Note: Descriptions are shown in the official language in which they were submitted.
CA 02487186 1996-11-21 1390PO1CA02
This application is a divisional of Canadian application serial
no. 2,190,898 filed November 21, 1996.
FIELD O)F THF. INVENTION
This invention relates to vertical geological information gathering methods
and apparatuses
for the purpose of monitoring mineral production and exploration.
BACKGROUND O>F THE INVENTION
As the valve of oil and gas has continued to rise, there has been increasing
interest in
methods for effectively retrieving all minerals from known mineral deposits
and for discovering -
ntw 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
l0 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 S dimensional geophone instrument for data collection, and removing the
instrument for mineral
production from the borehole. A three-directional geophone is capable of
detecting P waves and
$ waves. This allows for interpretation of: lithography, porosity, pore fluid
ype, pore shape,
depth of burial consolidation, anisotropic changes in pressure, and
anisotropic changes in
temperature. I-towever, if subsequent readings are to be obtained, production
must cease and the
20 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, prcHluce skewed
data from that
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CA 02487186 2005-07-05
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 survey 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-
wave and P-wave signals.
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 installing an instrument
below the surface of the earth, the method comprising:
drilling a deep borehole in the earth;
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CA 02487186 2005-07-05
attaching the instrument to a tubular member having an upper portion and a
lower portion, the instrument being attached to the lower portion of the
tubular member;
inserting the tubular member into the deep borehole;
fixing the lower portion of the tubular member and the instrument in the
deep borehole;
detaching the upper portion of the tubular member; and
covering the lower portion of the tubular member and the borehole over
with earth to insulate the instrument from vibrations generated at and above
the surface
of the earth.
BRIEF DESCRIPTION OF THE DRAWINGS
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;
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CA 02487186 2005-07-05
FIG. 4b is a cross-sectional view of a seismic instrument for use in a
vertical
borehole;
FIG. 4c is a cross-sectional view of a seismic instrument for use in a
vertical
borehole;
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-geophone;
FIG. 4g is a cross-sectional view in the Z axis direction of the instrument at
the
Z-
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CA 02487186 1996-11-21
gcophone;
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
3 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 configuration 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 limitation of the
scope of the invention
which includes other equally effective embodiments.
l ~ DETAILED DESCRIPTION OT THE INVENTION
Referring to Figures l and 2, there is shown a cross-sectional .~iew oC a
vertical seismic
instrument welt (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
SO 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 filled (203) with
cement to permanently
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CA 02487186 1996-11-21
fix the casing (l0) 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 (I ) 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). Cemcnt 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 concrctc
first fills the space between the pipe (30) and the smaller diameter section
(3) and encircles the
IO instruments (40). Finally, ttx 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 welt
{ 1 ). Instruments may be installed in this way both on land and offshore.
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 formation 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
borchole 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
wet( as the
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CA 02487186 1996-11-21
insttuaicats. This method is preferred wlka it is less expensive to Icave the
drill apparatuses in
the borehole rather than pull them out. A high pressure water noaIe 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 drilling apparatus (310) is shown. The
drill bit (30 i )
S is driven by a downhole motor (302). The downhole motor (302} is povvercd by
mud pump
pressure which is pumped by a Pump (304) at the sarfa<x. A coil tube (305)
connects the pump
{304) to the downhole motor (302). As the bocelwk {30~ is drilled deeper, the
coil tube (305) -
is reeled off a tuix spool {307) and ova a wheel (308). The wheel {308) is
positioned aver the
bocehole (30~ so that the coil tube (305) may extend from the wheel (308) and
down into the
borrhole(306). 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 (3 t0) i3 the Fleet Modci 40-
20 Coiled
Tubing Unit produced by Vita Intemationai, Inc. This unit Isas the following
characteristics:
Injector Head lltatiag: Up.to 40,000 Ib.
Drive: Hydrostatic powered planetary to sprocket 8c chain final drive.
Sped: 220 Ft Max.
Braking System: Main brake-fail-safe wet type, Auxiliary brake--Band type-air
actuated.
Straigbtcner: Manuallhydraulic system. .
Gripping System: Lebus grooving with multiple hold-down rollers.
Sine Range: To 3 1/2".
Truck, trailer, skid mounted.
Hydraulic leveling and centering.
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CA 02487186 1996-11-21
ATTnRNEY DOCl:ET MIMBER 1'~t1619US
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.
S
Power Equipment: Up to 200 HP Diexl.
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. '
StoragelWork Reel
Flaage Dia: 120"
IS Tubing O.D. Core Diameter Capacity
2 3/8" 96" 3,000 Ft.
2" 80" 7,000 Ft.
1 3/4" 72" 9,600 Ft.
I 1!2" 72" 14,000 Ft.
1 1 /4" 72" I 9,000 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 (~01 ) comprises three
geophones: a X-
geophone (402) positioned to read waves along an X axis. a Y-geophone (403)
positioned to read
3S waves along a Y axis, and a Z-geophone (404) positioned to read waves along
a Z axis. A cable
(40S) runs through the instrument (401 ) for transmission of readings received
by the geophones.
The instrument (401 ) also has a water-tight housing structure (406) that
seals the cable (40S) and
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CA 02487186 1996-11-21
the gcophones {402), (403) and (404) within. The cable (405) is itself sealed
on the 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 which connect to the geophoncs. 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 (40p) enters the housing
(406) at both ends.
Interior seals (408) also form a water-tight barrier betv4cen the housing
(406) and the cable (405).
The cable (405) and housing (406) may be sealed with either 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 instnunent,
an electromagnetic instrument, and a radiation sensing instrument.
Referring to Figure 4b, there is depicted the housing (406) and the geophones
(402), {403)
and (444) 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
(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 show~rt as tiewcd 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 Fieures 4e - 4g there ace
holes (411), (412)
and (4 ( 3) 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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CA 02487186 1996-11-21
ATTOIWEY DOCKET NUMBHIt P70619Vs
In this configuration, a centralizes {501) is fixed to the pipe (502) which is
used to insert the
instrument (503). The centralizes 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
S borehole to prevent the pipe from contacting the sides of the boreholc. A
cable (506) extends
from both ends of the instrument (503) and is attached to the pipe (502) by
the upper and tower
collars (504), Additionally, the instrument (503) can be attached to the pipe
{502) by wrapping
waterproof tape around both the instrument (~03) and the pipe (502).
Referring to Figure 6, a configuration for attaching the instrument to the
pipe is shown.
In this conE'iguration, two centralizcrs (601 ) and (604) attach the cable
(606) to the pipe (602).
Here, no centralizes encircles the instrument, but rather one centratizer is
above (601 ) the
instrument and the other blow {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 eentraliz~ers may also be attached at various
locations to keep the
pipe from contacting the borehole sides. A centralizes could be attached every
10 feet, even
where no instruments arc 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 borehole with a
drill apparatus. Next,
a seismic instrument, such as a three-dimensional gec~phone, is inserted (702)
into the borehole.
CA 02487186 1996-11-21
The instrument is then permanently Gxed (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
S 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 (?09) for
comparison with the frst
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. 1n 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 (3i) 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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CA 02487186 1996-11-21
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 brae readings are desired.
A similar embodiment of the invention is to install the pipe without attaching
an
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 instn~ments are removed for use at other locations. Each time
readings need to be
taken, the instruments are simply lowered again into the pipe.
l0 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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