BR112019017523B1 - WELL ACCESS APPLIANCE AND METHOD - Google Patents

Abstract

The device for gaining access to a well through a side access passage comprises a flexible conduit which is to be inserted into the well through the side access passage so as to deviate from a lateral insertion direction towards a generally downward direction down the well, the flexible conduit comprising a probe at a front end thereof, the probe comprising a spring of at least 0.5 m in length. The apparatus comprises a probe canister for accommodating the probe prior to being inserted into the well and while the probe is exposed to well pressure in the probe canister, the probe canister accommodating the probe with at least part of the probe extending along a curved path. The apparatus may comprise a guide for insertion along the side access passage and to assist in deflecting the flexible conduit from a side insertion direction, the guide being resiliently biased so that when a front end portion extends out of the side access passage into the well, the resilient bias causes the front end portion to be directed (...).

Description

[001] The present invention relates to apparatus and methods for gaining access to a well.

[002] Wells created for oil and gas production often have at least one side access passage that provides communication between the inside of the well and the outside. The side access passage may consist of a side opening in a shaft wall together with a culvert radially outward from the side opening. The radially outer culvert extends through a valve projecting radially from the well wall. The valve can be opened to allow communication between the sidewall and additional radially external components.

[003] Sometimes, it is desirable to access the interior of wells in order to remove blockages or perform other intervention operations in the well. To this end a side access passage can be used to insert an intervening conduit, such as spiral tubing or hose, which is then required to be transported down the well.

[004] It is known from document WO 2011/071389 to provide an injection module for lateral insertion and bending of a spiral steel pipe through a side access passage of a well. The injection module connects to the side access passage through a flange connection. The injection module includes an inserter that is driven forward by injection equipment from an initial position rearward (or radially outward from the well) of the side access passageway to an inserted position in which a front end of the inserter extends out of the side access passageway and into an annulus of the wellbore. The inserter has an internal guide conduit along which spiral tubing can be passed forward by a conveyor device. The guide conduit has a curved portion at its front end, whereby it deviates from a horizontal orientation to a downward vertical orientation, so that as the spiral pipe is led forward it is flexed from a horizontal direction of travel to a downward vertical direction. Due to the limited space available for bending the spiral pipe, the bending radius is small and the spiral pipe is plastically deformed. The guide conduit also has a straight portion forward of the curved portion for straightening the plastically deformed spiral pipe so that it can continue forward and down the well as it is guided by the conveyor device. However, it can be difficult to achieve consistent straightening so coiled tubing can have a tendency to deviate from the downward direction as it is carried forward and this can limit the depth in the well that coiled tubing reaches.

[005] Another approach to accessing a well is to use an intervention hose, usually produced from a steel-reinforced polymer, which is more flexible than steel spiral tubing and is generally not subject to plastic deformation when it is flexed from an initial horizontal orientation to a downward vertical orientation. It is known from WO 2010/014326 to provide a conduit assembly for inserting a hose into a well via a side access passage. In this document, it is proposed to provide a polymeric insert that is inserted into the side access passage at its front end, the insert being positioned at the bottom of the passage and having a curved upper face that is intended to guide the hose from horizontal to vertical orientation as it is led into the well. This can serve to protect the bottom surface of the hose from a relatively sharp edge at the front end of the side access passage as the hose flexes from horizontal to vertical.

[006] WO 2010/014326 also discloses a weight assembly at the front end of the hose. The weight assembly comprises multiple pivot elements that allow it to shift from horizontal to vertical at the front end of the side access passage as the hose is initially led forward.

[007] Viewed from one aspect, the invention provides an apparatus for gaining access to a well through a side access passage, comprising a flexible conduit that must be inserted into the well through the side access passage so as to deviate from a lateral insertion direction to a generally downward direction of the well, the flexible conduit comprising a probe at a front end thereof, the probe comprising a spring at least 0.5 m in length.

[008] The invention also provides a method for gaining access to a well through a side access passage, comprising:

[009] Insert a flexible conduit into the well through the side access passage so that the flexible conduit deviates from a lateral insertion direction to a generally downward direction down the well, the flexible conduit comprising a probe at a front end thereof, and the probe comprising a spring of at least 0.5 m in length.

[010] A probe comprising a spring can deviate from the lateral insertion direction to the generally downward direction without plastic deformation. It can naturally restore itself to an undeviated state. In this way, it can inherently self-righte itself, without having to rely on gravitational forces provided by weights or heavy material on a chain or the like.

[011] In confined spaces or heavily contaminated by solid or viscous materials such as mud, the use of a probe comprising a spring can help meet the challenge of penetrating a well. If the spring encounters an obstruction while the flexible conduit is being inserted into the well, it may deflect laterally to pass the obstruction and may then self-right out.

[012] In a possible use of the device, the probe can be rotated and the spring can then act as a corkscrew. This can aid vertical penetration in congested regions, such as those filled with old drilling mud. Opposite rotation can help pull the probe free of such congested regions. Rotation can be accomplished by rotating the flexible conduit so as to impart torque to the probe at its front end. If the flexible conduit is supported on a drum or similar, the drum can be carried on a gimbal-type structure to allow for such rotation.

[013] The spring may be at least 1 or 2 or 3 or 4 or 5 or 10 or 20 or 50 or 100 or 200 m long. The spring can have a length of up to 10 or 20 or 50 or 100 or 200 or 300 or 400 or 500 m. The spring may have a length in a defined range between any of the minimum and maximum lengths mentioned above. An exemplary range is 5 to 50 m. The spring itself can act as a weight that helps pull the flexible conduit into the well. Longer spring lengths will increase the amount of weight and therefore can help with that traction.

[014] The spring can be used with or without an internal component, depending on the required function. Typical components may be, however, without limitation: a hollow flexible conduit containing pressure, a fiber optic conduit, an electrical conduit, or optical or electrical sensors. The spring may have various sensors, tools or hydraulically actuated components attached to it, as required. In one application, flexible conduit is used for fluid circulation, such as injecting intervention fluids into a well; in that case, a liquid-containing conduit can be provided internally in the spring. However, this is not always necessary, as the spring itself may have sufficient liquid transport capacity.

[015] The flexible conduit may comprise a hose with the spring connected to a front end of the hose. This connection may comprise a connecting tube which receives the hose at one end and receives the spring at the other end. An example of a connection tube is a "Chinese finger", which can be soaked in epoxy resin.

[016] The spring can extend continuously and substantially throughout the length of the probe. The spring may be a helical spring. The probe can be defined as the portion of flexible conduit that extends forward from a connection between a front end of the hose and a rear end of the probe. The total length of the probe can then be the length between its rear end at the connection and its front end. The hose can be produced from a polymeric material, with or without metallic reinforcement.

[017] The apparatus may comprise a probe container to accommodate the probe before it is inserted into the well and while the probe is exposed to well pressure in the probe container. The probe vessel can provide an environment to accommodate the probe with complete pressure containment of wellbore pressure or annular space pressure. Appropriate seals can be provided at the front and rear ends of the probe container. The probe container can accommodate the probe with at least part of the probe extending along a curved path.

[018] Viewed from another aspect, the invention provides an apparatus for gaining access to a well through a side access passage, comprising a flexible conduit to be inserted into the well through the side access passage, the flexible conduit comprising a probe at a front end thereof, and the apparatus comprising a probe container to accommodate the probe before being inserted into the well and while the probe is exposed to well pressure in the probe container, wherein the probe container accommodates the probe in which at least part of the probe extends along a curved path.

[019] The invention also provides a method for gaining access to a well through a side access passage, comprising:

[020] connecting a probe container to the side access passage in a pressure-tight manner, the probe container accommodating a probe at a front end of a flexible conduit in which at least part of the probe extends along a curved path;

[021] expose the probe in the probe container to the well pressure; It is

[022] insert the flexible conduit into the well through the probe container and the side access passage.

[023] In this aspect of the invention, the probe may comprise a spring. The probe spring may extend continuously substantially the entire length of the probe. The probe spring can be a coil spring.

[024] By accommodating at least part of the probe extending along a curved path, the length of the probe can be contained in a relatively small space. Therefore, even probes several meters long can be accommodated without taking up too much space.

[025] The probe container may provide an elongated chamber which itself follows a curved path. The curved path can extend for part of a revolution or for one or more revolutions. The probe container may comprise a flexible tube, such as a tube or hose, which may be pressurized by being exposed to the pressure of the well or annulus of the well. A flexible tube is well suited to accommodate the probe where at least part of the probe extends along a curved path. The probe container can be supported by being wound onto a coil. This would allow the probe canister to have a curved path that spans multiple revolutions. Therefore, this makes it easy to accommodate a relatively long probe in a small amount of space.

[026] The apparatus may comprise a drive mechanism for advancing the probe container towards or along the side access passage. This can be useful if it is desired to provide a guide to assist in diverting the flexible conduit from a lateral insertion direction to a generally downward direction, due to the fact that by advancing the probe container forward, this guide can be positioned at a front end of the side access passage where the diversion is to occur. This tab is discussed further below.

[027] The forward advance of the probe container may be above a certain stroke length, for example, between 10 cm and 1 m. In general, the stroke length should be sufficient to advance a front end of the probe container along the side access passage. A support for the probe cup, such as a coil as discussed above, can therefore be configured to accommodate movement of the probe cup along the length of the stroke.

[028] The drive mechanism can be configured either to advance the probe container forward or to retract it. A suitable drive mechanism is disclosed in WO 2011/071389.

[029] Due to the probe container accommodating the probe in which at least part of the probe extends along a curved path, there is some versatility regarding the positioning of the probe container in relation to the well. If the probe does not follow a curved path, it may not be possible to position it in a confined space immediately adjacent to the well and radially outward from the well. For example, if the probe container comprises a flexible hose, this can be manipulated into a format that deals with space constraints, which allows for different angles of approach to the wellbore and allows a rear portion of the probe container to be arranged at a distance from the wellbore.

[030] A seal around the probe canister, ie a probe canister seal, may be provided. The seal can be configured to allow forward advancement of the probe canister. In embodiments where the probe canister is configured to be advanced forward, for example by the drive mechanism, then the probe canister seal may be of the stuffing box type, which allows foreward and/or aft movement of the probe canister while maintaining the seal.

[031] The probe container may comprise an insertion tube for advancing forward along the side access passage. The probe canister seal may seal around the insertion tube. The insertion tube can be rigid. In embodiments where the probe container comprises a flexible tube, as discussed above, that flexible tube can be connected to a rear portion of the insertion tube. The insertion tube and flexible tube can be advanced forwards and/or backwards together, for example along the length of the stroke.

[032] The apparatus may comprise a seal around the flexible conduit that seals between the flexible conduit and an inner periphery of the probe container, i.e. a flexible conduit seal. This flexible conduit seal may be of a known stuffing box type. The flexible conduit seal may be located on the back of the probe canister.

[033] The apparatus can be used to gain access to a well through a side access passage, while providing complete containment of well pressure or annular space pressure, for example, during an intervention. This can be achieved, for example, by a first seal around the probe container and a second seal around the flexible conduit, as discussed above. The first seal can be located ahead of the second seal. The first seal may be provided at a front end portion of the probe container and the second seal may be provided at a rear end portion of the probe container.

[034] An injector can be provided to drive the flexible conduit into the well, generally aided by the weight of the probe, as discussed above. The injector can be supplied behind the probe canister. The flexible conduit seal may be located at the front of the injector.

[035] The apparatus may comprise a guide for insertion along the side access passage and to assist in diverting the flexible conduit from a lateral insertion direction to a generally downward direction, the guide being resiliently biased so that when a front end portion thereof extends out of the side access passage into the well, the resilient bias causes the front end portion to be directed at least partially down the well.

[036] Viewed from another aspect, the invention provides an apparatus for gaining access to a well through a side access passage, comprising a flexible conduit to be inserted into the well through the side access passage, and a guide for insertion along the side access passage and to assist in diverting the flexible conduit from a lateral insertion direction, the guide being resiliently biased so that when a front end portion thereof extends out of the side access passage into the well, the resilient bias cause the front end portion to be directed in a direction other than the side insertion direction.

[037] The invention also provides a method for gaining access to a well through a side access passage, comprising:

[038] insert a guide along the side access passage in a side insertion direction, whereby the guide is resiliently biased so that, when a front end portion thereof extends out of the side access passage into the well, the resilient bias causes the front end portion to be directed in a direction different from the side insertion direction; It is

[039] insert a flexible conduit into the well through the side access passage in the direction of lateral insertion, and the guide assists the deviation of the flexible conduit from the direction of lateral insertion.

[040] In this aspect of the invention, the flexible conduit may comprise a probe at its front end, the probe comprising a spring. The probe spring may extend continuously substantially the entire length of the probe. The probe spring can be a coil spring.

[041] The different direction may be an at least partially downward direction. The different direction may be an at least partially downward direction. The guide can thus assist in diverting the flexible conduit from the lateral insertion direction to the generally downward direction.

[042] The guide may comprise an engaging member to engage a radially external surface of an internal wall extending down the well, such as the wall of a well casing, casing hanger, production pipe or pipe hanger, to help restrict movement of the guide in the circumferential direction of the radially external surface. By restricting such movement, the front end portion of the guide can be helped to be directed in the at least partially downward direction.

[043] The different direction may be a direction at least partially circumferential with respect to the well. The different direction may be at least partially circumferential with respect to the well. This may be desirable if a front end of the flexible conduit is intended to be diverted around a radially internal well annular space from the side access passage. It may be desirable to deliver fluid through the flexible conduit to the annular space of the well at a location spaced circumferentially from the side access passage. Such a fluid may, for example, be a sealant that must be used to repair a seal between radially internal and external well components, such as between a well casing and an internal surface of an external well wall or between a production pipeline and the external wall. The sealant can be formulated to have a floating or sinking density depending on where it is desired to be housed. The front end of the flexible conduit can be advanced substantially all around the annular space of the well and then withdrawn while discharging fluid, so as to distribute the fluid substantially all around the annular space.

[044] The apparatus may comprise a nozzle at the front end of the flexible conduit. This can be used to deliver fluid, for example to deliver sealant into an annular well space. A front end of the flexible conduit, such as a nozzle, may have a convex front surface. This can help to help the flexible conduit move around an annular space after it has been deflected in an at least partially circumferential direction.

[045] In embodiments, in an initial position, the guide can be held within a portion of the apparatus itself, such as a chamber or guide passage leading to the side access passage of the well. At that time, it can be constrained to be in a generally straightened format, against resilient bias. Such a restriction can also be provided by the side access passage as the guide is inserted therealong. However, since the front end portion of the guide extends out of the side access passage at its front end (or with respect to well geometry, at the radially inboard end of the side access passage), the resilient bias causes the front end portion to be directed in a direction other than the side insertion direction. If the resilient bias is such that the guide's natural state is to bend in a 90° curve, the guide can adopt a state in which its front end points perpendicular to the side insertion direction. For example, if the lateral insertion direction is a horizontal direction (for example, a radial direction in relation to a well), then, as the guide advances forward, the guide can adopt a state in which its leading end points vertically downwards or a state in which its leading end points circumferentially in relation to an annular space.

[046] The guide can be considered as having a first profile when it is in a chamber or guide passage that leads to the side access passage of the well, and this first profile is seen in the direction of the lateral insertion. It is restricted to this first profile, against its resilient polarization. However, since the guide extends at least partially outside the side access passage, it can then occupy a second profile as seen in the side insertion direction, which extends outside the first profile as seen in that direction. It can therefore then extend out of a profile of the side access passage, as seen towards the side insertion. As the guide will normally form a curved path as its front end portion extends out of the side access passage into the well, part of the curved path may be in the profile of the side access passage and part of the curved path may be outside of that profile. Thus, the radius of curvature followed by the flexible conduit when its direction is deflected by the guide can be greater compared to a situation where the flexible conduit simply flexes around a radially inner edge of the side access passage. This can limit the degree of bending required by the flexible conduit to obtain a deviation from its direction.

[047] The guide may comprise a helical spring. The flexible conduit can be guided along a hollow portion within the coil spring.

[048] Viewed from a further aspect, the invention provides an apparatus for gaining access to a well through a side access passage, comprising a head portion configured to be inserted into the side access passage and guide a flexible conduit into the well and a cutting blade configured to cut the flexible conduit as it extends into the well.

[049] The invention also provides a method for gaining access to a well through a side access passage, comprising:

[050] insert a head portion into the side access passage;

[051] guide a flexible conduit into the well along the head portion; It is

[052] Cut the flexible conduit or a component attached to the flexible conduit with a cutting blade when the flexible conduit or component extends into the well.

[053] If a problem arises with the flexible conduit in the well, or if, for example, an intervention work in the well has been completed and there is no need to recover the flexible conduit from the well, this aspect of the invention provides for cutting the flexible conduit when it extends into the well, for example, in an annular space of the well.

[054] The flexible conduit behind the cut can be retracted from the side access passage and the head portion can also be retracted. In the usual case where a well gate valve has been opened to allow access through the side access passage, that gate valve can be closed after such retraction. Therefore, there is no need to provide an additional out-hole valve, such as a blowout preventer valve, which would take up out-hole space. In many well intervention operations, the space available outside the well is very limited.

[055] The flexible conduit may have at least one component attached to it, such as a nozzle or other tool, and it may be desired or necessary to cut that component instead of the flexible conduit.

[056] The cutting blade can be arranged to cooperate with the head portion.

[057] The cutting blade can be supported, at least partially, by the head portion.

[058] The cutting blade can extend forward in the direction of the side insertion. It may extend forwardly from a location behind the head portion and along its length.

[059] The cutting blade can be moved forward with respect to a front part of the head portion to effect the cut.

[060] The cutting blade and the head portion will normally be configured so that the cutting blade cuts the flexible portion when the head portion is disposed in the side access passage. The cutter blade and the head portion may be configured such that the cutter blade cuts the flexible forward portion of the side access passage, i.e., in the well, for example, in the annular space of the well.

[061] The head portion may comprise a cutting surface opposite the cutting blade, so that during the cutting of the flexible conduit the cutting blade cuts the flexible conduit as the cutting blade advances towards the cutting surface. The cut surface can provide a support for the flexible conduit to hold it in place when the conduit is being cut. The cutting surface can be engaged by the cutting blade after completing the cut. The cutting surface may be provided as a rearward facing surface at the front of the head portion.

[062] The apparatus may comprise a resilient device configured to compress in the lateral insertion direction of the head portion during cutting of the flexible conduit.

[063] The resilient device can allow the cutting blade to advance in relation to a main body of the head portion. The main body can be prevented from advancing further by engagement with a portion of the well, such as a radially inner surface of an annular space.

[064] The resilient device can be configured to compress when the front of the head portion is prevented from advancing further by engagement with a portion of the well, such as a radially inner surface of an annular space.

[065] The resilient device may comprise a spring, for example a compression spring, acting between a support for the cutting blade and the front of the head portion. The apparatus may be configured so that, when it is desired to cut the flexible conduit, the holder is advanced towards the side insertion, the front of the head portion being prevented from advancing further by engagement with a portion of the well, such as a radially inner surface of an annular space, and the spring then compresses to allow the holder and cutting blade to advance relative to the front of the head portion and thereby sever the flexible conduit. At that time, the flexible conduit may be disposed between the front of the head portion and the cutting blade. The cutting surface described above may be provided as a rearward facing surface on the front of the head portion.

[066] The resilient device may comprise a resilient body that supports the cutting blade. The resilient body may have a front engaging portion for engagement with the flexible conduit. The apparatus can be configured so that when it is desired to cut the flexible conduit, a rear portion of the resilient body is advanced forward in the side insertion direction and the front engaging portion is prevented from advancing further by engaging with the flexible conduit, the cutting blade then advances forward of the front engaging portion to cut the flexible conduit.

[067] Viewed from another aspect, the invention provides an apparatus for gaining access to a well through a side access passage, comprising a flexible conduit to be inserted into the well through the side access passage and a guide for insertion along the side access passage at least partially into the well and to assist in deflecting the flexible conduit from a lateral insertion direction to a downward direction, the guide comprising a first guide surface for engagement with a main front end of the flexible conduit during insertion thereof into the well to start said shifting of the flexible conduit from the lateral insertion direction to the downward direction and a second guide surface for supporting and guiding the flexible conduit underneath.

[068] The invention also provides a method for gaining access to a well through a side access passage, comprising:

[069] inserting a guide along the side access passage in a lateral insertion direction so that the guide extends at least partially into the well, the guide comprising a first guide surface and the guide comprising a second guide surface for supporting and guiding the flexible conduit underneath; It is

[070] Insert a flexible conduit into the well through the side access passage in the direction of side insertion, so that a front end tip of the flexible conduit engages the first guide surface of the guide to initiate the deviation of the flexible conduit from the side insertion direction to a downward direction.

[071] In use, due to the fact that the first and second guide surfaces are provided separately, as the main front end of the flexible conduit is pushed down during the insertion of the flexible conduit into the well, this can be done without frictional interaction of the leading front end with the second guide surface. This is different from known guide conduits, such as that of WO 2011/071389 or US 2010/319933, in which a circular cross-section guide conduit is provided and therefore restricts the flexible conduit around its entire circumferential periphery. Thus, the force required for inserting the flexible conduit can be reduced.

[072] The first guide surface may be located ahead of the second guide surface in the direction of lateral insertion. Thus, the initial engagement by the main front tip can be at a location on the first guide surface that is located forward of the second guide surface in the side insertion direction. When the main front end of the flexible conduit is pushed down during insertion of the flexible conduit into the well, deflection of the main front end by the first guide surface can occur by contacting the top of the main front end with the first guide surface, without the bottom of the main front end contacting the second guide surface.

[073] When the flexible conduit is advanced forward, it may cantilever project into a rear space adjacent to the first guide surface before being deflected downward by contact with the first guide surface. Thus, the frictional interaction of the flexible conduit with the second guide surface during the deviation of the flexible conduit from the lateral insertion direction to the downward direction can be avoided.

[074] The flexible conduit can adopt a radius of curvature as determined by the available space, instead of being determined by a circular cross-cut guide conduit that has a fixed radius of curvature.

[075] The second guide surface can be so as to curve downwards from the side insertion direction. It can be opened covered, at least where it curves downwards. Thus, the second guide surface can be configured to avoid restricting the flexible conduit from above. This can help reduce any frictional losses as the flexible conduit moves forward or backward. This second covered and open guide surface may be sideless, or may be in the form of a channel.

[076] In some embodiments, the first guide surface may be approximately 2 to 3 flexible conduit diameters ahead of the second guide surface.

[077] For a first part of its downward displacement in the well, the flexible conduit may not engage the second guide surface. As the flexible conduit is further inserted into the hole, its weight will normally tend to cause the flexible conduit to engage the second guide surface, so that the radius of curvature at this stage is reduced compared to during the first part of the downstroke. However, at this stage, the flexible conduit will normally not engage the first guide surface, again tending to reduce frictional resistance.

[078] The flexible conduit may comprise a spring at its front end. As with other aspects of the invention, the flexible conduit may comprise a probe at its front end, the probe comprising a spring. A spring is particularly suitable for its leading front end to engage the first guide surface to initiate deflection of the flexible conduit from the side insertion direction to the downward direction. In embodiments, the spring naturally adopts a straight longitudinal shape, so that once the spring has passed the first guide surface, it automatically straightens out to progress downwards into the borehole.

[079] The guide may comprise a first guide part on which the first guide surface is provided and a second guide part on which the second guide surface is provided, the first guide part and the second guide part being movable longitudinally with respect to each other in the direction of lateral insertion. It can be beneficial to adjust the spacing between the first and second guide surfaces depending on the diameter of the flexible conduit and/or its rigidity.

[080] The relative movement of the first and second guide parts can also provide for the implantation of a guide tongue, which can form at least part of the second guide surface. The guide tongue can move from an upper position within the profile of the side access passage, as seen in the direction of the side insertion, to a lower position in which it extends downwardly outside that profile. This displacement can occur when the first and second parts of the guide are moved relative to each other, removing a constraint that keeps the guide tongue in the upper position.

[081] By providing a guide tongue in this way, it is possible to provide an increased radius of curvature between the side insertion direction and a downward direction, compared to when all of this curvature is provided within the profile of the side access passage as seen in the side insertion direction. This bend radius is generally applicable when the weight of the flexible conduit is causing it to engage the second guide surface.

[082] The relative movement of the first and second guide parts can also be useful for cutting the flexible conduit as described in relation to the relevant aspect of the invention above. The cutting blade can be fixed in the side insertion direction with respect to one of the guide parts, for example the second guide part, and the cutting surface can be fixed in the side insertion direction or with respect to the other of the guide parts, for example the first guide part.

[083] The first and second guide parts can be telescopically arranged with respect to each other to provide said relative longitudinal movement.

[084] The first guide part can be arranged radially outward from the second guide part.

[085] The first guide part can be provided by the insertion tube as described elsewhere in this document, and the first guide surface is provided in the insertion tube. The second guide part may be provided by the front guide device, as described elsewhere in the present document, with the second guide surface being provided at the front guide device.

[086] The invention in its various aspects is suitable for application in the oil and gas industry and, in particular, in oil or gas production wells or injection wells.

[087] The side access passage will generally be to a wellhead or a production tree. It can be at an angle to the horizontal or it can extend horizontally. The side access passage can be through an annular space exit from a wellhead, or a service or kill exit from a production tree.

[088] The flexible conduit can be used for well intervention operations, such as removing blockages, creating blockages or conducting a sealing operation. Thus, the flexible conduit can be a well intervention conduit.

[089] Certain preferred embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings in which:

[090] Figure 1 is a schematic cross-sectional view showing an embodiment of the apparatus according to the present invention connected to a wellhead;

[091] Figure 2 is a side view of a device guide;

[092] Figure 3 is a top plan view of the guide in Figure 2;

[093] Figure 4 is a side view showing a connection between a hose and a probe;

[094] Figure 5 is a side view showing an alternative type of connection between a hose and a probe;

[095] Figures 6 to 9 are respective schematic cross-sectional views, similar to figure 1, showing the apparatus in different stages of its operation;

[096] Figure 10 is a perspective overview of a second embodiment with certain external parts omitted to reveal internal components;

[097] Figure 11 is a perspective view of a front guide device and a rear guide barrel of the apparatus of Figure 10;

[098] Figure 12 is another perspective view of the front guide device and the rear guide barrel;

[099] Figure 13 is a perspective view of the front guide device;

[100] Figure 14 is a side view of a front part of the front guide device and a cutting blade;

[101] Figure 15 is a perspective view showing the front part and the cutting blade;

[102] Figure 16 is a perspective view showing the front;

[103] Figures 17A to 17D are respective side views of the apparatus of Figure 10, showing the apparatus in different stages of its operation;

[104] Figures 18A to 18E are respective additional perspective views of the apparatus of Figure 10 at different stages of its operation;

[105] Figure 19 is a schematic view of a third embodiment; It is

[106] Figures 20A to 20L are respective schematic views of the third embodiment, showing the apparatus in different stages of its operation.

[107] Figure 1 shows the apparatus 10 connected to a wellhead 12. The wellhead has an annular external wall 14 formed with a lateral opening 16 and a valve 18 having through it a gallery 20 that is aligned with the lateral opening 16 in the external wall 14.

[108] The gallery 20 and the side opening 16 together form a side access passage, which provides access to the outside of the outer wall 14, to the inside of the side opening 16 or to the space radially inwards of the side opening.

[109] The valve 18 has a radially outer flange 19. The wellhead 12 has an annular cavity 22, known as the annulus, between a radially outer surface of a well casing 24 and an inner surface of the outer wall 14. The well casing 24 is supported by a casing hanger 26 that is in sealed engagement with the inner surface of the outer wall 14.

[110] Wellhead 12 is of standard construction. Wellhead 12 is of standard construction. Valve 18 is normally a gate valve which, when closed, closes access from the outside to the side opening of the wellhead 16.

[111] In this embodiment, the apparatus 10 is shown being used to gain access to the annular cavity 22 between the radially outer surface of the well casing 24 and the inner surface of the outer wall 14. In another use of the apparatus 10, it can gain access to an annular space between a radially outer surface of a production pipeline and an outer wall. This production piping can be hung from a pipe hanger that is in sealed engagement with the inside surface of the outside wall.

[112] Apparatus 10 for gaining access to the shaft through the side access passage will now be described. The apparatus comprises a probe container 28 having an insertion tube 30, which can be rigidly connected to the rear of the insertion tube 30, a flexible tube 32. At the front end of the insertion tube 30, a guide in the form of a guide spring 34 is provided. In this embodiment, the guide spring is a helical spring. The insertion tube 30 is connected at its rear end in a pressure-tight manner to a front end of the flexible tube 32. The flexible tube 32 may be a pipe or hose which can be pressurized by being exposed to the pressure of the annular space 22 and which can also extend along a curved path. In the embodiment shown in Figures 6 to 9, the probe canister 28 is wound on a probe canister barrel or spool 36. At its rear end, the probe canister 28 is pressure-tightly connected to an injector 38. The injector 38 may be of a known type for driving or forward injecting a hose into a well, as described in US 6,186,239, for example.

[113] The probe container 28 comprising the insertion tube 30 and the flexible tube 32 are moved together axially back and forth by a drive mechanism 40. This may be of a known type, such as that described in WO 2011/071389. The drive mechanism is configured to advance the probe canister 28 from a retracted position, as shown in Figure 1, along a given length of stroke, to an advanced position. In the embodiment of Figures 6 to 9, the probe container 28 is shown in a retracted position in Figure 6 and a forward position in Figure 9.

[114] At its forward end, i.e., its radially inner end relative to the wellhead, the apparatus 10 has a flange 42 for making a sealed and bolted connection (neither bolts nor gasket shown) to the radially outer flange 19 of the wellhead valve 18. Behind the flange 42, the apparatus has a guide chamber 44 which includes a return outlet 46 to allow fluid displaced from the annular space of the wellhead to exit the apparatus. A probe container seal 48 at the rear of the guide chamber 44 seals around the insertion tube 30 of the probe container 28. The seal is of a conventional stuffing box type and allows the insertion tube to reciprocate back and forth while maintaining a pressure tight barrier between the interior of the guide chamber 44, which is itself exposed to the pressure of the annular space 22 and the atmosphere.

[115] The natural and untensioned state of the guide spring34 is for it to define a curved path, bending 90°, as seen in Figure 1 or Figure 9. It is then resiliently biased to adopt this curved shape, and is able to do so when the probe canister is in the advanced position. As seen in the embodiment of Figure 6, when the probe container 28 is in the retracted position, the guide spring 34 is constrained in the guide chamber 44 so as to be in a generally straightened state.

[116] Figures 2 and 3 show views of the guide spring 34 when the probe container is in the advanced position. An engagement member 47 is attached to a front portion of the guide spring 34, on its upper surface when the guide spring 34 is constrained by the guide chamber 44, as seen in Figure 6, which becomes its radially inner surface relative to the wellhead as the guide spring 34 emerges from the side opening 16 in the outer annular wall 14 of the wellhead. The purpose of the engagement member 47 is to engage a radially outer surface of the liner hanger 26 to help restrict movement of the guide spring 34 in a circumferential direction of the radially outer surface. The engagement member 47 has a concave surface 49 to mate with the radially outer surface of the liner hanger 26. The concave surface 49 is provided on a radially outer periphery of the guide spring 34 and faces radially outward with respect to the guide spring 34.

[117] A flexible conduit 50 comprises a hose 52 and, at a front end of the hose 52, a probe in the form of a downhole spring 54. The hose is carried in a hose drum 56 (see Figures 6 to 9) and extends forward thereof through the injector 38. A flexible conduit seal 58 located in front of the injector 38 seals around the hose 52. conventional stuffing box type and allows the hose to be routed forward while maintaining a pressure tight barrier between the interior of the probe vessel, which is exposed to the pressure of the annular space of the well 22 and the atmosphere.

[118] Figures 4 and 5 show, respectively, two possible types of connection between the hose 52 and the downhole spring 54. Figure 4 shows a "Chinese finger" tube 57 with the downhole spring 54 inserted at one end and the hose 52 inserted at the other end. Prior to assembly, tube 57 is soaked in epoxy glue. Spring 54 and hose 52 are then inserted until they come together and are then pulled back slightly to cause tube 57 to grip the spring and hose, whereupon the glue is left to set.

[119] An alternative connection between the hose 52 and the spring 54 is shown in Figure 5. In this case an end portion of the hose 52 fits within an end portion of the spring and the natural resilience of the spring squeezes the outside of the hose and forms a locking connection. During assembly of this connection, the spring is gripped approximately 15 cm from its end and then the end is twisted against the spring's torsion direction in order to increase the inside diameter of the spring. The end portion of the hose is inserted into the expanded end portion of the spring, and the spring tension is released by rotating its end in the torsion direction of the spring, thus reducing the inner diameter in a controlled manner. Thus, a latched connection is formed.

[120] The process of gaining access to a well through the side access passage will be described with reference to Figures 6 to 9. Figure 6 shows the apparatus with the probe container 28 in the retracted position and the hose 52 of the flexible conduit 50 wound around the hose drum 56. The probe in the form of the downhole spring 54 is contained in the flexible tube 32 of the probe container 28 and thus the flexible tube 32 and the spring 54 are wound together in probe canister spool 36. The interior of probe canister 28 extending from insertion tube 30 back to flexible conduit seal 58 is subject to well annular space pressure. This is ensured by the probe canister seal 48 at the rear of the guide chamber 44 sealing around the insertion tube 30 of the probe can 28 and by the flexible conduit seal 58 located ahead of the injector 38 which seals around the hose 52. It should be noted that the downhole spring 54 does not extend through the flexible conduit seal 58. The flexible conduit seal 58 can thereby seal against the relatively smooth surface of hose 52 rather than against a corrugated surface of coiled downhole spring 54.

[121] The downhole spring can have a length of many meters, for example, up to 50 m or more, while contained in the probe canister 28 wound around the probe canister spool 36 and while in a sealed, pressurized environment. By containing the downhole spring 54 with at least part of its length extending along a curved path (in this embodiment being wound inside the probe cup 28 around the probe cup coil 36), a desired length of the downhole spring can be used without taking up a large amount of space. A long length of the downhole spring allows it to have a large weight, which greatly assists the insertion of flexible conduit in the well.

[122] As seen in Figure 6, guide spring 34 is constrained in guide chamber 44 so that it is generally straight along most of its length. At this stage, it is maintained in this state against its own resilient bias.

[123] Figure 6 also shows valve 18 in a closed condition. Guide spring 34 projects a small amount into valve gallery 20. Once the flange 42 of the apparatus 10 has been pressure-tightly secured to the wellhead flange 19, i.e., the state shown in Figure 6, the valve 18 is opened, allowing the interior of the guide chamber 44 and the probe vessel 28 to be exposed to pressure in the annular space of the well, the drive mechanism 40 is operated to advance the probe vessel 28 forward, thereby advancing the insertion tube 30 of the borehole forward. probe canister through probe canister seal 48, to the advanced position shown in Figure 7. During this advancement, the guide spring 34 moves along the side access passageway comprising the valve gallery 20 and the side opening 16 in the annular outer wall 14, while the side access passageway continues to constrain the guide spring 34 in its generally straightened state. As the front end of the guide spring 34 emerges from the side access passageway into the annular space 22, its front end portion adopts a downwardly curved condition caused by the tendency of the spring toward its natural, unstressed state. During this process, the concave surface 49 of the engagement member 47 engages the radially outer surface of the casing hanger 26 and this helps to prevent the guide spring from moving in the circumferential direction of the annular space.

[124] Once the probe canister 28 and guide spring 34 have been advanced forward to the advanced position shown in Figure 7, the flexible conduit 50 can be driven forward through the flexible conduit seal 58 by the injector 38. The downhole spring 54 at the front end of the hose 52 advances from the position shown in Figure 7 along the insertion tube 30 and then along the guide spring 34, which it deviates from a generally horizontal orientation to a vertically downward orientation, as seen in Figure 8. As the insertion process continues, the length of the downhole spring 54 hanging in the annular space of the wellbore 22 increases and the weight of the downhole spring 54 in the annular space correspondingly increases, thereby assisting with the further advancement of the flexible conduit 50.

[125] Figure 9 shows the situation where a rear end of the downhole spring 54 has passed in front of the guide spring 34, with the entire length of the probe container 28 being occupied by the hose 52. After this stage, the forward advance of the hose 52 can continue under the weight of the downhole spring and its own weight and assisted, if necessary, by the injector 38. When the front end of the downhole spring reaches a desired position, it can perform different tasks. These include, but are not limited to, fluid circulation or holding one or more registration sensors in desired locations.

[126] When it is desired to remove the flexible conduit 50 from the well, the injector 38 can be operated in reverse to pull it up. Hose 52 is then wound on hose drum 56 and downhole spring 54 is retracted back into probe bucket 28 wound on probe bucket spool 36.

[127] In the embodiment described, the probe is flexed as it passes through the guide spring 34 thrown forward. Because the probe comprises a spring, it does not undergo plastic deformation during this bending, unlike spiral tubing. It does not undergo a permanent change in straightness and therefore does not need to be straightened after bending. It straightens automatically. There is also no self-hardening that could result from plastic deformation.

[128] If the rig encounters an obstacle as it descends the borehole, it may flex and, once the orientation of its front end has been sufficiently altered, it can then go around the obstacle. Once this is done, it can self-righte. In doing so, it relies on its own resilience rather than its weight, as would be the case with conventional hinged weights, such as pieces of metal or heavy material on a chain. In a mud-blocked space and/or a small space, the spring can then bypass the obstruction where a chain would not be able to.

[129] After a sufficient length of probe has been inserted into the well, its weight will contribute to a pull on the length of flexible conduit above the probe.

[130] The apparatus can provide complete pressure containment of wellbore pressure or annular space pressure during an intervention. This is achieved by the probe comprising the downhole spring 54 being contained in the probe container 28 in a pressure-tight manner, with the probe container being sealed outside at its forward end adjacent the well and being sealed at its rear end. The seal at the front end allows the insertion tube 30 of the probe container 28 to be advanced forward the length of the stroke to advance the guide spring 34 along the side access passage and to be retracted back upon completion of an operation, while maintaining seal integrity. The seal is at the rear and allows the flexible conduit to pass forward through the seal as the flexible conduit is moved down the well, and rearward when pulled back up again, while maintaining the integrity of the seal. The pressure containment system provides a pressure tight path for the downhole spring 54 to be guided towards and into the wellbore.

[131] The internal diameter and curvature of the probe container 28 are adequate to allow the flexible conduit 50 comprising the hose 52 and the downhole spring 54 to be moved back and forth without becoming stuck or trapped due to buckling and/or excessive friction between the flexible conduit and the inner wall of the probe container 28.

[132] A second embodiment of the apparatus will be described with reference to Figures 10 to 18.

[133] Figure 10 shows the apparatus 10 for connection to a wellhead 12 in the same way as for the first embodiment. At its forward end, i.e. its radially inner end relative to the wellhead, the apparatus 10 has a flange 42 for making a sealed and bolted connection to the radially outer flange 19 of the wellhead valve 18, as seen in Figure 1.

[134] The apparatus is based on the tool described in WO 2017/129632, but modified to include aspects of the invention described in this document. The apparatus has a housing 60 in which an output shaft 62 formed with an external screw thread (not shown) is arranged to be rotatably driven by means of a gear box 64. An internally threaded nut 66 (corresponding to the nut 40 of WO 2017/129632 ) is mounted on the output shaft 62 and is prevented from rotating during rotational driving of the output shaft 62, so that when the output shaft output is actuated, the nut 66 moves longitudinally forwards or backwards, depending on the direction of rotation.

[135] The apparatus is provided with a longitudinally extending chamber 68, in which a hydraulic unit 70 is movable longitudinally, forwards or backwards. Hydraulic unit 70 is connected to nut 66 so as to move longitudinally with it.

[136] A rear guide pipe 73 extends through the hydraulic unit 70. The hydraulic unit 70 has a cylindrical outer wall 76 in which a front hydraulic chamber 72 and a rear hydraulic chamber 74 are defined. A front seal 78 and a rear seal 80 are provided between the rear guide barrel 73 and the cylindrical outer wall 76 of the hydraulic unit 70. is movable longitudinally with respect to the hydraulic unit 70 in a sealed manner. A pair of intermediate seals 82 are provided between the rear guide barrel 73 and the cylindrical outer wall 76, separating the front and rear hydraulic chambers 72, 74.

[137] At its rear end, the rear guide pipe 73 is sealingly connected to a flexible tube 32 of a probe container 28, this flexible tube corresponding to the flexible tube 32 described in relation to the first embodiment. A hose 52, which also corresponds to that described in relation to the first embodiment, extends inside the flexible tube 32 from the rear to the front of the apparatus 10. Only a portion of the hose 52 is shown in Figure 10, supported by a head portion in the form of a front guide device 84 and which projects forwards and downwards therefrom. Front guide device 84 is to be inserted into a side access passage of wellhead 12 and in Figure 10 is shown in a forward advanced position.

[138] The apparatus 10 has an insertion tube 30 of the probe container 28. A rear end of the insertion tube 30 is sealingly connected to the front of the hydraulic unit 70, so that when the nut 66 moves forward or backward and causes the hydraulic unit 70 to move forward or backward, the insertion tube 30 is also caused to move forward or backward.

[139] The front guide device 84 is slidably disposed longitudinally in the insertion tube 30. As can be seen in more detail in Figures 11 and 12, a spring 86 is seated in a seat 88 at the front end of the rear guide barrel 73 and extends forward for connection with the front guide device 84. rear guide 73 during the advancement of these components towards and into the wellhead 12, but if forward movement of the front guide device 84 is resisted (as will be described later), the spring compresses to allow forward movement of the rear guide pipe 73 relative to the front guide device 84.

[140] A pair of guide bars 90 (only one being visible in Figures 11 and 12) extend forward from the seat 88. A front end portion of each guide bar 90 is received in a respective slot 92 in a wall of the front guide device 84. Each front end portion engages a forward facing support 83 of the front guide device 84 under spring force 86, limiting the front guide device 84 in its advanced position in relation to the rear guide barrel 73.

[141] Flexible conduit 50 extends forward into rear guide barrel 73 and actually along the middle of spring 86 (not shown in Figures 10 to 11). Front guide device 84 comprises a longitudinally extending and upwardly facing channel 95 to guide hose 52 from a front end of spring 86 toward the front of front guide device 84. Channel 95 slopes upward from back to front as it extends longitudinally. Channel 95 has a front portion 96 (see Figure 13) where it curves downwards. A pivotally mounted guide pawl 94 is provided at the front end of the front guide device 84. The guide pawl 94 is arranged to assume an upper position when the front guide device 84 is being advanced forward or backward along the side access passage, so that its profile, when viewed in the direction of a side insertion, is relatively confined and is capable of fitting within the inside diameter of the insertion tube 30, which, in turn, can then be have an outside diameter small enough to fit within the side access passage. Guide pawl 94 is shown in the upper position in Figures 11 and 12.

[142] The insertion tube 30 has an opening 98 in its downward facing wall (see Figure 16). The guide pawl 94 is arranged to fall by gravity to a lower position when advanced to a position advanced enough to emerge through the opening 98. The guide pawl 94 is shown in the lowest position in Figure 13. The guide pawl 94 has a guide pawl channel 100 that aligns with the curved front portion 96 of the channel 95 when the guide pawl 94 is in its lower position.

[143] As seen in Figures 10, 14, 15 and 16, the insertion tube 30 is provided at its front end with a deflection member 102 which assists in diverting the flexible conduit 50 from a lateral insertion direction to a downward direction. The flexible conduit 50 may comprise a probe in the form of a downhole spring 54, as described in connection with the first embodiment. The deflection member 102 is attached to the insertion tube 30. It has an upper face 104 at a first angle with respect to the longitudinal direction, an intermediate face 106 at a second angle, and a lower face 108 at a third angle. In this embodiment, the first angle is 30°, the second angle is 45° and the third angle is 90°.

[144] As seen in Figure 12, a cutter blade 110 extends forward from the seat 88 at the forward end of the rear guide barrel 73. The cutter blade 110 is T-shaped in cross section. The lower member of the cutting blade "T" 110 extends along a longitudinally extending slot 112 in the front guide device 84, so as to be slidable relative thereto and at least partially supported by it. The insertion tube 30 within which the front guide device 84 extends longitudinally can also provide some support for the cutting blade 110. The "T" shape of the cutting blade 110 also serves to provide it with inherent rigidity against buckling.

[145] At its front end, the cutting blade 110 has a cutting edge 113 for cutting hose 52 or other flexible conduit components. As will be described below, as the cutter blade 110 advances forward relative to the front guide device 84, its cutting edge moves towards the bottom face 108 of the deflection member 102 until, after making a cut, it engages with the bottom face 108, as seen in Figures 14 and 15.

[146] Figures 17A to 17D and Figures 18A to 18E show the apparatus of the second embodiment in different stages of operation, and the sequence of operation will be described with reference to those Figures.

[147] Figure 18A shows part of the apparatus when the insertion tube 30 is in a retracted position, which is the condition of the apparatus when the flange 42 is to be bolted sealingly to the flange 19 of the wellhead 12. At this stage, the front end of the insertion tube 30 projects a short distance into the side access passage of the wellhead 12. Once the apparatus has been attached to the wellhead 12, the wellhead valve 18 can be be opened to allow the space within the insertion tube 30 and the remainder of the probe container 28 to be exposed to the well pressure.

[148] Figure 18B shows part of the apparatus when the insertion tube 30 is in an advanced position. The insertion tube has been advanced into this position by operating the gearbox 64 to cause the nut 66 to be driven longitudinally forward and thereby move the hydraulic unit 70 longitudinally forward with it. During this process, the front guide device 84 is in a recessed position relative to the insertion tube 30. The guide tongue 94 is in its upper position, with its profile seen in the lateral insertion direction contained within the inside diameter of the insertion tube 30. At this stage, a portion of the front end of the front guide device 84 projects forward out of the side access passage of the wellhead 12 and into the annular cavity 22 (see Figure 1).

[149] Figure 17A shows the status of the hydraulic unit 70 at this stage, with the intermediate seal pair 82 located in a recessed position. As seen in Figures 11, 17A and 18B, the front end portions of the guide bars 90 are engaged with the forward bearings 83 of the front guide device 84 and are held in that engagement by the compressive force of the spring 86 which urges the front guide device 84 forward with respect to the seat 88 at the front end of the rear guide barrel 73.

[150] In order to cause the guide tongue 94 to drop by gravity to its lowest position, it is necessary that it be advanced forward enough to emerge through the opening 98 in the insertion tube 30, as seen in Figure 17B. This is achieved by advancing the front guide device 84 with respect to the insertion tube 30, caused by operating the hydraulic unit 70 by pressurizing the rear hydraulic chamber 74 and causing the pair of intermediate seals 82 to advance forward and therefore causing the rear guide barrel 73 to advance forward. During this forward advance, the spring 86 does not compress and therefore the front guide device 84 is maintained in an advanced position with respect to the rear guide barrel 73.

[151] The flexible conduit 50, as described with respect to the first embodiment, is then driven forward through the apparatus and into the well. The flexible conduit 50 comprises a hose 52 and, at a front end of the hose 52, a probe in the form of a downhole spring 54. As the flexible conduit 50 is driven forward, the downhole spring 54 is guided along the channel 95. The channel slopes upwards from back to front as it extends longitudinally and the front end of the downhole spring 54 is guided along the channel towards the to the deflection member 102 attached to the front end of the insertion tube 30. With continued advancement, the front end of the spring 54 engages the top face 104 of the deflection member 102 (see Figure 14) and is deflected generally downward by the top face 104, due to the top face being at an angle to the longitudinal direction. Moving further forward, the front end of spring 54 engages intermediate face 106 which helps deflect it further downwards until it begins to advance downwards into annular cavity 22.

[152] Initially, due to the spring tending to self-straighten, the same channel curve 95 turns in the downward direction without necessarily coming into contact with the guide tongue channel 100. The spring curves with a relatively large radius of curvature and therefore offers relatively low resistance to drive further advancement of the flexible conduit 50.

[153] Figure 18C shows hose 52 being carried forward behind spring 54. At this stage, the hose is not in contact with guide pawl channel 100, due to it taking the maximum radius of bend available to it between the front of channel 95 and the faces of deflection member 102. As the amount of flexible conduit 50 in annular cavity 22 increases, its weight tends to do causing hose 52 to fall into guide pawl channel 100. In some embodiments, the weight required for flexible conduit 50 to engage guide pawl channel 100 may occur while spring 54 is still emerging from insertion tube 30, before hose 52 has reached the front of insertion tube 30.

[154] The combination of the curved front portion 96 of channel 95 and the guide tongue channel 100 (see Figure 13) allows for the transition of the flexible conduit slightly upward orientation in channel 95 so that the downward orientation in the wellbore occurs with a relatively large radius of curvature. Approximately 45° to 50° of the change in direction occurs in the front curved portion 96 and approximately 45° of the change in direction occurs in the guide tongue channel 100. Part of the curvature occurs within the profile of the insertion tube 30 as seen in the direction of the side insertion, and the remainder of the curvature occurs outside this profile, thus increasing the radius of curvature compared to that which would be available if only the space within the profile was used.

[155] After a well intervention operation is completed, it is normally desired to remove the flexible conduit 50 from the well. During this process, the guide tongue channel 100 and the curved front portion 96 serve to guide the flexible conduit 50 from the downward direction to the horizontal direction. The relatively large radius of curvature provided by the guide tongue channel 100 and curved front portion 96 assists in managing the transition at this stage, when relatively large stress forces may be present due to the weight of the portion of flexible conduit 50 extending down the wellbore.

[156] Once the flexible conduit 50 has been removed from the pit and apparatus 10, the guide pawl 94 can be returned to its upper position by operating the hydraulic unit in reverse, i.e., pressurizing the front hydraulic chamber 72. The rear guide barrel 73 is retracted rearwards, bringing the front guide device 84 with it. Thereafter, the insertion tube 30 is withdrawn by operating the gearbox 64 to cause the nut 66 to be driven longitudinally backwards and thereby move the hydraulic unit 70 longitudinally backwards with it. The insertion tube 30 reaches the retracted position shown in Figure 18A and the valve 18 of the wellhead 12 is closed. Apparatus 10 can then be removed from the wellhead.

[157] There may be occasions when flexible conduit 50 becomes stuck in the well and cannot be removed. Apparatus 10 of the second embodiment permits cutting of flexible conduit 50 at a location within the wellbore. Once this is done, the flexible hose portion behind the cut can be retracted and the procedure described above for removing the apparatus 10 from the well can be performed. This allows the well valve 18 to be used to close off the side access passage in the usual way.

[158] The process by which the flexible conduit 50 is cut will be described below with reference to Figures 17B to 17D and Figures 18D and 18E.

[159] Figure 17B shows the insertion tube 30 and the front guide device 84 in position for normal deployment and retraction of the flexible conduit 50. The hydraulic unit 70 is operated by pressurizing the rear hydraulic chamber 74 to move the rear guide tube 73 forward from the position shown in Figure 17B to that shown in Figure 17C. Spring 86 is not compressed during this process and therefore rear guide barrel 73 and front guide device 84 maintain the same relative positions. Once the insertion tube 30 is attached to the hydraulic unit 70, it maintains its position and the front guide device 84 moves forward with respect to the insertion tube 30. As a result, the front of the front guide device 84 and the guide pawl 94 pivotally attached thereto move towards the deflection member 102. This condition is shown in Figures 17C and 18D.

[160] The rear hydraulic chamber 74 of the hydraulic device 70 is further pressurized to move the rear guide barrel 73 forward. At this stage, the hose 52 occupies the space between the guide pawl channel 100 and the deflection member 102, creating additional resistance to advancing the front guide device 84. The advancement of the rear guide barrel 73 therefore causes the spring 86 to compress and the guide bars 90 to advance along the slots 92 in the wall of the front guide device 84. This condition is shown in Figures 17D and 18E .

[161] Cutter blade 110 extends forward from seat 88 at the front end of rear guide barrel 73. Cutter blade 110 advances with rear guide barrel 73 and its cutting edge 113 begins to cut hose 52. The completed cut is shown in Figure 18E. Figure 14 shows the cutter blade 110 in a fully advanced position, with its cutting edge 113 engaging the bottom face 108 of the deflection member 102.

[162] A third embodiment of the apparatus 10 will be described with reference to Figure 19. A third embodiment of the apparatus 10 will be described with reference to Figure 19. The apparatus has the same features as those of the second embodiment, except that the front guide device 84 is fixed with respect to the rear guide barrel 73, without the spring 86 being provided between these two components. The third embodiment also lacks the deflection member 102 of the second embodiment, but employs a different arrangement, as described below.

[163] A resilient body 107 is attached to a connecting surface 105 at the front of the front guide device 84. A cutting blade 110 is also attached to the connecting surface 105 and extends forward into a slot provided in the resilient body 107. The resilient body 107 is capable of being resiliently compressed in the longitudinal direction, i.e. the direction of lateral insertion into the side access passage of a well. The resilient body 107 can be produced from a suitable elastomeric material.

[164] The insertion tube 30 has at its front end a deflection surface 103 at an angle of approximately 45 ° to the lateral insertion direction. The deflection surface 103 is generally aligned with a mouth 109 of the channel 95 through the resilient body 107, which runs up the length of the resilient body. Ahead of the mouth 109 of channel 95, channel 95 has a curved front portion 96 providing a transition from upward curvature to a downward direction.

[165] The operation of the third embodiment will be described with reference to Figures 20A to 20L.

[166] Figure 20A shows the apparatus in its configuration for deploying flexible conduit 50 in a well. The flexible conduit 50 has at its front end a probe in the form of a downhole spring 54. This is advanced forward along the front guide device 84 and into the channel 95 in the resilient body 107. The channel 95 guides the spring 54 upwards. The spring emerges from the mouth 109 of the channel 95 and strikes against the deflection surface 103 of the insertion tube 30, causing the spring to deflect from a generally horizontal or upward orientation to a downward orientation. With further advancement of spring 54, it adopts the positions shown in sequence in Figures 20B to 20D. As can be seen in Figure 20D, between the mouth 109 of the channel 95 and the most front part of the insertion tube 30, the spring is not closely guided, but instead can adopt the largest available radius in the space between the resilient body 107 and this front part.

[167] Hose 52 is attached behind downhole spring 54 and is also advanced forward. It follows the path of spring 54, as shown in Figures 20E to 20G. At the stage shown in Figure 20H, the weight of the spring 54 and hose 52 forward and under the insertion tube 30 has drawn the hose 52 from the large radius condition shown in Figure 20G to the smaller radius condition shown in Figure 20H, so that the hose 52 then rests against the curved front portion 96 of the channel 95. At this stage, the radius of curvature adopted by the hose 52 is necessarily reduced, due to the effect of gravity.

[168] As in the second embodiment, it may be desirable to cut the flexible conduit 50 at a location where it is in the well. The cutting procedure will be described with reference to Figures 20J to 20L. In Figure 20J, the front guide device 84 has been advanced forward with respect to the insertion tube 30, by the operation of the hydraulic device 70 described in relation to the second embodiment. The resilient body 107 engages the hose 52 and therefore its front end encounters additional resistance to advance. The hydraulic unit 70 is operated to move the front guide device 84 forward despite this resistance, causing the resilient body 107 to compress in the direction of lateral insertion or in the longitudinal direction of the resilient body 107. The cutting blade 110 is attached to the connecting surface 105 in front of the front guide device 84, so that the cutting blade 110 advances along the slot in the resilient body to reach the front part thereof, as shown in Figure 2 0K. At this stage, the cutting edge 113 engages with the hose 52.

[169] As the hydraulic unit is operated to advance the front guide device 84 further forward, the cutter blade 110 moves forward and cuts through the hose 52, as seen in Figure 20L. Once this is done, the flexible hose portion at the rear of the cut can be retracted and the procedure described above in relation to the second embodiment for removing the apparatus 10 from the well can be carried out. This allows the well valve 18 to be used to close off the side access passage in the usual way.

[170] Although not shown, the various embodiments of the apparatus may include a shut-off valve, of a type known in the art, which can be closed if a leak occurs in the pressure containment system.

Claims (13)

1. Apparatus (10) for gaining access to a well through a side access passage, the side access passage comprising a side opening (16) in a wall of the well, the apparatus (10) characterized in that it comprises: a flexible conduit (50) which is to be inserted into the well through the side access passage, the flexible conduit (50) comprising a probe at a front end thereof; a probe container (28) for accommodating the probe before it is inserted into the well and while the probe is exposed to well pressure in the probe container (28), the probe container (28) comprising an insertion tube (30) and a flexible tube (32), wherein the insertion tube (30) is connected at its rear end in a pressure-tight manner to a front end of the flexible tube (32), the probe container accommodating the probe with at least part of the probe extending along a short path go; and a drive mechanism (40) for advancing the probe container (28) toward and along the side access passage. 2. Apparatus according to claim 1, characterized in that the probe comprises a spring (54). 3. Apparatus according to claim 2, characterized in that the probe spring (54) extends continuously substantially throughout the entire length of the probe (28). 4. Apparatus according to claim 1 or 2, characterized in that the probe spring (54) is a helical spring. Apparatus according to any one of claims 1 to 4, characterized in that it comprises a flexible conduit seal (58) around the flexible conduit (50) and a seal between the flexible conduit (50) and an inner periphery of the probe container (28). Apparatus according to any one of claims 1 to 5, characterized in that it comprises a coil (36) on which the probe container (28) is wound. 7. Apparatus according to any one of claims 1 to 6, characterized in that it comprises a guide (34) for insertion along the side access passage and to assist in deflecting the flexible conduit (50) from a lateral insertion direction to a generally downward direction, the guide (34) being resiliently actuated so that when a front end portion thereof extends out of the side access passage into the well, the resilient actuation causes the front end portion to be directed at least partially downwards in the pit. 8. Apparatus according to claim 7, characterized in that it comprises a guide chamber (44) configured to guide the guide (34) to the side access passage of the well and a probe container seal (48) at the rear of the guide chamber configured to seal around the probe container (28). Apparatus according to any one of claims 7 or 8, characterized in that the guide (34) comprises a helical spring. 10. Apparatus according to any one of claims 7 to 9, characterized in that the guide comprises an engaging member (47) for engaging a radially outer surface of an inner wall extending downwards from the well to help restrict movement of the guide (34) in a circumferential direction of the radially outer surface. 11. Apparatus according to any one of claims 1 to 10, characterized in that the probe container provides an elongated chamber that follows a curved path extending through one or more revolutions. 12. Method of gaining access to a well through a side access passage, the side access passage comprising a side opening (16) in a wall of the well, the method characterized in that it comprises: connecting a probe container (28) to the side access passage in a pressure-tight manner, the probe container (28) comprising an insertion tube (30) and a flexible tube (32), wherein the insertion tube (30) is connected at its rear end, in a watertight manner to snapping, to a front end of the flexible tube (32), the probe container accommodating a probe at a front end of a flexible conduit (50) with at least part of the probe extending along a curved path; exposing the probe in the probe container (28) to well pressure; advancing the probe container (28) toward and along the side access passage using a drive mechanism (40); and inserting the flexible conduit (50) into the well through the probe container (28) and the side access passage. 13. Method according to claim 12, characterized in that it comprises providing complete pressure containment of tube pressure or annular pressure during an intervention.