CN104471178A - Method and system for sealing an annulus around a tubular element - Google Patents

Abstract

The present invention relates to a method and system for sealing an annulus surrounding a tubular element in a wellbore. The method comprises the following steps: i) introducing a first drilling fluid into the wellbore; ii) drilling an open hole section of the wellbore using a drilling tool suspended at the end of the tool string; iii) pumping a second drilling fluid comprising particles into the wellbore; iv) filtering particles from the second drilling fluid near the downhole end of the tubular element; v) extending the tubular element into an open hole section of the wellbore while simultaneously directing at least a portion of the filtered particles to an annulus between the tubular element and a wall of the wellbore. Steps i) to v) may be repeated as many times as desired.

Description

Method and system for sealing an annulus around a tubular element

technical field

The present invention relates to a system and method for sealing an annulus surrounding a tubular element. The system and method can be applied to zonal isolation along a liner in a wellbore.

Background technique

The technique of radially expanding tubular elements finds increasing application in the industry for the production of oil and gas from subterranean formations. The wellbore is typically provided with one or more casings or liners to provide stability to the wellbore wall and/or to provide zonal isolation between different earth formations. The terms "casing" and "liner" refer to tubular elements used to support and stabilize the walls of a wellbore. Typically, the casing extends from the surface into the wellbore, while the liner extends further into the wellbore from a certain depth. However, in the context of this document, the terms "casing" and "liner" are used interchangeably without any specific distinction.

In conventional wellbore configurations, several casings are spaced at different depths and placed in a nested arrangement. Here, each subsequent casing is run through the preceding casing and therefore has a smaller diameter than the preceding casing. As a result, the cross-sectional area of the wellbore available for hydrocarbon production decreases with increasing depth.

To alleviate this deficiency, one or more tubular elements may be radially expanded at a desired depth in the wellbore, for example, to form an expanded casing, an expanded liner, or a wrap against an existing casing or liner. layer. Furthermore, it has been proposed to radially expand each subsequent casing so that its diameter is substantially equal to that of the preceding casing, thereby forming a single diameter wellbore. Thus, it is achieved that the usable diameter of the wellbore remains substantially constant along its depth (section) compared to conventional nested arrangements.

WO-2008/006841 discloses a wellbore system for radially expanding a tubular element in a wellbore. The walls of the tubular element are caused to bend radially outward and in axially opposite directions to form an expanded section extending around the unexpanded section of the tubular element. The length of the expanded tubular section is increased by moving (eg, forcing or pushing) the unexpanded section into the expanded section. Here, the expanded section maintains the expanded tubular shape. At its top end, the unexpanded section may be expanded, for example, by adding tube sections or by unwinding, folding and welding the sheet material to form a tubular shape.

When using the system of WO-2008/006841 to line a wellbore, the annulus between the expanded tubular element and the wellbore wall is relatively small compared to conventional casing systems. The expanded tubular section will be in close proximity to or even engage the wellbore wall. As a result, it is not possible to perform conventional cementing operations, which are typically used to establish zonal isolation when conventional casings in a nested arrangement are used.

In conventional cementing operations, when cementing the liner, pumping can be used to form the Consolidated mud. Otherwise, cement slurry may be pumped through the inner fluid passage of the casing while remaining between the two cement plugs.

Since the annulus between the inverted tubing and the borehole is relatively small when using the system of WO-2008/006841, a relatively high differential pressure is required to pump the cement slurry into the annulus. Also, pumping cement slurry into the small annulus may result in non-uniform filling of the annulus. Additionally, the everted tube may engage the borehole wall along at least a portion of its length such that the annulus may lack a continuous flow path from its downhole end to the surface. When the inverted tubular member engages the borehole wall along a certain length and thereby establishes zonal isolation, it will be impossible for circulating fluid or cement slurry to flow through the annulus.

Contents of the invention

The present invention aims to overcome the above-mentioned problems.

Accordingly, the present invention provides a method for sealing an annulus surrounding a tubular element in a wellbore, wherein the tubular element is an expandable tubular element surrounding a tool string, wherein the wall of the expandable tubular element The downhole end portion is bent radially outward and in an axially opposite direction to define an expanded tubular section extending around the unexpanded tubular section, the method comprising the steps of:

i) introducing a first drilling fluid into the wellbore;

ii) drilling an open hole section of the wellbore using a drilling tool suspended at the end of the tool string;

iii) pumping a second drilling fluid comprising particles into the wellbore;

iv) filtering particles from the second drilling fluid near the downhole end of the tubular element;

v) extending the tubular element into the open hole section by pushing the unexpanded tubular section into the expanded tubular section while at the same time directing at least a portion of the filtered particles into the gap between the expanded tubular section and the borehole wall annulus.

The method of the present invention does not require circulating cement through the annulus. This method also enables the sealing of the annulus in combination with a system for expanding the liner in the wellbore by everting the liner. Also, for example in the case where said annular space between said casing and surround is too small to allow pumping of cement slurry or where said cement slurry is pumped at a pressure exceeding the maximum output pressure of the available pumping equipment In this case, the method of the invention is suitable for isolating an annulus surrounding a conventional casing.

In one embodiment, steps i) to v) are repeated as often as desired. For example, frequency repetition as needed provides adequate interlayer isolation in the annulus. Also, the entire annulus can be filled with particulate matter.

In another embodiment, the step of filtering out particles comprises moving a drill string provided with a filter member uphole until said filter member engages the downhole end of the tubular member.

The step of introducing the first drilling fluid into the wellbore may comprise moving the drill string provided with the filter member downhole until the filter member is disengaged from the downhole end of the tubular member.

Alternatively, the particles may be at least partially ferromagnetic, wherein the step of filtering out the particles comprises arranging a magnet at the downhole end of the tubular member to attract at least a portion of the particles.

By moving the unexpanded tubular section downwardly relative to the expanded tubular section, the tubular element is effectively turned inside out. The tubular element is gradually expanded without an expander being pushed, pulled or pumped through the tubular element. The expanded tubular section may form a casing or liner in the wellbore. The expanded tubular liner may have a collapse resistance suitable for stabilizing or supporting the wellbore wall.

Preferably, the wall of the tubular element comprises a material which is plastically deformable during expansion. The expanded tubular section will retain the expanded shape due to plastic deformation (ie, permanent deformation) of the walls of the expandable tubular element. No external force or pressure needs to be applied to maintain the expanded tubular section in its expanded form. For example, if the expanded tubular section engages the borehole wall, no additional radial force or pressure needs to be applied to hold the expanded tubular section against the borehole wall.

The wall of the tubular element may comprise metal such as steel or any other ductile material capable of being plastically deformed by eversion of the tubular element. The expanded tubular section preferably has sufficient collapse resistance to support or stabilize the borehole wall. Depending on the respective formation, the collapse resistance of the expanded tubular section may exceed, for example, 100 bar to 150 bar. The crush resistance may be in the range of, for example, 200 bar to about 1600 bar or greater, such as in the range of about 400 bar to 800 bar or greater.

Suitably, the bending region is caused to move in an axial direction relative to the remaining tubular section by moving the remaining tubular section in an axial direction relative to the expanded tubular section. For example, the expanded tubular section is axially fixed in position and the unexpanded tubular section is moved through the expanded tubular section in the axial direction in order to induce bending of the wall.

In order to induce said movement of the remaining tubular sections, the remaining tubular sections are subjected to an axial compressive force for inducing said movement. The axial compressive force is preferably derived at least in part from the gravity of the remaining tubular section. The pushing means may induce said movement by applying additional external force to the remaining tubular section to supplement the weight of the unexpanded tubular section. The additional force applied by the pusher can be upward or downward. For example, as the length, and thus weight, of the unexpanded tubular section increases, it may be necessary to apply an upward force to the unexpanded tubular section in order to maintain the total force applied to the unexpanded section within a predetermined range. Keeping the total force within said range will prevent uncontrolled bending or buckling of the flexure region.

If the bending zone is at the lower end of the tubular element, whereby the remaining tubular section is axially shortened at its lower end due to the movement of said bending zone, it is preferred that the remaining tubular section corresponds to said The axial shortening extends axially at its upper end. The remaining tubular section is progressively shortened at its downhole end due to continuous reverse bending of the wall. Thus, the process of wall reverse bending can be continued until the desired length of the expanded tubular section is reached by extending the remaining tubular section at its upper end to compensate for its shortening at the lower end. The remaining tubular section is enabled to extend at its upper end, eg by connecting the tubular portion to the upper end in any suitable way, such as welding. Alternatively, the remaining tubular sections can be provided as continuous tubing unwound from a spool and subsequently inserted into the wellbore.

Optionally, the bending zone can be heated to facilitate bending of the tubular wall.

Description of drawings

The present invention will be described in detail below by way of example with reference to the accompanying drawings, in which:

Figure 1 shows a vertical cross-section of the lower part of the system for radially expanding a tubular element;

Figure 2 shows a vertical cross-section of an example of an upper part of the system of Figure 1;

Figure 3 shows a vertical cross-section of another example of the upper part of the system of Figure 1;

Figure 4 shows a vertical cross-section of a borehole representing a first step in the method according to the invention;

Figure 5 shows a vertical cross-section of a borehole representing the second step in the method according to the invention;

Figure 6 shows a vertical cross-section of a borehole representing a third step in the method according to the invention;

Figure 7 shows a vertical cross-section of a borehole representing the fourth step in the method according to the invention;

Figure 8 shows a vertical cross-section of one embodiment of a system for use in a method according to the invention;

Figure 9 shows a vertical cross section of another embodiment of a system for use in a method according to the invention;

Figure 10 shows a vertical cross-section of yet another embodiment of a system for use in a method according to the invention;

Figure 11 shows a vertical cross-section of one embodiment of a filter for use in a method according to the invention in a first position; and

Figure 12 shows a vertical cross-section of the filter of Figure 11 in another position.

Detailed ways

In the drawings and description, the same reference numerals refer to the same parts.

FIG. 1 shows a borehole 1 formed in a subterranean formation 2 . A radially expandable tubular element 4 , such as an expandable steel liner, extends from the surface 6 down into the wellbore 1 . The tubular element 4 comprises an unexpanded tubular section 8 and a radially expanded tubular section 10 . The unexpanded section 8 extends within the expanded section 10 . Preferably, the outer diameter of the expanded tubular section 10 is substantially equal to the diameter of the borehole 1 .

Although the borehole shown in Figure 1 extends vertically into the formation 2, the invention is equally applicable to any other borehole. For example, the borehole 1 may extend at least partially along a horizontal direction. In the following, the upper end of the borehole refers to the end at the surface 6 and the lower end refers to the downhole end.

At its lower end, the wall of the unexpanded section 8 bends radially outwards and in an axially reversed (upward in FIG. 1 ) direction so as to form a curved downhole section 12, thereby defining the curved region of the tubular element 4. 14. The curved section 12 is U-shaped in cross-section and interconnects the unexpanded section 8 and the expanded section 10 .

A drill string 20 may extend from the surface through the unexpanded liner section 8 to the lower end of the wellbore 1 . The downhole end of the drill string 20 is provided with a drill bit 22 . The drill bit includes, for example, a directional drill bit 24 having an outer diameter slightly smaller than the inner diameter of the unexpanded liner section 8; and a reamer section 26 whose outer diameter is adapted to drill the wellbore 1 to its nominal diameter. The reamer section 26 may be retracted radially to a smaller outer diameter, allowing it to pass through the unexpanded liner section 8 so that the drill bit 22 can be retrieved through the unexpanded liner section 8 to the surface. The drill string 20 may include a multi-section drill pipe section 28 . The drill pipe sections 28 may be interconnected at respective ends by male and female connections 30 . The annular space 32 between the drill string 20 and the unexpanded tubular element 8 is referred to as the drilling annulus 32 .

Although not shown in detail, the connector 30 includes, for example, a threaded male and female connector. Connector 30 may comprise a male threaded sub at each end, wherein a short length of coupling member (not shown) with female threads is used to join together with the respective subs of the drill string, or with a Joints with male threads on one end and female threads on the other end are joined together. The threaded connection may comprise a connection standardized by the American Petroleum Institute (API).

FIG. 1 also shows a drill floor 40 which is raised relative to the surface 6 and surrounds the upper end of the drill string 20 and the upper end of the unexpanded tubular section 8 . Drill floor 40 is part of a drilling rig, however not fully shown. A pipe jacking machine 42 , for example arranged below the drill floor, surrounds the unexpanded section 8 . The pipe jacking machine is supported by the chassis 43, for example. The underframe 43 provides stability and may eg be connected to a drilling rig or supported on the ground surface 6 . The pipe jacking machine may comprise one or more motors 46 arranged on the chassis and one or more conveyor belts 48 capable of being driven by respective motors. Each belt 48 engages the outside of the unexpanded section 8 . The conveyor belt 48 is able to apply a force to said unexpanded section 8 in order to force the movement of the unexpanded section into the expanded section 10 . Other embodiments of the pipe jacking machine 42 capable of applying downward or upward force to the unexpanded section are contemplated.

A sealing device 50 is connectable to the upper end of the expanded liner section 10 in order to seal the unexpanded liner section 8 relative to the expanded liner section 10 . Here, the sealing device 50 enables the unexpanded liner section 8 to slide relative to the sealing device 50 in the axial direction. The sealing arrangement includes a conduit 52 connected to a pump (not shown) for pumping fluid into the blind annulus 44 (ie, the annulus between the unexpanded liner section 8 and the expanded liner section 10 ). Alternatively the fluid is pumped out of the blind annulus 44 . The annulus 44 is referred to as a blind annulus because it is closed at the downhole end by the curved region 14 . The sealing arrangement comprises one, two or more annular seals 56,58. Seals 56, 58 engage the outside of the unexpanded section 8 and prevent the fluid from leaving the blind annulus. Preferably, the sealing arrangement 50 comprises at least two seals 56, 58 in order to provide at least one additional seal for increased safety and reliability in the event of possible failure of the first seal.

The sealing device 50 can be considered as a blind annular blowout preventer (BABOP). Accordingly, the seals 56, 58, the connection connecting the sealing device 50 to the upper end of the expanded section 10, and the valve or valves (not shown) used to close the conduit 52 will all be designed to withstand at least Fluid pressure developed in controlled conditions. Depending on the formation, the seal 50 is for example designed to withstand pressures which, in the event of a blowout, can be expected to be, for example, in the range of 200 bar to 1600 bar, for example approximately 400 bar to 800 bar or more. In conjunction with well control situations, such pressures can be generated, for example in the blind annulus 44 , in the event of failure, for example due to breakage of the expandable tubular member 4 .

The expanded liner section 10 is axially secured against axial movement by any suitable securing means. The expanded liner section 10 may be fixed at the surface at its upper end. For example, the upper end of the expanded section may be connected to a ring or flange 59, eg by welding and/or screwing. The ring can be attached to or integrated in any suitable structure at the surface, such as the seal 50 . The inner diameter of the ring may be larger than the outer diameter of the expanded section. Alternatively, the expanded section 10 may be secured to the borehole wall 224, for example, by virtue of friction between the expanded liner section 10 and the borehole wall 224 as a result of the expansion process. Alternatively or additionally, the expanded liner section 10 can be anchored, for example to the borehole wall, by any suitable anchoring means.

At the interface indicated by the line II-II, the lower part of the system shown in FIG. 1 can be connected to the upper part as shown in FIGS. 2 and 3 .

Figure 2 shows the top drive 60 connected to an upper end connection part 62 which is rotatable relative to the top drive. Preferably, the upper end connection part comprises a collarless tube having a smooth outer surface. The end 64 of the connection part remote from the top drive is provided with a threaded connection 30 as described above. Threaded end 64 is connected to other drill string sections 66 . Generally, other drill string sections 66 will be substantially identical to drill string sections 28, as shown in FIG. 1 . At the interface shown by line II, other drill pipe sections 66 can be connected to the upper end of the drill string 20 shown in FIG. 1 .

The drilling annulus seal 70 may cover the top end of the drilling annulus 32 . The sealing device 70 comprises a housing 72 which surrounds the connection part 62 and provides an inner space 74 . At the top end, near the top drive 60 , the housing may include one, two or more seals 76 , 78 that engage the outside of the tube 62 . Preferably, the seals 76 , 78 enable the housing to slide along the tube 62 . At opposing ends, the housing may include one, two or more seals 80 , 82 that engage the outside of the other expandable tube section 84 . In addition to the seal, the housing may also include grippers 106 that may engage the outside and/or inside of the pipe segment 84 . An activation line 88 is connected to the housing for activating or releasing the seals 80 , 82 and/or the retainer 106 . A fluid conduit 90 is connected to the interior space 74 for supplying or draining fluid (drilling fluid) into and out of the annular space 32 .

The sealing device 70 may include an extension piece or insertion tube 100 . The insertion tube extends inside the other expandable tube section 84 . The insertion tube may include seals 102 , 104 and/or a retainer 106 to engage the upper end of the tube segment 84 . The insertion tube may also include a seal 108 to engage the lower end of the tubular section 84 and a seal 110 to engage the interior of the upper end of the unexpanded tubular section 8 (shown in FIG. 1 ). A backing gas tool 198 may be incorporated in the insertion tube between the seals 108,110. The backup gas tool covers the inner interface between the other expandable tubular section 84 and the unexpanded tubular section 8 .

The insertion tube may be at least slightly longer than the tube section 84 so that the insertion tube may extend into the unexpanded section 8 which will enable the insertion tube to be used as an alignment tool for aligning the tube section 84 and the unexpanded section 8 .

In practice, the length of the pipe section 84 may be in the range of about 5-20 meters, for example about 10 meters. The insertion tube will, for example, be about 2% to 10% longer than the tube section 84, for example 5% longer. An annular space 112 is provided between the insertion tube and the tube 62 to provide a fluid connection from the annulus 32 to the space 74 and the conduit 90 .

Sealing device 70 may be referred to as a drilling annulus blowout preventer (DABOP) 70 . Seals 76-82, retainer 106 and one or more valves (not shown) used to close conduits 88 and 90 will all be designed to withstand at least the fluid pressures that may arise in a well control situation. The drilling annulus blowout preventer 70 is designed, for example, to withstand a pressure in the range of about 200 bar to 800 bar or more, for example about 400 bar, depending on the specific conditions of the formation and the expected maximum pore pressure.

The drilling annulus blowout preventer may include any number of seals. Drilling annulus blowout preventer 70 may include one seal 76 and one seal 80, or multiple seals. In a practical embodiment, two seals 76, 68 sealing the tube 62 and two seals sealing the tubular section 84 would provide, for example, a balance between failure-safety and reliability on the one hand and cost on the other. balance between. For example, the dual protection provided by the inner seals 102 , 104 engaging the interior of the expandable tube 84 and the outer seals 80 , 82 engaging the exterior of the expandable tube 84 enhances the reliability and tightness of the sealing device 70 .

FIG. 3 shows the upper part of the system of FIG. 1 . The unexpanded liner segment 8 is formed at its upper end from a (metal) sheet 130 wound on a mandrel 132 . The metal sheet 130 has opposing edges 133 , 134 . After unwinding from the reel 132, the metal sheet 130 is bent into a tubular shape and the edges 133, 134 are interconnected, for example by welding, so as to form the unexpanded tubular section 8. As a result, the expandable tubular element 4 may comprise a longitudinal weld 135 .

The fluid conduit 136 extends from inside the unexpanded tubular section 8 to above the upper end of the unexpanded tubular section 8 . The fluid conduit 136 may be connected at its lower end to or integrally formed with a tube 138 located in the unexpanded tubular section 8 . A first annular seal 140 seals the pipe 138 from the unexpanded liner section 8 and a second annular seal 142 seals the pipe 138 from the drill string 20 . The fluid channel 136 is in fluid communication with the interior space of the tube 138 via an opening 144 provided in the wall of the tube 138 . Furthermore, the tube 138 is provided with gripper means 146 which allow the tube 138 to slide upwards relative to the unexpanded liner section 8 but prevent it from sliding downwards. The first annular seal 140 allows the pipe 138 to slide upwardly relative to the unexpanded liner section 8 .

The upper section shown in FIG. 3 can be combined with the lower section shown in FIG. 1 , wherein, however, the unexpanded tubular section 8 is continuously formed around the drill string 20 . Here, some of the features shown in FIG. 1 are omitted in FIG. 3 in order to improve the clarity of FIG. 3 , such as seal 50 , pipe jacking machine 42 and drill floor 40 .

A method of sealing an annulus surrounding a liner according to the present invention will be described in the subsequent steps below. The sequence of steps performed may be repeated to provide a lined and zone-isolated wellbore.

FIG. 4 shows a wellbore 1 set in a subterranean formation 2 . The wellbore is provided with an expandable liner 4 . The liner comprises an unexpanded section 8 and a radially expanded section 10 . The expanded section 10 is clad against the borehole wall 224 or a relatively small annular space 202 may be left between the expanded section 10 and the borehole wall 224 . A drill string 20 extends through the liner 4 and is provided at its downhole end 200 near the bottom of the wellbore 1 with a drill bit 22 . The drill bit may include a directional drill bit 24 and a reamer segment 26 .

The annulus 202 between the expanded section 10 and the borehole wall 224 is provided with a layer of sealing material 204 providing a previously sealed section 206 of the borehole.

In a first step, starting from the previously sealed section 206 , the borehole 1 is drilled continuously without reversing the liner 4 , resulting in an open hole section 208 . The diameter of the open hole section 208 may be slightly larger than the outer diameter of the expanded liner section 10 after reaming with the reamer 26 . Here, slightly larger means in the range of about 0.1 mm to 20 mm, typically several millimeters or less. During drilling, the wellbore 1 including the open hole section 208 is filled with drilling fluid 210 .

In a second step ( FIG. 5 ), a filter member 212 is arranged at the bend region 14 of the liner 4 . The filter member may have any shape suitable for resting at a predetermined location at or near the curved region 14 . The particles 220 are then included in the drilling fluid 210 and pumped downhole through the drill bit 22 and subsequently captured by the filter member 212 .

As shown in FIG. 5 , the filter member may have a cylindrical body 214 that fits within the inner diameter of the unexpanded liner segment 8 . The cylindrical body is provided with a radially extending flange member 216 to engage the curved region 14 and hold the filter member in place. The flange member 216 may be retracted to enable introduction of the filter member through the inside channel of the unexpanded liner segment 8 . The outer diameter of flange member 216 may be approximately equal to or less than the outer diameter of expanded liner segment 10 to allow particles to pass through the flange member and reach annulus 202 .

The filter member is, for example, provided with openings or fluid channels which are essentially permissive for drilling fluid to pass through, but which are smaller than the average particle size of the particles 220 . For example, the filter member may comprise openings provided with a metal mesh whose openings are smaller than said particle size of the particles.

In a third step ( FIG. 6 ), the tubular member 4 is further everted. As a result, the curved region will engage the filter member 212 and move it downhole. During eversion of the liner 4 , the drilling fluid 210 comprising said particulate matter 220 is pumped downhole via the drill string 20 . Filter 212 will capture particles 220 in the return flow of drilling fluid. The trapped particles 220 will pass through the filter member on the outside and into the annulus 202 . Thus, the particles 220 fill the annulus, close the annulus and provide interzonal isolation in the annulus of the most recently lined section of the wellbore.

A thin layer 222 of particles in the annulus is trapped between the expanded tubular section 10 and the borehole wall 224 . The thin layer may have a thickness comparable to that of the annulus 202, for example in the range of about 10 mm or less.

In a fourth step ( FIG. 7 ), after the tubular element 4 has been everted and extended a predetermined distance along the borehole section 208, the filter member 212 is removed from the borehole and passed down the borehole via the drill string 20. Any excess particles 212 not trapped in the annulus 202 are flushed away by pumping an appropriate fluid (no particles).

After completion of the fourth step, the process can be repeated from the first step (FIG. 4).

It should be noted that the method described above is also suitable for providing a bed of particles or other particulate matter in the annulus surrounding a conventional non-eversioned liner. If the liner is not everted, but the liner can only be introduced into the wellbore until a threshold length is reached, this is because friction between the liner and the particles will eventually prevent further movement of the liner.

The filter 212 shown in Figure 11 allows for continuous processing. Here, the wellbore can be drilled and the pipe 4 everted continuously. The particles 220 are pumped down batchwise or continuously. The total amount of particles in the drilling fluid is at least sufficient to provide a sufficient amount of particles trapped below the filter 212 in the annulus between the expanded liner section 10 and the borehole wall. Particles are trapped between the outside of the cartridge filter section and the borehole wall 224 . The downhole end of the cartridge filter section is provided with flexible fins 252 . The fins preferably have a circular shape. Alternatively, the fins may consist of a plurality of fins which together form said circular shape. The flaps 252 have a closed position ( FIG. 11 ) in which the flaps 252 at least partially close the gap between the cartridge filter segment 252 and the drill string 20 . When the fluid pressure of the fluid below the flaps exceeds a predetermined threshold pressure, the flaps 252 may open to an open position ( FIG. 12 ), in which at least a portion of the gap between the cartridge filter segment 252 and the drill string 20 Open to provide fluid passage.

When the flaps 252 on the inside of the filter section 252 are in the closed position ( FIG. 11 ), the flaps at least partially seal the annulus between the drill string and the filter section. This allows pressure to build in the annulus between filter section 250 and borehole wall 224 . The pressure has somewhat compacted the particles trapped between the filter section 250 and the borehole wall 224 . Due to the eversion of the tubular element 4, particles are trapped between the expanded liner section 10 and the borehole wall 224, thereby compacting the particles even more.

When the pressure differential across the flaps 252 exceeds a threshold pressure, eg, due to too much drilling fluid flowing from the bit, one or more flaps open (FIG. 12). Opening the fins allows for a balance between circulation of the drilling fluid (including delivery of particles to the annulus and removal of cuttings from the borehole) and compaction of the particles by the filter 212 . This also prevents particles from clogging the drilling annulus between the drill string 20 and the unexpanded tubular section 8 .

The flap 252 can be moved between the closed position and the open position in a variety of ways. The transition from off to on may eg be gradual or instantaneous. Progressive here means that the flexible flaps will gradually open eg by bending. The latter allows to open the annulus steplessly and to any predetermined percentage between a percentage of 0 and 100%, depending on the pressure difference. Thus, the flaps enable an intermediate position in which the annulus is partly closed and partly open, eg in a half-open position. The flaps can be made, for example, of flexible rubber with suitable bending stiffness. Additionally, the geometry and shape of the fins can be designed such that the predetermined bend is related to the pressure differential. Momentary opening causes the flaps to move in a stepped fashion (ie, either open or closed) from a closed position to an open position. The latter roughly corresponds to the mechanism of a light switch.

The length of layer 222 is for example in the range of about 1 km or less, for example about 500 meters down to several meters. The zonal isolation treatment of the present invention is semi-continuous and avoids tripping the drill string in the wellbore.

The present invention enables the trapping of particles 220 between the expanded liner section 10 and the borehole wall while at the same time limiting the ability of the particles to seal the annulus 202 between the expanded liner section 10 and the borehole wall, i.e. preventing The particles plug other parts of the wellbore.

As the particles 220 are pumped downhole through the drill string 20 , they need to be trapped in the annulus at the curved region 14 . To this end, a practical example includes:

1) The filter member 212 floats in the applied drilling fluid (Fig. 8). The filter member is free to move along the drill string 20 . The curved region 14 prevents upward (wellhead) movement of the filter member, thereby holding the filter in place.

During drilling of the wellbore, the filter member 212 is moved downhole to allow cuttings to pass through the filter. As the drill string 20 moves downhole while drilling, the radially extending ridges 230 may engage the filter member 212 and force the filter member to move downhole with the drill pipe away from the bend region 14 .

2) A filter member 212 ( FIG. 9 ) is attached to the drill pipe 20 . The filter member may typically have a cylindrical body that is longer than the cylindrical body of other embodiments of the filter member. The filter member may not be provided with a flange member. The exact position of the drill rod 20 relative to the curved region 14 is not critical because the filter is relatively long.

3) A (strong) magnet 240 may be placed in the annulus 44 between the expanded liner section and the unexpanded liner section (Fig. 10). The particles are chosen to be at least partially ferromagnetic. While pumping the particles, the magnets attract and trap the particles at the curved region 14 . At the inside of the unexpanded liner section 8, the velocity of the (drilling) fluid is faster, while below or at the curved region 14 the fluid flow will stagnate. As a result, the ferromagnetic particles will attach to the curved region 14 of the liner 14 and will not plug the annulus between the unexpanded liner section 8 and the drill pipe 20 . While the liner 4 is everted, the particles attached to the curved region will be transported to the annulus 202 and trapped in said annulus 202 .

Particles may, for example, be carried by a fluid flow. Alternatively, the particles may float in the special drilling fluid used. As a result, a relatively low density of particles is required.

Particles may include one or more of the following:

• Swell rubber, elastomer or clay. Swelling here may mean that the material from which the particles are made will swell when in contact with a certain fluid, such as water or hydrocarbons. If the particles 220 swell, the interlaminar isolation of the annulus 202 will improve over time. The degree of swelling of the particles during deployment is preferably kept to a minimum, eg 0% to 10% in volume or diameter. The degree of swelling of the particles upon deployment is preferably greater than during deployment, for example between 100% and 200% in volume or diameter, eg up to 1000% in volume. For suitable materials see eg US-7578347.

• Non-swellable rubber, elastomer or drill cuttings. During the expansion of the liner 4 the particles are ground and a tight packed layer 222 is formed.

• Particles comprising an active ingredient that will help retain remaining fluid in the annulus. Active ingredients may include, for example, one or more of superabsorbent polymers or chemically reactive substances. The active ingredient may be released, for example, by dispersion from the particles during a predetermined dispersion time, or by dissolvable capsules, or capsules that break when crushed during expansion of the liner.

The density of naturally buoyant particles is less than that of the drilling fluid. Typically, the drilling fluid has about the same density as water, ie, about 1 specific gravity (SG). For example, the density of the drilling fluid may range from 0.8 SG to 5 SG or eg in the range of 1 SG to 2.5 SG. The choice of drilling fluid may depend on a variety of factors, including the nature of the formation. The density of the buoyant particles is lower than that of the drilling fluid, preferably the difference between the density and the density of the drilling fluid is 0.1 SG or more. The density of the buoyant particles may range from 0.7SG to 2.4SG.

Particles may have non-uniform particle sizes. The particle size distribution may depend, for example, on the size of the annulus 202 or the permeability of the formation. The largest particles may be as large as or slightly larger than the annulus 202 between the expanded liner section 10 and the borehole wall 224 . The annular space is for example in the range of 0.1 mm to 20 mm, or for example in the range of 3 mm to 6 mm. The size of the smallest particles may depend on the formation and the drilling fluid selected. The smallest particles can fill the voids between the larger particles, thereby producing a dense packing. The particle size of the smallest particles can be nanoparticles or larger. Preferably, the particle packs in the annulus have a lower permeability than the formation at the corresponding location.

In another embodiment, instead of having sealing particles that can be used at the front of the site of the pipe inversion (ie, bend region 14 ), particles that are lighter than mud particles can be used. The particles have a tendency to travel upwards due to their buoyancy. An annulus is created below the inversion site by placing an impermeable tube at the inversion region with a smaller outer diameter than the bore and with a (kinematic) seal for the original (uninverted) SOCCS tube. Particles that are lighter than mud have a natural tendency to collect in the space and thus act as the required sealing material around the inversion tube. When the tubing is reversed and the expanded section is extended, at least a portion of the particles trapped between the impermeable tubing and the borehole wall will be transported into the annulus between the expanded tubular section 10 and the borehole wall. Once within the annulus described below, the particles may provide interlayer isolation as described above with respect to other embodiments.

In a practical embodiment, the diameter and/or wall thickness of the liner 4 can be selected such that the expanded liner section 10 is pressed against the borehole wall 224 during the expansion process. The expanded liner 10 may thus seal against and/or stabilize the wellbore wall. Also, the expanded liner may compress particles 220 between its outer surface and the borehole wall.

The wall thickness of the liner 4 may be equal to or greater than about 2 mm (0.08 inches). The thickness of the wall of the liner 4 may eg be greater than 2.5 mm, eg approximately between 3 mm and 30 mm, or approximately 3.2 mm to 10 mm. The outer diameter of the unexpanded section may be about 50 mm (2 inches) or greater, for example in the range of about 50 mm to 400 mm (16 inches). The expanded section may have an outer diameter suitable or typical for hydrocarbon wellbores. The wall of the liner may comprise a relatively strong material, such as metal or preferably steel, or may be made of solid metal or solid steel. Accordingly, the liner 4 can be designed with suitable crush strength to support the borehole wall and/or withstand internal or external pressure when drilling against a hydrocarbon reservoir.

During wellbore extension, the length and thus weight of the unexpanded liner section 8 will gradually increase. Accordingly, the downward force exerted by the pushing means 42 can be gradually reduced corresponding to the progressively increasing weight of the unexpanded liner section 8 . As the weight increases, the downward force may eventually need to be replaced by an upward force to maintain the total force within a predetermined range. This prevents buckling of the liner section 8 .

During drilling, the unexpanded liner section 8 is advanced into the wellbore, while the drill string 20 is also progressively advanced into the wellbore 1 . The unexpanded liner section 8 may be pushed into the wellbore at approximately twice the speed of the drill string 20 such that the curved region 14 remains a relatively short distance above the drill bit 22 . Here, the short distance represents the length L1 of the open-hole section 208 (ie, the unlined section) of the wellbore 1 (see FIGS. 1 and 4 ). The method of the invention enables the length L1 of the open hole section to always be less than, for example, about 100 meters, or less than 50 meters during the drilling of the wellbore.

The unexpanded liner section 8 may be supported by the drill string 20 , for example by support means (not shown) connected to the drill string, which supports the curved region 14 . In that case, an upward force is suitably applied to the drill string 20, which is then transmitted to the unexpanded liner section 8 through the support means. Also, the weight of the unexpanded liner section 8 can then be transferred to the drill string and used to provide thrust applied to the drill string 22 .

Drilling fluid containing drill cuttings is discharged from the wellbore 1 via the output conduit 90 . Alternatively, drilling fluid may be circulated in a reverse mode in which drilling fluid is pumped into the wellbore via conduit 90 and discharged from the wellbore via drill string 20 .

When it is required to retract the drill string 20 to the surface, such as when the drill bit 22 is replaced or when the drilling of the wellbore 1 is complete, the reamer section 26 can be compressed to its radially retracted mode, in which the radial diameter smaller than the inner diameter of the unexpanded liner section 8. Subsequently, the drill string 20 can be withdrawn to the surface through the unexpanded liner 8 .

With the wellbore system of the present invention, it is achieved that the wellbore is progressively lined during the drilling process with the liner everted just above the drill bit, as a result there is always only a relatively short open hole section 208 during the drilling process . Here, short may mean that the length L1 ( FIG. 1 ) of the open-hole section is less than 1 km, for example, the length L1 is in the range of about 10 meters to 300 meters. Advantages of a short open hole section include limiting the potential for inflow into the wellbore, which minimizes the resulting pressure rise or deviation and simplifies and improves well control. The advantages of such a short open hole section will be most pronounced during drilling into reservoirs containing hydrocarbon fluids in subterranean formations. In view of this, for many applications it is preferred if the eversion of the liner is only applied during drilling into a reservoir of hydrocarbon fluids or into a formation section containing an anomaly treatment while the rest of the wellbore is lined or cased in a conventional manner. Alternatively, depending on the circumstances, the eversion process of the liner may be initiated at the surface or at a selected downhole location during drilling.

Given the short open hole section during drilling, the risk of wellbore fluid pressure gradients exceeding the rock formation's fracturing gradient or wellbore fluid pressure gradient falling below the rock formation's pore pressure gradient is significantly reduced. Thus, significantly longer intervals can be drilled with a single nominal diameter than in conventional drilling practices where stepped reduced diameter casing must be placed at selected intervals.

Also, if the wellbore is drilled through the oil shale formation, this short open hole section eliminates possible problems due to the heaving tendency of the oil shale.

After the wellbore has been drilled to the desired depth and the drill string has been removed from the wellbore, the section of the unexpanded liner section still remaining in the wellbore can be left in the wellbore, or the section can be severed from the expanded liner section and retracted to the surface.

In the event that a section of unexpanded liner remains in the wellbore, there are a number of options for completing the well. For example, as outlined below.

A) A fluid such as brine is pumped into the blind annulus 44 between the unexpanded liner section and the expanded liner section to pressurize the annulus and increase the crush strength of the expanded liner section 10 . Optionally, one or more holes are provided in the curved region 14 to allow circulation of the pumped fluid.

B) Cement is pumped into the blind annulus 44 to create a solid body between the unexpanded liner section 8 and the expanded liner section 10 after the cement hardens. Cement expands as it hardens.

C) Radially expanding (ie, cladding) the unexpanded liner section against the expanded liner section, eg, by pumping, pushing, or pulling the expander through the unexpanded liner section.

In the examples above, the expansion of the liner is initiated either at the surface or at a downhole location. In the case of an offshore wellbore, where the offshore platform is positioned above the wellbore, it may be advantageous to initiate the swelling process at the offshore platform, at or above the water surface. Here, the curved zone is moved from the offshore platform to the seabed and then into the wellbore. Thus, the formed expanded tubular element forms not only a liner in the wellbore but also a riser extending from the offshore platform to the seabed. There is thus no need for a separate riser.

Also, conduits such as electrical wires or optical fibers for communication with downhole equipment can extend in the annulus between the expanded and unexpanded sections. Such a catheter can be attached to the outer surface of the tubular element prior to expansion of the tubular element. Furthermore, the expanded and unexpanded liner sections can be used as electrical conductors to transmit data and/or power downhole.

Since any section of the unexpanded liner section that remains in the wellbore after the eversion process is complete will be subjected to less lenient loading conditions than the expanded liner section, such unexpanded liner section The segments may have smaller wall thickness or may be of lower quality and steel grade. For example, it may be made from a tube having a relatively low yield strength or a relatively low crush resistance rating.

As an alternative to leaving a section of the unexpanded liner section in the wellbore after the expansion treatment, the entire liner can be expanded using the method described above so that the unexpanded liner section remains in the wellbore. In this case, an elongated member, such as a tubing string, can be used to apply the necessary downward force to the unexpanded liner section during the final stages of the expansion process.

To reduce friction between the unexpanded liner section and the expanded liner section during the expansion process, a friction reducing layer, such as a Teflon layer, may be applied between the unexpanded liner section and the expanded liner section. For example, a friction reducing layer can be applied to the outer surface of the unexpanded section 8 . Reducing the friction layer reduces the force required to evert the liner and push the unexpanded section into the wellbore. Thus, the force is kept further below the so-called critical buckling load, which is the force at which the unexpanded liner buckles or fails. As an alternative or in addition to a friction reducing layer, centering pads and/or rollers can be applied in the blind annulus between the unexpanded and expanded sections in order to reduce friction and annulus clearance.

As an alternative to expanding the expanded liner section against the wellbore wall (as described), it is possible to expand the expanded liner section against another tubular element already present in the wellbore (eg, casing or liner) of the inner surface.

Although an embodiment of the invention including a top drive has been described, the invention is equally suitable for use with alternative drilling systems. The latter may include, for example, a downhole motor instead of a top drive. The downhole motor is a drilling tool included in the drill string directly above the drill bit. By activating the pressurized drilling fluid, it causes the drill bit to rotate without rotation in the drill string. Examples of downhole motors include positive displacement motors and downhole turbine motors. Also, any other drilling tool may be arranged for drilling the borehole. Such a drilling tool may, for example, include an abrasive jet suspended at the end of the tubing string.

Likewise, the invention is also suitable for directional drilling, ie the ability to adjust the direction of drilling while drilling. For example, a downhole motor can be used as a deflection tool in directional drilling where it is located between the drill bit and the bent sub or where the housing of the motor can be bent,

The invention is not limited to the above-described embodiments thereof, wherein numerous variants are conceivable within the scope of the appended claims. For example, individual features of respective embodiments may be combined.

Claims (15)

1. the method for sealing the annular space around the tube element in well,

Wherein, described tube element is the expandable tube element around tool post, wherein, the downhole end part of the wall of described expandable tube element radially outward and axially rightabout bends, thus define the section of expandable tubular extended around non-expandable tubular section, said method comprising the steps of:

I) the first drilling fluid is incorporated in described well;

Ii) drilling tool being suspended in the end of described tool post is used to get out the Open-Hole Section of described well;

Iii) the second drilling fluid comprising particle is pumped in described well;

Iv) near the downhole end of described tube element, particle is filtered out from described second drilling fluid;

V) by making described tube element extend in the Open-Hole Section of well in expandable tubular section described in described non-expandable tubular section being pushed into, and being directed at least partially to the annular space between the described section of expandable tubular and well bore wall simultaneously by the particle filtered out.

2. method according to claim 1, comprises repetition step I) to step vi v)).

3. method according to claim 1 and 2, wherein, the described particle guiding to annular space is described annular space filler particles layer.

4. method according to claim 1, wherein, the step filtering out particle comprises:

-make at well head the drillstring motion being provided with filter member, until described filter member engages the downhole end of described tubular element.

5. method according to claim 4, wherein, comprises the step that the first drilling fluid is incorporated in described well:

-make in down-hole the drillstring motion being provided with filter member, until the described downhole end of described filter member and described tubular element is disengaged.

6. method according to claim 1, wherein, filtration step uses filter for installation, and described filter for installation comprises:

-fillter section, described fillter section extends to described well from the downhole end of described tubular sections; With

The fin of-flexibility, described fin is arranged in the downhole end place of described fillter section, to close the annular space between described fillter section and drill string at least in part.

7. method according to claim 6, wherein, when the pressure reduction of described fin both sides exceedes threshold pressure, the annular space that the fin of described flexibility will be opened between described fillter section and described drill string at least in part.

8. method according to claim 6, wherein, described fin is made up of one or more fin section, and described one or more fin section forms round-shaped together.

9. method according to claim 1, wherein, described particle is ferromagnetic at least partly, and the step wherein filtering out particle comprises:

-magnet is arranged in the described downhole end place of described tubular element, to attract described particle at least partially.

10. method according to claim 1, wherein, described particle swelling when contacting with predetermined fluid at least partially.

11. methods according to claim 10, wherein, described predetermined fluid comprises water or hydrocarbon.

12. methods according to claim 1, comprise the following steps:

-impermeable pipe is arranged in the downhole end place of described tube element, the external diameter of described impermeable pipe is less than the external diameter of described well, and (motion) seal be included between described impermeable pipe and the downhole end of described tube element, thus produce annular space at the downstream part of the downhole end of described tube element;

-guarantee that the grain density of the particle in described second drilling fluid is lower than the mud density in described second drilling fluid;

-wherein, the step filtering out particle from described second drilling fluid comprises and being gathered in described annular space because of their buoyancy by described particle.

13. 1 kinds of systems for sealing the annular space around the tube element in well, described system comprises:

-tool post, described tool post has the drilling tool being suspended in downhole end place, for getting out the barefoot interval of described well;

-expandable tube element, described expandable tube element is around described tool post, wherein, the downhole end part of the wall of described expandable tube element radially outward and axially rightabout bends, thus defines the section of expandable tubular extended around non-expandable tubular section;

-introducing device, described introducing device is used for the first drilling fluid to be incorporated in described well;

-pumping installations, described pumping installations is used for the second drilling fluid comprising particle to be pumped in described well;

-filter for installation, described filter for installation is arranged near the downhole end of described tube element, for particle is filtered out from the second drilling fluid, and for by the annular space described in guiding at least partially in the particle filtered out between expandable tubular section and well bore wall.

14. systems according to claim 13, wherein, described filter for installation is selected from following group:

-fillter section, described fillter section extends to described well from the downhole end of described tubular sections; And flexible flap, described flexible flap is arranged in the downhole end place of described fillter section, to close the annular space between described fillter section and drill string at least in part;

-be arranged in the impermeable pipe at the downhole end place of described tube element, the external diameter of described impermeable pipe is less than the external diameter of described well, and (motion) seal be included between described impermeable pipe and the described downhole end of described tube element, thus produce annular space at the downstream part of the downhole end of described tube element.

15. systems according to claim 13, described system is for implementing the method according to any one in aforementioned claim.