CN212671590U - Well bore structure in geological conditions with faults - Google Patents

Abstract

The utility model provides a well structure under the geological conditions of existence fault, this well structure includes: a first open-time casing string; the second open-time casing string is arranged in the first open-time casing string and is descended to the upper part of the first set of fault; a third open-time casing string, wherein the third open-time casing string penetrates through the first set of fault; the fourth secondary casing string is arranged in the third secondary casing string, and the fourth secondary casing string is lowered to the top of an oil-gas target layer; and the fifth opening tail pipe string is put into the oil and gas target layer and is suspended on the inner wall of the fourth opening tail pipe string. Through the utility model discloses, when having alleviated the well drilling and having met the fault, the technical problem of accidents such as lost circulation, the wall of a well collapses, the sticking of tool appears easily.

Description

Well bore structure in geological conditions with faults

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 under the geological conditions who has the fault.

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 particularity of the pressure of the stratum to be drilled and the geological conditions needs to be fully considered, different casings are used for sealing different pressure and complex strata, and possible accidents and complex risks in the well drilling process 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 complex and variable geological conditions, the drilling is often performed on faults and even multiple sets of faults, and the construction challenge on the well body structure is very large.

Areas such as the edge of the Sichuan basin, the front of the garage of the Tarim basin, the south edge of the quasi-Geer basin and the like are subjected to strong extrusion stress due to geological structures, the stratum is strongly deformed, and the fault is very developed. When a fault is encountered during drilling in ultra-deep well drilling in the regions, because rock at a fault well section is broken, the formation pore pressure is relatively low, and the formation structural stress is relatively large, serious accidents and complex conditions such as well leakage, well wall collapse, drill sticking and the like are easy to occur during drilling.

SUMMERY OF THE UTILITY MODEL

The utility model aims at providing a well body structure under the geological conditions that has the fault to when alleviating the well drilling and meeting the fault, appear the technical problem of accidents such as lost circulation, the wall of a well collapses, the sticking of a well easily.

The above object of the present invention can be achieved by the following technical solutions:

the utility model provides a well bore structure under geological conditions that has the fault, include:

a first open-time casing string;

the second open-time casing string is arranged in the first open-time casing string and is descended to the upper part of the first set of fault;

a third open-time casing string, wherein the third open-time casing string penetrates through the first set of fault;

the fourth secondary casing string is arranged in the third secondary casing string, and the fourth secondary casing string is lowered to the top of an oil-gas target layer;

and the fifth opening tail pipe string is put into the oil and gas target layer and is suspended on the inner wall of the fourth opening tail pipe string.

In a preferred embodiment, the wellbore structure comprises a third open deepened casing string that traverses a second set of faults located below the first set of faults.

In a preferred embodiment, the third opening step is to use an expanded steel pipe for the deepened casing string.

In a preferred embodiment, the third opening deepened casing string is suspended from the open hole wall suspended above the second set of faults.

In a preferred embodiment, the third open casing string is made of expanded steel pipe.

In a preferred embodiment, the third open secondary casing string is suspended from an inner wall of the second open secondary casing string.

In a preferred embodiment, the fourth split casing string comprises a fourth split tailpipe string suspended from an inner wall of the second split casing string.

In a preferred embodiment, the wellbore construction includes a fourth secondary tieback casing run-in to the top end of the fourth secondary liner string.

In a preferred embodiment, the first open-ended casing string is a ladder lock casing string.

In a preferred embodiment, the second casing string is an air tight buckle casing string.

The utility model discloses a characteristics and advantage are:

the utility model provides a well body structure under geological condition with fault, the first opening casing string is arranged on the superficial stratum, the upper loose, unstable and easily lost well section can be sealed, and the support is provided for the next well mouth installation; the second opening casing is arranged on the upper part of the first casing in series and can seal the stratum which is easy to leak shallow gas and low pressure. The third opening casing string seals the first set of fault, so that accidents such as collapse and drill sticking caused by well leakage and instability of the well wall can be avoided when the fault is drilled. And the fourth-time casing string seals the stratum with higher pore pressure at the upper part of the reservoir, so that conditions are created for further reducing drilling fluid density drilling by protecting the oil and gas reservoir in the open time. And the fifth opening tail pipe is used for serially sealing the oil-gas target layer.

Through the well body structure, the condition of drilling to an oil and gas target layer can be established, the problems of accidents such as well leakage, well wall collapse, drill sticking and the like easily occurring in well drilling caused by geological faults are solved, the oil and gas geological target under the complex geological condition can be realized, the oil and gas exploration and development requirements are met, and the economic benefit of the oil and gas exploration and development is increased.

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 well structure under geological conditions with faults according to the present invention;

fig. 2a is a schematic diagram of a well structure under geological conditions with faults and a fault matching in a stratum provided by the present invention;

FIG. 2b is a graph of a fault in the formation versus formation pore pressure;

fig. 3 is a schematic diagram of a method for constructing a well structure in a geological condition with a fault according to 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; 302. a hanger;

40. a fourth secondary casing string; 41. a fourth sub tail pipe string; 42. the fourth secondary is connected back to the sleeve; 401. a fourth secondary well section; 402. a quarto secondary tail pipe hanger;

50. fifthly, opening a tail pipe string; 501. a fifth open-hole interval; 502. a fifth secondary liner hanger;

60. thirdly, opening a deepened casing string; 601. opening a deepened well section for the third time; 602. an open hole hanger;

71. a first set of faults; 72. a second set of faults; 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.

Example one

The utility model provides a well structure under the geological conditions of existence fault can be constructed according to following construction method, 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, drilling the second open-time well section 201 to the upper part of the first casing fault layer 71, and putting a second open-time casing string 20 in for well cementation; step S30, drilling a third open-time well section 301, drilling the third open-time well section 301 through the first set of fault 71, putting the third open-time casing string 30 in, and cementing a well; step S40, drilling a fourth secondary well section 401, drilling the fourth secondary well section 401 to the top of the oil-gas target layer 73, descending a fourth secondary casing string 40, and cementing wells; and S50, drilling a fifth well opening section 501, drilling the fifth well opening section 501 to the oil-gas target layer 73, lowering the fifth well opening tail pipe string 50, and suspending the fifth well opening tail pipe string 50 on the inner wall of the fourth well opening sleeve string 40 to fix the well.

In the construction method, the first open-time casing string 10 is arranged on a superficial stratum, can seal a loose, unstable and easily lost well section at the upper part and provides support for the next well mouth installation; the second open-time casing string 20 is arranged on the upper portion of the first casing fault 71 and can seal a shallow gas and low-pressure easily-leaked stratum. The third opened casing string 30 seals the first casing fault 71, so that accidents such as collapse and drill sticking caused by well leakage and instability of the well wall can be avoided when the fault is drilled. The fourth-time casing string 40 seals the stratum with higher pore pressure at the upper part of the reservoir, and creates conditions for further reducing drilling fluid density drilling by protecting the oil and gas reservoir in the open time. The fifth primary tailpipe string 50 seals the hydrocarbon destination 73.

The well body structure can be suitable for ultra-deep wells, the condition of drilling to an oil and gas target layer 73 can be established through the well body structure establishing method, the problems of accidents such as well leakage, well wall collapse and drill sticking easily occurring in well drilling caused by geological faults are solved, the oil and gas geological target under complex geological conditions can be realized, the oil and gas exploration and development requirements are met, and the economic benefit of the oil and gas exploration and development is increased.

In step S10, a roller cone drill bit may be used for drilling, after drilling the shallow formation, the drill bit is lifted out, the first casing string 10 is lowered, cement is injected into the annulus between the first casing string 10 and the formation to perform well cementation, the upper loose, unstable and easily lost well section is sealed, and a support is provided for next wellhead installation. Specifically, the first opening casing string 10 can adopt a buttress buckle casing string, and a roller bit with the diameter of 444.5mm is used for drilling to the well depth of 500m, so that large discharge is fully circulated, rock debris in the well is carried cleanly, and the casing is ensured to be smoothly put in; and (3) pulling out the drill bit, setting the deviated ladder buckling casing string with the diameter of 365.13mm and the wall thickness of 13.88mm, injecting cement slurry to perform well cementation in an annular space between the casing and the stratum by adopting an interpolation method forward injection and backward extrusion mode, returning the cement to the wellhead, and solidifying the injected cement slurry to form a well cementation cement sheath 100.

In step S20, a roller cone or PDC drill bit may be used to drill to the upper portion of the first casing fault 71, the drill bit is pulled out, the second casing string 20 is lowered, cement is injected into the annular space between the second casing string 20 and the formation and the upper casing to fix the well, and shallow gas and low-pressure easily-lost formation are sealed. The second casing string 20 can adopt an air-tight buckle casing string, specifically, a PDC drill bit with the diameter of 333.4mm can be used, after the well is drilled to the depth of 3600m, the drill bit is taken out, a drifting drilling tool combination is replaced, full drifting is carried out, and smooth running of the casing is ensured; and (3) setting a gas-tight sealing buckle sleeve string with the diameter of 273.05mm and the wall thickness of 13.84mm, injecting cement into the annular space between the sleeve and the stratum and between the sleeve and the upper layer sleeve in a double-rubber-plug double-density mode for cementing, returning the cement to a wellhead, and sealing the upper gas layer and the low-pressure stratum easy to leak.

In an embodiment of the present invention, the constructing method includes step S60 between step S30 and step S40, and step S60 includes: and drilling a third opened deepened well section 601, drilling the third opened deepened well section 601 through a second set of fault 72 below the first set of fault 71, and putting the third opened deepened casing string 60 into the well to fix the well. As shown in fig. 2a, the inner diameter of the first split casing string 10, the inner diameter of the second split casing string 20, the inner diameter of the third split casing string 30, the inner diameter of the third split deepened casing string 60, the inner diameter of the fourth split casing string 40, and the inner diameter of the fifth split tailpipe string 50 are sequentially decreased. The third opening deepens the casing string 60 to seal the second casing fault 72, so that accidents such as collapse and drill sticking caused by well leakage and instability of the well wall during fault drilling can be avoided. By using the construction method, a six-opening-time well bore can be constructed, and the third opening-time casing string 30 and the third opening-time deepened casing string 60 are used for respectively sealing faults.

The fault well section rock is broken, the stratum pore pressure is relatively low, the stratum structure stress is large, and accidents such as well leakage, well wall collapse and drill sticking are easy to occur in well drilling, so that one or more layers of casings are required to be specially put into the well body structure to seal the fault well section. If complex geological conditions of a plurality of sets of faults exist, a casing is respectively put into each set of fault to seal off a fault well section, the condition that the casing layer of a well body structure is not enough or the size of a well completion casing is too small easily occurs, the oil and gas geological discovery or exploitation requirements cannot be met, the oil and gas geological target cannot be realized, and the oil and gas exploration and development process is severely restricted. Referring to the formation pore pressure profile 81 of FIG. 2b, the pressure at each depth of the formation 80 varies significantly with the presence of faults.

In step S30, the third open casing string 30 may be installed on the wellhead or may be installed in a suspended manner.

Preferably, the third opened casing string 30 is made of expanded steel pipe, and the expanded steel pipe has a larger inner diameter, so that the number of casing layers below the expanded steel pipe can be increased conveniently. Specifically, cement is injected into annular spaces between the expansion steel pipe and the ground layer and between the expansion steel pipe and the upper casing pipe, drilling fluid is then injected into the expansion steel pipe, the expansion steel pipe is pressed and expanded in a hydraulic or mechanical mode, an artificial well wall is formed, and the first casing fault 71 is sealed. The expansion steel pipe can be formed by connecting multiple sections of expansion steel pipe bodies with the length of about 10 meters, both ends of each section of expansion steel pipe body are provided with threads, and two adjacent sections of expansion steel pipe bodies are connected through the threads. The expansion steel pipe body and the threaded connection structure keep the sealing performance and higher strength before expansion, in the expansion process and after expansion, and the inner diameter of the expansion steel pipe after expansion meets the requirement of passing a drill bit and a drilling tool combination under the condition of opening. As shown in fig. 2a, the third open-ended casing string 30 is suspended on the inner wall of the second open-ended casing string 20, which is beneficial to reducing the one-time height return of the annular injection cement outside the third open-ended casing string 30 and reducing the casing usage amount.

Drilling the third open-time well section 301 in the step S30, and using a reamer while drilling to enlarge the diameter of the well hole by more than 10%, so that the annular space between the third open-time casing string 30 and the stratum is increased, the well cementation quality is improved, the lower open-time casing string with larger diameter is convenient to run; and the upper opening times can adopt a borehole and a casing with a smaller diameter, which is beneficial to improving the drilling speed of the drill bit, reducing the drilling construction period and saving the consumption of the casing and cement slurry. Specifically, in step S30, a reamer of PDC or roller cone drill bit may be used to drill through the first casing string 71, while the borehole diameter is enlarged by more than 10%, the drill bit is lifted out, the third open-ended casing string 30 of the matched size is run in, the top of the third open-ended casing string 30 is connected to a suspension device, and the third open-ended casing string 30 is suspended on the inner wall of the second open-ended casing string 20.

Preferably, the third opening deepens the casing string 60 and adopts an expanded steel pipe, and the inner diameter of the expanded steel pipe is larger, so that the casing layers below the expanded steel pipe can be increased. Specifically, cement is injected into the annular space between the expansion steel pipe and the ground layer and the annular space between the expansion steel pipe and the upper casing, drilling fluid is then injected into the expansion steel pipe, the expansion steel pipe is pressed and expanded in a hydraulic or mechanical mode, an artificial well wall is formed, and the second casing fault 72 is sealed. The expansion steel pipe can be formed by connecting multiple sections of expansion steel pipe bodies with the length of about 10 meters, both ends of each section of expansion steel pipe body are provided with threads, and two adjacent sections of expansion steel pipe bodies are connected through the threads. The expansion steel pipe body and the threaded connection structure keep the sealing performance and higher strength before expansion, in the expansion process and after expansion, and the inner diameter of the expansion steel pipe after expansion meets the requirement of passing a drill bit and a drilling tool combination under the condition of opening. As shown in fig. 2a, the third deepened casing string 60 is suspended above the second set of faults 72 in the open hole wall, which is beneficial to making the third deepened casing string 60 more stably installed and the construction process simpler. The third opening deepened well section 601 is drilled in the step S60, and the diameter of the well bore is enlarged by more than 10% by using the reamer while drilling, so that the annular space between the third opening deepened casing string 60 and the stratum is increased, the well cementation quality is improved, the lower opening is facilitated, and the casing string with larger diameter is fed in. Specifically, a reamer of a PDC or roller cone drill bit may be used to drill through the second set of faults 72, simultaneously enlarge the diameter of the wellbore by more than 10%, pull out the drill bit, run in a third opening deepening casing string 60 of a matched size, connect the top of the third opening deepening casing string 60 with an open hole suspension device, and suspend the third opening deepening casing string 60 in the open hole wall above the second set of faults 72.

Furthermore, the third opened casing string 30 and the third opened deepened casing string 60 both adopt expanded steel pipes, in the construction method, the third opened casing string 30 and the third opened deepened casing string 60 respectively seal the first set of fault 71 and the second set of fault 72, so that accidents such as collapse and drill sticking caused by well leakage and instability of the well wall can be avoided during fault drilling; the expanded steel pipe has larger inner diameter after expansion, so that the size of the casing below the expanded steel pipe can be conveniently increased, and the casing level of a well structure below the expanded steel pipe can be increased; the opening times above the expansion steel pipe can adopt a borehole and a casing pipe with smaller diameter, which is beneficial to improving the drilling speed of the drill bit, reducing the drilling construction period and saving the consumption of the casing pipe and cement slurry.

Step S30 and step S60 are performed in sequence, in a specific embodiment, the third open sub string 30 is made of expanded steel pipe, and step S30: drilling through a first set of fault 71 by using a drill-following reamer of a phi 241.3mm PDC drill bit to reach the well depth of 4500m, simultaneously expanding the diameter of a well hole to 273mm, pulling out the drill bit, replacing the drill bit with a drifting drilling tool combination, fully drifting and ensuring that an expansion steel pipe is smoothly put in; an expansion steel pipe with the outer diameter phi 219m and the wall thickness of 12mm is put to the bottom of the well, the top of the expansion steel pipe is connected with a hanger 302, and the expansion steel pipe is hung on the inner wall of the second opening casing string 20; and injecting cement into the annular space between the expanded steel pipe and the stratum and between the expanded steel pipe and the upper casing string, injecting drilling fluid into the expanded steel pipe to pressurize and expand the expanded steel pipe, wherein the inner diameter of the expanded steel pipe reaches phi 220mm after expansion, waiting for setting of the annular cement, and sealing the first set of fault 71. The third opening deepened casing string 60 adopts an expanded steel pipe, and the step S60: drilling through the second set of fault 72 by using a drill reamer of a phi 215.9mm PDC drill bit to the well depth of 5200m, simultaneously expanding the diameter of the well hole to 241mm, pulling out the drill bit, replacing the drill bit with a drifting drilling tool combination, fully drifting and ensuring that the expanded steel pipe is smoothly lowered; an expansion steel pipe with the outer diameter phi 194mm and the wall thickness of 11mm is put in series to the bottom of the well, the top of the expansion steel pipe is connected with an open hole hanger 602, and the expansion steel pipe is hung on the open hole well wall above the second set of fault 72; and injecting cement into the annular space between the expansion steel pipe and the stratum, injecting drilling fluid into the expansion steel pipe to pressurize and expand the expansion steel pipe, enabling the inner diameter of the expanded steel pipe to reach phi 196mm after expansion, waiting for setting of the annular cement, and sealing the second set of fault 72.

The fourth sub string 40 may be installed uphole or may be suspended. With the fourth sub string 40 installed uphole, the fourth sub string 40 may be casing extending from downhole to uphole of the fourth sub section 401. With fourth split casing string 40 disposed in a suspended manner, fourth split casing string 40 includes fourth split tailpipe string 41, and fourth split tailpipe string 41 may be suspended from the inner wall of second split casing string 20.

As shown in fig. 2a and 2b, fourth split casing string 40 is preferably arranged in a suspended manner, a high pore pressure formation below the formation is drilled using a PDC or roller cone drill bit, the formation is drilled to the top of an oil and gas target 73, the drill bit is tripped out, fourth split tailpipe string 41 is run in to the bottom of the well, the top of fourth split tailpipe string 41 is connected to fourth split tailpipe hanger 402, fourth split tailpipe string 41 is suspended from the inner wall of second split casing string 20, and cement is injected into the annulus between fourth split tailpipe string 41 and the formation and upper casing for cementing. Specifically, a phi 190.5mm PDC drill bit is used for drilling the stratum at the lower part of the second set of fault 72, after the stratum is drilled to the well depth of 6700m, the drill bit is taken out, a drifting drilling tool combination is replaced, full drifting is carried out, and the fourth sub tail pipe string 41 is ensured to be smoothly put in; a fourth sub tail pipe string 41 with the diameter of 168.28mm, the wall thickness of 12.07mm and an air sealing buckle is put to the bottom of the well; the top of fourth split tail pipe string 41 is connected to fourth split tail pipe hanger 402, and fourth split tail pipe string 41 is hung on the inner wall of second split casing string 20 at a well depth of 3400 m. And injecting cement into the annular space between the fourth secondary tail pipe string 41 and the stratum and the upper casing for cementing, returning the cement to the position of the four secondary tail pipe hanger 402 at the top of the fourth secondary tail pipe string 41, and sealing the stratum with relatively high pore pressure at the upper part of the reservoir, thereby creating conditions for further reducing drilling fluid density drilling for protecting the oil and gas reservoir in the open time. The fourth secondary tail pipe string 41 adopts a tail pipe suspension technology, so that the one-time height return of annular cement injection is effectively reduced, the situation that the ground surface pump pressure is too high during annular cement injection of the fourth secondary tail pipe string 41 leaks a lower stratum to cause well leakage complexity is avoided, meanwhile, the weight of a casing pipe can be reduced by adopting tail pipe suspension, the well depth of the tail pipe in the well can be increased, and the deeper complex stratum is sealed.

Further, in the case where the fourth sub-casing string 40 is arranged in a suspended manner, the construction method includes step S70 provided after step S50, and step S70 includes: and (5) running a fourth secondary tieback casing 42 to the top end of the fourth secondary tail pipe string 41, and cementing. During construction, the fourth secondary tieback casing 42 is put in the position of the fourth secondary tail pipe hanger 402 at the top of the fourth secondary tail pipe string 41, and cement is injected into the annular space between the fourth secondary tieback casing 42 and the second open-secondary casing string 20 to perform well cementation. Specifically, 168.28mm fourth-time tieback casing 42 is put in, the fourth-time tieback casing 42 is put in the position of the fourth-time tail pipe hanger 402 at the top of the fourth-time tail pipe string 41 in depth, and cement is injected into the annular space between the fourth-time tieback casing 42 and the second open-time casing string 20 for cementing.

After the fourth open-time tail pipe string 41 is suspended for well cementation, casing tieback is not carried out, tieback operation of the fourth open-time tieback casing 42 is carried out after the fifth open-time tail pipe string 50 is suspended for well cementation, the gap of a drilling tool combination in the air above the four open-time tail pipe hanger 402 at the top of the fourth open-time tail pipe string 41 when the fifth open-time well section 501 is drilled is increased, the drilling fluid circulation equivalent density when a small well hole in the fifth open-time well section 501 is drilled is reduced, and therefore the risk of complicated well leakage of a target layer is reduced.

In step S50, a PDC or roller cone drill bit may be used to drill to the well depth of the oil-gas target layer 73, the drill bit is lifted out, the fifth open-time liner string 50 is lowered, the top of the fifth open-time liner string 50 is connected to the fifth open-time liner hanger 502, the fifth open-time liner string 50 is suspended on the inner wall of the fourth open-time liner string 41, and cement is injected into the annular space between the fifth open-time liner string 50 and the formation and upper casing to perform well cementation and seal the oil-gas target layer 73. Specifically, drilling to a target layer by using a phi 139.7mm PDC drill bit, pulling out the drill bit after the footage reaches 200m, changing into a drifting drilling tool combination, fully drifting, and ensuring that the fifth-opening tail pipe string 50 is smoothly lowered; setting a fifth-opening secondary tail pipe string with the diameter of 114.3mm, the wall thickness of 8.56mm and the air-tight sealing and tail buckling depth of 50-7000 m; the top of the fifth open secondary tail pipe string 50 is connected with a fifth open secondary tail pipe hanger 502, the fifth open secondary tail pipe string 50 is hung on the inner wall of the fourth open secondary tail pipe string 41, the well depth is 6500m, cement is injected into the annular space between the fifth open secondary tail pipe string 50 and the ground and the upper casing pipe to perform well cementation, and the cement returns to the position of the fifth open secondary tail pipe hanger 502 of the fifth open secondary tail pipe string 50 to seal the oil and gas target layer 73. After the fourth tieback operation of tieback casing 42 is completed, the operation is shifted to a fifth perforating completion operation of opening secondary tail pipe string 50.

The fifth-start liner string 50 adopts a liner hanging well cementation technology, a casing is not connected back, the one-time height return of 50 annular cement of the fifth-start liner string is reduced, the situation that the well leakage of a target layer is complex due to overhigh ground pump pressure during the annular cement injection of the fifth-start liner string 50 is favorably avoided, the using amount of the casing is reduced, and the cost is saved.

The construction method is suitable for complex geological conditions of one or more faults existing in a deep stratum, can be widely applied to the field of drilling of ultra-deep wells of oil and gas fields of fault development of the deep stratum, and improves the comprehensive benefits of oil and gas exploration and development. By applying the construction method, accidents and complex conditions such as well leakage, collapse, drill sticking and the like can be effectively avoided during fault drilling; the casing layer is added, and the problem that the casing layer of the well structure is not enough due to geological faults is solved; and the drilling construction period can be shortened, the using amount of the casing pipe is reduced, the oil-gas target layer 73 can be safely and quickly drilled, the oil-gas geological target under the complex geological condition is realized, and the economic benefit of oil-gas exploration and development is increased.

Example two

The utility model provides a well structure under the geological conditions of fault exists, as shown in figure 1 and figure 2a, this well structure includes: the second casing string 20 is arranged in the first casing string 10, and the second casing string 20 is lowered to the upper part of the first casing fault 71; the third open-time casing string 30 penetrates the first casing layer 71; the fourth sub-casing string 40 is arranged in the third sub-casing string 30, and the fourth sub-casing string 40 is lowered to the top of the oil-gas target layer 73; the fifth primary liner string 50 is lowered into the oil and gas destination 73, and the fifth primary liner string 50 is suspended from the inner wall of the fourth secondary casing string 40.

The first open-time casing string 10 is arranged on a superficial stratum, can seal 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 is arranged on the upper portion of the first casing fault 71 and can seal a shallow gas and low-pressure easily-leaked stratum. The third opened casing string 30 seals the first casing fault 71, so that accidents such as collapse and drill sticking caused by well leakage and instability of the well wall can be avoided when the fault is drilled. The fourth-time casing string 40 seals the stratum with higher pore pressure at the upper part of the reservoir, and creates conditions for further reducing drilling fluid density drilling by protecting the oil and gas reservoir in the open time. The fifth primary tailpipe string 50 seals the hydrocarbon destination 73.

By adopting the well body structure, the problems of well leakage, well wall collapse, drill sticking and other accidents easily occurring in well drilling caused by geological faults are relieved, the requirements of oil-gas exploration and development are met, an oil-gas geological target under complex geological conditions can be realized, and the economic benefit of the oil-gas exploration and development is increased.

In an embodiment of the present invention, the wellbore structure includes a third opening deepening casing string 60, and the third opening deepening casing string 60 runs through a second set of faults 72 located below the first set of faults 71.

Specifically, the well bore structure further comprises a well cementing cement sheath 100 for cementing a first casing string 10, a second casing string 20, a third casing string 30, a third casing string 60, a fourth casing string 40 and a fifth casing string 50.

In an embodiment of the present invention, the third open-ended casing string 30 is an expanded steel pipe.

In an embodiment of the present invention, the third open-ended sleeve string 30 is suspended on the inner wall of the second open-ended sleeve string 20.

In an embodiment of the present invention, the third opening deepens the casing string 60 and uses an expanded steel pipe.

In an embodiment of the present invention, the third opening deepens the casing string 60 and hangs on the open hole well wall above the second casing layer 72

In an embodiment of the present invention, fourth split casing string 40 includes fourth split tail pipe string 41, and fourth split tail pipe string 41 is suspended from the inner wall of second split casing string 20.

Further, the wellbore configuration includes a fourth sub casing 42, and fourth sub casing 42 is run into the top of fourth sub tailpipe string 41.

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 (10)

1. A well structure in a geological condition in which a fault exists, comprising:

a first open-time casing string;

the second open-time casing string is arranged in the first open-time casing string and is descended to the upper part of the first set of fault;

a third open-time casing string, wherein the third open-time casing string penetrates through the first set of fault;

the fourth secondary casing string is arranged in the third secondary casing string, and the fourth secondary casing string is lowered to the top of an oil-gas target layer;

and the fifth opening tail pipe string is put into the oil and gas target layer and is suspended on the inner wall of the fourth opening tail pipe string.

2. A well structure in a faulted geological condition according to claim 1, characterized in that it comprises a third cut deepened casing string which penetrates a second set of faults located below the first set of faults.

3. The faulted geological condition wellbore construction of claim 2 wherein said third cut deepens the casing string with expanded steel tubing.

4. The faulted geological condition wellbore structure of claim 2, wherein the third cut deepens the casing string from suspending the open hole wellbore wall above the second set of faults.

5. The faulted geological condition wellbore structure of claim 1, wherein said third open-ended casing string is comprised of expanded steel tubing.

6. The faulted geological condition wellbore structure of claim 1, wherein said third open casing string is suspended from an inner wall of said second open casing string.

7. The faulted geological condition wellbore structure of claim 1, wherein the fourth split casing string comprises a fourth split tailpipe string suspended from an inner wall of the second split casing string.

8. The faulted geological condition well bore structure of claim 7, comprising a fourth secondary tieback casing run-in to the top of the fourth secondary liner string.

9. The faulted geological condition wellbore structure of claim 1, wherein the first open casing string is a ladder lock casing string.

10. The faulted geological condition wellbore structure of claim 1, wherein the second open casing string is a gas tight buckle casing string.

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