CA2044011A1 - Flushing and dredging method for wellbores and equipments therefor - Google Patents
Flushing and dredging method for wellbores and equipments thereforInfo
- Publication number
- CA2044011A1 CA2044011A1 CA 2044011 CA2044011A CA2044011A1 CA 2044011 A1 CA2044011 A1 CA 2044011A1 CA 2044011 CA2044011 CA 2044011 CA 2044011 A CA2044011 A CA 2044011A CA 2044011 A1 CA2044011 A1 CA 2044011A1
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- Prior art keywords
- lubricator
- wellbore
- pipe
- pressure hose
- jet nozzle
- Prior art date
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Abstract
ABSTRACT OF THE DISCLOSURE
A method for flushing and dredging a wellbore and equipments therefor are described. The method is easy to practice and is highly effective. According to the method, a high-pressure hose constructed of an inner resin tube and an outer resin sheath and having a jet nozzle at a leading end thereof is lowered into a pipe, which is disposed within the wellbore, through a lubricator arranged in a wellhead equipment. Water is introduced into the high-pressure hose to jet water out through the jet nozzle, whereby water flushes the in-side of the pipe and blows up substances so flushed off and/or materials so dredged up. At the same time, a compressed gas is injected through a gas-lift means provided on the pipe, whereby the flushed-off sub-stances and dredged-up materials are discharged from the wellbore with the aid of the expanding injection gas.
A method for flushing and dredging a wellbore and equipments therefor are described. The method is easy to practice and is highly effective. According to the method, a high-pressure hose constructed of an inner resin tube and an outer resin sheath and having a jet nozzle at a leading end thereof is lowered into a pipe, which is disposed within the wellbore, through a lubricator arranged in a wellhead equipment. Water is introduced into the high-pressure hose to jet water out through the jet nozzle, whereby water flushes the in-side of the pipe and blows up substances so flushed off and/or materials so dredged up. At the same time, a compressed gas is injected through a gas-lift means provided on the pipe, whereby the flushed-off sub-stances and dredged-up materials are discharged from the wellbore with the aid of the expanding injection gas.
Description
.,,. ''* ~
TITLE OF THE INVENTION:
FLUSHING AND DREDGING METHOD FOR WELLBORES AND
EQUIPMENTS THEREFOR
BACKGROUND OF ~HE INVENTION
1) Field of the Invention The present invention relates to a method ~or flushing and dredging wellbores and also to equipments therefor. Specifically, the present invention is con-cerned with the removal o~ deposits on wellbor~ casing pipes or the like inserted under the ground and also with the dredging o~ sand and like materials lying in the pipes or the like.
TITLE OF THE INVENTION:
FLUSHING AND DREDGING METHOD FOR WELLBORES AND
EQUIPMENTS THEREFOR
BACKGROUND OF ~HE INVENTION
1) Field of the Invention The present invention relates to a method ~or flushing and dredging wellbores and also to equipments therefor. Specifically, the present invention is con-cerned with the removal o~ deposits on wellbor~ casing pipes or the like inserted under the ground and also with the dredging o~ sand and like materials lying in the pipes or the like.
2) Description of the Related Art Conventional wellbore cleaning techniques include inter ali2 brushing, acid treatment, and water jatting.
Concept diagrams of these techni~ues are shown in FIGS. 4(a~ to 4(c), respectively.
According to the brushing technique depicted in FIG. 4(a), a metal pipe 22 equipped with a brush 23 is lowered into a pipe and deposits are rubbed off by the brush. In the acid treatment teçhnique shown in FIG.
4(b), an acid is spotted into a pipe to wash th~ pipe by acid reaction. Turning ~inally to the water jet cleaning technique illustrated in FIG. 4~cj, a metal . . . . .
.
,, , ' , , ' ' : ' . ' ' ' , ~
.
pipe 22 ~itted with a nozzle 25 is lowered in a pipe and water is injecte.d through the metal pipe, so that cleaning is conducted by water and the like which is being jetted out through the nozzle.
Conventional wellbore dredging techniques include gas-llft dredging and pump dredging as show~ in FIGS.
5(a) and 5(~), respectivsly.
The gas-lift dredging technigue o-~ FIG~ 5(a3 can be applied to pipes of a relatively large diameter.
metal pipe 22 is lowered close to a top layer 27, and a gas is injected through a gas-lift pipe 26 attached to the metal pipe 22 so that mud, sand and the like are brought up with the gas.
According to the pump dredging techni~ue depicted in FIG. 5(b), water is pumped out through a metal pipe 22 to blow up mud, sand and the like. This technique does not require any gas~ t pipe so that it can be applied to small-diameter pipes.
In the case of a horizontal pipe, ~or example, a pipeline or the like rather than a wellbore, the water jet technique or the like is applied. Namely, a high~
pressure hose fitted with a nozzle is inserted into the pipe and water i5 jetted out through the nozzle to clean the pipe.
A pipe inserted in a wellbore extends as deep as several hundreds of meters or, in some instances, one thousand meters or more under the ground and downwardly includes a pipe 12 with a number of holes per~orated therethrough as shown in FIGS. 4(a3, 4~b) and 4~c).
The precipitation of mud, sand, rust and/or the liXe inside the pipe 12 no lsnger permits production of a desired gas or liquid through the holes, ~o that not only cleaning but also dredging are required periodi-cally.
However, th2re has heretofore been no simple and effective method for cleaning and dredging wellbore~.
The various cleaning methods described above have n~
dredging ef~ects. In the bru~hing, acid-treatment and water-jet cleaning techniques, metal pipes are con-nected and lowered as deep as several hundreds of meters. To conduct these techniques, it is necassary to improve the soil foundation, to rig up a derrick as tall as several tens of metexs above the ground and also to set heavy machinery such as a winch. Eno~mou~
work i~ therefore needed even ~or the cleaning work alone.
Further, the convantional dredging techniques re-~uire the use of metal pipes in a similar manner as the conventional cleaning technique, so that the extent of work is similar to that required Eor the cleaning work.
.
~ ~3 ~
Gas-lift dred~ing requires lowering of not only a metal pipe but also a gas-lift pipe into a wellbore so that this technique cannot be applied to small-diam~ter wellbores. Pump dredging is therefore applied to small-diameter wellbores. This techni~ue however results in development of a pressur~ lo~s while water flows upwards between a metal pipe and a wellbore pipe and a hydraulic head up to the wellhead o~ the wellbore. Consequently, a water stream pumped out from the metal pipe tends to be lost through holes in the wellbore pipe. The ability to upwardly convey mud and sand to the ground is therefore extremely small. The pump dred~ing techni~ue tends to force out mud and sand only through the holes in the wellbore pipe, so that, : 15 in reality, the wellbore pipe is soon filled up again with mud and sand, just as it was before dredging. In tho case of small-diameter wellbores in particular; it may therefore be more economical to drill a new wellbore and to complete the same rather than to dredge a mud- and sand-filled wellbore.
It has also been proposed to use a special metal for the metal pipe 22 to impart flexibility thereto to be coiled on a reel so that the derrick can be ob-viated. However, this proposal also requires a trailer and crane to the order of several tens of tons and, in addition, special equipment, engine and the like ~or injecting the pipe. Large-scale worX is there~ore needed. This technique is fundamentally the same as the conventional cleaning and dredging techniques al-though the metal pipe has ~lexibility.
On the other hand, the water-jet flushing techni-que which makes use of a high-pressure hose and can be applied to pipelines and the like uses a light-weight hose and can therefore be practiced with relative ease.
Since such pipelines and the lika lie horizontally, it is unnecessary to vertically li~t up and dredge mud and sand several hundreds o~ meters. This techniqu~ is therefore totally diffarent ~rom those applied to wellbores.
SUMMARY OF THE INVENTION
An object o~ the present invention is to provide an easy and effective method Por flushing and dredging a wellbore and also equipments therefor.
In one aspect of the present invention, ~here is thus provided a method for Plushing and dredging a wellbore. The mathod comprises lowering a hi~h-pressure hose into a pipe, which i~ disposed within the wellbore, through a lubricator arranged in a wellhead assembly, said hose being constructed oP an inner resin -- 6 ~
tube and an outer resin sheath and ha~ing a jet nozzle at a leading end thereof; and intrcducing water into the high-pressure hose to j~t water out through the jet nozzle, whereby water flushes the inside of the pipe and blows up substances so flushed off and/or materials so dredged up; and, at the same time, injecting a com-pressed gas through a gas~ t means provided on the pipe, whereby the flushed-off substances and dredged-up materials are discharged from the wellbore with the aid of the expanding injection gas.
The present invention has made it possible to easily flush and dredge wellbores reaching as deep as from several hundred of meters to one thousand meters or mora under the ground. In particular, the present invention can be easily applied even to wellbores whose diameters are so small that theix cleaning and dredging have heretofore heen difficult.
Use of a high-pressure hose according to the present invention, such as that described above, can xealize a weight reduction. This obviates the need for a lar~e-scale facility as required to date, such as a derriak. Referring to FIG. 2(a~, an inner tube 203 of a high-pressure hose 2 is made o~ a resin so that the inner tube 203 undergoes less deformation. It is therefore possible to avoid the high-pressure hose being stretched by the tensile expansion resulting from vertically lowering the high-pressure hose, which could cause its inner diameter to be extremely reduced to result in a considerable pressure 10s5. An out r sheath 201 of the high-pressure hose 2 is also made of a resin. ~ reinforcement layer 202 is disposed between the inner tube 203 and the outer sheath 201. This makes it possible to avoid such a trouble that the high-pressure hose 2 could b2come no longer movable due to friction between packers 701 in a lubricator (see FIG. 3). Further, the combined use of the water jet technique and gas-lift technique allows effective flushing and dredging to be conducted concurrently.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGS. l(a) and l(b) ~chematically illustrate an equipment ~or performing flushing and dredging in ac-cordance with the present invention;
FIG. 2(a~ is a ~ragmentary, axial cross-section ~`
of a high-pressure hose useful in the practice of the present invention;
F~G. 2(b) is a partly cross-sectional, side view o~ a jet nozzle useful in the practice of the present invention;
FI~. 3 is an axial cross section of a lubricator ., . ~
.
~:`
, according to the present invention, applied to pipes having parts of diffarent diameters;
FIGS~ 4(a), ~(b) and ~(c) show conventional cleaning techniques, respectively; and FIGS. 5(a) and 5(b) illustrate conventional dredging techniques.
DETAILED DESCRIPTION OF THE INVENTION
AND_PRÆFERRED EMBODIMENTS
FIGS. l(a) and l(b) show concept diagrams o~ an ~quipment suitable for use in the practice of the pres-ent invention, in whi~h FIG. l(a) depicts tha equi.pment in the wellbore while FIG. l(b) illustrates the equip-ment on the wellhead.
An outline of the high-pressur~ hose 2 is shown in FIG. l~a). Preferably, small orifices are formed in a jet nozzle 1 such that they extend toward an entrance of a wellbore, in other words, toward an extension of a longitudinal central axis of the high-pressure hose 2 in directions greater than O degree but not exceeding 90 degrees relative to the extension, namely, at angles ~ (0<~<90~ as seen in the drawing and water can hence be jetted out in the directiQns, because mud, sand and the like fluttering above the jet noæzle can be lifted upwards by the outward and upward watex streams and can .
hence be prevented .from ~alling downwards beyond the jet nozzle 1. In other words, pumping effects by ~uch jet water streams can be used.
It is pre~erable that a straight pipe portion 11 : 5 is provided between the jet nozzle 1 and the high-pressure hose 2. The length o~ the straight pipe por-tion 11 is greater than the inner diameter of a casing pipe 4. ~he term "straight pipe portion" as used herein means a portion which does not have flexibility unli.ke the high-pressure hose 2. A metal pipe or the like may be used. As an alternative~ a metal strip may be wound on the high pressure hose 2. If this straight pipe portion is omitted or its length is shorter than the length described abo~e, it will be difficult to : 15 smoothly move the high-pressure hose 2 up and down through the pipe inside the wellbore~
Many high-pressure hoses may have to be connected together depending on the depth of a wellbore. In such a case, the high-pressure hoses are connected by joints. Since the outer diameter o~ each joint is grea~er than the outer diameter of the high-pressure hoses, conventional lubricators do not work. It is therefore necessary to use a lubri~ator for pip~s hav-ing different outer diameters, which has such a struc-ture that two conventional lubricators are connected '~
~; ~
together in an axial direction. This structure is shown in FIG. 3. In this lubricator Por pipes of dif-ferent diameters, a cylindrical hollow packer 701 defining an outer conical surface and a cylindrical hollow packer ram 702 having an inner conical surface engageable with the outer conical sur~ace of the packer are combined together to form a ~irst lubricator unit.
The ~irst lubricator unit and a second lubricator unit oP the same type as the first lubricator unit are ar-rangsd with an axial interval 704 therebetween within a casing 705. Each packer is ~ixed inside the casing.
First and second means ~03 are also proYided for inde-pendently moving the respective packer rams in an axial direction, whereby forces for pushing the packers by ~he corresponding packer rams can be adjusted.
Upon causi~g each joint portion of the high-pressure hose to pass the lubricator, the lubricator unit on the entrance side is opened while the lubricator unit on the exit side is maintained closed.
The joint portion is inserted to a point between the entrance-side lubricator and the exit~side lubricator unit. Aft r the entrance-side lubricator unit is closed, the exit-side lubricator is opened and the joint portion is then caused to pass to the exit.
Procedures employed in examples and comparative examples, which will be described subsequently, will be described in accordance with FIGS. l(a) and 1(~.
A gas-lift compressor (not shown) was operated to inject a compressed gas into a well~ore through a gas-lift pipe 3, whereby gas and brine were ~lew back from the wellbore (pre-flushing3. A tripod 8, sheaves 5,6 and a lubricator 7 for pipes having parts of different diameters were arranged. A straight pipe portion ll following a jet nozæle 1 was attached to a leading end of the high-pressure hose 2. The high-pressure hose 2 was then lowered into the wellbore through the lubricator 7~ When the high-pressure hose 2 reached a flushing or drsdging depth~ a high-pressure pump (not shown) was operated to jet out high-pressure water through the jet nozzle 1 so that flushing and dredging were performed. During sand dredging, the high-pressure hose 2 was frequently mo~ed up and down in or-der to effectiv~ly utilize the pumping effect of a jet water stream. This operation is also effective in pre-venting the high-pressure hose 2 from being stuck by sand. The dredging was conducted in the following man ner. After the dredging of a certain section was oper~
ated, the high-pressure hose 2 was reeled up to the depth before the dredging, and the high-pressure pump was stopped to pause the jetting of water through the ;
jet nozzle 1. The high-pressure hose 2 was again lowered to the prior dredged depth to confirm whether or not a portion of the dredged section had been refilled with sand and then to restart into the next sectio~. During the flushing and dredging, constant attention was paid to the quality (contamination, sand, etc.) of brine pumped up to the wellhead. ~he flushing and dredging work was ~topped when deposits and the like were no longer observed no matter how far the jet nozzle 1 was lowered.
Example 1 and Comparative Example 1 ; Following the procedure~ described above, flush-ing and dredging of a wellbore of 1,000 m depth wexe conducted. PVC pipes of 3 inches in diameter (internal diameter: 73 mm) were employed as casing pipes. As a hi~h-pressure hose, a firsk high-pressure hose and a second high-pressure hose were used by connecting them together. The first high-pressure hose had an outer diameter of 21 mm and an innsr diameter of lZ.8 mm, was made of an inner tube 203, an outer sheath 201 and a reinforcement layer 202, and had a rated pressure of 1,000 ~gf/cm2. Both the inner tube and outer sheath were made of nylon-12, while the reinforcement layer was made of high-tensile steel wires. ~he second high-: 25 pressure hose had an outer diameter of 20.4 mm and an inner diameter of 12.8 mm, was made of an inner tube, an outer sheath and a reinforcement layer, and had a rated pressure o~ 700 kgf/cm2. The inner tube was made of nylon-12, the outer sheath of polyurethane, and the reinforcement layer of high-tensile steel wires. Any material can be used for the reinl~orcement layers as long as it has reinforcing effects.
The jet nozzle body 1 has a construction as shown by way of example in F~G. 2(b). In thi~ drawing, six reverse jetting orifices 101 o~ 1 mm in diameter extend toward an extension of a central longitudinal axis of the high-pressure hose at an angle 0 of 30 relative to the extension. In additiont two oxi~ices 102 of 1 mm in diameter are also perforated ~o as not only to flush but also to rotate the jet nozzle body 1 by water stream. Further, th~ length of the straight pip~ por tion 11 between the jet nozzle 1 and the high-pr~ssura hose 2 was set at 40 cm. As the tripod 8 shown in FIG.
"~ l(b), a tripod having a height of about 3 m and an inter-leg distance of about 2 m was employed. This tripod was small enough to be carried by two men.
The results of the practice of the present in~en-tion as described above are shown in Table 1, together with the rPsults obtained by conducting similar work in ; 25 accordance with a conventional method. The effects of remo~al of sand and the like were judged by a conven-tional m~thod.
Example 2 and Comparative Example 2 Flushing and dr~dging operations, which were similar to Example 1 and Comparative Example 1 respec-tively, were conducted to wellbores of 370 m in depth.
As a high-pressure hose~ only the high-pressure hose whose rated pressure was 700 kgf/cm2 was used. The results of the operations are shown in Table 2.
The costs of the respective oparations are all indicated in r21ation to the co~t o~ the operation in Example 1, the latter being expressing as 100.
As is und~rstood from the examples and compara~
tive examples, the present invention makes it possible to significantly reduce both the working days and cost and further requires a much smaller space. This latt~r advantageous ~eature permits dredging of wellbores whose dredging has heretofore been impossible due to the existence of a nearby building.
: 20 ,. .
. . .
: ' . .
:~ , Table 1 - ~ .. ___ Example 1 Comp. Ex. 1 _ ... ... _ Method Invention Pump dredging , _ _ ._ .__ Days required for preparation and 1 day 10 days disassembly - .
Days required for dredging work 15 days 15 days . . __ ..
Workers 2 workers 4 workers Site re~uired for 2 at least dredging work appxox. 26 m approx. 972 m2 . ~ - , . _ _ . __, . .
Cost 100 (standard) 680 . ._ .. . .
Removal of sand, .
etc. complete lncomplete .~ ._ __ __ _ __.
~, i .
- . . ~, .
... , ~ . .
., ' Table 2 _ Example 2 Comp. Ex. 2 . _ ~ ,., .
Nethod Invention Pump dredging _ Days required for preparation and 1 day 10 days disassembly . . _ _ .
Days required for dredging work 2 days 2 days . _ ._. . __ .~
Workers 2 workers 4 wo kers . __ .. _ ..
dredging work approx. 26 m2 approx. 972 m2 .. _ ... _ _ Cost 9 160 .__ __ Removal o~ sand, etc. complete incomplete _,.
;
' .
Concept diagrams of these techni~ues are shown in FIGS. 4(a~ to 4(c), respectively.
According to the brushing technique depicted in FIG. 4(a), a metal pipe 22 equipped with a brush 23 is lowered into a pipe and deposits are rubbed off by the brush. In the acid treatment teçhnique shown in FIG.
4(b), an acid is spotted into a pipe to wash th~ pipe by acid reaction. Turning ~inally to the water jet cleaning technique illustrated in FIG. 4~cj, a metal . . . . .
.
,, , ' , , ' ' : ' . ' ' ' , ~
.
pipe 22 ~itted with a nozzle 25 is lowered in a pipe and water is injecte.d through the metal pipe, so that cleaning is conducted by water and the like which is being jetted out through the nozzle.
Conventional wellbore dredging techniques include gas-llft dredging and pump dredging as show~ in FIGS.
5(a) and 5(~), respectivsly.
The gas-lift dredging technigue o-~ FIG~ 5(a3 can be applied to pipes of a relatively large diameter.
metal pipe 22 is lowered close to a top layer 27, and a gas is injected through a gas-lift pipe 26 attached to the metal pipe 22 so that mud, sand and the like are brought up with the gas.
According to the pump dredging techni~ue depicted in FIG. 5(b), water is pumped out through a metal pipe 22 to blow up mud, sand and the like. This technique does not require any gas~ t pipe so that it can be applied to small-diameter pipes.
In the case of a horizontal pipe, ~or example, a pipeline or the like rather than a wellbore, the water jet technique or the like is applied. Namely, a high~
pressure hose fitted with a nozzle is inserted into the pipe and water i5 jetted out through the nozzle to clean the pipe.
A pipe inserted in a wellbore extends as deep as several hundreds of meters or, in some instances, one thousand meters or more under the ground and downwardly includes a pipe 12 with a number of holes per~orated therethrough as shown in FIGS. 4(a3, 4~b) and 4~c).
The precipitation of mud, sand, rust and/or the liXe inside the pipe 12 no lsnger permits production of a desired gas or liquid through the holes, ~o that not only cleaning but also dredging are required periodi-cally.
However, th2re has heretofore been no simple and effective method for cleaning and dredging wellbore~.
The various cleaning methods described above have n~
dredging ef~ects. In the bru~hing, acid-treatment and water-jet cleaning techniques, metal pipes are con-nected and lowered as deep as several hundreds of meters. To conduct these techniques, it is necassary to improve the soil foundation, to rig up a derrick as tall as several tens of metexs above the ground and also to set heavy machinery such as a winch. Eno~mou~
work i~ therefore needed even ~or the cleaning work alone.
Further, the convantional dredging techniques re-~uire the use of metal pipes in a similar manner as the conventional cleaning technique, so that the extent of work is similar to that required Eor the cleaning work.
.
~ ~3 ~
Gas-lift dred~ing requires lowering of not only a metal pipe but also a gas-lift pipe into a wellbore so that this technique cannot be applied to small-diam~ter wellbores. Pump dredging is therefore applied to small-diameter wellbores. This techni~ue however results in development of a pressur~ lo~s while water flows upwards between a metal pipe and a wellbore pipe and a hydraulic head up to the wellhead o~ the wellbore. Consequently, a water stream pumped out from the metal pipe tends to be lost through holes in the wellbore pipe. The ability to upwardly convey mud and sand to the ground is therefore extremely small. The pump dred~ing techni~ue tends to force out mud and sand only through the holes in the wellbore pipe, so that, : 15 in reality, the wellbore pipe is soon filled up again with mud and sand, just as it was before dredging. In tho case of small-diameter wellbores in particular; it may therefore be more economical to drill a new wellbore and to complete the same rather than to dredge a mud- and sand-filled wellbore.
It has also been proposed to use a special metal for the metal pipe 22 to impart flexibility thereto to be coiled on a reel so that the derrick can be ob-viated. However, this proposal also requires a trailer and crane to the order of several tens of tons and, in addition, special equipment, engine and the like ~or injecting the pipe. Large-scale worX is there~ore needed. This technique is fundamentally the same as the conventional cleaning and dredging techniques al-though the metal pipe has ~lexibility.
On the other hand, the water-jet flushing techni-que which makes use of a high-pressure hose and can be applied to pipelines and the like uses a light-weight hose and can therefore be practiced with relative ease.
Since such pipelines and the lika lie horizontally, it is unnecessary to vertically li~t up and dredge mud and sand several hundreds o~ meters. This techniqu~ is therefore totally diffarent ~rom those applied to wellbores.
SUMMARY OF THE INVENTION
An object o~ the present invention is to provide an easy and effective method Por flushing and dredging a wellbore and also equipments therefor.
In one aspect of the present invention, ~here is thus provided a method for Plushing and dredging a wellbore. The mathod comprises lowering a hi~h-pressure hose into a pipe, which i~ disposed within the wellbore, through a lubricator arranged in a wellhead assembly, said hose being constructed oP an inner resin -- 6 ~
tube and an outer resin sheath and ha~ing a jet nozzle at a leading end thereof; and intrcducing water into the high-pressure hose to j~t water out through the jet nozzle, whereby water flushes the inside of the pipe and blows up substances so flushed off and/or materials so dredged up; and, at the same time, injecting a com-pressed gas through a gas~ t means provided on the pipe, whereby the flushed-off substances and dredged-up materials are discharged from the wellbore with the aid of the expanding injection gas.
The present invention has made it possible to easily flush and dredge wellbores reaching as deep as from several hundred of meters to one thousand meters or mora under the ground. In particular, the present invention can be easily applied even to wellbores whose diameters are so small that theix cleaning and dredging have heretofore heen difficult.
Use of a high-pressure hose according to the present invention, such as that described above, can xealize a weight reduction. This obviates the need for a lar~e-scale facility as required to date, such as a derriak. Referring to FIG. 2(a~, an inner tube 203 of a high-pressure hose 2 is made o~ a resin so that the inner tube 203 undergoes less deformation. It is therefore possible to avoid the high-pressure hose being stretched by the tensile expansion resulting from vertically lowering the high-pressure hose, which could cause its inner diameter to be extremely reduced to result in a considerable pressure 10s5. An out r sheath 201 of the high-pressure hose 2 is also made of a resin. ~ reinforcement layer 202 is disposed between the inner tube 203 and the outer sheath 201. This makes it possible to avoid such a trouble that the high-pressure hose 2 could b2come no longer movable due to friction between packers 701 in a lubricator (see FIG. 3). Further, the combined use of the water jet technique and gas-lift technique allows effective flushing and dredging to be conducted concurrently.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGS. l(a) and l(b) ~chematically illustrate an equipment ~or performing flushing and dredging in ac-cordance with the present invention;
FIG. 2(a~ is a ~ragmentary, axial cross-section ~`
of a high-pressure hose useful in the practice of the present invention;
F~G. 2(b) is a partly cross-sectional, side view o~ a jet nozzle useful in the practice of the present invention;
FI~. 3 is an axial cross section of a lubricator ., . ~
.
~:`
, according to the present invention, applied to pipes having parts of diffarent diameters;
FIGS~ 4(a), ~(b) and ~(c) show conventional cleaning techniques, respectively; and FIGS. 5(a) and 5(b) illustrate conventional dredging techniques.
DETAILED DESCRIPTION OF THE INVENTION
AND_PRÆFERRED EMBODIMENTS
FIGS. l(a) and l(b) show concept diagrams o~ an ~quipment suitable for use in the practice of the pres-ent invention, in whi~h FIG. l(a) depicts tha equi.pment in the wellbore while FIG. l(b) illustrates the equip-ment on the wellhead.
An outline of the high-pressur~ hose 2 is shown in FIG. l~a). Preferably, small orifices are formed in a jet nozzle 1 such that they extend toward an entrance of a wellbore, in other words, toward an extension of a longitudinal central axis of the high-pressure hose 2 in directions greater than O degree but not exceeding 90 degrees relative to the extension, namely, at angles ~ (0<~<90~ as seen in the drawing and water can hence be jetted out in the directiQns, because mud, sand and the like fluttering above the jet noæzle can be lifted upwards by the outward and upward watex streams and can .
hence be prevented .from ~alling downwards beyond the jet nozzle 1. In other words, pumping effects by ~uch jet water streams can be used.
It is pre~erable that a straight pipe portion 11 : 5 is provided between the jet nozzle 1 and the high-pressure hose 2. The length o~ the straight pipe por-tion 11 is greater than the inner diameter of a casing pipe 4. ~he term "straight pipe portion" as used herein means a portion which does not have flexibility unli.ke the high-pressure hose 2. A metal pipe or the like may be used. As an alternative~ a metal strip may be wound on the high pressure hose 2. If this straight pipe portion is omitted or its length is shorter than the length described abo~e, it will be difficult to : 15 smoothly move the high-pressure hose 2 up and down through the pipe inside the wellbore~
Many high-pressure hoses may have to be connected together depending on the depth of a wellbore. In such a case, the high-pressure hoses are connected by joints. Since the outer diameter o~ each joint is grea~er than the outer diameter of the high-pressure hoses, conventional lubricators do not work. It is therefore necessary to use a lubri~ator for pip~s hav-ing different outer diameters, which has such a struc-ture that two conventional lubricators are connected '~
~; ~
together in an axial direction. This structure is shown in FIG. 3. In this lubricator Por pipes of dif-ferent diameters, a cylindrical hollow packer 701 defining an outer conical surface and a cylindrical hollow packer ram 702 having an inner conical surface engageable with the outer conical sur~ace of the packer are combined together to form a ~irst lubricator unit.
The ~irst lubricator unit and a second lubricator unit oP the same type as the first lubricator unit are ar-rangsd with an axial interval 704 therebetween within a casing 705. Each packer is ~ixed inside the casing.
First and second means ~03 are also proYided for inde-pendently moving the respective packer rams in an axial direction, whereby forces for pushing the packers by ~he corresponding packer rams can be adjusted.
Upon causi~g each joint portion of the high-pressure hose to pass the lubricator, the lubricator unit on the entrance side is opened while the lubricator unit on the exit side is maintained closed.
The joint portion is inserted to a point between the entrance-side lubricator and the exit~side lubricator unit. Aft r the entrance-side lubricator unit is closed, the exit-side lubricator is opened and the joint portion is then caused to pass to the exit.
Procedures employed in examples and comparative examples, which will be described subsequently, will be described in accordance with FIGS. l(a) and 1(~.
A gas-lift compressor (not shown) was operated to inject a compressed gas into a well~ore through a gas-lift pipe 3, whereby gas and brine were ~lew back from the wellbore (pre-flushing3. A tripod 8, sheaves 5,6 and a lubricator 7 for pipes having parts of different diameters were arranged. A straight pipe portion ll following a jet nozæle 1 was attached to a leading end of the high-pressure hose 2. The high-pressure hose 2 was then lowered into the wellbore through the lubricator 7~ When the high-pressure hose 2 reached a flushing or drsdging depth~ a high-pressure pump (not shown) was operated to jet out high-pressure water through the jet nozzle 1 so that flushing and dredging were performed. During sand dredging, the high-pressure hose 2 was frequently mo~ed up and down in or-der to effectiv~ly utilize the pumping effect of a jet water stream. This operation is also effective in pre-venting the high-pressure hose 2 from being stuck by sand. The dredging was conducted in the following man ner. After the dredging of a certain section was oper~
ated, the high-pressure hose 2 was reeled up to the depth before the dredging, and the high-pressure pump was stopped to pause the jetting of water through the ;
jet nozzle 1. The high-pressure hose 2 was again lowered to the prior dredged depth to confirm whether or not a portion of the dredged section had been refilled with sand and then to restart into the next sectio~. During the flushing and dredging, constant attention was paid to the quality (contamination, sand, etc.) of brine pumped up to the wellhead. ~he flushing and dredging work was ~topped when deposits and the like were no longer observed no matter how far the jet nozzle 1 was lowered.
Example 1 and Comparative Example 1 ; Following the procedure~ described above, flush-ing and dredging of a wellbore of 1,000 m depth wexe conducted. PVC pipes of 3 inches in diameter (internal diameter: 73 mm) were employed as casing pipes. As a hi~h-pressure hose, a firsk high-pressure hose and a second high-pressure hose were used by connecting them together. The first high-pressure hose had an outer diameter of 21 mm and an innsr diameter of lZ.8 mm, was made of an inner tube 203, an outer sheath 201 and a reinforcement layer 202, and had a rated pressure of 1,000 ~gf/cm2. Both the inner tube and outer sheath were made of nylon-12, while the reinforcement layer was made of high-tensile steel wires. ~he second high-: 25 pressure hose had an outer diameter of 20.4 mm and an inner diameter of 12.8 mm, was made of an inner tube, an outer sheath and a reinforcement layer, and had a rated pressure o~ 700 kgf/cm2. The inner tube was made of nylon-12, the outer sheath of polyurethane, and the reinforcement layer of high-tensile steel wires. Any material can be used for the reinl~orcement layers as long as it has reinforcing effects.
The jet nozzle body 1 has a construction as shown by way of example in F~G. 2(b). In thi~ drawing, six reverse jetting orifices 101 o~ 1 mm in diameter extend toward an extension of a central longitudinal axis of the high-pressure hose at an angle 0 of 30 relative to the extension. In additiont two oxi~ices 102 of 1 mm in diameter are also perforated ~o as not only to flush but also to rotate the jet nozzle body 1 by water stream. Further, th~ length of the straight pip~ por tion 11 between the jet nozzle 1 and the high-pr~ssura hose 2 was set at 40 cm. As the tripod 8 shown in FIG.
"~ l(b), a tripod having a height of about 3 m and an inter-leg distance of about 2 m was employed. This tripod was small enough to be carried by two men.
The results of the practice of the present in~en-tion as described above are shown in Table 1, together with the rPsults obtained by conducting similar work in ; 25 accordance with a conventional method. The effects of remo~al of sand and the like were judged by a conven-tional m~thod.
Example 2 and Comparative Example 2 Flushing and dr~dging operations, which were similar to Example 1 and Comparative Example 1 respec-tively, were conducted to wellbores of 370 m in depth.
As a high-pressure hose~ only the high-pressure hose whose rated pressure was 700 kgf/cm2 was used. The results of the operations are shown in Table 2.
The costs of the respective oparations are all indicated in r21ation to the co~t o~ the operation in Example 1, the latter being expressing as 100.
As is und~rstood from the examples and compara~
tive examples, the present invention makes it possible to significantly reduce both the working days and cost and further requires a much smaller space. This latt~r advantageous ~eature permits dredging of wellbores whose dredging has heretofore been impossible due to the existence of a nearby building.
: 20 ,. .
. . .
: ' . .
:~ , Table 1 - ~ .. ___ Example 1 Comp. Ex. 1 _ ... ... _ Method Invention Pump dredging , _ _ ._ .__ Days required for preparation and 1 day 10 days disassembly - .
Days required for dredging work 15 days 15 days . . __ ..
Workers 2 workers 4 workers Site re~uired for 2 at least dredging work appxox. 26 m approx. 972 m2 . ~ - , . _ _ . __, . .
Cost 100 (standard) 680 . ._ .. . .
Removal of sand, .
etc. complete lncomplete .~ ._ __ __ _ __.
~, i .
- . . ~, .
... , ~ . .
., ' Table 2 _ Example 2 Comp. Ex. 2 . _ ~ ,., .
Nethod Invention Pump dredging _ Days required for preparation and 1 day 10 days disassembly . . _ _ .
Days required for dredging work 2 days 2 days . _ ._. . __ .~
Workers 2 workers 4 wo kers . __ .. _ ..
dredging work approx. 26 m2 approx. 972 m2 .. _ ... _ _ Cost 9 160 .__ __ Removal o~ sand, etc. complete incomplete _,.
;
' .
Claims (6)
1. A method for flushing and dredging a wellbore, which comprises:
lowering a high-pressure hole into a pipe, which is disposed within the wellbore, through a lubricator arranged in a wellhead assembly, said hose being con-structed of an inner resin tube and an outer resin sheath and having a jet nozzle at a leading end there-of; and introducing water into the high-pressure hose to jet water out through the jet nozzle, whereby water flushes the inside of the pipe and blows up substances so flushed off and/or materials so dredged up; and, at the same time, injecting a compressed gas through a gas-lift means provided on the pipe, to lift the flushed-off substances and dredged-up materials from the wellbore with the aid of the expanding injection gas.
lowering a high-pressure hole into a pipe, which is disposed within the wellbore, through a lubricator arranged in a wellhead assembly, said hose being con-structed of an inner resin tube and an outer resin sheath and having a jet nozzle at a leading end there-of; and introducing water into the high-pressure hose to jet water out through the jet nozzle, whereby water flushes the inside of the pipe and blows up substances so flushed off and/or materials so dredged up; and, at the same time, injecting a compressed gas through a gas-lift means provided on the pipe, to lift the flushed-off substances and dredged-up materials from the wellbore with the aid of the expanding injection gas.
2. The method of claim 1, wherein, upon jetting out water through the jet nozzle, water is also jetted out from the orifices toward an entrance of the wellbore in a direction greater than 0 degree but not exceeding 90 degrees relative to an extension of a lon-gitudinal central axis of the high-pressure hose.
3. The method of claim 1, wherein a straight portion longer than an inner diameter of the wellbore pipe is provided between the high-pressure hose and the jet nozzle.
4. A high-pressure hose for flushing and dredg-ing a wellbore, comprising:
an inner resin tube;
an outer resin sheath;
a reinforcement layer disposed between the inner resin tube and the outer resin sheath:
a jet nozzle provided at a leading end of the hose and forming at least one orifice extending from a side of the leading end of the hose toward an extension of a longitudinal central axis of the hose in a direc-tion greater than 0 degree but not exceeding 90 degrees relative to the extension; and a straight portion having a length greater than an inner diameter of a pipe disposed within the wellbore and provided between the high-pressure hose and the jet nozzle.
an inner resin tube;
an outer resin sheath;
a reinforcement layer disposed between the inner resin tube and the outer resin sheath:
a jet nozzle provided at a leading end of the hose and forming at least one orifice extending from a side of the leading end of the hose toward an extension of a longitudinal central axis of the hose in a direc-tion greater than 0 degree but not exceeding 90 degrees relative to the extension; and a straight portion having a length greater than an inner diameter of a pipe disposed within the wellbore and provided between the high-pressure hose and the jet nozzle.
5. A lubricator for pipes having parts of dif-ferent diameters, comprising:
a first lubricator unit composed in combination of a cylindrical hollow packer defining an outer coni-cal surface and a cylindrical hollow packer ram having an inner conical surface engageable with the outer con-ical surface of the packer;
a second lubricator unit composed in combination of a cylindrical hollow packer defining an outer coni-cal surface and a cylindrical hollow packer ram having an inner conical surface engageable with the outer con-ical surface of the packer;
a casing enclosing therein said first and second lubricator units with an axial interval therebetween, each of said packers being fixed on said casing; and first and second means for independently moving the first and second packer rams in an axial direction, respectively, whereby forces for pushing the packers by the corresponding packer rams can be adjusted.
a first lubricator unit composed in combination of a cylindrical hollow packer defining an outer coni-cal surface and a cylindrical hollow packer ram having an inner conical surface engageable with the outer con-ical surface of the packer;
a second lubricator unit composed in combination of a cylindrical hollow packer defining an outer coni-cal surface and a cylindrical hollow packer ram having an inner conical surface engageable with the outer con-ical surface of the packer;
a casing enclosing therein said first and second lubricator units with an axial interval therebetween, each of said packers being fixed on said casing; and first and second means for independently moving the first and second packer rams in an axial direction, respectively, whereby forces for pushing the packers by the corresponding packer rams can be adjusted.
6. The method of any one of claims 1-3, wherein the lubricator is the lubricator of claim 5; and, upon causing a joint portion of the high-pressure hose -said joint portion having a larger diameter than the high-pressure hose - to pass through the lubricator, one of the lubricator units, said one lubricator unit being located on a side of an entrance, is opened while the other lubricator unit on a side of an exit is maintained closed, the joint portion is inserted to a point between said one lubricator unit on the side of the entrance and said the other lubricator unit on the side of the exit, the lubricator unit on the side of the entrance is closed, the lubricator unit on the side of the exit is opened and the joint portion is then caused to pass through the lubricator unit on the side of the exit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2044011 CA2044011A1 (en) | 1991-06-07 | 1991-06-07 | Flushing and dredging method for wellbores and equipments therefor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2044011 CA2044011A1 (en) | 1991-06-07 | 1991-06-07 | Flushing and dredging method for wellbores and equipments therefor |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2044011A1 true CA2044011A1 (en) | 1992-12-08 |
Family
ID=4147751
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2044011 Abandoned CA2044011A1 (en) | 1991-06-07 | 1991-06-07 | Flushing and dredging method for wellbores and equipments therefor |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2044011A1 (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108825155A (en) * | 2018-08-09 | 2018-11-16 | 鞍山万维科技有限公司 | Underbalance injection stream dredging vacuum suction covers outer method for removing blockage in a kind of well |
| CN113107578A (en) * | 2021-04-09 | 2021-07-13 | 河南理工大学 | Coal seam drilling hole combined blockage removal method for pneumatic regrinding powder discharge and chemical suspension powder discharge |
| CN113877396A (en) * | 2021-10-28 | 2022-01-04 | 浙江利达环保科技股份有限公司 | A spray column that is used for industrial desulfurization to have a mediation function |
-
1991
- 1991-06-07 CA CA 2044011 patent/CA2044011A1/en not_active Abandoned
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108825155A (en) * | 2018-08-09 | 2018-11-16 | 鞍山万维科技有限公司 | Underbalance injection stream dredging vacuum suction covers outer method for removing blockage in a kind of well |
| CN108825155B (en) * | 2018-08-09 | 2024-03-29 | 上海万维亿通装备制造有限公司 | Method for removing blockage outside underground unbalanced jet dredging vacuum suction sleeve |
| CN113107578A (en) * | 2021-04-09 | 2021-07-13 | 河南理工大学 | Coal seam drilling hole combined blockage removal method for pneumatic regrinding powder discharge and chemical suspension powder discharge |
| CN113107578B (en) * | 2021-04-09 | 2022-05-20 | 河南理工大学 | Coal seam drilling hole combined blockage removal method for pneumatic regrinding powder discharge and chemical suspension powder discharge |
| CN113877396A (en) * | 2021-10-28 | 2022-01-04 | 浙江利达环保科技股份有限公司 | A spray column that is used for industrial desulfurization to have a mediation function |
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