CA1232836A - Borehole packers - Google Patents
Borehole packersInfo
- Publication number
- CA1232836A CA1232836A CA000447390A CA447390A CA1232836A CA 1232836 A CA1232836 A CA 1232836A CA 000447390 A CA000447390 A CA 000447390A CA 447390 A CA447390 A CA 447390A CA 1232836 A CA1232836 A CA 1232836A
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- casing
- water
- substance
- sampling
- packers
- Prior art date
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Abstract
A B S T R A C T
A packer for isolating sections of boreholes, to facilitate multilevel groundwater monitoring in a single borehole, is disclosed. The packer includes a water-expandable substance installed in sleeve-like fashion around a casing in the borehole, and covered by an expandable membrane. Holes are provided in the casing behind the water-expandable substance, so that when the casing is filled with water, water flows to the substance, the substance expands, and the membrane is pressed against the borehole wall, thereby effecting a seal to isolate the desired section. The use of a number of packers within a borehole, either singly or in pairs, is contemplated. Instead of being installed directly around the casing, the packers may be conveniently installed around lengths of pipe which are subsequently spliced in with lengths of the casing pipe. The preferred water-expandable substance is a sealant proprietary to the Dow Chemical Company and sold by them under their trade mark DOWELL, but bentonite clay or other suitable water-expandable substances are also contemplated.
A packer for isolating sections of boreholes, to facilitate multilevel groundwater monitoring in a single borehole, is disclosed. The packer includes a water-expandable substance installed in sleeve-like fashion around a casing in the borehole, and covered by an expandable membrane. Holes are provided in the casing behind the water-expandable substance, so that when the casing is filled with water, water flows to the substance, the substance expands, and the membrane is pressed against the borehole wall, thereby effecting a seal to isolate the desired section. The use of a number of packers within a borehole, either singly or in pairs, is contemplated. Instead of being installed directly around the casing, the packers may be conveniently installed around lengths of pipe which are subsequently spliced in with lengths of the casing pipe. The preferred water-expandable substance is a sealant proprietary to the Dow Chemical Company and sold by them under their trade mark DOWELL, but bentonite clay or other suitable water-expandable substances are also contemplated.
Description
This invention relates generally to devices for sampling granddaughter to monitor granddaughter quality and hydraulic head, and relates particularly to packers adapted to isolate sections of Berlioz to facilitate water-level measurements and the extraction of water samples from the sections so isolated.
The identification and delineation of granddaughter quality zones and hydraulic head in fractured bedrock is difficult due to the complex nature of flow in the fracture networks. The rates of granddaughter flow and chemical concentration can be greatly different from one fracture to another. At sites where contaminated granddaughter is expected to occur, contaminants may be present in fractures which intersect only a small segment of the total Barlow.
Because of these complexities and uncertainties, it is often appropriate to acquire samples from numerous depth intervals at each monitoring site when monitoring granddaughter quality in fractured rock. This can be accomplished by drilling separate Berlioz to different depths at each site for installation of a nest of piezometers or observation wells, or by the installation of a multilevel monitoring device in a single hole at each site. The use of piezometers in several Berlioz at each monitoring site is often prohibitively expensive for detailed monitoring of granddaughter quality.
Accordingly, there is a need for devices which facilitate the acquisition of water samples and hydraulic head measurements from numerous depth levels within a single Barlow. Typical devices comprise a casing installed in the Barlow, with samples being extracted at various levels ~32~336 through the casing wall from the annular space between the casing wall and the Barlow wall. Such devices must include seals or packers which isolate each annular space to be monitored from those above and those below.
Various devices have been used in the past as packers. One of the most common arrangements has been the use of pneumatically inflatable packers. Such packers require pressurized air or water supply means, and are thus somewhat cumbersome. In most designs, air or water supply tubes must be run down the Barlow, and such tubes occupy precious space within the casing. With time, many such packers tend to deflate and therefore generally are not suitable as a permanent means of granddaughter monitoring.
It is an object of the present invention to provide improved packers for sealing and isolating sections of Berlioz so that intervals between packers can be used for granddaughter monitoring.
Accordingly, in the present invention there is provided a packer intended for sealing the space between a Barlow wall and a hollow casing within the Barlow. An expandable membrane is installed in sleeve-like fashion around the casing where the seal is desired, and its ends are sealed against the casing. There is a water-expandable substance between the membrane and the casing. Water is supplied to the substance by filling the casing with water, apertures being provided in the casing to permit water to flow to the substance. Expansion of the substance presses the expandable membrane against the Barlow wall, thereby effecting the desired seal.
~3~:~36 In accordance with another aspect of the invention, there is provided a packer assembly of the same general construction, adapted for connection between sections of casing, for sealing the Barlow at the connection location.
Methods of isolating Barlow sections using packers of the present invention are also provided.
The preferred embodiment of the invention will now be described with reference to the accompanying drawings, in which:
Fugue is a diagram of a multilevel granddaughter sampling assembly installed in a Barlow, showing the use of a number of packers of the present invention to isolate sections of the Barlow;
Fugue is a diagram of a smaller area of the overall assembly; and Fugue is a detailed view of a packer assembly of the present invention, showing the packer in cross-section.
Referring first to Figs. 1 and 2, the multilevel device will be described.
The device consists of a bundle of tubes 2 contained within a PVC pipe (casing) 3 that is capped on the bottom 4. Each of the tubes is connected to a 90 degree elbow 5, which protrudes through the casing into the annular space 9 between the Barlow wall and the casing. Each tube extends to a different depth in the casing so that water can be drawn from different depths in the Barlow 1. The annular space associated with each tube is isolated from above and below by the packers 10 of the present invention, which expand to effect a seal across the annular space ~232~6 wherever desired, thereby permitting monitoring of discrete zones, e.g. open fractures, joints or faults or other permeable zones 8. Obviously, if large segments are to be monitored, the packers can be placed farther apart and need not be used in pairs to isolate small segments.
The number of tubes that can be installed in a single Barlow depends on the diameter of the Barlow and on the diameter of the tubes. It is an advantage of the present invention that no tubes are required to be dedicated to packer inflation, so more sampling tubes can be accommodated within a given casing diameter.
Referring now to Fugue, the packers themselves will be described. The packers 10 employ a sealant substance which expands when contacted by water. The preferred sealant, to be described in more detail hereinafter, resembles a soft light rubber, and is formed into a cylindrical sleeve 15 in a mold. The sleeve is placed around precut lengths of PVC pipe 16, the same type of pipe that is used for the casing 3. The sleeves used in test installations were 9 cm. long. If desired, much longer sleeves of sealant can also be made. The packers can be conveniently joined into the casing using standard thread less couplings 18 with a small amount of solvent joiner. Solvent can be avoided entirely if the joins are done by heat welding. Steel pipe can be used instead of PVC
pipe if greater strength is desired.
It is of course apparent that the packers can be installed around the casing itself before the casing is inserted in the Barlow, rather than around separate pieces ~2~32~
of pipe, and such an installation is within the scope of the invention. However, for convenience in manufacture and construction, it is much easier to install the packers around precut lengths of pipe and to then splice these packer assemblies in between lengths of casing.
The sleeve 15 must be isolated from the granddaughter in the Barlow along the outside of the casing because the sealant contains compounds that have significant volubility. The outside of the sleeve 15 of sealant is therefore covered with a flexible rubber membrane 20 held in place above and below the sleeve by plastic or metal strap clamps 22. The straps sit in grooves cut into the PVC pipe.
Above and below each sleeve, double or triple strap clamps can be used to minimize the potential for leakage.
The sealant must be contacted by water from inside the casing to cause volume expansion to occur. To provide for this water contact, holes 25 are drilled radially around the PVC pipe. Monofilament nylon screen cloth 27 (210 mesh) is taped around the pipe and over the holes. The sealant sleeve 15 is installed around the PVC pipe, with the screen 27 in place between the pipe 16 and the sleeve 15. The purpose of the screen is to facilitate entry of water from inside the PVC casing into the very thin annuls 29 between the exterior of the pipe 16 and the interior surface of the sleeve 15 of sealant. Because the bottom 4 of the casing is capped and because the elbows 5 connected to the tubes are tightly sealed where they protrude from the casing into the Barlow, the water for expansion of the sealant is provided by filling the inside of the casing 3 with foreign water. If the elbows have a water-tight fit where they pass through Sue the PVC pipe and if all of the casing couplings are sealed, this water cannot mix with formation water at any time.
Whether or not leakage of fluid occurs from the casing can be determined by filling the water column in the casing up to the surface and monitoring the water level with time A standard thread less PVC coupling 18 is joined onto each end of the length of pipe 16 containing the packer assembly. Packers can be constructed and taken to the field in a fully-assembled state.
The sealant preferred for use in the construction of the packers is a proprietary product of the Dow Chemical Company and is sold by them under their trade mark DWELL.
More particularly, it is sold by the DWELL Division of the Dow Chemical Company as "Dwell Chemical Seal Ring". It is an elastic polymer which, when placed as a slurry, sets into a rubber-like material. It is capable of imbibing water to swell to more than 150~ of its original volume. It is prepared by adding a powdered polymer to a premixed fluid phase. The polymer disperses readily and is easily mixed with a minimum of stirring or agitation. The chemistry of the reaction results in a permanent cross-linkage of the molecules which should be inert to further reaction.
The sleeve 15 of sealant is formed by mixing the DWELL sealant components together and pouring this mixture into appropriately-shaped metal or plastic molds constructed in a machine shop. The rubber-like cylindrical sleeves 15 are removed from the molds after an overnight setting period. When the sleeve of sealant is contacted by water from inside the casing in the Barlow, it expands until it I Pi presses tightly against the wall of the Barlow. In a trial field site, the outside diameter of the sleeve was initially 6.7 cm and it expanded to fill the Barlow, which had a diameter of 7.5 cm. The thickness of the sleeve expanded from 0.35 cm to 0.75 cm. Various diameters have been used in laboratory prototypes. The seal is capable of expanding to a much larger diameter if necessary. The sleeves expand sufficiently to cause the packers to squeeze tightly against the wall of the Barlow.
As an alternative to the DWELL sealant, compressed rings of expansible powdered bentonite clay can be used. The rings can be stacked up on the casing segment to achieve whatever length of packer is desired. The stacked rings are covered with the rubber membrane 20 in exactly the same manner as described above for the DWELL sealant sleeve.
It will be appreciated that any suitable water-expansible substance could be used in place of DWELL
sealant or bentonite clay. Such other substances are within the broad scope of the invention.
The size of the sleeve 15 is such that the outside diameter of the membrane 20 prior to expansion is slightly smaller than the outside diameter of the coupling 18 on each end of the length of PVC pipe 16 used for the packer assembly. This arrangement provides protection for the membrane 20 when the complete monitoring device is lowered down the Barlow. Scraping of the couplings on the wall of the Barlow would occur rather than scraping of the thin, less durable membrane.
11 23;~
Each sampling port 14 is constructed by drilling a hole in a length of PVC casing 3 so that the 90 degree elbows 5 and tubes 2 can be attached to form the sampling ports. The elbows consist of commercially-produced threaded plastic elbows or of a heat-bent piece of narrow-diameter PVC pipe. A packer 10 is attached by means of coupling joints 18 above and below the length of casing 3 containing the sampling ports 14. Lengths of PVC casing 3 are coupled into the assembly to provide spacing between the sampling intervals. Packers can be coupled into these lengths of casing to provide additional assurance that the Barlow intervals between sampling zones are effectively sealed.
Conventional piezometers that are used for granddaughter monitoring, normally with a single piezometer in each Barlow, have a sand pack around the piezometer tip and a bentonite or grout seal on top of the sand pack. In formations with low permeability and consequently low flushing rates, reactions between the slow moving water in the sand pack and a grout or bentonite seal may disturb the chemical conditions of the granddaughter that is sampled, even if the sand pack and seal are placed properly in the hole.
The multilevel monitoring device described here avoids most of this uncertainty because the sealant 15 is isolated from the formation water by the protective rubber membrane 20. If reactions with the rubber are f concern, the rubber ~6j~ I Ahab membrane can be covered with a Tony membrane.
: . .
It is necessary to be vigilant with respect to identification of the effects of tears in the membrane 20 that could impact the chemistry of the granddaughter samples.
There is also the possibility that one or more of the g ~23~33~ii packers might not provide an adequate seal in the Barlow.
Uncertainty in this regard can be decreased by the use of longer sleeves 15 and more packers in situations where Barlow roughness and degree of fracturing are particularly adverse.
Although the multilevel device described should be viewed as a permanent monitoring installation in much the same manner as normal wells or piezometers, there is a possibility that the device can be removed from the Barlow after a period of use. When DWELL sealant is not in contact with water, considerable shrinkage occurs. If the water in the casing is removed, the seals will shrink and thereby provide an opportunity for removal of the assembly. This has been demonstrated in the laboratory, although removal has not yet been attempted at a field site. For it to be feasible in the field, it may be necessary to circulate warm air in the casing after the casing water is removed so that the sealant shrinks at a rapid rate.
Although the multilevel monitoring device described here was developed for use in fractured rock, it is expected that it will also be useful in deposits of consolidated clay. However, for the packers to effectively seal the various sampling levels, the hole needs to be free from in filling that would occur if inter beds of cohesion less gravel, sand or silt are present within the clue deposit.
When used in clay, the sampling ports 14 should be covered with sleeves of screening or permeable plastic that would reduce the potential for clogging.
~2~2~36 Although the packers described here are presented in the context of their use as components in a multilevel sampling device, they can also be used to form the seals above the screens on conventional standpipe-type piezometers or observation wells. In this situation a packer is placed just above the screen or sand pack. Water is supplied to the packer via a small tube which extends down the inside or outside of the piezometer casing. The rubber sleeve isolates the packer material from the granddaughter in the Barlow and in the formation.
The above description of the preferred embodiment of the invention is provided by way of example only, and should not be interpreted so as to unduly restrict the broad scope of the invention as described generally.
The identification and delineation of granddaughter quality zones and hydraulic head in fractured bedrock is difficult due to the complex nature of flow in the fracture networks. The rates of granddaughter flow and chemical concentration can be greatly different from one fracture to another. At sites where contaminated granddaughter is expected to occur, contaminants may be present in fractures which intersect only a small segment of the total Barlow.
Because of these complexities and uncertainties, it is often appropriate to acquire samples from numerous depth intervals at each monitoring site when monitoring granddaughter quality in fractured rock. This can be accomplished by drilling separate Berlioz to different depths at each site for installation of a nest of piezometers or observation wells, or by the installation of a multilevel monitoring device in a single hole at each site. The use of piezometers in several Berlioz at each monitoring site is often prohibitively expensive for detailed monitoring of granddaughter quality.
Accordingly, there is a need for devices which facilitate the acquisition of water samples and hydraulic head measurements from numerous depth levels within a single Barlow. Typical devices comprise a casing installed in the Barlow, with samples being extracted at various levels ~32~336 through the casing wall from the annular space between the casing wall and the Barlow wall. Such devices must include seals or packers which isolate each annular space to be monitored from those above and those below.
Various devices have been used in the past as packers. One of the most common arrangements has been the use of pneumatically inflatable packers. Such packers require pressurized air or water supply means, and are thus somewhat cumbersome. In most designs, air or water supply tubes must be run down the Barlow, and such tubes occupy precious space within the casing. With time, many such packers tend to deflate and therefore generally are not suitable as a permanent means of granddaughter monitoring.
It is an object of the present invention to provide improved packers for sealing and isolating sections of Berlioz so that intervals between packers can be used for granddaughter monitoring.
Accordingly, in the present invention there is provided a packer intended for sealing the space between a Barlow wall and a hollow casing within the Barlow. An expandable membrane is installed in sleeve-like fashion around the casing where the seal is desired, and its ends are sealed against the casing. There is a water-expandable substance between the membrane and the casing. Water is supplied to the substance by filling the casing with water, apertures being provided in the casing to permit water to flow to the substance. Expansion of the substance presses the expandable membrane against the Barlow wall, thereby effecting the desired seal.
~3~:~36 In accordance with another aspect of the invention, there is provided a packer assembly of the same general construction, adapted for connection between sections of casing, for sealing the Barlow at the connection location.
Methods of isolating Barlow sections using packers of the present invention are also provided.
The preferred embodiment of the invention will now be described with reference to the accompanying drawings, in which:
Fugue is a diagram of a multilevel granddaughter sampling assembly installed in a Barlow, showing the use of a number of packers of the present invention to isolate sections of the Barlow;
Fugue is a diagram of a smaller area of the overall assembly; and Fugue is a detailed view of a packer assembly of the present invention, showing the packer in cross-section.
Referring first to Figs. 1 and 2, the multilevel device will be described.
The device consists of a bundle of tubes 2 contained within a PVC pipe (casing) 3 that is capped on the bottom 4. Each of the tubes is connected to a 90 degree elbow 5, which protrudes through the casing into the annular space 9 between the Barlow wall and the casing. Each tube extends to a different depth in the casing so that water can be drawn from different depths in the Barlow 1. The annular space associated with each tube is isolated from above and below by the packers 10 of the present invention, which expand to effect a seal across the annular space ~232~6 wherever desired, thereby permitting monitoring of discrete zones, e.g. open fractures, joints or faults or other permeable zones 8. Obviously, if large segments are to be monitored, the packers can be placed farther apart and need not be used in pairs to isolate small segments.
The number of tubes that can be installed in a single Barlow depends on the diameter of the Barlow and on the diameter of the tubes. It is an advantage of the present invention that no tubes are required to be dedicated to packer inflation, so more sampling tubes can be accommodated within a given casing diameter.
Referring now to Fugue, the packers themselves will be described. The packers 10 employ a sealant substance which expands when contacted by water. The preferred sealant, to be described in more detail hereinafter, resembles a soft light rubber, and is formed into a cylindrical sleeve 15 in a mold. The sleeve is placed around precut lengths of PVC pipe 16, the same type of pipe that is used for the casing 3. The sleeves used in test installations were 9 cm. long. If desired, much longer sleeves of sealant can also be made. The packers can be conveniently joined into the casing using standard thread less couplings 18 with a small amount of solvent joiner. Solvent can be avoided entirely if the joins are done by heat welding. Steel pipe can be used instead of PVC
pipe if greater strength is desired.
It is of course apparent that the packers can be installed around the casing itself before the casing is inserted in the Barlow, rather than around separate pieces ~2~32~
of pipe, and such an installation is within the scope of the invention. However, for convenience in manufacture and construction, it is much easier to install the packers around precut lengths of pipe and to then splice these packer assemblies in between lengths of casing.
The sleeve 15 must be isolated from the granddaughter in the Barlow along the outside of the casing because the sealant contains compounds that have significant volubility. The outside of the sleeve 15 of sealant is therefore covered with a flexible rubber membrane 20 held in place above and below the sleeve by plastic or metal strap clamps 22. The straps sit in grooves cut into the PVC pipe.
Above and below each sleeve, double or triple strap clamps can be used to minimize the potential for leakage.
The sealant must be contacted by water from inside the casing to cause volume expansion to occur. To provide for this water contact, holes 25 are drilled radially around the PVC pipe. Monofilament nylon screen cloth 27 (210 mesh) is taped around the pipe and over the holes. The sealant sleeve 15 is installed around the PVC pipe, with the screen 27 in place between the pipe 16 and the sleeve 15. The purpose of the screen is to facilitate entry of water from inside the PVC casing into the very thin annuls 29 between the exterior of the pipe 16 and the interior surface of the sleeve 15 of sealant. Because the bottom 4 of the casing is capped and because the elbows 5 connected to the tubes are tightly sealed where they protrude from the casing into the Barlow, the water for expansion of the sealant is provided by filling the inside of the casing 3 with foreign water. If the elbows have a water-tight fit where they pass through Sue the PVC pipe and if all of the casing couplings are sealed, this water cannot mix with formation water at any time.
Whether or not leakage of fluid occurs from the casing can be determined by filling the water column in the casing up to the surface and monitoring the water level with time A standard thread less PVC coupling 18 is joined onto each end of the length of pipe 16 containing the packer assembly. Packers can be constructed and taken to the field in a fully-assembled state.
The sealant preferred for use in the construction of the packers is a proprietary product of the Dow Chemical Company and is sold by them under their trade mark DWELL.
More particularly, it is sold by the DWELL Division of the Dow Chemical Company as "Dwell Chemical Seal Ring". It is an elastic polymer which, when placed as a slurry, sets into a rubber-like material. It is capable of imbibing water to swell to more than 150~ of its original volume. It is prepared by adding a powdered polymer to a premixed fluid phase. The polymer disperses readily and is easily mixed with a minimum of stirring or agitation. The chemistry of the reaction results in a permanent cross-linkage of the molecules which should be inert to further reaction.
The sleeve 15 of sealant is formed by mixing the DWELL sealant components together and pouring this mixture into appropriately-shaped metal or plastic molds constructed in a machine shop. The rubber-like cylindrical sleeves 15 are removed from the molds after an overnight setting period. When the sleeve of sealant is contacted by water from inside the casing in the Barlow, it expands until it I Pi presses tightly against the wall of the Barlow. In a trial field site, the outside diameter of the sleeve was initially 6.7 cm and it expanded to fill the Barlow, which had a diameter of 7.5 cm. The thickness of the sleeve expanded from 0.35 cm to 0.75 cm. Various diameters have been used in laboratory prototypes. The seal is capable of expanding to a much larger diameter if necessary. The sleeves expand sufficiently to cause the packers to squeeze tightly against the wall of the Barlow.
As an alternative to the DWELL sealant, compressed rings of expansible powdered bentonite clay can be used. The rings can be stacked up on the casing segment to achieve whatever length of packer is desired. The stacked rings are covered with the rubber membrane 20 in exactly the same manner as described above for the DWELL sealant sleeve.
It will be appreciated that any suitable water-expansible substance could be used in place of DWELL
sealant or bentonite clay. Such other substances are within the broad scope of the invention.
The size of the sleeve 15 is such that the outside diameter of the membrane 20 prior to expansion is slightly smaller than the outside diameter of the coupling 18 on each end of the length of PVC pipe 16 used for the packer assembly. This arrangement provides protection for the membrane 20 when the complete monitoring device is lowered down the Barlow. Scraping of the couplings on the wall of the Barlow would occur rather than scraping of the thin, less durable membrane.
11 23;~
Each sampling port 14 is constructed by drilling a hole in a length of PVC casing 3 so that the 90 degree elbows 5 and tubes 2 can be attached to form the sampling ports. The elbows consist of commercially-produced threaded plastic elbows or of a heat-bent piece of narrow-diameter PVC pipe. A packer 10 is attached by means of coupling joints 18 above and below the length of casing 3 containing the sampling ports 14. Lengths of PVC casing 3 are coupled into the assembly to provide spacing between the sampling intervals. Packers can be coupled into these lengths of casing to provide additional assurance that the Barlow intervals between sampling zones are effectively sealed.
Conventional piezometers that are used for granddaughter monitoring, normally with a single piezometer in each Barlow, have a sand pack around the piezometer tip and a bentonite or grout seal on top of the sand pack. In formations with low permeability and consequently low flushing rates, reactions between the slow moving water in the sand pack and a grout or bentonite seal may disturb the chemical conditions of the granddaughter that is sampled, even if the sand pack and seal are placed properly in the hole.
The multilevel monitoring device described here avoids most of this uncertainty because the sealant 15 is isolated from the formation water by the protective rubber membrane 20. If reactions with the rubber are f concern, the rubber ~6j~ I Ahab membrane can be covered with a Tony membrane.
: . .
It is necessary to be vigilant with respect to identification of the effects of tears in the membrane 20 that could impact the chemistry of the granddaughter samples.
There is also the possibility that one or more of the g ~23~33~ii packers might not provide an adequate seal in the Barlow.
Uncertainty in this regard can be decreased by the use of longer sleeves 15 and more packers in situations where Barlow roughness and degree of fracturing are particularly adverse.
Although the multilevel device described should be viewed as a permanent monitoring installation in much the same manner as normal wells or piezometers, there is a possibility that the device can be removed from the Barlow after a period of use. When DWELL sealant is not in contact with water, considerable shrinkage occurs. If the water in the casing is removed, the seals will shrink and thereby provide an opportunity for removal of the assembly. This has been demonstrated in the laboratory, although removal has not yet been attempted at a field site. For it to be feasible in the field, it may be necessary to circulate warm air in the casing after the casing water is removed so that the sealant shrinks at a rapid rate.
Although the multilevel monitoring device described here was developed for use in fractured rock, it is expected that it will also be useful in deposits of consolidated clay. However, for the packers to effectively seal the various sampling levels, the hole needs to be free from in filling that would occur if inter beds of cohesion less gravel, sand or silt are present within the clue deposit.
When used in clay, the sampling ports 14 should be covered with sleeves of screening or permeable plastic that would reduce the potential for clogging.
~2~2~36 Although the packers described here are presented in the context of their use as components in a multilevel sampling device, they can also be used to form the seals above the screens on conventional standpipe-type piezometers or observation wells. In this situation a packer is placed just above the screen or sand pack. Water is supplied to the packer via a small tube which extends down the inside or outside of the piezometer casing. The rubber sleeve isolates the packer material from the granddaughter in the Barlow and in the formation.
The above description of the preferred embodiment of the invention is provided by way of example only, and should not be interpreted so as to unduly restrict the broad scope of the invention as described generally.
Claims (7)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. Apparatus for taking samples from several different levels in a borehole, comprising:
a casing of rigid, hollow, tubular construction, which is dimensioned to pass easily down the borehole;
several sampling-tubes, arranged in a bundle inside the casing, each terminating in a sampling-port;
where the sampling-ports are open to the space between the casing and the borehole;
where the sampling-ports and the sampling-tubes are sealed with respect to the casing, the sealing arrangement being such that water from the said space can enter the sampling-tubes through the sampling-ports, but cannot enter the interior of the casing;
pairs of sealing-packers, where the sealing-packers each encircle the casing, and are arranged to isolate between them a respective one of the sampling-ports, one of the packers of the pair above the port, the other below;
where the packers are made from a water-expandable substance;
means for keeping the substance isolated from water in the said space;
holes formed radially through the casing and so placed that the substance in each of the packers is exposed through the holes to the interior of the casing;
means for flooding the interior of the casing with water from outside the barehole, in such a manner that the flooding water contacts the substance in all the packers through the holes.
a casing of rigid, hollow, tubular construction, which is dimensioned to pass easily down the borehole;
several sampling-tubes, arranged in a bundle inside the casing, each terminating in a sampling-port;
where the sampling-ports are open to the space between the casing and the borehole;
where the sampling-ports and the sampling-tubes are sealed with respect to the casing, the sealing arrangement being such that water from the said space can enter the sampling-tubes through the sampling-ports, but cannot enter the interior of the casing;
pairs of sealing-packers, where the sealing-packers each encircle the casing, and are arranged to isolate between them a respective one of the sampling-ports, one of the packers of the pair above the port, the other below;
where the packers are made from a water-expandable substance;
means for keeping the substance isolated from water in the said space;
holes formed radially through the casing and so placed that the substance in each of the packers is exposed through the holes to the interior of the casing;
means for flooding the interior of the casing with water from outside the barehole, in such a manner that the flooding water contacts the substance in all the packers through the holes.
2. Apparatus of claim 1, in which said water-expandable substance is a primarily organic chemical substance which draws water into its structure when exposed to water.
3. Apparatus of claim 2, in which said chemical substance is the sealant sold by the Dow Chemical Company under its trade mark DOWELL.
4. Apparatus of claim 1, where the means for keeping the substance isolated from water in the said space comprises several expandable membranes, one to each packer, installed in sleeve-like fashion around the water-expandable substance, the membrane being sealed top and bottom to the casing.
5. Apparatus of claim 1, in which said water-expandable substance is a compressed mass of clayey material containing bentonite which expands when exposed to water.
6. Apparatus of claim 1, where a thin screen is interposed around the circumference of the casing, between the casing and the water-expandable substance.
7. Method of isolating sampling-ports at several different levels in a borehole, comprising the steps;
of providing a hollow casing within the borehole, and several pairs of packing rings encircling the casing;
of arranging each pair of packing rings to straddle respective sampling-ports, where the several sampling-ports are set each at a different level of the borehole;
of making the packing rings from a water-expandable substance;
of sealing the substance from water in the borehole;
of providing holes in the casing, which are so positioned that the substance is accessible from the inside of the casing through the holes;
of flooding the casing with water to the extent that water soaks into the substance through the holes;
and of leaving the casing flooded.
of providing a hollow casing within the borehole, and several pairs of packing rings encircling the casing;
of arranging each pair of packing rings to straddle respective sampling-ports, where the several sampling-ports are set each at a different level of the borehole;
of making the packing rings from a water-expandable substance;
of sealing the substance from water in the borehole;
of providing holes in the casing, which are so positioned that the substance is accessible from the inside of the casing through the holes;
of flooding the casing with water to the extent that water soaks into the substance through the holes;
and of leaving the casing flooded.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US51190183A | 1983-07-08 | 1983-07-08 | |
| US511,901 | 1983-07-08 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1232836A true CA1232836A (en) | 1988-02-16 |
Family
ID=24036916
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000447390A Expired CA1232836A (en) | 1983-07-08 | 1984-02-14 | Borehole packers |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1232836A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111058797A (en) * | 2020-01-02 | 2020-04-24 | 成都理工大学 | Hole enlarging and sealing method |
-
1984
- 1984-02-14 CA CA000447390A patent/CA1232836A/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111058797A (en) * | 2020-01-02 | 2020-04-24 | 成都理工大学 | Hole enlarging and sealing method |
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| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |