CA2487186C

CA2487186C - Method and apparatus for installing electronic equipment below soft earth surface layer

Info

Publication number: CA2487186C
Application number: CA002487186A
Authority: CA
Inventors: Sven O. Havig
Original assignee: Petroleum Geo Services Inc
Current assignee: Petroleum Geo Services Inc
Priority date: 1996-11-21
Filing date: 1996-11-21
Publication date: 2006-02-14
Anticipated expiration: 2016-11-21
Also published as: CA2487186A1; CA2190898C; CA2190898A1

Abstract

A method for monitoring production mineral reservoirs, the method comprising: 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 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. A method for installing instruments below the surface of the earth, the method comprising: drilling a borehole with a drill apparatus; inserting as instrument in the borehole; and permanently fixing the instrument in the borehole. An instrument for receiving seismic data, the instrument comprising: 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.

Description

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 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;

2 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;

3 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-

4 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

5 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

6 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.

7 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

8 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.

9 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.

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

11 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.

12

Claims

I CLAIM

1. A method for installing an instrument below the surface of the earth, the method comprising:
drilling a deep borehole in the earth;
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.