Note: Descriptions are shown in the official language in which they were submitted.
Nov-20-96 12:16P P.04
2190898
A'TT'ORNEY DOCKET NUMBER P70619US
FIELD OF THE INVENTION
This invention relates to vertical geological information gathering methods
and apparatuses
for the purpose of monitoring mineral production and exploration.
BACKGROUND OF THE INVENTION
As the value of oil and gas has continued to rise, there has been increasing
interest in
methods fox effectively retrieving all minerals from known mineral deposits
and for discovering -
new reservoirs. Information about the rate of depletion and the migration of
minerals within a
mineral reservoir allow operators to apply the most effective production
techniques to the
particular reservoir conditions. Accurate monitoring of mineral depletion from
a given reservoir
requires replication of accurate surveys over a Long period of time. Also,
because differently
placed and coupled receivers provide altered results, the seismic receivers
need to be placed and
coupled similarly for surveys conducted at different times.
One example of an earlier method entails drilling a production borehole,
inserting a three-
I ~ dimensional geophone instrument for data collec:ion, and removing the
instrument for mineral
production from the borehole. A three-directional geophone is capable of
detecting P waves and
S waves. This allows for interpretation of.- lithography, porosity, pore fluid
t<~-pe, pore shape,
depth of burial consolidation, anisotropic changes in pressure, and
anisotropic changes in
temperature. However, if subsequent readings are to be obtained, production
must cease and the
instrument must be reinserted into the borehole. The position and coupling of
the geophone
receiver will not be the same as before and will, therefore, produce skewed
data from that
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CA 02190898 2004-12-14
initially taken. Thus, even though this method detects both S and P waves, it
is difficult to
compare subsequent surveys because of different geophone positioning and
coupling.
A second example of an earlier method comprises deploying geophones at various
locations on the surface and taking readings. Once the survey is completed,
the receivers are
retrieved for subsequent use at another survey project. In an ocean survey,
the water and mud
layer typically kill the S waves so that they do not propagate up into the mud
or water where
they could be received by seismic instruments positioned there. This is also
true for the soft earth
surface layer of land surveys. Thus, the data collected at the surface is not
as accurate as data
collected from deep within a borehole. Also, like the previous method, if
sum.ey data is to be
collected at a later time, the receivers must be re-deployed upon the surface.
Again, the receivers
are not likely to be positioned and coupled as in the first survey.
Therefore, in order to provide accurate surveys of reservoirs over time, there
is a need for
repeatability in the location of seismic receivers and in detection of both S-
v~~ave and P-wave
signals.
1~
SUMMARY OF THE INVENTION
According to one aspect of the invention, there is provided a method for
monitoring
production mineral reservoirs.
One embodiment of this aspect comprises: A method for monitoring a mineral
reservoir,
the reservoir being in a geologic formation of interest, the method
comprising: preparing a
nonproduction borehole to receive a monitoring instrument, the borehole being
bottomed out
beneath the soft earth surface layer and above the geologic formation of
interest; installing the
instrument in the borehole; generating a first set of seismic waves; receiving
said first set of
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CA 02190898 2004-12-14
seismic waves; generating at least one more set of seismic waves; receiving at
least one more set
of seismic waves; and comparing at least one reception of said first set of
seismic waves with at
least one reception of at least one more set of seismic waves, wherein at
least one set of seismic
waves is generated outside said borehole.
Another embodiment of this aspect comprises: permanently installing a geophone
in a
borehole; generating a first set of seismic waves; receiving a first set of
seismic data with the
geophone; recording the first set of data of said receiving a first set of
seismic data; generating a
second set of seismic waves after sufficient time has passed for conditions in
the
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A'(TnRNEY DOCKET NUMBER P70619US
reservoir to have changed from the generating a first set of seismic waves;
receiving a second set
of seismic data with the geophone; and recording the second set of seismic
data of said receiving
a second set of seismic data.
According to another aspect of the invention, there is provided a method for
installing
instruments below the surface of the earth. One embodiment of this aspect
comprises: drilling
a borehole with a drill apparatus; inserting an instrument in the borehole;
and permanently fixing
the instrument in the borehole. _
According to a further aspect of the invention, there is provided an
instrument for
receiving seismic data. One embodiment of the aspect comprises: a geophone
component which
operates in an X-direction; a geophone component which operates in an Y-
direction; a geophone
component which operates in an Z-direction; and a housing for the geophone
components which
is permanently fixed in a borehole.
According to a further aspect of the invention, there is provided a system for
collecting
seismic information. One embodiment of this aspect comprises: a signal source;
a signal receiver
1 ~ permanently fixed in a borehole; a control unit that sends and receives
infortnatian to and from
the signal source and the signal receiver; and communicators of data between
the control unit and
the signal receiver and the signal source.
According to a still further aspect of the invention, there is provided a
method for
monitoring production mineral reservoirs. One embodiment comprises: installing
a pipe
?0 permanently in a borehole; lowering in a first instance an electronic
instrument into the pipe;
reading a first set of data with the electronic instrument; removing the
electronic instrument from
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the pipe; lowering in a second instance the electronic instrument into the
pipe after sufficient time
has passed for conditions in the reservoir to have changed; and reading a
second set of data with
the electronic instrument.
BRIEF DESCRIPTION OF THE DRAWING
The present invention is better understood by reading the following
description of
nonlimitative embodiments with reference to the attached drawings, wherein
like parts in each
of the several figures are identified by the same reference character, which
are briefly described
as follows:
FIG. 1 is a cross-sectional view of an instrument in a vertical borehole;
FIG. 2 is an outline of a method for installing an instrument in a vertical
borehole;
FIG. 3 is a cross-sectional view of a coil tube drilling apparatus;
FIG. 4a is a cross-sectional view of a seismic instrument for use in a
vertical borehole;
FIG. 4b is a cross-sectional view of a seismic instrument for use in a
vertical borehole;
1. FIG. 4c is a cross-sectional view of 3 seismic instrument for use is a
vertical borehoie;
FIG. 4d is a cross-sectional view of a seismic instrument for use in a
vertical borehole;
FIG. 4e is a cross-sectional view in the Z axis direction of the instrument at
the X-
geophone;
FIG. 4f is a cross-sectional view in the Z axis direction of the instrument at
the Y-
0 geophone;
FIG. 4g is a cross-sectional view in the Z axis direction of the instrument at
the Z-
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AZTORNEY DOCKFf NUMBER P70619US
geophone;
FIG. 5 is a diagram of a configuration of the instrument attached to a pipe
for insertion
in the borehole;
FIG. 6 is a diagram of a configuration of the instrument attached to a pipe
for insertion
in the borehole;
FIG. 7 is an outline of a method for monitoring a production reservoir;
FIG. 8 is a diagram of a configuration of the invention with an instrument
attached to an -
exterior of the pipe and an instrument attached to an interior of the pipe;
and
FIG. 9 is a diagram of a confguration of the invention with an upper section
of the pipe
removed.
It is to be noted, however, that the appended drawings illustrate only typical
embodiments
of the invention and are therefore not to be considered a limitafion of the
scope of the invention
which includes other equally effective embodiments.
1 ~ DETAILED DESCRIPTION OT THE INVENTION
Referring to Figures l and 2, there is shown a cross-sectional view of a
vertical seismic
instrument well (1) and an outline of a method for installing the instrument.
The method
comprises drilling (201) a first section (2) of the well to a depth of about
50 feet. This first
section (2) is relatively wider than deeper second section (3) of the well yet
to be drilled. A
'_'0 larger diameter casing (10) (for example, 3.5 to 4.5 inches) is installed
(202) in this first section
(2). The space between the casing (10) and the earth is f lled (203) wuh
cement to permanently
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2190898
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ATTORNEY DOCKET NUMBER P70619US
fix the casing (10) in position. A smaller diameter section (3) (for example,
about 2.4 inches)
is then drilled (204) below the larger diameter casing ( 10) to a depth of
about 700 to 1000 feet
(this depth could be much deeper given the particular environment surrounding
the borehole).
A seismic instrument (40) is then attached (205) to a pipe (30) and the pipe
is inserted (206} into
the well ( 1 ). The end of the pipe (30) extends nearly to the bottom of the
well ( 1 ) and the
instrument (40) is attached to the pipe (30) at a depth of about 300 to 400
feet (this depth may
be changed according to the desired instrument configuration). Cement is then
pumped (207) into
the pipe (30} so that it flows down the pipe (30) and out a hole (31) at the
bottom. The concrete
first fills the space between the pipe (30) and the smaller diameter section
(3) and encircles the
instruments (40). Finally, the concrete fills the space between the pipe (30)
and the larger
diameter casing ( 10). Once the concrete sets, the instrument {40) is
permanently fixed in the well
( 1 ). Instruments may be installed in this way both on land and of~'shore.
In some environments, the instruments may be fixed in the borehole by allowing
the
borehole walls to collapse on the instrument. At times this will provide
superior coupling of the
instrument to the surrounding fornnation because of the uniformity of material
around the
instrument.
As the cost of the drilling apparatuses become less expensive, it will be more
efficient to
attach the seismic instrument directly to the coil tube itself. The coil tube
is then left in the
borehole while the instruments are permanently fixed in the borehole. Concrete
is pumped into
the borehole through the coil tube so as to flow up and around the instruments
as before. The
drill bit and downhole motor are then permanently fixed in the borehole as
well as the
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NOU 20 '96 13:15 PRGE.009
CA 02190898 2004-04-05
instruments. This method is preferred when it is less expensive to leave the
drill apparatuses in
the borehole rather than pull them out. A high pressure water no~zte is one
type of drilling
apparatus that may eventually become so inexpensive to merit leaving in the
borehole.
Referring to Figure 3, a coil tube drill'mg' apparatus {310) is shown. The
drill bit (301)
S is driven by a downhole motor (302). The downhole motor (302) is powered by
mud pump
pressure which is pumped by a pump (304) at the surface. A coil tube (305)
connects the pump
(304) to the downhole motor (302). As the borehole (30~ is drilled deeper, the
coil tube (305) -
is reeled off a tube spool (30'1) and over a wheel (308). The wheel (308) is
positioned over the
borehole (306) so that the coil tube (305) may extend from the wheel {308) sad
down into the
borehole(30~. The drill preferably comprises a rotating pipe string
connected to a drill bit which turns the drill bit.
One example of the coil tube drilling apparatus (310) is the Fleet Model 40-20
Coiled
Tubing Unit produced by Vita International, Inc. This unit has the following
characteristics:
Injector Head Rating: Up to 40,000 lb.
Drive: Hydrostatic powered planetary to sprocket & chain final drive.
Speed: 220 Ft. Max.
Braking System: Main brake-Fail-safe wet type, Auxiliary brake-Band type-air
actuated.
Straightener: Manuallhydrautic system.
Grippiag System: Lebus grooving with multiple hold-down roElcrs.
Size Itaage: TO 3 112".
Truck, trailer, skid mounted.
Hydraulic leveling and centering.
8
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2190898
ATTORNEY OOCi~ET NUMBER P70619US
Mast: Up to 30 Ft. for wellhead clearance with capability for self
loading/unloading of
storagelwork reef.
Optional Equipment: Winches, pumps, etc. per customer requirements.
Power Equipment: Up to Z00 HP Diesel.
Hydraulics: Injector and Storage/Work Reels-Sunstrand Hydrostatic, Max
Pressure -
5000 PSI.
Leveling, raising, winding and lateral positioning: Conventional gear type
pump with max
-. pressure - 3000 PSI.
Storage/Work Reel -
Flaage Dia: 120"
Tubing O.D. Core Diameter Capacity
2 3/8" 96" 3,000 Ft.
2" 80" 7,000 Ft.
1 314" 72" 9,600 Ft.
I 1/2" 72" 14,000 Ft.
1 I /4" 72" 19,000 Ft.
1" 72" 30,000 Ft.
Tubing Reel Cradle: Side frames are hydraulically opened to facilitate easy
change out
of reels.
Controls:
A. Electric over hydraulic for injector reel; storage reel and traverse
(winding).
B. Conventional for raising, leveling, centering. winches, etc.
Available installed in control cabin mounted on truck or trailer. Item A is
available with
50' remote capability.
Referring to Figure 4a, there is a seismic instrument (401 ) for permanent
fixation in a
borehole as seen along a Y axis. The instrument (401 ) comprises three
geophones: a X-
geophone (402) positioned to read waves along an X axis. a Y-geophone (403)
positioned to read
waves along a Y axis, and a Z-geophone (404) positioned to read waves along a
Z axis. A cable
{405) runs through the instrument (401) for transmission o~ readings received
by the geophones.
The instrument {401 ) also has a water-tight housing structure (40b) that
seals the cable (405) and
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the geophones (402), (403) and (404) within. The cable (405) is itself sealed
on die portions
which extend out from the housing (406). The portions of the cable (405) in
the interior of the
housing (406) are at connection points wltich connect to the geophones. Thus,
in order to
maintain a water-tight barrier for the entire instrument (401), seals (407)
are formed between the
cable (405) and the housing (406) where the cable {40S) enters the housing
(406) at both ends.
Interior seals (408) also form a water-tight barrier between the housing (406)
and the cable {405).
The cable (445) and housing (406) may be sealed with eider glass, epoxy or O-
rings depending
on the particular application.
Other types of instruments are also possible. These include: a temperature
instrument,
a pressure instrument, a hydrophone, a gravimetry resistance instrument, a
resistivity instrument,
an electromagnetic instrument, and a radiation sensing instrument.
Referring to Figure 4b, there is depicted the housing {406) and the geophones
(402), {403)
and (404) as viewed along an X axis. Referring to Figure 4c, the housing (406)
and geophones
(402), (403) and (404) are shown as viewed along a Y axis. Referring to Figure
4d, the housing
1S (406) and geophones (402), (403) and (404) are shown as viewed along a Y
axis. In Figure 4e,
a cross section of the X-geophone (402) is shown as viewed along the Z axis.
In Figure 4f, the
Y-geophone (403) is shown as viewed along the Z axis. In Figure 4g, the Z-
geophone (404) is
shown as viewed along the Z axis. Notice also in Figures 4e - 4g there are
holes (411), (412)
and (413) in the housing (406). The cable (405) passes through and connects to
each geophone
in these holes.
Referring to Figure 5, a configuration for attaching the instrument to the
pipe is shown.
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A1TORNEY DOCKET NUMBER p70619US
In this configuration, a centralizer (501 ) is fixed to the pipe (502) which
is used to insert the
instrument (503). The centralizer comprises upper and lower collars (504} and
bows (SOS) which
extend between and connect the collars (504). The bows (505) are somewhat
flexible and have
a wider outside diameter than the collars {504) so that they can flex against
the sides of the
borehole to prevent the pipe from contacting the sides of the borehole. A
cable (506) extends
from both ends of the instrument (503) and is attached to the pipe (502} by
the upper and lower
collars (504). Additionally, the instrument (503) can be attached to the pipe
(502} by wrapping
waterproof tape around both the instrument (503) and the pipe (502).
Referring to Figure 6, a configuration for attaching the instrument to the
pipe is shown.
In this co~guration, two centralizers (641 ) and (604) attach the cable (606)
to the pipe (602}.
Here, no centralizer encircles the instrument, but rather one centralizer is
above (601) the
instrument and the other below (604). Again, the instrument (603} can be
attached to the pipe
(602) by wrapping waterproof tape around both the instrument (603) and the
pipe (602).
Also, it should be understood that multiple instruments may be attached to a
single pipe
at various locations. Multiple centraIizers may also be attached at various
locations to keep the
pipe from contacting the borehole sides. A centralizer could be attached every
10 feet, even
where no instruments are attached.
Referring to Figure 7, there is shown a method for monitoring a production
mineral
reservoir. The method is to install a seismic instrument permanently in the
substrata near the
reservoir to be monitored. This is done by drilling (701) a borehote with a
drill apparatus. Next,
a seismic instrument, such as a three-dimensional geophone, is inserted (702)
into the borehole.
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ATTORNEY DOCKET' NUMBER P70619US
The instrument is then permanently fixed {703) in the borehole by filling the
borehole with
concrete. This not only fixes the position of the instrument in one location,
but it couples the
instrument to the substrata. Coupling enables the instrument to perceive
seismic waves traveling
through the strata because the instrument is actually attached to the strata.
The next step in the
method is to generate {704} a first set of seismic waves. These waves are
reflected in the strata
and are received (705) by the instrument. This data is recorded (706} so that
mineral producers
will have knowledge of reservoir conditions at that point in time. Later, a
second set of seismic -
waves are generated (707). These waves again are reflected in the strata and
are received (708)
by the instrument. This second set of data is also recorded (709) for
comparison with the first
set of data.
In this method, the seismic source may also be placed in a borehole adjacent
to the
borehole for the receiver instruments. This allows the seismic wave to travel
from the seismic
source, down into the lower strata, be reflected back up toward the surface,
and be received by
the receiver instruments without travelling through an S-wave killing, soft
earth, surface layer.
Referring to Figure 8, there is shown a configuration of the instruments
placed within the
borehole. In this embodiment an instrument (40) is attached to the exterior of
the pipe (30). The
pipe (30) is inserted into the borehole so that the instrument (40) is about
half way down the
borehole. The pipe (30) is permanently fixed in the borehole by pumping
concrete down the
center of the pipe (30) so that the concrete comes out a hole (31) in the
bottom of the pipe {30).
The concrete then rises in the borehole (3) between the pipe (30) and the
borehole walls so that
it surrounds the instrument {40). A plug {60) is then used to push the
concrete down the pipe
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ATTORNEY DOCKET NUiNBER F~0619US
so that interior of the pipe above the plug (60) is not filled with concrete.
A second instrument
(50) is then placed down in the interior of the pipe for readings. This
instrument (50) may be
retrieved and reinserted each time readings are desired.
A similar embodiment of the invention is to install the pipe without attaching
an
S instrument (40) to the outside of the pipe (30}. The cement is still removed
from the interior of
the pipe (30) by the plug (60}. In this embodiment, no instruments are
permanently fixed in the
borehole. Rather, instruments are lowered into the pipe for taking readings.
Once the readings
are taken, the instruments are removed for use at other locations. Each time
readings need to be
taken, the instruments are simply lowered again into the pipe.
Referring to Figure 9, there is shown a diagram of a configuration for
installing the
instruments below the soft earth surface layer. In this configuration, the
instrument (40) is
attached to the exterior of the pipe (30} and the space between the pipe (30)
and the borehole
walls is filled with concrete as well as the inside of the pipe (30).
Particular to this embodiment
is the detachment of the upper portion of the pipe (30). The pipe (30) and
borehole (3) are
covered over with earth. This keeps the top of the pipe (30) from acting like
an antenna by
insulating the instrument from vibrations generated at and above the surface
of the earth. These
vibrations tend to interfere with the seismic reading being obtained by the
instruments.
It is to be noted that the above described embodiments illustrate only typical
embodiments
of the invention and are therefore not to be considered a limitation of the
scope of the invention
which includes other equally effective embodiments.
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