CN212671589U - Well body structure penetrating high-pressure layer and basalt collapsed layer - Google Patents
Well body structure penetrating high-pressure layer and basalt collapsed layer Download PDFInfo
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- CN212671589U CN212671589U CN202021455173.XU CN202021455173U CN212671589U CN 212671589 U CN212671589 U CN 212671589U CN 202021455173 U CN202021455173 U CN 202021455173U CN 212671589 U CN212671589 U CN 212671589U
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Abstract
The utility model provides a pass well body structure on high-pressure layer and basalt collapsed layer, this well body structure under the geological conditions who passes high-pressure layer and basalt collapsed layer includes: a first open-time casing string; a second open-time casing string arranged in the first open-time casing string; a third open-time casing string, wherein the third open-time casing string is arranged at the top of the high-pressure layer; a fourth secondary casing string; the fourth secondary sleeve string penetrates through the high-voltage layer and is arranged at the upper part of the basalt collapsed layer; a fifth open-time casing string, wherein the fifth open-time casing string penetrates through the basalt collapsed layer and is lowered to the upper part of an oil gas target layer; and the sixth opening tail pipe string is arranged in the oil and gas target layer. Through the utility model discloses, when having alleviated and having the geological conditions on high-pressure layer and basalt collapsed the layer under the well drilling, accident and complicated technical problem such as overflow, lost circulation, the wall of a well collapses, the sticking of a well easily appear.
Description
Technical Field
The utility model relates to a technical field of oil and natural gas exploration and development especially relates to a well body structure who passes high-pressure layer and basalt layer that collapses.
Background
In the exploration and development of petroleum and natural gas, an oil-gas channel is required to be established between the ground and an underground oil-gas layer, namely an oil-gas well. In the construction of oil and gas wells, the formation is sealed off with casing and the outer wall of the casing is secured to the formation with cement to form a set of casing and cement combinations. The combination of the casing and the cement is the well structure. The well structure is one of the key contents of oil and gas exploration, and the pore pressure of the stratum to be drilled and the particularity of geological conditions need to be fully considered, different casings are used for sealing different pressure and complex strata, and possible accidents and complex risks in well drilling are eliminated or reduced.
At present, the deep stratum is used for exploration and development of oil and gas resources, the well depth of an oil and gas ultra-deep well is 6000m-9000m generally, and 8000m is broken through at present. In the ultra-deep well drilling, due to the fact that geological conditions are complex and changeable, drilling often meets a complex stratum pore pressure system, stratum lithology is changeable, high-pressure layers, leakage layers and collapse layers appear alternately, the geological conditions are complex, and the construction challenge to a well body structure is large.
The ultra-deep well of the Sichuan basin often drills complex strata such as high-pressure saline water, mudstone strata, basalt strata and the like in deep strata, when a conventional well body structure is adopted, accidents and complications such as overflow, well leakage, collapse, drill jamming and the like frequently occur in drilling, the handling of the accidents and the complications can bring huge economic loss to oil-gas drilling, and even finally, the drilling cannot be continued to a target layer of oil gas, so that a well hole is scrapped.
SUMMERY OF THE UTILITY MODEL
The utility model aims at providing a pass high-pressure layer and basalt layer that collapses's shaft structure to alleviate when having the geological conditions on high-pressure layer and basalt layer that collapses well drilling, appear easily that accident and complicated technical problem such as overflow, lost circulation, the wall of a well collapse, card bore.
The above object of the present invention can be achieved by the following technical solutions:
the utility model provides a well body structure of passing high-pressure layer and basalt layer that collapses, include:
a first open-time casing string;
a second open-time casing string arranged in the first open-time casing string;
a third open-time casing string, wherein the third open-time casing string is arranged at the top of the high-pressure layer;
a fourth secondary casing string; the fourth secondary casing string penetrates through the high-voltage layer and is lowered to the upper part of the basalt collapsed layer, and the high-voltage layer is sealed by the fourth secondary casing string;
a fifth open-time casing string, wherein the fifth open-time casing string penetrates through the basalt collapsed layer and is lowered to the upper part of an oil-gas target layer, and the basalt collapsed layer is sealed by the fifth open-time casing string;
and the sixth opening tail pipe string is arranged in the oil and gas target layer.
In a preferred embodiment, the fourth open string is suspended from an inner wall of the third open string by a four-split liner hanger.
In a preferred embodiment, the fifth open-ended casing string comprises a fifth open-ended tailpipe string that is suspended.
In a preferred embodiment, the fifth open-ended liner string is suspended from the inner wall of the third open-ended casing string by a fifth open-ended liner hanger.
In a preferred embodiment, the wellbore structure includes a fifth open-time tieback casing run into the top end of the fifth open-time liner string.
In a preferred embodiment, the sixth open-ended liner string is suspended from the inner wall of the fifth open-ended casing string by a sixth open-ended liner hanger.
In a preferred embodiment, the first open sub string extends through the open earth formation and the leaky formation, and the second open sub string extends through the upper shallow gas and low pressure thief zone.
In a preferred embodiment, the fifth opening liner string is a straight-coupling liner string.
The utility model discloses a characteristics and advantage are:
the utility model provides a pass the shaft structure on high-pressure layer and basalt layer that collapses, first time casing string seals loose, unstable and the easy lost circulation well section in upper portion, for well head installation on next step, provides the support. The second opening casing string seals the shallow gas and low-pressure easily-lost stratum.
And the third open-time casing is serially connected to the upper part of the high-pressure layer to seal off the stratum with relatively low pore pressure at the upper part, so that the phenomenon that the stratum with relatively low pore pressure at the upper part has lost circulation due to the fact that the density of drilling fluid is improved when the drilling is carried out on the high-pressure layer is avoided.
After the fourth secondary well section drills through the high-pressure layer, the fourth secondary casing string is arranged to seal the stratum instead of drilling into the basalt collapsed layer at the lower part and then arranging the casing to seal the stratum, the fourth secondary casing string seals and separates the high-pressure layer which needs high-density drilling fluid to maintain the stability of the well wall, accidents such as overflow and well wall collapse of the high-pressure layer at the upper part caused by the reduction of the density of the drilling fluid when the well drilling into the basalt collapsed layer can be effectively avoided, the high-pressure layer suitable for the drilling of the high-density drilling fluid at the upper part is sealed by the fourth secondary casing string, and conditions are created for the drilling of the drilling fluid density reduced at the lower part.
And the fifth open-time casing string seals the easy-to-collapse basalt collapsed layer, so that conditions are created for further reducing drilling fluid density drilling by protecting the reservoir stratum in the open-time mode. And the sixth opening tail pipe seals the oil gas target layer in series.
Through the well body structure, the condition of drilling a target layer of oil and gas can be established, and the technical problems of accidents and complexity such as overflow, well leakage, well wall collapse, drill sticking and the like easily occurring when drilling under the geological condition with a high-pressure layer and a basalt collapsed layer are solved.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.
Fig. 1 is a schematic structural diagram of a shaft structure passing through a high-pressure layer and a basalt collapsed layer, provided by the present invention;
fig. 2a is a schematic diagram of the well structure passing through the high-pressure layer and the basalt collapsed layer provided by the present invention matching with each structural layer in the stratum;
FIG. 2b is a plot of formation pore pressure versus formation pore pressure;
fig. 3 is a schematic diagram of a construction method of a shaft structure passing through a high-pressure layer and a basalt collapsed layer provided by the present invention.
The reference numbers illustrate:
100. cementing a cement sheath;
10. a first open-time casing string; 101. a first open-time interval;
20. a second opening sleeve string; 201. a second open-secondary interval;
30. a third opening of a secondary casing string; 301. a third open-hole section;
40. a fourth secondary casing string; 401. a fourth secondary well section; 402. a quarto secondary tail pipe hanger;
50. a fifth opening sleeve string; 51. fifthly, opening a tail pipe string; 52. fifthly, splicing the sleeve once; 501. a fifth open-hole interval; 502. a fifth secondary liner hanger;
60. a sixth starting tail pipe string; 601. a sixth open-hole sub; 602. a six-start secondary liner hanger;
71. a high pressure layer; 711. a high pressure brine layer; 712. a high pressure mudstone formation; 72. a basalt collapsed layer; 73. a hydrocarbon target zone;
80. an earth formation; 81. a formation pore pressure profile.
Detailed Description
The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative work belong to the protection scope of the present invention.
In the face of a complex stratum with a high-pressure layer 71 and a basalt collapsed layer 72, due to the unreasonable well body structure, the limitation of the casing layer and the like, in a conventional well body structure, a plurality of stratum pore pressure systems and complex strata with different properties exist in the same well section. The pore pressure and collapse pressure of the high-pressure brine layer 711 and the mudstone stratum are higher, and high-density drilling fluid is required to be adopted for drilling in order to avoid overflow and borehole collapse accidents; the basalt collapsed layer 72 has lower leakage pressure and stratum fracture pressure, and low-density drilling fluid is required to be adopted for drilling in order to avoid well leakage and borehole collapse accidents. If the drilling is performed through the upper high-pressure brine layer 711, the middle mudstone stratum and the lower basalt collapsed stratum 72, and then the casing is set for packing, after the drilling is performed into the basalt collapsed stratum 72, the drilling fluid in the well section cannot simultaneously meet the high density of the high-pressure brine layer 711 and the mudstone stratum and the low density requirement of the basalt collapsed stratum 72, and accidents such as overflow of the high-pressure brine layer 711, collapse of the mudstone stratum, well leakage of the basalt collapsed stratum 72, drill jamming and the like are easily caused.
Example one
The utility model provides a well structure of passing through high-pressure zone and basalt collapsed zone can adopt following construction method to construct, as shown in FIG. 2a and FIG. 3, this construction method includes: step S10, drilling a first open time well section 101, putting in a first open time casing string 10, and cementing a well; step S20, drilling a second open-time well section 201, putting in a second open-time casing string 20, and cementing a well; step S30, drilling a third open-time well section 301, drilling the third open-time well section 301 to the upper part of the high-pressure layer 71, putting a third open-time casing string 30, and cementing a well; step S40, drilling a fourth secondary well section 401, drilling the fourth secondary well section 401 through the high-pressure layer 71, drilling the basalt collapsed layer 72, descending a fourth secondary casing string 40, and cementing; step S50, drilling a fifth open-time well section 501, drilling the fifth open-time well section 501 through the basalt collapsed layer 72 and to the upper part of the oil-gas target layer 73, and putting in the fifth open-time casing string 50 for well cementation; and step S60, drilling the sixth-open-time well section 601 to the oil-gas target layer 73, putting the sixth-open-time tail pipe string 60 in, and cementing.
In the construction method, the first open-time casing string 10 seals a loose, unstable and easily-lost well section at the upper part, and provides support for next well mouth installation. The second open-time casing string 20 seals shallow gas and low pressure lost-to-earth formations.
The third opened casing string 30 is lowered to the upper part of the high-pressure layer 71 to seal off the stratum with relatively low upper pore pressure, so that the stratum with relatively low upper pore pressure due to the fact that the density of drilling fluid is improved when the drilling is performed on the high-pressure layer 71 in the next opening process is prevented from leaking.
After the fourth secondary well section 401 drills through the high-pressure layer 71, the fourth secondary casing string 40 is lowered to seal the stratum instead of drilling into the basalt collapsed layer 72 at the lower part and then lowering into the casing to seal the stratum, the fourth secondary casing string 40 seals the high-pressure layer 71 which needs high-density drilling fluid to maintain the stability of the well wall, accidents such as overflow and well wall collapse of the upper high-pressure brine layer 711 caused by the reduction of the density of the drilling fluid when drilling into the basalt collapsed layer 72 can be effectively avoided, the fourth secondary casing string 40 seals the high-pressure layer 71 which is suitable for the drilling of the high-density drilling fluid at the upper part, and conditions are created for the drilling of the drilling fluid density reduction at the lower part.
The fifth open-time casing string 50 seals the easy-to-collapse basalt collapsed layer 72, and creates conditions for further reducing drilling fluid density drilling for protecting the reservoir stratum by opening times. The sixth open tailpipe string 60 seals the destination layer 73 of oil and gas.
The well body structure can be suitable for ultra-deep wells, and the condition of drilling the ultra-deep oil and gas target layer 73 can be established through the well body structure, so that the technical problems of accidents and complexity such as overflow, well leakage, well wall collapse, drill sticking and the like easily occurring when drilling under the geological condition with a high-pressure layer and a basalt collapsed layer 72 are relieved.
In step S10, a roller bit with a diameter of 660.4mm may be used, after drilling through the surface unconsolidated formation and the formation prone to leakage, the bit is pulled out, the first casing string 10 with a diameter of 508mm is lowered, cement is injected into the annular space between the first casing string 10 and the formation to fix the well, the upper loose, unstable and prone to leakage well section is sealed, and a support is provided for the next wellhead installation. Specifically, after a roller bit with the diameter of 660.4mm is used and the well is drilled to the depth of 200m, large discharge is fully circulated, rock debris in the well is carried completely, and the first opening casing string 10 is ensured to be smoothly put in; the first open-time casing string 10 is a casing string with the diameter phi 508mm, the wall thickness 11.13mm and a ladder-shaped buckle, a drill bit is lifted out, the first open-time casing string 10 is put in, the annular space between the first open-time casing string 10 and the stratum is well-cemented in a positive injection and reverse injection cement-pouring mode, cement returns to a wellhead, and injected cement slurry is solidified to form a well-cementing cement ring 100.
In step S20, a roller cone bit or PDC bit with a diameter of 444.5mm may be used to drill through the upper shallow gas and low-pressure leakage layer, and then the bit is removed, a second open casing string 20 with a diameter of 365.13mm is inserted, cement is injected into the annular space between the second open casing string 20 and the formation and the upper casing to fix the well, and the shallow gas and low-pressure easily-leaked formation is sealed. Specifically, a roller bit with the diameter of 444.5mm or a PDC bit is used, after the drill bit is drilled to the well depth of 1500m, the drill bit is taken out, a drifting drilling tool combination is replaced, full drifting is carried out, and the second-opening casing string 20 is guaranteed to be smoothly put in; the second open-time casing string 20 adopts a phi 365.13mm, the wall thickness is 13.88mm, and a ladder buckling casing string is adopted, the second open-time casing string 20 is put in, cement is injected into the annular space between the casing and the ground layer and the upper casing pipe in an interpolation method for well cementation, and the cement returns to the wellhead.
In step S30, a phi 333.4mm pdc drill bit may be used, after drilling to the top of the high-pressure layer 71, the drill bit is pulled out, the phi 273.05mm third open casing string 30 is lowered, cement is injected into the annular space between the third open casing string 30 and the formation and the upper casing to fix the well, and the formation with relatively low upper pore pressure is sealed. Specifically, a phi 333.4mm PDC drill bit is used for drilling to the well depth of 4500m and the top of the high-pressure layer 71, the drill bit is taken out and replaced by a drifting drilling tool assembly for full drifting, and the third-opening casing string 30 is ensured to be smoothly put in; the third open-time casing string 30 adopts a phi 273.05mm, the wall thickness is 13.84mm, the casing string is buckled through air sealing, the third open-time casing string 30 is put into the third open-time casing string, a double-rubber plug and double-density cement slurry system is adopted, cement is injected into the annular space between the third open-time casing string 30 and the ground layer and the upper layer casing for well cementation, and the cement returns to the wellhead.
In an embodiment of the present invention, the fourth opening casing string 40 is suspended on the inner wall of the third opening casing string 30. By adopting a tail pipe suspension technology, the one-time height return of the annular cementing of the casing is effectively reduced, and the complex well leakage of the basalt stratum caused by overhigh ground pumping pressure during annular cementing of the casing is avoided.
Drilling the fourth secondary well section 401 can use a phi 241.3mm PDC drill bit, after drilling through the upper high-pressure layer 71, the drill bit is taken out, a phi 219.08mm fourth secondary casing string 40 is put to the bottom of the well, the top of the fourth secondary casing string 40 is connected with a fourth secondary liner hanger 402, the fourth secondary casing string 40 is hung on the inner wall of the third secondary casing string 30, cement is injected into the annular space between the fourth secondary casing string 40 and the stratum and the annular space between the fourth secondary casing string and the upper casing string for well cementation, the stratum needing high-density drilling fluid drilling is sealed, and accidents and complications such as overflow, collapse, well leakage and drill sticking caused by the reduction of the density of the drilling fluid are avoided. Specifically, a phi 241.3mm PDC drill bit is used for drilling the fourth sub well section 401 to the well depth of 6400m, and after the upper high-pressure layer 71 is drilled through, the drill bit is taken out, a drifting drilling tool combination is replaced, full drifting is carried out, and smooth descending of the fourth sub well section 401 is guaranteed; the fourth secondary casing string 40 can be a direct-connection buckling tail pipe string with the diameter of 219.08mm and the wall thickness of 12.7mm, the fourth secondary casing string 40 is lowered to the well depth of 6398m, the top of the fourth secondary casing string 40 is connected with the fourth secondary tail pipe hanger 402, and the fourth secondary casing string 40 is hung on the inner wall of the third open secondary casing string 30 at the well depth of 4300 m; and (3) injecting cement into the annular space between the fourth secondary casing string 40 and the stratum and the layer casing by adopting a high-density salt-resistant cement slurry system for cementing, returning the cement to the position of the fourth secondary liner hanger 402, and sealing a high-pressure saline layer 711 and a high-pressure mudstone stratum 712 suitable for drilling by the high-density drilling fluid at the upper part, thereby creating conditions for drilling by reducing the density of the drilling fluid in the next time. In the construction method, the casing string 40 is not connected back to the casing for the fourth time, so that the use amount of the casing can be reduced, and the drilling cost is saved.
The fifth casing string 50 may be installed at the wellhead or may be provided in a suspended manner. With the fifth open-sub string 50 installed uphole, the fifth open-sub string 50 may be casing extending from downhole to uphole of the fifth open-sub section 501. In the case where the fifth primary casing string 50 is provided in a suspended manner, the fifth primary casing string 50 includes a fifth primary tail string 51, and the fifth primary tail string 51 may be suspended from an inner wall of the third primary casing string 30.
The fifth split casing string 50 is preferably arranged in a suspended manner, as shown in fig. 2a, the fifth split casing string 50 comprising a fifth split tailpiece string 51, the fifth split tailpiece string 51 being arranged in a suspended manner. The fifth primary tail pipe string 51 may be suspended from the third primary casing string 30 or the fourth primary casing string 40. More preferably, the fifth open secondary tail pipe string 51 is suspended from the inner wall of the third open secondary casing string 30. In the fifth open-hole sub-well section 501, after drilling the basalt stratum, the tail pipe suspension technology is adopted, so that the one-time height return of the annular space cement injection of the fifth open-hole sub-tail pipe string 51 is effectively reduced, the phenomenon that the basalt collapsed layer 72 leaks due to overhigh ground pump pressure when the annular space cement injection of the fifth open-hole sub-tail pipe string 51 is avoided, meanwhile, the weight of the casing can be reduced by adopting the tail pipe suspension, the well depth of the casing running is increased, and the deeper complex stratum is sealed.
The PDC drill bit with the diameter of 190.5mm can be used, after the basalt collapsed layer 72 is drilled through, the drill bit is taken out, the fifth initial casing string 50 with the diameter of 168.28mm is put into the well bottom, the top of the fifth initial casing string 50 is connected with the fifth initial liner hanger 502, the fifth initial casing string 50 is hung on the inner wall of the third initial casing string 30, and cement is injected into the annular space between the fifth initial casing string 50 and the ground layer and the upper layer casing for well cementation. Specifically, a phi 190.5mm PDC drill bit is used for drilling to the well depth of 7000m, and after the basalt collapsed layer 72 is drilled through, the drill bit is taken out and replaced by a drifting drilling tool combination for full drifting, so that the fifth-opening casing string 50 is ensured to be smoothly put in; the fifth opening casing string 50 adopts a straight-connection tail pipe string with the diameter of 168.28mm and the wall thickness of 12.07mm, and the fifth opening casing string 50 is put into the well to the depth of 6998 m; the top of the fifth casing string 50 is connected with a fifth casing liner hanger 502, and the fifth casing string 50 is hung on the inner wall of the third casing string 30 at the well depth of 4000 m. And injecting cement into the annulus of the fifth open-time casing string 50, the stratum and the upper casing for cementing, returning the cement to the position of the fifth open-time liner hanger 502, and sealing the easily collapsed basalt collapsed layer 72 to create conditions for further reducing drilling fluid density drilling for protecting the reservoir stratum by the open-time.
Further, in the case where the fifth opening string 50 is arranged in a suspended manner, the construction method includes step S70 provided after step S60, and step S70 includes: and (5) running the fifth-time tieback casing 52 to the top end of the fifth-time tail pipe string 51, and cementing. And (3) running the fifth open-time tieback casing 52, wherein the running depth of the fifth open-time tieback casing 52 is the position of the fifth open-time liner hanger 502, and injecting cement into the annular space between the fifth open-time tieback casing 52 and the third open-time casing string 30 for cementing. The fifth open-time tieback casing 52 can be 168.28mm casing string, specifically, the fifth open-time tieback casing 52 is set, the setting depth of the fifth open-time tieback casing 52 is the position of the fifth open-time liner hanger 502, and cement is injected into the annular space between the fifth open-time tieback casing 52 and the third open-time casing string 30 for cementing. And after the casing tie-back operation is completed, the operation is shifted to a sixth perforating completion operation of the secondary tail pipe string 60.
After the fifth-opening-time liner string 51 is suspended for well cementation, casing tieback is not carried out, and tieback operation of the fifth-opening-time tieback casing 52 is carried out after the sixth-opening-time liner string 60 is suspended for well cementation, so that annular space of the drilling tool assembly above the fifth-opening-time liner hanger 502 during drilling of the sixth-opening-time well section 601 is increased, drilling fluid circulation equivalent density during drilling of the sixth-opening-time well section 601 is reduced, and the risk of complicated well leakage of a target layer is reduced.
The sixth open-ended tailpipe string 60 may be wellhead mounted or may be suspended. Preferably, sixth open liner string 60 is suspended from the inner wall of fifth open liner string 50. In step S60, a PDC drill bit with a diameter of 139.7mm may be used to drill into the target formation, the drill bit is lifted out, a sixth open-ended tailpipe string 60 with a diameter of 114.3mm is lowered in, the top of the sixth open-ended tailpipe string 60 is connected to a sixth open-ended tailpipe hanger 602, the sixth open-ended tailpipe string 60 is suspended on the inner wall of the fifth open-ended tailpipe string 51, and cement is injected into the annulus between the sixth open-ended tailpipe string 60 and the formation and the upper casing to fix the well and seal the target formation 73 of the oil gas. Specifically, a phi 139.7mm PDC drill bit is used for drilling to a target layer 73 of oil and gas, after the drilling footage reaches 200m, the drill bit is taken out, a drifting drilling tool combination is replaced, full drifting is carried out, and smooth running of a casing is ensured; the sixth opening tail pipe string 60 can be a long round buckle tail pipe string with the diameter of 114.3mm and the wall thickness of 8.56mm, and the sixth opening tail pipe string 60 is put into the well to the well depth of 7500 m; the top of the sixth-opening secondary tail pipe string 60 is connected with a sixth-opening secondary tail pipe hanger 602, the sixth-opening secondary tail pipe string 60 is hung on the inner wall of the fifth-opening secondary tail pipe string, the well depth is 6800m, cement is injected into the annular space between the sixth-opening secondary tail pipe string 60 and the ground and the upper casing for well cementation, the cement returns to the position of the sixth-opening secondary tail pipe hanger 602, and the oil gas target layer 73 is sealed.
The sixth-opening secondary tail pipe string 60 adopts a tail pipe suspension well cementation technology, does not tie back the casing pipe, reduces the one-time height return of annular cementing of the casing pipe, avoids the complex leakage of a target layer caused by overhigh ground pump pressure when the annular cementing of the casing pipe is performed, reduces the using amount of the casing pipe and saves the cost.
Example two
The utility model provides a pass well body structure on high-pressure layer and basalt collapsed layer, as shown in figure 1 and figure 2a, this well body structure includes: a first open-time casing string 10, a second open-time casing string 20, a third open-time casing string 30, a fourth open-time casing string 40, a fifth open-time casing string 50 and a sixth open-time casing string 60; a second open-time casing string 20 is put into the first open-time casing string 10; the third opened secondary casing string 30 is lowered to the top of the high-pressure layer 71; the fourth secondary casing string 40 penetrates through the high-voltage layer 71 and is lowered to the upper part of the basalt collapsed layer 72, and the fourth secondary casing string seals the high-voltage layer; the fifth open-time casing string 50 penetrates through the basalt collapsed layer 72 and is lowered to the upper part of the oil-gas target layer 73, and the basalt collapsed layer is sealed by the fifth open-time casing string; the sixth open tailpipe string 60 runs into the destination layer 73 of oil and gas.
In the construction method, the first open-time casing string 10 seals a loose, unstable and easily-lost well section at the upper part, and provides support for next well mouth installation. The second open-time casing string 20 seals shallow gas and low pressure lost-to-earth formations.
The third opened casing string 30 is lowered to the upper part of the high-pressure layer 71 to seal off the stratum with relatively low upper pore pressure, so that the stratum with relatively low upper pore pressure due to the fact that the density of drilling fluid is improved when the drilling is performed on the high-pressure layer 71 in the next opening process is prevented from leaking.
After the fourth secondary well section 401 drills through the high-pressure layer 71, the fourth secondary casing string 40 is lowered to seal the stratum instead of drilling into the basalt collapsed layer 72 at the lower part and then lowering into the casing to seal the stratum, the fourth secondary casing string 40 seals the high-pressure layer 71 which needs high-density drilling fluid to maintain the stability of the well wall, accidents such as overflow and well wall collapse of the upper high-pressure brine layer 711 caused by the reduction of the density of the drilling fluid when drilling into the basalt collapsed layer 72 can be effectively avoided, the fourth secondary casing string 40 seals the high-pressure layer 71 which is suitable for the drilling of the high-density drilling fluid at the upper part, and conditions are created for the drilling of the drilling fluid density reduction at the lower part.
The fifth open-time casing string 50 seals the easy-to-collapse basalt collapsed layer 72, and creates conditions for further reducing drilling fluid density drilling for protecting the reservoir stratum by opening times. The sixth open tailpipe string 60 seals the destination layer 73 of oil and gas.
The well body structure can be suitable for ultra-deep wells, and by adopting the well body structure, the condition of drilling the ultra-deep oil and gas target layer 73 can be established, and the technical problems of accidents and complexity such as overflow, well leakage, well wall collapse, drill sticking and the like easily occurring when drilling under the geological condition with a high-pressure layer and a basalt collapsed layer 72 are relieved.
Specifically, the well bore structure further comprises a cementing cement sheath 100 for cementing a first casing string 10, a second casing string 20, a third casing string 30, a fourth casing string 40, a fifth casing string 50 and a sixth casing string 60.
In an embodiment of the present invention, the fourth opening liner string 40 is suspended from the inner wall of the third opening liner string 30 by the fourth opening liner hanger 402.
In an embodiment of the present invention, the fifth opening casing string 50 includes a fifth opening tail pipe string, and the fifth opening tail pipe string is suspended.
In an embodiment of the present invention, the fifth-start extension string is suspended on the inner wall of the third-start extension string 30 by the fifth-start extension hanger 502.
The utility model discloses an among the embodiment, well bore structure includes the tieback sleeve pipe of fifth division, and the top to the tieback tail pipe cluster of fifth division is gone into down to the tieback sleeve pipe of fifth division.
In one embodiment of the present invention, the sixth open-ended tailpipe string 60 is suspended from the inner wall of the fifth open-ended casing string 50 by a sixth open-ended tailpipe hanger 602.
In an embodiment of the present invention, the first casing string 10 runs through the surface stratum with loose earth and the stratum with easy leakage, and the second casing string 20 runs through the upper shallow gas and the low pressure leakage layer.
The above description is only for the embodiments of the present invention, and those skilled in the art can make various changes or modifications to the embodiments of the present invention according to the disclosure of the application document without departing from the spirit and scope of the present invention.
Claims (9)
1. A well bore structure passing through a high pressure zone and a basalt collapsed zone, comprising:
a first open-time casing string;
a second open-time casing string arranged in the first open-time casing string;
a third open-time casing string, wherein the third open-time casing string is arranged at the top of the high-pressure layer;
the fourth secondary casing string penetrates through the high-voltage layer and is lowered to the upper part of the basalt collapsed layer, and the fourth secondary casing string seals the high-voltage layer;
a fifth open-time casing string, wherein the fifth open-time casing string penetrates through the basalt collapsed layer and is lowered to the upper part of an oil-gas target layer, and the basalt collapsed layer is sealed by the fifth open-time casing string;
and the sixth opening tail pipe string is arranged in the oil and gas target layer.
2. The wellbore structure traversing high-pressure and basalt collapsed layers of claim 1, wherein the fourth split casing string is suspended from an inner wall of the third split casing string by a four split liner hanger.
3. The wellbore structure traversing high pressure and basalt collapsed layers of claim 2, wherein the fifth open liner string comprises a fifth open liner string, the fifth open liner string being suspended.
4. The wellbore structure traversing high pressure and basalt collapsed layers of claim 3, wherein the fifth primary string is suspended from an inner wall of the third primary string by a fifth primary string hanger.
5. The wellbore structure through a high pressure zone and a basalt collapsed zone of claim 3, comprising a fifth open-secondary tieback casing run to a top end of the fifth open-secondary liner string.
6. The wellbore structure traversing high pressure and basalt collapsed layers of claim 1, wherein the sixth open liner string is suspended from an inner wall of the fifth open liner string by a sixth open liner hanger.
7. The wellbore structure traversing high pressure and basalt collapsed layers of claim 1, wherein the first open casing string penetrates an earth surface unconsolidated layer and a leaky formation, and the second open casing string penetrates an upper shallow gas and low pressure thief layer.
8. The wellbore structure traversing a high-pressure layer and a basalt collapsed layer of claim 1, wherein the high-pressure layer comprises a high-pressure brine layer, a high-pressure mudstone formation, or a high-pressure carbonate formation.
9. The wellbore structure traversing high-pressure and basalt collapsed layers of claim 1, wherein the fifth casing string employs a straight-link tail string.
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