Patent Description:
Subsurface safety valves (SSSVs) are well known in the oil and gas industry and provide one of many failsafe mechanisms to prevent the uncontrolled release of wellbore fluids should a wellbore system experience a loss in containment. Typically, subsurface safety valves comprise a portion of a tubing string set in place during completion of a wellbore. Although a number of design variations are possible for subsurface safety valves, the vast majority are flapper-type valves that open and close in response to longitudinal movement of a flow tube. Since subsurface safety valves provide a failsafe mechanism, the default positioning of the flapper valve is usually closed in order to minimize the potential for inadvertent release of wellbore fluids. The flapper valve can be opened through various means of control from the earth's surface in order to provide a flow pathway for production to occur.

In many instances, the flow tube can be regulated from the earth's surface using a piston and rod assembly that may be hydraulically charged via a control line linked to a hydraulic manifold or control panel. The term "control line" will be used herein to refer to a hydraulic line configured to displace the flow tube of a subsurface safety valve downward upon pressurization, or otherwise to become further removed from the exit of a wellbore. When sufficient hydraulic pressure is conveyed to a subsurface safety valve via the control line, the piston and rod assembly forces the flow tube downward, which causes the flapper valve to move into its open position upon. When the hydraulic pressure is removed from the control line, the flapper valve can return to its default, closed position using a biasing spring and/or downhole pressure. A self-closing mechanism, such as a torsion spring, can also be present to promote closure of the flapper valve should a loss of hydraulic pressure occur.

Some subsurface safety valves can also employ a second hydraulic line configured to counterbalance the effects of the control line and to provide an additional means of regulating the flow tube. The term "balance line" will be used herein to refer to a hydraulic line configured to displace the flow tube of a subsurface safety valve upward upon pressurization, or otherwise to become less removed from the exit of a wellbore. A balance line, when present, can operate in a similar manner to a control line and can also be controlled from the earth's surface. Accordingly, the terms "control line" and "balance line" can alternately be defined in terms of the propensity of these lines toward keeping a subsurface safety valve open or closed when pressurized. That is, a pressurized control line tends to force a subsurface safety valve toward an open position, whereas a pressurized balance line tends to force a subsurface safety valve toward a closed position. A balance line can also reduce section pressure acting on a piston by reducing the pressure differential.

Depending on operational considerations, a subsurface safety valve may be placed hundreds to thousands of feet downhole. During downhole placement of a subsurface safety valve, numerous opportunities exist for inadvertent damage to occur to the control line and/or the balance line, including line severance, thereby rendering the line(s) inoperative for regulating the subsurface safety valve. Line damage can also occur after a subsurface safety valve has been set in place and is in operational use. In addition to issues associated with the control line and/or the balance line, subsurface safety valves themselves may become damaged due to corrosion or scaling and no longer function properly. In the event of hydraulic failure or related damage to a subsurface safety valve, very expensive and time-consuming workover operations may be needed to replace the non-functioning valve. <CIT> relates to subterranean operations and to a method and system for opening and closing a subsurface valve used in conjunction with such operations. <CIT> relates to a balanced type down-hole surface controlled valve and a method for utilizing the same. It further relates to a balanced rod and piston type safety valve used in subsurface down-hole applications. <CIT> relates to a subsurface safety valve and to situations where an insert safety valve is deployed above a malfunctioning lower safety valve and shares an existing control line that extends to the lower safety valve. <CIT> relates to a well safety valve controlling flow through a well tubing using a hydraulic control line extending from the well surface to one side of an actuating piston and cylinder assembly for opening the valve. <CIT> relates to a well safety valve system.

<CIT> relates to a well safety system comprising a tubing retrievable safety valve adaptable for being connected in a well tubing string with means therein, responsive to pressure, for opening and closing the valve. The tubing retrievable safety valve is to be connected, in the tubing string, below a landing nipple for receiving a secondary safety valve. The safety valve and landing nipple are connected by a common conduit for conducting a suitable pressure fluid for control and balance of the safety valve and a secondary valve landed in the landing nipple.

The following figures are included to illustrate certain aspects of the present disclosure and should not be viewed as exclusive embodiments. The subject matter disclosed is capable of considerable modifications, alterations, combinations, and equivalents in form and function, as will occur to one having ordinary skill in the art and the benefit of this disclosure.

The present disclosure generally relates to subterranean wellbore operations and equipment and, more specifically, to mechanisms for transferring hydraulic regulation from a primary safety valve to an insert safety valve. The scope of the invention is set out in independent claims <NUM>, <NUM> with alternatives as set out in the dependent claims.

One or more illustrative embodiments incorporating the features of the present disclosure are presented herein. Not all features of a physical implementation are necessarily described or shown in this application for the sake of clarity. It is to be understood that in the development of a physical implementation incorporating the embodiments of the present disclosure, numerous implementation-specific decisions may be made to achieve the developer's goals, such as compliance with system-related, business-related, government-related and other constraints, which may vary by implementation and from time to time. While a developer's efforts might be time-consuming, such efforts would be, nevertheless, a routine undertaking for one having ordinary skill in the art and the benefit of this disclosure.

In the description herein, directional terms such as "above", "below", "upper", "lower", and the like, are used for convenience in referring to the accompanying drawings. In general, "above", "upper", "upward" and similar terms refer to a direction toward the exit of a wellbore, often toward the earth's surface, and "below", "lower", "downward" and similar terms refer to a direction away from the exit of a wellbore, often away from the earth's surface.

The embodiments of <FIG> are not according to the invention and are present for illustration purposes only. <FIG> shows an illustrative schematic of an example wellbore system containing a tubing string having a nipple and a tubing-retrievable safety valve attached thereto. The tubing-retrievable safety valve may represent a primary safety valve of the wellbore system. The terms "tubing-retrievable safety valve," "primary safety valve," and "safety valve" are synonymous and may be used interchangeably herein. In wellbore system <NUM>, wellbore <NUM> penetrates subterranean formation <NUM>. Although wellbore <NUM> is depicted as being substantially vertical in <FIG>, it is to be recognized that one or more non-vertical sections may also be present and are fully consistent with the embodiments of the present disclosure. Tubing string <NUM> is disposed within at least a portion of the length of wellbore <NUM>, with annulus <NUM> being defined between the exterior of tubing string <NUM> and the interior of wellbore <NUM>. Tubing string <NUM> further defines an internal flow pathway therethrough (not shown in <FIG>). Safety valve <NUM> is interconnected to tubing string <NUM> and is configured to regulate fluid flow above and below safety valve <NUM> within the internal flow pathway, including shutting off fluid access in the event of an emergency. Safety valve <NUM> may have at least one hydraulic line connected thereto (two shown in <FIG>, e.g., control line <NUM> and balance line <NUM>), as discussed in more detail below. Control line <NUM> and balance line <NUM> may extend from the earth's surface in order to allow operation of safety valve <NUM> to take place from a rig, wellhead installation, or subsea platform located on the earth's surface or the ocean's surface. Nipple <NUM> may also be arranged within an upper portion of tubing string <NUM>, or nipple <NUM> may be integral with safety valve <NUM>. An insert safety valve may be positioned in nipple <NUM> and actuated, as discussed in further detail below.

<FIG> show detailed schematics of an illustrative tubing-retrievable safety valve that is operable by a single hydraulic control line. With continued reference to <FIG>, <FIG> show progressive cross-sectional side views of illustrative safety valve <NUM> and its hydraulic operating mechanisms. <FIG> depicts an upper portion of safety valve <NUM> and <FIG> depicts a successive lower portion of safety valve <NUM>. Safety valve <NUM> includes housing <NUM> that is coupled to tubing string <NUM> at opposing ends of housing <NUM> (tubing string <NUM> shown only in <FIG>). It is to be recognized that safety valve <NUM> depicted in <FIG> is merely illustrative of many possible configuration for a hydraulically operated safety valve. Hence, other safety valves may operate using similar principles, and the depicted valve configuration should not be considered limiting.

Control line port <NUM> may be provided in housing <NUM> for connecting a hydraulic control line (not shown in <FIG>) to safety valve <NUM>. When appropriately connected to control line port <NUM>, the hydraulic control line establishes fluid communication with piston bore <NUM> defined in housing <NUM>, thereby allowing hydraulic fluid pressure to be conveyed thereto. Piston bore <NUM> may be an elongate channel or conduit that extends substantially longitudinally along a portion of the axial length of safety valve <NUM>.

Piston assembly <NUM> is arranged within piston bore <NUM> and is configured to translate axially therein. Piston assembly <NUM> includes piston head <NUM> that mates with and otherwise biases up stop <NUM> defined within piston bore <NUM> when piston assembly <NUM> is forced upwards. Up stop <NUM> may be a radial shoulder defined by housing <NUM> within piston bore <NUM>, which has a reduced diameter and an axial surface configured to engage a corresponding axial surface of piston head <NUM>. Up stop <NUM> may generate a mechanical metal-to-metal seal between the two components to prevent the migration of fluids (e.g., hydraulic fluids, production fluids, and the like) therethrough. Other configurations of up stop <NUM> that are configured to arrest axial movement of piston assembly <NUM> are also possible.

Piston assembly <NUM> may also include piston rod <NUM> that extends longitudinally from piston assembly <NUM> through at least a portion of piston bore <NUM>. At a distal end of piston rod <NUM>, it may be coupled to actuator sleeve <NUM> for affecting motion of flow tube <NUM>. Flow tube <NUM> is movably arranged within safety valve <NUM>. More particularly, actuator sleeve <NUM> may engage biasing device <NUM> (e.g., a compression spring, a series of Belleville washers, or the like) arranged axially between actuator sleeve <NUM> and actuation flange <NUM> that forms part of the proximal end of flow tube <NUM>. As actuator sleeve <NUM> acts upon biasing device <NUM> with axial force, actuation flange <NUM> and flow tube <NUM> correspondingly move axially in the direction of the applied force (i.e., downward with increasing hydraulic pressure). Down stop <NUM> may be arranged within the piston bore <NUM> in order to limit the range of axial motion of piston assembly <NUM>. A metal-to-metal seal may be created between piston assembly <NUM> and down stop <NUM> such that the migration of fluids (e.g., hydraulic fluids, production fluids, and the like) therethrough is generally prevented.

Safety valve <NUM> further includes flapper valve <NUM> that is selectively movable between open and closed positions to either prevent or allow fluid flow through internal flow pathway <NUM> defined through the interior of safety valve <NUM>. Flapper valve <NUM> is shown in <FIG> in its default, closed position such that fluid flow into internal flow pathway <NUM> from downhole (i.e., to the right of <FIG>) is substantially blocked. At least one torsion spring <NUM> biases flapper valve <NUM> to pivot to its closed position.

Upon hydraulic pressurization and downward movement of piston rod <NUM>, flow tube <NUM> is also displaced downward, eventually overcoming the force associated with torsion spring <NUM> and any associated downhole fluid pressures. At this point, flapper valve <NUM> moves from its closed position to an open position (shown in phantom in <FIG>). When the hydraulic pressure is released, flow tube <NUM> is displaced upwardly and the spring force of torsion spring <NUM> moves flapper valve <NUM> back to its closed position.

Safety valve <NUM> may further contain lower chamber <NUM> within housing <NUM>. In some embodiments, lower chamber <NUM> may form part of piston bore <NUM>, such as being an elongate extension thereof. Power spring <NUM>, such as a coil or compression spring, may be arranged within lower chamber <NUM> and correspondingly biases actuation flange <NUM> and actuation sleeve <NUM> upwardly, which, in turn, also biases piston assembly <NUM> in the same direction. That is, power spring <NUM> also resists the hydraulic pressure applied from the hydraulic control line and helps to prevent flapper valve <NUM> from being opened inadvertently. Accordingly, expansion of the power spring <NUM> causes piston assembly <NUM> to move upwardly within piston bore <NUM>. It should be noted that in addition to power spring <NUM>, other types of biasing devices, such as a compressed gas with appropriate sealing mechanisms, may be employed similarly.

As mentioned above, a hydraulic line may provide hydraulic pressurization to safety valve <NUM> at control line port <NUM>. However, more than one hydraulic line may be present in certain types of safety valves. For example, referring again to <FIG>, safety valve <NUM> may be controllable by dual hydraulic lines, such as control line <NUM> and balance line <NUM>. The DEPTHSTAR® tubing-retrievable safety valve from Halliburton Energy Services, Inc. is one illustrative example of a safety valve that is controllable by dual hydraulic lines. Control line <NUM> may provide for hydraulic pressurization of safety valve <NUM> in a manner similar to that described above in reference to <FIG>. That is, hydraulic pressurization of control line <NUM> may force a flow tube downward to open safety valve <NUM>. In contrast, hydraulic pressurization of balance line <NUM> may tend to force the flow tube upwardly. That is, balance line <NUM> counteracts the hydraulic pressurization provided by control line <NUM> and further supplements the upward forces tending to keep safety valve <NUM> closed. Similarly, balance line <NUM> can reduce the section pressure by reducing a pressure differential acting on the flow tube. Other mechanisms for actuating safety valve <NUM> through pressurization of control line <NUM> and balance line <NUM> can also be envisioned by one having ordinary skill in the art.

As depicted in <FIG>, control line <NUM> and balance line <NUM> extend to safety valve <NUM> within annulus <NUM>, in close proximity to tubing string <NUM>. However, other configurations for control line <NUM> and balance line <NUM> are also possible. In alternative configurations, for instance, control line <NUM> and/or balance line <NUM> may be located in the internal flow pathway of tubing string <NUM> or be defined, at least in part, in a sidewall of tubing string <NUM> or a component thereof (e.g., within the sidewall of nipple <NUM> or an associated sub). Regardless of their particular configurations, control line <NUM> and balance line <NUM> allow safety valve <NUM> to be controlled hydraulically from the earth's surface.

As discussed above, failure of control line <NUM> or balance line <NUM> can render safety valve <NUM> at least partially inoperable. Failure of control line <NUM> can be particularly detrimental, since failure of this line can lead to an inability to maintain safety valve <NUM> in an open position. Similarly, failure of safety valve <NUM> itself (e.g., due to corrosion or scaling) may prevent effective hydraulic control from taking place. To address the foregoing issues that may arise when safety valve <NUM> has become inoperable, hydraulic communication with safety valve <NUM> may be discontinued and transferred to an insert (secondary) safety valve located above safety valve <NUM> within tubing string <NUM>, as discussed herein. Specifically, the insert safety valve may be placed or inserted in tubing string <NUM> within the internal flow pathway (bore) of nipple <NUM>, particularly after safety valve <NUM> has failed. In alternative embodiments, the insert safety valve may be placed in tubing string <NUM> below safety valve <NUM>. Accordingly, the term "insert safety valve" will be used herein to refer to a secondary safety valve that is used to replace or otherwise supplement an inoperative primary safety valve <NUM>. The terms "insert safety valve" and "secondary safety valve" may be used interchangeably herein. Insert safety valves are not considered to be a redundant backup of the primary safety valve <NUM>, but are instead placed in-line in response to a failed primary safety valve <NUM> to supplant its operation. Effective replacement of a primary safety valve <NUM> with an insert safety valve can allow production of wellbore fluids to continue without conducting an expensive and time-consuming workover operation to withdraw tubing string <NUM> for valve repair or exchange. Safety valve <NUM> and the insert safety valve contained within nipple <NUM> may be separated by any distance, which may range from inches to thousands of feet.

Various mechanisms for affecting hydraulic control of an insert safety valve, particularly an insert safety valve that is controllable by dual hydraulic lines, are discussed further herein. Advantageously, the disclosure herein allows an existing control line <NUM> and an existing balance line <NUM> to be used for regulating the insert safety valve, rather than deploying one or more new lines and increasing the number of penetrations through a tubing hanger. Further, the disclosure herein provides for discontinuing hydraulic communication with safety valve <NUM> in the course of re-establishing it with the insert safety valve. That is, the disclosure herein allows the lower portions (i.e., the initially operative portions) of control line <NUM> and balance line <NUM> to be shut off so that hydraulic communication with safety valve <NUM> no longer takes place. In the case of an insert safety valve placed below safety valve <NUM>, the term "lower portion" no longer directly corresponds to the geometric disposition of the line being shut off. Accordingly, the terms "initially operative portion" or "primary portion" will refer herein to the portion of a hydraulic line initially being used to regulate safety valve <NUM>, regardless of the geometric disposition of the line. Alternately, the term "lower portion" will refer herein to the portion of control line <NUM> or balance line <NUM> initially used to regulate safety valve <NUM> before subsequently being shut off, regardless of the geometric disposition of the line.

With reference again being made to <FIG>, an insert safety valve may be positioned in an internal flow pathway (not shown in <FIG>) defined within nipple <NUM>, which comprises a portion of tubing string <NUM> above safety valve <NUM>. Nipple <NUM> may also be located below safety valve <NUM> for similar reasons to those discussed above, or dual nipples may also be provided above and below safety valve <NUM>, where the dual nipples serve different functions. With continued reference being made to <FIG>, a portion of the internal flow pathway may comprise the bore of nipple <NUM> and any profile features defined therein. The profile features within the bore may allow the insert safety valve to be properly seated, sealed and retained therein. For example, nipple <NUM> may comprise a landing shoulder or threading within the bore to ensure proper seating of the insert safety valve. Properly locating the insert safety valve within the bore may help to establish hydraulic communication with control line <NUM> and balance line <NUM>. Appropriate sealing may also be provided about the insert safety valve in order to isolate the hydraulic fluids traveling thereto from control line <NUM> and balance line <NUM>, thereby allowing these lines to exert independent hydraulic control of the insert safety valve.

According to various embodiments of the present disclosure, mechanical switching of the hydraulic flow pathways defined by control line <NUM> and balance line <NUM> may redirect their hydraulic communication from safety valve <NUM> to the bore of nipple <NUM>, thereby allowing hydraulic regulation of an insert safety valve to take place. The mechanical switching may take place within nipple <NUM> itself or within a sub that is separate from nipple <NUM>. Upon mechanical switching the hydraulic communication from control line <NUM> and balance line <NUM> to the bore of nipple <NUM>, hydraulic regulation of safety valve <NUM> is discontinued in favor of an insert safety valve within nipple <NUM>. Specifically, the embodiments of the present disclosure allow the insert safety valve to be regulated hydraulically with control line <NUM> and balance line <NUM> following mechanical switching of these lines. That is, opening and closing of the insert safety valve may take place through appropriately pressurizing and de-pressurizing control line <NUM> and balance line <NUM>. Advantageously, the embodiments of the present disclosure allow both control line <NUM> and balance line <NUM> to be switched for operating the insert safety valve, thereby maintaining the desirable features afforded by dual hydraulic lines in operating safety valve <NUM>. Various configurations for affecting mechanical switching of these lines are described in more detail hereinafter. In order for hydraulic regulation of an insert safety valve to take place, control line <NUM> and balance line <NUM> are placed in latent hydraulic communication with the internal flow pathway of nipple <NUM> (latent hydraulic communication and internal flow pathway not shown in <FIG>). As used herein, the term "latent hydraulic communication" will refer to a portion of a hydraulic flow pathway that does not undergo hydraulic pressurization until a triggering event occurs to change the configuration of the flow pathway. In the various embodiments described herein, the triggering event involves a mechanical switching action, as described in further detail below.

In order to facilitate latent hydraulic communication within nipple <NUM>, control line <NUM> and balance line <NUM> may be coupled with corresponding ports defined on the exterior of nipple <NUM> and/or at least a portion of these lines may be defined within the sidewall of nipple <NUM>. Under normal operational conditions (i.e., when safety valve <NUM> is still functional), hydraulic pressurization actuates safety valve <NUM> and bypasses the locations where latent hydraulic communication is later established. Hydraulic fluid may pass through nipple <NUM> in performing this action, but without accessing the portions of these lines that are in latent hydraulic communication with the bore of nipple <NUM>. Accordingly, the embodiments of the present disclosure describe various configurations in which the lower portions (i.e., initially active portions) of control line <NUM> and balance line <NUM>, each leading to safety valve <NUM>, may be bypassed following activation of the hydraulic lines establishing latent hydraulic communication within nipple <NUM>.

<FIG> show schematics of an illustrative nipple configuration in which dual sliding sleeves may affect switching of control line <NUM> and balance line <NUM>. In the interest of clarity, the disposition of nipple <NUM> and safety valve <NUM> within tubing string <NUM> is not depicted in <FIG>. In most instances, elements having a common structure and function to those of previously described FIGURES will be assigned a common reference character in the drawings and will not be discussed again in detail. A configuration similar to that depicted in <FIG> may be used in some embodiments, although other configurations are certainly possible. <FIG> shows the normal operational state of wellbore system <NUM>, in which both control line <NUM> and balance line <NUM> maintain hydraulic communication with safety valve <NUM>. Specifically, upper portion 20a of control line <NUM> is connected to control line port 21a, and lower portion 20b of control line <NUM> is connected to control line port 21b. Lower portion 20b of control line <NUM> leads to safety valve <NUM> and establishes hydraulic communication therewith. Hydraulic communication between upper portion 20a and lower portion 20b takes place through control line conduits 25a and 25b, each defined within the sidewall of nipple <NUM>. Hydraulic communication between control line conduits 25a and 25b is maintained through recess <NUM>, which is defined between sliding sleeve <NUM> and the internal profile of nipple <NUM>. Similarly, upper portion 22a of balance line <NUM> is connected to balance line port 23a, and lower portion 22b of balance line <NUM> is connected to balance line port 23b. Balance line conduits 27a and 27b and recess <NUM> extend in between upper portion 22a and lower portion 22b of balance line <NUM>. Recess <NUM> is defined between sliding sleeve <NUM> and the internal profile of nipple <NUM>. In the normal operational configuration of <FIG>, hydraulic pressurization does not extend into internal flow pathway <NUM> of nipple <NUM>, other than within recesses <NUM> and <NUM>. Seals 32a, 32b, 33a and 33b maintain hydraulic fluid within recesses <NUM> and <NUM> such that the fluid does not enter the remaining portions of internal flow pathway <NUM>. Sliding sleeves <NUM> and <NUM> may be maintained in position by various retention mechanisms, such as shear pins and the like (not depicted in <FIG>), until the transfer of hydraulic control is desired.

<FIG> shows the nipple configuration of <FIG> after axial displacement of sliding sleeves <NUM> and <NUM> affects transfer of hydraulic regulation. In particular, by repositioning sliding sleeve <NUM>, recess <NUM> no longer maintains hydraulic communication between control line conduits 25a and 25b. Instead, hydraulic fluid is free to enter internal flow pathway <NUM> of nipple <NUM> from control line conduit 25a, thereby effectively shutting off lower portion 20b of control line <NUM>. Similarly, by repositioning sliding sleeve <NUM>, recess <NUM> no longer maintains hydraulic communication between balance line conduits 27a and 27b, and hydraulic fluid from balance line conduit 27a is free to enter internal flow pathway <NUM> of nipple <NUM>. By positioning an insert safety valve (not depicted in <FIG> and <FIG>) within internal flow pathway <NUM>, upper portion 20a of control line <NUM> and upper portion 22b of balance line <NUM> may be used to hydraulically control an insert safety valve within nipple <NUM>, as described hereinafter.

<FIG> shows the nipple configuration of <FIG> with insert safety valve <NUM> in place after axial displacement of sliding sleeves <NUM> and <NUM>. As shown in <FIG>, insert safety valve <NUM> is positioned within internal flow pathway <NUM> of nipple <NUM> such that insert safety valve <NUM> may receive hydraulic fluid from control line conduit 25a and balance line conduit 27a in order to undergo hydraulic pressurization. Seals 36a-36c around insert safety valve <NUM> contain the hydraulic fluid from each source within a defined space and keep the two sources of hydraulic fluid from mixing with one another. Specifically, seals 36a and 36b direct hydraulic fluid from control line conduit 25a to control line port <NUM> on insert safety valve <NUM>, and seals 36b and 36c direct hydraulic fluid from balance line conduit 27a to balance line port <NUM> on insert safety valve <NUM>. Seal 36b thereby prevents the two sources of hydraulic fluid from mixing with one another, thereby allowing control line <NUM> and balance line <NUM> to be independently regulated in operating insert safety valve <NUM>. Insert safety valve <NUM> may be a flapper-type valve, such as one similar to that depicted in <FIG>, and it may be operated by appropriately pressurizing and depressurizing control line <NUM> and balance line <NUM> to open and close the flapper valve (details not shown). Further, insert safety valve <NUM> may be of a similar design to safety valve <NUM> that it has replaced, or it may be of an entirely different design. For example, the mechanism for actuating the flapper valve may differ between safety valve <NUM> and insert safety valve <NUM>.

Sliding sleeves <NUM> and <NUM> may be configured for axial displacement by any suitable technique. In some embodiments, a wireline tool, such as a jarring mechanism, may be used to affect the axial displacement of sliding sleeves <NUM> and <NUM>. Suitable wireline tools for this purpose will be familiar to one having ordinary skill in the art. In other embodiments, the placement of insert safety valve <NUM> within internal flow pathway <NUM> may axially displace sliding sleeves <NUM> and <NUM>. Suitable features of sliding sleeves <NUM> and <NUM> that allow their axial displacement by a wireline tool or insert safety valve positioning will be familiar to one having ordinary skill in the art.

Suitable techniques for positioning insert safety valve <NUM> within nipple <NUM>, such as through wireline, braided line, or coiled tubing deployment, will be familiar to one having ordinary skill in the art. Threading, landing shoulders and like structures intended to facilitate positioning of insert safety valve <NUM> may be present as part of the internal profile of nipple <NUM>. In the interest of clarity, these features are not depicted in any particular detail in <FIG>. Before or after placing insert safety valve <NUM>, safety valve <NUM> may be mechanically locked in an open position such that it is permanently bypassed within tubing string <NUM>, thereby turning its fluid control function over to insert safety valve <NUM>.

Once hydraulic communication has been transferred to nipple <NUM>, insert safety valve <NUM> may be operated in a substantially similar manner to that of safety valve <NUM> by pressurizing and depressurizing control line <NUM> and balance line <NUM> in a desired manner. Further, in alternative embodiments, a single-line insert safety valve may be used as an alternative to a dual-line insert safety valve, such as that depicted in <FIG>. Single-line insert safety valves may be utilized upon redirecting hydraulic flow from at least one of control line <NUM> or balance line <NUM> to internal flow pathway <NUM>, as discussed in brief above.

In alternative embodiments, a sliding sleeve may be coupled to various structures configured to transfer hydraulic regulation from a primary safety valve to an insert safety valve. Axial displacement of the sliding sleeve may indirectly affect hydraulic switching in such configurations. Specifically, a sliding sleeve may be mechanically coupled to a piston assembly in order to affect its axial displacement for switching between a primary safety valve and an insert safety valve.

<FIG> and <FIG> show schematics of an illustrative nipple configuration in which dual sliding sleeves may affect switching of a control line and a balance line through axial motion of a piston assembly. Whereas sealing is maintained around sliding sleeves <NUM> and <NUM> in the nipple configurations of <FIG> in order to allow hydraulic pressurization of a primary safety valve to take place, sealing in the nipple configurations of <FIG> and <FIG> is instead provided around a piston assembly, as discussed in further detail below.

Referring now to <FIG>, control line conduits 25a and 25b are defined within nipple <NUM> and establish hydraulic communication with safety valve <NUM> (not shown in <FIG> and <FIG>) via recess <NUM> that is defined about piston assembly <NUM>. Specifically, hydraulic fluid flows through control line conduit 25a to control line conduit 25b via recess <NUM> in order for hydraulic regulation of safety valve <NUM> to take place using control line <NUM>. Similarly, hydraulic fluid flows through balance line conduit 27a to balance line conduit 27b via recess <NUM> defined about piston assembly <NUM> in order for hydraulic regulation of safety valve <NUM> to take place using balance line <NUM>. Piston assemblies <NUM> and <NUM> are housed within cavities <NUM> and <NUM>, respectively, each of which is open to internal flow pathway <NUM> within nipple <NUM>. In <FIG>, hydraulic fluid does not enter either of cavities <NUM> or <NUM> and remains within recesses <NUM> and <NUM> in the course of passing to safety valve <NUM>. Seals 48a and 48b around piston assembly <NUM> maintain hydraulic fluid within recess <NUM>, and seals 48c and 48d around piston assembly <NUM> likewise maintain hydraulic fluid within recess <NUM>.

With continued reference to <FIG>, rods 50a and 50b are operably connected to piston assemblies <NUM> and <NUM>, respectively. Arms 52a and 52b, in turn, operably connect sliding sleeves <NUM> and <NUM>, respectively, to rods 50a and 50b. Hence, axial displacement of sliding sleeves <NUM> and <NUM> can affect a corresponding displacement of piston assemblies <NUM> and <NUM> within cavities <NUM> and <NUM>, respectively. Although not depicted in <FIG> and <FIG>, the movement of piston assemblies <NUM> and <NUM> may be optionally resisted by a spring or similar biasing device.

<FIG> shows the nipple configuration of <FIG> after axial displacement of sliding sleeves <NUM> and <NUM>. Upon moving sliding sleeves <NUM> and <NUM> downwardly, a corresponding change in the position of piston assemblies <NUM> and <NUM> occurs within cavities <NUM> and <NUM>, respectively. Upon moving piston assemblies <NUM> and <NUM>, recesses <NUM> and <NUM> are no longer positioned to maintain hydraulic communication to lower portion 20b of control line <NUM> and lower portion 22b balance line <NUM>. Instead, upon switching, hydraulic fluid from control line conduit 25a can enter cavity <NUM> and progress to internal flow pathway <NUM> of nipple <NUM>, and hydraulic fluid from balance line conduit 27a can similarly enter cavity <NUM> and access internal flow pathway <NUM>. Upon placing an insert safety valve (not shown in <FIG> and <FIG>) in internal flow pathway <NUM>, hydraulic operation of this valve may be realized. Placement of the insert safety valve and sealing about the insert safety valve may take place in a similar manner to that depicted in <FIG> and will not be depicted again in the interest of brevity. Again, through providing appropriately placed sealing around the insert safety valve, the hydraulic fluid from control line conduit 25a and balance line conduit 27a may be kept separate from one another, thereby allowing control line <NUM> and balance line <NUM> to independently operate the insert safety valve.

In the nipple configurations described above, the mechanical switching mechanism for transferring hydraulic regulation from safety valve <NUM> to an insert safety valve resides within nipple <NUM> itself. That is, the switching effect is integral with nipple <NUM>. Specifically, in the previously described embodiments, switching of the hydraulic regulation may take place by virtue axial displacement of sliding sleeves <NUM> and <NUM>, each of which is disposed within nipple <NUM>. In alternative embodiments, switching of the hydraulic regulation from safety valve <NUM> to the insert safety valve may take place in a sub that is spaced apart from nipple <NUM>. Further disclosure in this regard follows below. As used herein, the term "sub" will refer to a short section of a tubular string that is separate from nipple <NUM>. In some embodiments, switching of the hydraulic regulation may be affected by one or more sliding sleeves housed within the sub. Other mechanisms for switching hydraulic regulation within a sub are also discussed hereinbelow and may be implemented based upon various design considerations. For example, one may choose to provide the mechanical mechanism for switching hydraulic regulation within a sub instead of within nipple <NUM> in order to simplify the ease of manufacturing of nipple <NUM>. Further, just as the various mechanisms for providing mechanical switching of hydraulic regulation may be separately provided in a sub, the various configurations for a sub that are depicted and described hereinafter may be alternatively implemented as an integral portion of nipple <NUM>. However, using a sub that is separate from nipple <NUM> may allow the sub to be located at a relatively shallow depth to facilitate switching using wireline tools, while nipple <NUM> can be located at an arbitrary depth as dictated by downhole conditions or customer preferences.

<FIG> shows an illustrative schematic of a wellbore system containing a tubing string having a sub, a nipple and a tubing-retrievable safety valve attached thereto. <FIG> bears various similarities to <FIG> and may be better understood by reference thereto. Only differences resulting from the incorporation of sub <NUM> within tubing string <NUM> will be discussed further herein. Whereas control line <NUM> and balance line <NUM> were contiguous in <FIG> and proceeded directly from the earth's surface to tubing retrievable safety valve <NUM>, sub <NUM> intervenes in these lines in <FIG>. Specifically, upper portion 20a of control line <NUM> and upper portion 22b of balance line <NUM> extend to sub <NUM> in <FIG>. Lower portion 20b of control line <NUM> and lower portion 22b of balance line <NUM> likewise extend from sub <NUM> to safety valve <NUM>. Also extending from sub <NUM> to nipple <NUM> are latent control line <NUM> and latent balance line <NUM>. Under normal operational conditions in which safety valve <NUM> is still being regulated, latent control line <NUM> and latent balance line <NUM> are simply inactive and nipple <NUM> is bypassed. Once deployment and actuation of an insert safety valve within nipple <NUM> is desired, a mechanical switching mechanism within sub <NUM> can be actuated to shut off lower portion 20b of control line <NUM> and lower portion 22b of balance line <NUM>. In doing so, latent control line <NUM> and latent balance line <NUM> become active and allow diversion of hydraulic fluid to nipple <NUM> to take place, thereby allowing the insert safety valve to be hydraulically regulated. That is, sub <NUM> can establish hydraulic communication between upper portion 20a of control line <NUM> and latent control line <NUM> and between upper portion 22b of balance line <NUM> and latent balance line <NUM>, thereby allowing hydraulic regulation of an insert safety valve to take place. Various mechanisms within sub <NUM> for transferring hydraulic regulation to nipple <NUM> via latent control line <NUM> and latent balance line <NUM> are discussed hereinafter. Although <FIG> has depicted lower portion 20a of control line <NUM> and lower portion 22b of balance line <NUM> as completely bypassing nipple <NUM>, it is to be recognized that these lines may also pass through the sidewall of nipple <NUM>, if desired, without departing from the scope of the present disclosure. When these lines pass through nipple <NUM> in such a manner, they are not disposed such that they establish hydraulic communication with internal flow pathway <NUM>.

In some embodiments, sliding sleeve configurations similar to those depicted in <FIG> and <FIG> may be implemented in sub <NUM>. By way of illustration, <FIG> and <FIG> show schematics of an illustrative sub in which hydraulic regulation may be switched by way of one or more sliding sleeves housed within the sub. The mechanical switching mechanism afforded by sliding sleeves <NUM> and <NUM> in <FIG> and <FIG> bears similarities to that of <FIG> and accordingly will only be discussed further in brief herein.

Referring in more detail to <FIG> and <FIG>, sub <NUM> contains sliding sleeves <NUM> and <NUM> within internal flow pathway <NUM>. Recesses <NUM> and <NUM> are defined between sliding sleeves <NUM> and <NUM> and the body of sub <NUM>, thereby allowing hydraulic fluid to flow between upper portion 20a and lower portion 20b of control line <NUM> and between upper portion 22a and lower portion 22b of balance line <NUM>. In the configuration of <FIG>, latent control line <NUM> is not in hydraulic communication with recess <NUM> and is inactive. Latent balance line <NUM> is similarly not in hydraulic communication with recess <NUM> and is similarly inactive. Upon axially displacing sliding sleeves <NUM> and <NUM>, however, as shown in <FIG>, hydraulic communication is established between upper portion 20a of control line <NUM> and latent control line <NUM>, and similarly between upper portion 22a of balance line <NUM> and latent balance line <NUM>. In <FIG>, hydraulic fluid no longer flows through lower portion 20b of control line <NUM> and lower portion 22b of balance line <NUM>, thereby shutting off these lines and effectively deactivating safety valve <NUM>.

<FIG> and <FIG> show schematics of another illustrative sub in which hydraulic regulation may be switched by way of one or more sliding sleeves housed within the sub. In the interest of conciseness and brevity, <FIG> and <FIG> only show a sliding sleeve and related components for transferring hydraulic regulation from lower portion 20b of control line <NUM> to latent control line <NUM>. However, it is to be recognized that a similar switching mechanism may be provided to transfer hydraulic regulation of lower portion 22b of balance line <NUM> to latent balance line <NUM>. Separate sliding sleeves may be used for this purpose, or a single sliding sleeve may be used to switch both lines simultaneously. When a single sliding sleeve is used, separated, the sliding sleeve may be appropriately sealed to maintain separation between the hydraulic fluid originating from control line <NUM> and balance line <NUM>.

<FIG> shows as illustrative side view schematic of sub <NUM> in which sliding sleeve <NUM> may cause transfer of hydraulic regulation from control line <NUM> to latent control line <NUM>. As shown in <FIG>, upper portion 20a control line <NUM> enters the top of sub <NUM>, and lower portion 20b of control line <NUM> exits through the bottom. Within the sidewall of sub <NUM>, upper portion 20a of control line <NUM> is in hydraulic communication with piston chamber <NUM>. Piston chamber <NUM> contains piston assembly <NUM> and spring <NUM>. The spring force of spring <NUM> pushes piston assembly <NUM> toward piston seat <NUM>. Piston seat <NUM> is located at the upper terminus of lower portion 20b of control line <NUM>. If mating occurs between piston assembly <NUM> and piston seat <NUM>, hydraulic flow to lower portion 20b of control line <NUM> terminates. Under normal operational conditions, hydraulic pressure from hydraulic fluid within upper portion 20a of control line <NUM> tends to resist the spring force and displace piston assembly <NUM> away from piston seat <NUM>, thereby keeping the entirety of control line <NUM> open. Seal <NUM> within piston chamber <NUM> allows sufficient hydraulic pressure to build to resist the spring force.

As long as there is sufficient hydraulic pressure present in upper portion 20a of control line <NUM> to resist the spring force, lower portion 20b of control line <NUM> may remain open. If lower portion 20b of control line <NUM> is breached or otherwise becomes inoperable, it may no longer be possible to build sufficient hydraulic pressure to resist the spring force and keep piston assembly <NUM> from mating with piston seat <NUM>. Thus, if sufficient hydraulic pressure is not maintained, piston assembly <NUM> may automatically close and seal off lower portion 20b of control line <NUM>. As described further hereinbelow, sub <NUM> may contain further mechanisms that promote mating of piston assembly <NUM> and piston seat <NUM> to accomplish this purpose.

Referring still to <FIG>, branch <NUM> intersects upper portion 20a of control line <NUM> within the body of sub <NUM> and extends to its interior. Shearable lug <NUM> blocks branch <NUM> from releasing hydraulic fluid into the interior of sub <NUM> and holds sliding sleeve <NUM> in place. Shearable lug <NUM> may be held in place with sliding sleeve <NUM> and optionally may be further secured in place by a compression fit and/or a retaining ring (snap ring). Recess <NUM> is defined within sliding sleeve <NUM>, and seals 78a and 78b are maintained on either side of recess <NUM>.

In order to switch hydraulic regulation from lower portion 20b of control line <NUM> to latent control line <NUM>, sliding sleeve <NUM> is axially displaced into a second position, as shown in <FIG>. Shearable lug <NUM> breaks in the axial displacement process and opens branch <NUM> to the interior of sub <NUM>. Sliding sleeve <NUM> may be hardened to promote the shearing process. Hence, until shearable lug <NUM> is broken, safety valve <NUM> remains operative and all sealing is advantageously metal-to-metal. Upon being axially displaced, recess <NUM> receives the exiting hydraulic fluid from branch <NUM> and transfer it to latent control line <NUM>. Latent control line <NUM> also extends to the interior of sub <NUM>.

Referring still to <FIG>, branch <NUM> extends between latent control line <NUM> and piston chamber <NUM>. Hydraulic fluid exiting branch <NUM> tends to displace piston assembly <NUM> toward piston seat <NUM>. That is, the hydraulic fluid within branch <NUM> at the upend of piston chamber <NUM> aids spring <NUM> in affecting closure of lower portion 20b of control line <NUM> by translating piston assembly <NUM>. Even if the hydraulic pressures are the same in upper portion 20a of control line <NUM> at piston seat <NUM> and in branch <NUM> at the upend of piston chamber <NUM>, the directions of the hydraulic forces are in opposition to one another, thereby allowing the spring force to mate piston assembly <NUM> against piston seat <NUM>. Concurrently, hydraulic fluid can flow through the remainder of latent control line <NUM> onward toward nipple <NUM>.

Alternately, by employing a modified sliding sleeve <NUM>, shearable lug <NUM> may be omitted in the configurations of <FIG> and <FIG> while still achieving a similar result. In particular, branch <NUM> may be left open by omitting shearable lug <NUM>, and replacing the depicted sliding sleeve <NUM> with a sliding sleeve having appropriate sealing on either side of the exit of branch <NUM>. Hence, by moving sliding sleeve <NUM> an appropriate distance (e.g., see <FIG> and <FIG>), hydraulic fluid may flow from branch <NUM> to branch <NUM> to achieve a similar result to that described above. This alternative configuration, however, may lack the metal-to-metal sealing benefits described above.

Alternative configurations of a sub that may affect switching of control line <NUM> and balance line <NUM> without utilizing axial displacement of a sliding sleeve are also possible. For example, in illustrative configurations, a sub may include a side pocket in which a replaceable spool or other like replaceable valve system may be disposed. Under normal operational conditions, a first replaceable spool may be housed in the side pocket to operate safety valve <NUM> by control line <NUM> and balance line <NUM>. The first replaceable spool may be housed in the side pocket initially, or it may be deployed in the side pocket after the tubing string is set in place. Once operation of an insert safety valve within nipple <NUM> is desired, the first replaceable spool may be substituted with a second replaceable spool (e.g., through wireline deployment techniques) in order to transfer hydraulic regulation of both lines to the insert safety valve. Alternately, separate replaceable spools may be used for shifting control line <NUM> and balance line <NUM>, although this may necessitate a greater number of downhole wireline interventions.

<FIG> and <FIG> show schematics of another illustrative sub in which hydraulic regulation may be switched by way of a removable spool in a side pocket for directing hydraulic flow. As shown in <FIG>, side pocket <NUM> is defined within the sidewall of sub <NUM>. Side pocket <NUM> contains a replaceable spool to direct the hydraulic regulation in an appropriate manner. Upper portion 20a of control line <NUM> and upper portion 22b of balance line <NUM> enter the body of sub <NUM> and make a fluid connection to side pocket <NUM>. In the normal operational configuration of <FIG>, first replaceable spool <NUM> contains internal conduits 90a and 90b that maintain hydraulic communication between the upper and lower portions of control line <NUM> and balance line <NUM>, respectively. Latent control line <NUM> and latent balance line <NUM> also make fluid connections to side pocket <NUM>. However, when first removable spool <NUM> is present, there are no appropriately placed internal conduits to connect these lines to upper portion 20a of control line <NUM> and upper portion 22a of balance line <NUM>.

Seals 92a-g are present upon first replaceable spool <NUM> to allow hydraulic fluid to be conveyed between upper portion 20a and lower portion 20b of control line <NUM> and between upper portion 22a and lower portion 22b of balance line <NUM>. Specifically, seals 92a-92c allow upper portion 20a and lower portion 20b of control line <NUM> to be in hydraulic communication with one another, and seals 92c-92e allow upper portion 22a and lower portion 22b of balance line <NUM> to be in hydraulic communication with one another. These seals also preclude mixing of the hydraulic fluid from the two different sources.

Once it becomes desired to regulate an insert safety valve, first removable spool <NUM> may be removed from side pocket <NUM>, and second removable spool <NUM> may be substituted in its place, as shown in <FIG>. Wireline techniques may be used to affect removal of first removable spool <NUM> and replacement with second removable spool <NUM>. Second removable spool <NUM> contains internal conduits 90c and 90d that establish hydraulic communication between upper portion 20a of control line <NUM> and latent control line <NUM> and between upper portion 22b of balance line <NUM> and latent balance line <NUM>. Hydraulic communication with lower portion 20b of control line <NUM> and lower portion 22b of balance line <NUM> are terminated in this process, since appropriately configured internal conduits are no longer present in second removable spool <NUM>. Again, appropriate sealing is provided to connect these lines to one another and preclude mixing of the hydraulic fluids.

In still further embodiments, a third removable spool (not shown in <FIG> and <FIG>) may be introduced after removing second removable spool <NUM>. In some embodiments, the third removable spool may contain no lines that are positioned to redirect the hydraulic flow. Accordingly, in some embodiments, the third removable spool may serve as a shut off mechanism when wellbore operations are concluded or suspended.

Again, it is to be recognized that the illustrative subs and their various switching mechanisms that are described hereinabove may be made to be contiguous with nipple <NUM>, if desired. Considerations for incorporating the switching mechanisms within nipple <NUM> may be based upon various operational and/or manufacturing considerations that may be determined by one having ordinary skill in the art. When incorporated within nipple <NUM>, the various switching mechanisms are generally located nearer the upper terminus of tubular string <NUM> than is the insert safety valve housed within nipple <NUM>.

In still other embodiments, a sliding sleeve within nipple <NUM> may switch both control line <NUM> and balance line <NUM> as an insert safety valve is inserted. In more specific embodiment, axial displacement of a sliding sleeve may move a recess to transfer hydraulic regulation of control line <NUM> into nipple <NUM> and actuate a piston to transfer hydraulic regulation of balance line <NUM> into nipple <NUM>. Further disclosure in this regard follows below.

The embodiments of <FIG> are not according to the invention and are present for illustration purposes only. <FIG> and <FIG> show schematics of an illustrative nipple configuration in which a sliding sleeve may affect switching of both a control line and a balance line. As shown in <FIG>, nipple <NUM> contains control lines ports 21a and 21b, to which are connected upper portion 20a and lower portion 20b of control line <NUM>, respectively. Also present are balance line ports 23a and 23b, to which are connected upper portion 22a and lower portion 22b of control line <NUM>, respectively. Control line conduits 25a and 25b are defined within the body of nipple <NUM> and establish hydraulic communication between upper portion 20a and lower portion 20b of control line <NUM>. Hydraulic fluid passes from control line conduit 25a to control line conduit 25b via recess <NUM> defined between sliding sleeve <NUM> and nipple <NUM>. Seals 96a and 96c maintain the hydraulic fluid within recess <NUM> and preclude it from entering internal flowpath <NUM>.

Piston assembly <NUM> is located in piston chamber <NUM>. Piston assembly <NUM> engages with sliding sleeve <NUM> as it is axially displaced (see <FIG>). Seals 106a-106c are disposed around piston assembly <NUM> in piston chamber <NUM>. Seals 106b and 106c allow hydraulic fluid from upper portion 22a to lower portion 22b of balance line <NUM> within piston chamber <NUM>.

Latent control line <NUM> is defined in sliding sleeve <NUM>. In the normal operational configuration of <FIG>, hydraulic fluid passes under seal 96b and can pressurize lower portion 20a of control line <NUM>. Hydraulic fluid from upper portion 20a of control line <NUM> is precluded from entering latent control line <NUM> by seal 96a. Referring now to <FIG>, after axially displacing sliding sleeve <NUM> downwardly, latent control line <NUM> enters into fluid communication with upper portion 20a of control line <NUM>, thereby allowing hydraulic regulation of an insert safety valve to be realized.

Similarly, axially displacement of sliding sleeve <NUM> results in engagement of piston assembly <NUM> and its corresponding axial displacement. Latent balance line <NUM> is defined within nipple <NUM> and establishes fluid communication between piston chamber <NUM> and internal flowpath <NUM>. In the normal operational condition of <FIG>, hydraulic fluid flows from upper portion 22a of balance line <NUM> to lower portion 22b of balance line <NUM> within piston chamber <NUM>. Hydraulic fluid is precluded from entering latent balance line by seal 106b. Referring again to <FIG>, after axially displacing sliding sleeve <NUM> and piston assembly <NUM> downwardly, hydraulic fluid may flow from upper portion 22a of balance line <NUM> to latent balance line <NUM> via piston chamber <NUM>, thereby allowing hydraulic regulation of the balance line of an insert safety valve to be realized.

Although <FIG> and <FIG> have shown a sliding sleeve that affects switching of both a control line and a balance line, it is to be recognized that a similar mechanism may affect switching of single-line safety valves as well. That is, in <FIG> and <FIG>, the components associated with upper portion 22a and lower portion 22b of balance line <NUM> may be omitted, and an insert safety valve having only a control line may be hydraulically regulated with upper portion 20a of control line <NUM> and latent hydraulic line <NUM> once switching takes place.

<FIG>, <FIG> show more detailed engineering schematics related to the nipple configuration of <FIG> and <FIG>. The engineering schematics of <FIG> show a sliding sleeve that only switches a control line. In contrast, the engineering schematics of <FIG> show a sliding sleeve that switches both a control line and a balance line.

Unless otherwise indicated, all numbers expressing quantities of ingredients, properties such as molecular weight, reaction conditions, and so forth used in the present specification and associated claims are to be understood as being modified in all instances by the term "about. " Accordingly, unless indicated to the contrary, the numerical parameters set forth in the specification and attached claims are approximations that may vary depending upon the desired properties sought to be obtained by the embodiments of the present disclosure. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claim, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.

Claim 1:
A wellbore system (<NUM>) comprising:
a tubing string (<NUM>) comprising a sub (<NUM>), a nipple (<NUM>) and a primary safety valve (<NUM>), the primary safety valve (<NUM>) being disposed in the tubing string (<NUM>) above or below the nipple (<NUM>);
a control line (<NUM>) and a balance line (<NUM>), each comprising an upper portion (20a, 22a) that extends to the sub (<NUM>), and a lower portion (20b, 22b) that extends from the sub (<NUM>) to the primary safety valve (<NUM>) and that is in hydraulic communication with the primary safety valve (<NUM>), the control line (<NUM>) and balance line (<NUM>) each in latent hydraulic communication with an internal flow pathway within the nipple (<NUM>) via a latent control line (<NUM>) and a latent balance line (<NUM>) that extend from the sub (<NUM>) to the nipple (<NUM>),
wherein
the wellbore system (<NUM>) comprises a switching mechanism housed within the sub (<NUM>) that is axially displaceable to establish hydraulic communication between an insert safety valve (<NUM>) positioned in a bore of the nipple (<NUM>) and the latent control line (<NUM>) and the latent balance line (<NUM>).