th e o il production.
The
easternmost
section
Figure
11
shows a
wide
band
of
geopressured
Hackberry
sha le t runcat ed by the unconformity a t the top of the Oligocene
which
protects
the sa l t face,
suggesting
a
large
area
of
undeveloped
storage potentia l .
The eas t-west sec tion
Figure 8 runs
th e length of
the
dome crossing
the
SPR
s to rage a re a
and
showing
one
of th e faults believed poss ib ly
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NORTH
SOUTH
1_1
_
....
6 :
•
41
•
41
•
81 11ft
1
. .
.
.
.
.
.
.
.
.
.
. .
·
.
1 0
IGOD
•
1- llIOII
2lIOII
PRO K
l IOII
«lOG
O
0
«lOG
........
........
-l OOO
•
•
•
SALT
7000
J
1
\
.
1 7000
/
-lIOOO
laaa I
ICIXII
nn
nn
NOTE: REFER TO TABLE I FOR
STRATIGRAPHIC SYMBOLS
p 29 3O
FIGURE 10
SECTION LO
ON
FIGURE 2
WEST H CK
SECTION C
V:H
=
I
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SALT
-
-
I
-
-
...
..
....
- -
...
-
,
..
-
.IF
V
r
I
.
.
.
.
. .
. .
.
·
.
.
.
.
.
.
.
.
.
.
I
,
I
·
.
•
•
11
.....
CAPROCK
NOTE: REfER
TO
TABLE I
fOR
STRATIGRAPHIC
SYMBOLS
fiGURE
SECTION
L
O
fiGURE
p.31·31
WEST H C
SECTION
V:H = :
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activated by cavern
creep
and bounding the tr iangle of greatest surface
subsidence. This faul t is th e sur face expression
of
a probable shear zone
separating active spines. I t shows on
both
sa l t and caprock maps. e have
no
evidence
that any
of
these faults intersect the caverns,or the well
casings.
Structural Interpretation
Dome-Related Fault iD : The
shear
zone observed
in the
new
wells
continues
outside
the
sa l t
as the single
radial
faul t on the dome Figures
1, 2)
that is
o il
productive, having been substantiated at th e northwest
corner
of
the
dome and
discussed
earl ier under the section on shear zones.
The West and
East
Hackberry Salt Domes, along
with
the Big Lake
structure to th e east,
form an east-west
ridge in the
middle of
the
Hackberry embayment, the most
prominent
Frio
feature
of the Gulf Coast.
I t
is
a large
depression
that was f il led in Oligocene middle Frio
time
with deep-water shale.
Big
Hill , a preViously
characterized
SPR dome,
l ies on
the
west edge of
th e
embayment [Ref. 8].
The rim syncline surrounding
the
sa l t
r idge represents
the
equilibrium
in the intrusive
sa l t
between the sands being deposited from the northwest
and
the
Hackberry Embayment.
SPR SYSTEM
CONSIDER TIONS
The
effects
of regional and local geology may
affect th e
SPR
operations in a variety
of
ways. These aspects
are
discussed in the
fol lowing pages.
Cavern
Configuration
The
five caverns
which were purchased from
the Olin Corp.,
6, 7,
8,
9, and
l l ex i s t ed
at the time of th e 1980
si te
characterization. The
geometry of
these caverns is
unchanged, but refinements in some of
the
technical
data
have been made; these
changes are
indicated in
Table
2,
along
with the
data from
the
17 new caverns,
101-117.
Caverns 101-
116 are single-well
caverns,
whereas 117 a two-well cavern, similar
to
the Phase
III
caverns
at Big
Hill .
Table 2 was compiled by Boeing
Petroleum Services
and Usts
the
most
relevant parameters
associated
with cavern integrity. All depths
are
given
in
feet below the bradeDbead
flange
(which
varies
from 4 to 19 f t
emsl),
but
cavern-induced subsidence
gradually lowering th e
mean
sea
level
values.
A
brief
description
of
the
data
follows:
·Cavern number
i s
shown on Figures 5
base
map), and 13
a ir photo)
-Date constructed indicates
time of
leaching,
but does not
include
workovers, etc performed subsequently.
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WEST HACKBERRY CAVERN GEOTECHNICAL PARAMETERS
DataCurrent to 6105191
Cavern
Date
Constructed
Cavern
Volume,
MMB
Top
Caprock
Top
Salt
Casing
Seat
Top
Cavern
BottomCavern,
Dale
Cavern
Height
H
Diameter
D
HID
Nearest
Cavern
Pillar
Thlckness P PID
Rool
Thickness
B
Distance
toDome
BID Edge E
EID
Distance
To Property
Line
BH
Eleva
198
6
1946 8.8
1598
1949 2582 3249 3390 01191
141
662
0.21
9 331 0.50
1300 1.96 480 0.73
350
5.2
7
1946
13.1
1551
1992 2393 2552 3494 01191
942 315
2.99
6 609 1.93
560 1.78 1650 5.24
189 4.3
8 1946 10.3
1515
2035
2337 2450
3449 12190 999
272 3.67
9
149 0.55
415 1.53 1700 6.25
239
13
9 1947
9.8
1550
2100 2525 .,.3213
-3555,02191
342 454
0.75
8
149 0.33
1113
2.45
1200
2.64
744
11.
11
1962 8.6
1529 2085 2790 -2951
3756
2 9
804
276
2.92 108 567 2.05
866 3.13 2500 9.06
349
10.
101
05181-1 2 83
11.2
1609 2050
2434
2555
4440
03191
1885
206
9.15 103 397 1.93
505 2.45 2600 12.62
735 18.
102
02182-11184
11.1 1621
2063
2440
2628
4498 03191
1870 206
9.08 103
448 2.17
565
2.74
2210 10.73
122
15
103 05181-01184
10.4 1558
2038 2432
2667
4423 01191
1756 205
8.57 101 397
1.94
629
3.07 1900 9.27 746 16.
104
05181-02184
11.5 1561
2076
2450 2625
4546 2 9 1921 206 9.33 102 450
2.18
549
2.67
3000
14.56
101
17
105
01181-01184 11. 5
1647
2058 2458 2640
4609
2 9 1969
204
9.65
104
492
2.41
582
2.85
3000
14.71
641
17
106
01184-08187
11.3
1660
2065 2402 2556 4346 2 9 1790 212
8.44
104 492 2.32 491 2.32 1560
7.36 154 16.
107
07181-07184
11.5
1608
2058 2473 2585
4556 12190
1971
204
9.66
103 470 2.30 527 2.58 1510
7.40 149 14.
108
02182-12184 11.5 1664
2053 2420 2596
-4440,01191 1844
212 8.70 112 513 2.42
543 2.56
1700
8.02
144 7.5
109
03184-11185 12. 0 1606
2057
2469
2563 4644 12190
2061 204.
10.10
9
386 1.89 526 2.58 1000
4.90
820
9.3
110
02182-03185 11. 2 1683
2072 2430 2567
4568
03191
2001 200
10,01
111 520 2.60
495
2.48
400 2.00 206
6.7
111
01182-04188 10.6 1980
2180 2534 2622
-4596,01191 1974 196
10.07 110 520
2.65
442 2.26
500
1.53 100
6.9
112
09183-01187
11.4
1650
2050 2437 2562
4532 2 9
1970
203
9.70 108 513 2.53 512
2.52 1800 8.87 157
7.9
113
07182-06185 12. 2
1920
2113
2772
2827
4692 12190
1865
216
8.63
114 518
2.40 714 3.31 500
2.31
106
6.2
114
09182-09185
11.3
1668
2073 2380 2520
4549 2 9 2029 200
10.15 113 518 2.59 447 2.24
1000 5.00
213
6.1
115
02184-06187
11.8 1713
2073 2450 2540
4634 2 9
2094
201
10.42 107 478 2.38 467 2.32
900
4.48
636
7.7
118
07182-09185
11.5
1773
2088 2520 2840
4718 12190
2078
199
10.44
114 542 2.72 552 2.77
1100 5.53
180 6.9
117
06185-09188 12.7 1594
2051
2412 2560
4609 06190
2049
211
9.71 108
421
2.00
509
2.41
2100 9.95
241 13.
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FIGURE 12 GENERALIZED CAVERN CONFIGURATIONS WEST HACKBERRY SPR SITE
0»
I
6 z
NI
9 11
101
~
103
104
105
~
..
sw
500
a
11III
N.llL
S
2500
3000
I
I
=I 3000
I
8.6 9.8
X 3500
3346
FT
.-
=I
3500
ti
01/91),
3450
FT
3420
FT
01/91)
12190
3540
FT
W
02191
0
I LEGEND
I
3724 FT
02191
4000
8.6 • Csvsm volums million bsrrels
=I 4000
3363 • OlllbrtneInlerfsC8deplhsnd dsle
0
200 400 600 800 1000 1200
4500
I
CAVERN WIDTH
I
4181 FT 03191). 4368;; ;;3/91
4356
FT
01191
4500
4518
FT
02191
4700
4700
\:.I,
CIt
2300 E
1
2300
106 107 108 109 110 111 112 113
11
4
115 116 117
2500
.
2500
4500
3500
4000
3000
4036 FT 02191
4224FT
12190
3761 FT 12190 4339 FT 02191
4179
FT
02191
4424
FT
12190 3928
FT
03/91)
FT
01191
3821
FT
01/91)
4528
FT 12190
3950 FT 02191
4554 FT 12190 1 4900
4900 [
4500
3000
t-
I i l l 2. 111 51
.11 5 .
112.0. 1i1O:9.
110.6
X 3500
t-
Il
W
0
4000
TA01l1601 ZJ
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• ... _
_.
_
••
_ _ ~ , •• •
__
._ , .
__
._
••• __
__ ..
__
••
_ __ . __ __
•• •
. _ ••
• ••
_
_ • _ ......
_ ,
Cavern
volume
, in millions
of barrels,
i s usually
about
10 larger
than the volume
of
stored material, allowing for brine in th e cavern
bottom.
·Top
of
caprock
and
sal t
respectively, are
the
uppermost
surfaces of
those
units .
·Casing
seat · and ·cavern
top
(or bottom)
is
e l f ~ e x p l a n a t o r y
·Cavern
Height H)
i s the distance
from
cavern top to bottom.
·Diameter D) is the cons truc ted diameter, Which is an idealized
(average) cylinder diameter that
would
correspond to the f inal
cavern
volume
with
the
given height.
H/O is
the rat io of the cavern heigh t to the constructed diameter,
providing
a measure
of
th e
cavern
shape.
·Pi l lar thickness (P)· is t he thi ckness of
the
pi l lar
of
sal t between
a cavern
and
i ts nearest neighbor.
P/O is the
rat io
of the
pi l lar
thickness and the const ructed
diameter,
providing
a relative measure of mechanical integrity.
Roof thickness B) i s
th e distance between th e top of the
cavern and
the
top of sal t .
B/O is the rat io
of
the roof thickness to the const ructed
diameter,
providing a
measure
of mechanical integrity.
Distance
to
dome
edge
(E)
is
the est imated
distance
between
the
cavern and the
outside
edge of dome sal t .
·E/O is the
rat io
of
the distance
to
th e
edge of dome to
th e
constructed diameter , providing
a measure of
mechanical integrity.
·Distance to
property
l ine is the closest
distance between
the
cavern
edge
and the SPR property l ine.
BHF Elevation
is
the
bradenhead
flange
elevation
in
1988,
rounded
to
0.1 f t .
The values shown in Table 2
ref lec t
the very
conservative design
approach used throughout the SPR system, espec ia ll y for
Caverns
W 101
117. The
preexisting
caverns (W 6-11) do not follow those same
guidelines, of course,
but
there have
been no s tabi l i ty
or safety issues
with them.
Cavern
Shapes
Figure 12 s w ~ current cavern shapes by best estimates.
Caverns
6-11 are
quite
well
mapped, having
been sonar
surveyed when
fi l led only
6
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V e r t i c a l ai r phot o
cavern locations.
a1 s ur f ace features
showing
p r n ~ 1 12 000.
10 y 90 sca e
37-38
~
eproduced f rom
best
available copy
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with
b rin e . However
data
used
to compile cavern
shapes
for W 101-117
were derived
from
s on ar r ec or ds
obtained
d ur in g c av er n
development,
an d
from o il f i l l an d in te rfa c e
records
obtained
during
leach an d
f i l l
operations. Because sonar
recordings
could
not
be obtained through oi l
the o il f i l l vs
volume
data r e s u l t in axisymmetric cavern
shapes
on the
drawings,whereas
in
fact
they
are N on et he le ss , t he
data
an d sonar
r ec o rd s o bt ai ne d
d ur in g c av er n
development
show
v er y s ym me tr ic al c av er n
shapes
fo r the
new
caverns W
101-117),
suggesting there is
a
general
absence
o f s ig n if ic a nt
mineralogical or s t ru c tu r al e f fe c ts
t h a t
have
re s ulte d in
p r e f e r e n t i a l l y
oriented
caverns. Cavern
W 111
is
a
notable
exception, with pronounced
assymetry
in
the
to p 2 f t .
Cavern
6.is
somewhat
s au ce r- sh ap ed , w i th
a
diameter
o f nearly 12
f t an d a height of about 14
f t .
The
aspect
r a t i o o f 0.21 using
the
constructed diameter) is the lowest in the SPR system an d there has been
c on ce rn o ve r possible
collapse o f
th e cavern roof.
However
the
twelve
plus
year h is to ry o f SPR
operations
combined
with the former 32-year
hi st ory
o f O l i n s brine
feedstock
e x tra c tio n at tests to i t s
long-term
s tabi l i ty . The September 1978 blowout and f ire
a t
t h i s cavern was
unrelated to the
low
aspect rat.io [Ref. 9].
Cavern
9
ha s
two lobes separated by a 6 0 f t neck at
about
337
f t
depth.
The
sa l t ledges
here
are
a
pot ent i al source for sa l t fal ls which
could
damage hanging
s t r i n g s
but
t h i s
has
not occurred.
Caverns
101-117 are for the most p a r t
unremarkable,
an d
s i g n i f i c a n t
deviations from
design
shapes
have
not
occurred. Caverns W
101, 102, and 1 3 have s l i g h t l y
wider
tops
than
an
id e a l
tapered cylinder,
a nd Ca ve rn
W 111
has
a
small ledge, o r s ho ul de rs , near
the
top.
The
s ma ll d ia me te r
above
t he s ho ul de rs
was
d e lib e ra te ly
caused
by
f i l l ing
with
o il d ur in g the las t
l ea ch in g s ta ge
to prevent
fu rth e r growth.
T he se m in or
departures
have
no
bearing
on
cavern
operation
an d
present
no
sa fe ty
or
i n t e g r i t y concerns.
Cavern
113 was constructed
with
the las t
cemented
casing s e t 27 f t deeper than the other Phase II wells. This re su lte d
in
a
s l i g h t l y deeper cavern top
and
th e cavern height
was reduced somewhat
so t hat the
nominal
to p an d
bottom
are
at 28 and 47
f t
re sp e c tiv e ly
[Ref. 10].
Cavern
112
ori gi nal l y
was
to have
been
constructed j us t west o f Cavern
113 b ut e xp lo ra ti on
revealed
a re -e n tra n t
an d f a u l t st ruct ure in the sa l t
face
along
the
north side of the dome resul t i ng in i n s u f f i c i e n t distance
to the edge of
sa l t
an d requiring t hat th e cavern be re -lo c a te d
south
of
Cavern
11
F igure 13 ).
Additional
Cavern
Space
In
the event
i t would become
n ec es sa ry t o abandon
one
or
more o f
the
exi st i ng
caverns,
or
to t ransfer o il
for some
reason,
there
is
probably
room for another cavern jus t
outside the DOE property
n o rth e a st
of Cavern
11 an d s ou th ea st o f abandoned
Olin
Caverns 3- 4
coal esced) .
To v e rify
t h a t s u f f i c i e n t pi l lar
space
e x i s t s
at this
location,
the
former Olin
caverns
would
need to be ope ned an d sonar
surveyed.
Space fo r
two other
caverns also
e x i s t s
immediately
south
of
Cavern W
106,
an d
southwest of
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Caverns
WH 108 and
117,
but neither
of
these l ocat ions a re
presently
on
O property.
Similarly, off
of O property,
j us t
west
of
Caverns 104, 102,
and 107
(Fig. 13), there are p ossib le locations where storage caverns
could
be
constructed,
with
cavern
roofs
at
-2500
f t
or
deeper.
These
depths
have
. already
led to
greater creep/subsidence rates a t West Hackberry. and th is
fact
combined with the already low elevation would have to be reconciled.
With th e exist ing cavern volume
to ta l
exceeding 275
million
b arre ls in
36 exist ing and five abandoned
caverns,
the
dome is approaching the
reasonable upper
l imit f or s to ra ge . All
of the
above
considerations
would
require
study
prior to
serious thought of expansion.
New
Olin Caverns 12., 13. 14
The Olin Chemicals Group completed th re e b ri ne wells in 1977 to
provide feedstock for i ts ch1or-a1kal i operat ions a t Lake Charles.
SPR
Cavern
116
is
th e
closest
adjacent
cavern
to
th is
group,
750
f t
northeast
of Olin 12 (Figs. 5. 13). Figure 14 shows
the
pi l la r thickness between
the two
caverns
to be more
than
500 f t
All
three
Olin well s were
ident ical
in
design, but
minor
var ia ti on s i n
tubing and cavern depths occur. The three wells produce brine which
consumes sa l t a t a rate of
about
one million barrels volume) annually.
Total cavern volume was
12.72
MM
(from
sonar) in
O c t o b ~ r
1989 and 1991
year-end estimates are 15.5
MM
1989 sona r r ecords show th e caverns
as elongated
cylinders
approximating
baseball
b ~ ~ ~ · .in shape,
with
th e large dimension a t the
bottom. The
highly
s Y m m e ~ i c a shapes are somewhat questionable because
the sonar survey was performed through two
hanging
str ings. At that time
the to ta l volume was 12.7
million barrels ,
with maximum diameters
of 188,
178,
and
173 f t
for Caverns
12 ,
13, and
14 , respectively.
All three wells
had
operated
in
the
bottom
injection
- top
recovery
mode, which produces
th e observed-shape
caverns.
A December 1989 Olin
l e t te r to
th e
Louisiana
Office of
Conservation,
Injection and.Mining Division, indicated that i ts
1989 sonar logging showed the
inter-cavern
distance between two caverns
was 205 f t So
as
to not exceed
the
200 f t separation s pe cif ie d in
Statewide
Order 29-M, Olin requested a change in
i t s
leach extraction
procedure for two of i t s wells, with the
apparent
intent of al ter ing the
shapes
to more regular cylindrical forms.
Because
the
wells
are
spaced
390
f t
apart,
and
because the
maximum
diameters
are already
being
approached
in two of
th e
three caverns there
is a l imit to
how
much more extraction ,of brine
is
,possible, perhaps as
much as twice the current
to ta l
or
roughly twelve
years.
a t current rates.
Olin management
personnel
indicated
they
had no
immediate plans
for
expansion to o.ther·
locations.
40
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· 5
Figure 14
O in Brine Caverns;
October 1989
Sonar Surveys
Cavern locations are
shown on Fig. 7
SPR
Cavern 116 shown
In two dimensions on
this cross section
5 08 =Volume, In
Million Barrels
-2860
•
-3036
5 08
3 59
4 05
1 4275
1 4560
-4660
I
4500
·4
t ·3
LL
C
J
-
C 3500
5000
o
200
... ...
so
150 250
FEEi
41
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x USA
Caverns 1-11
Oxy
USA
I nc . ope ra te s
11 storage caverns
containing
a
variety
of LPG
products Figs. 5, 15 ; Table 3 . Total storage volume in
m i d ~
was
sl ightly
more than 16 million barrels ,
with individual
caverns ranging
from
0.86 to
2.77 MMB.
Useable
storage volume is approximately 14 MMB.
Cavern
12
has been
permitted, and once constructed will
produce
brine
for
several years prior to product
storage; i ts location
is
north of
and
centered between caverns 1
and
3.
TABLE 3
OXY
USA
CAVERN DATA:
WEST IlACKBERRY
LA
Cavern
Volume,
Product
Casing
Tota l
Diameter ,
Diameter .
Las t
MMB
Seat
Depth
Maximum
Constructed
Sonar
ox-
1
1 . 61
Raw
-2252
-2855
249
138
17 May 91
ox-
2
0.98
Citco
nC-4
-:2254
-2891
244
105
19 Fe b
90
Ox-
3 0.86
Ci tco
nC-4
-2287
-2873
261
102
14
Dec
88
ox-
4
Ci tco
iC-4/BB
-2343
-3030
258
108
27
Mar
90
ox-
5
2.77
Propane
-2366
-3361
248
148
31 Mar
89
Ox-
6 1 .
66
Ethane
-2352
-3101
181
126
16
Apr 88
ox-
7
0.89
Propylene
-2328
-3175
115
87
08 Mar
90
ox-
8
1 . 53
fg B utane
-2347
-3106
176
120
30
Aug
89
ox-
9
2.00
Butane
-2345
-3091
273
139
09
Apr
90
Ox-l0
1.
35
fg Butane
-2561
-3583
144
97
03
Aug
90
Ox-l l .
1. 40
Propane -2566
-3383
145 110 15 Apr
88
Cavern shapes as revealed on
sonar
.records are a l l very symmetrical
Fig.
15 , at test ing to th e uniformity and purity of sal t and the general
lack
o f non -hal it e const it uent s
that
lead. to assymetry.
Oxy
Cavern
5
is
closest to
SPR
Cavern 112; the
web
thickness between them
is
700
f t a t
th e
closest
approach a t -3150 f t . Using constructed
diameter
values
average cylinders , the average pi l lar thickness increases to 780
f t .
Subsidence over. the
Oxy cavern f ield
has
been
monitored by way of
repet i t ive leveling on some six
occasions
in
the las t
seven years. The
data,
while
not
subjected
to
de ta i led sc ru t iny ,
show
very l i t t l e i f
any,
lowering
.of surface elevations. In view
of
th e
subst an t ia ll y l es s
storage
volume 6.6 of
the
SPR
to tal spread
out over 140 acres, combined
with
substantial ly
more sha llow cave rns average depth - 3132 f t a negligible
amount of subsidence is not unreasonable to expec t. The effect of cavern
depth on subsidence
is explained further
in Appendix
C
42
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Ox-1
Ox 2
Ox-3
Ox 4 Ox 5
Ox-6
Ox 7 Ox 8
Ox-g
Ox 1 Ox
-2000 .
=-----=r/--
Caprock
-2200
I
E Nis E
NIS E IW
NIS
E IW NIS EIW
NIS
-2400
-2600
-
I
\
\
\
\
\
\
0 89
Q
Q
-2800
l
LL
w
I
[
1
-
111 \
/ \ J 1 1
I
1
I 1.53
:
s:
-
o
-3000
Q
I
/
U l
1 1
11.40
C
. I
Legend
-3200
I
=
Cavern Volume,
I
I
r
/1.35
Million Barrels
-3400
l
I
0
100
200
300
. -. 1
150
250
FEET
-3600 l
I
Cavern Locations are
.shown on Fig. 7
-3800
Figure 15 Oxy USA Cavern Dep ths and Configurations;
Composite
section not a
cross
section.
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Subsidence
Subsidence p o t e n t i a l was d i s c u s s e d .i n the 1980
s i te
c h a r a c t e r i z a t i o n
r e p o r t an d
acknowledged to be
a
concern.
The
p r i n c i p a l
causes
o f
subsidence were
i dent i f i ed as f l ui d
withdrawal o f
water, gas,
an d oi l ,
cavern c o l l a p s e , an d cavern creep closure.
Ten
years o f
experience an d numerous
observations
can.now put these
an d o t h e r subsidence sources into accurate perspective, an d provide
numerical bounds on
each.
The
p r i n c i p a l
sources and.
average values,
in
order
o f importance,
are:
Subsidence
Category
UY :
a) cavern creep
closure
-0.20
b)
f l ui d withdrawal,
Black Lake)
-0.08
?
c)
regi onal
subsidence
0.010
d)
sea
level
r i s e 0.0075
e) other
subsidence/collapse
minor
f) cavern collapse none
a t
W
H
Understanding these
sources makes
i t
possible tO,estimate future
elevation
trends, an d to enable
remedial measures
to be planned, where
appropriate. Examinatior th e values
shows t h a t
s u bs id en c e i nd uc ed by
c av er n c re ep cl osure OVE the overall n um eric al b ud ge t, a lm os t to
the p o i n t
o f negating th, sources.
However, each
is
discussed
b r i e f l y ,
in
reverse
o rdE . impor t ance ,
to
show
how i t af f ect s
th e
SPR
si te :
Cavern
collapse
f)
h as o cc ur re d over numerous s o lu t io n -m i ne d c av er ns
in Texas and Louisiana,
generally
r esul t i ng from uncontrolled
brining
an d
e ro sio n i nt o the overlying caprock
and/or
overburden
[
Refs. I I ,
12].
Hindsight
in
each case u su al ly r ev ea ls t h e c ir cu m st an ce s t hat le d to
f a i l u r e .
.
Even though
today s solution
m1n1ng
t ec hn ol og y c an
avoid the
problems
t h a t previously
plagued
the
industry,
West
Hackberry ha s
some
older
caverns adjacent
to
the
SPR
property
about
which l i t t l e is known,
an d
some
p o t e n t i a l fo r
ins tabi l i ty
may e x i s t . Abandoned Olin Caverns
I ,
2, 3, 4,
an d
5
have
not
been sonar-logged
an d
the
i nt er nal
dimensions
are
u n c e r t a i n .
1989 volume
estimates [Ref.
1 3]
based
on
O li n p r od u ct io n
s ta t i s t i cs
showed t he fo ll ow in g
values:
Olin
1 & 2 -
147.7
dia x
600
h t;
1.83 MM vol. each)
Olin
3 4 -
179.8
dia x
600
h t;
2.71 MM vol. each)
Olin
5 -
80.2 dia
x
600 h t; 0.54 MM vol.
44
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55/110
These dimensions are the cylindrical forms
of known
cavern heights
constructed d iamet er s , u si ng the
assumed
maximum volumes based on
conservative
estimates
of
production
obtained
from
Olin Corporation
[Ref.
14]. The maximum
cavern diameters are assumed
to
be
wider; i t is known for
example,
that Caverns 1,2 and 3,4 ar e coalesced
[Ref.
1].
One
conclusion
based on
th e above estimates was
that the map Fig. 6.12
in the 198 report probably showed th e cavern extents to be somewhat larger
in maximum d iame te r t han
actual ly
exists . No doubt
th e
early
estimates
were
conservative intentionally and probably based on history,
as revealed
in the
ultrawide former
Olin Caverns
6
and 9.
Although
Olin Caverns 1-5
have
apparently
been stable for some 4 yrs, uncertainty re.mains.
Other
subsidence/collapse e
result ing
from
mining of sa l t
or
sulphur
has
occurred
a t numerous other domes in Texas
and Louisiana, but
mining is
absent a t
West Hackberry.
o w e ~ e r cracking
of
the
SPR
brine pond
l iner
in
1987-1988 may be related to
local
subsidence caused
by cation
exchange
reactions in the
underlying c layey
soils , upon
interact ion with
the
brine
in
ground
water
[Ref.
15].
This
l a t te r
aspect
is
discussed
further
under
Environmental Considerations.
Sea
Level Rise d is
occuring
in
the
Gulf of. Mexico a t a rate nearly
double th e g lob al rate.
The mean
r ise
in
the Gulf
is 0.23
cm/yr
0.0075
f t /yr an a lmost
ins ignif icant
amou