Abstract: A downhole tool is disclosed that includes an expandable liner, an expansion cone, and an expansion cone driver connected to the expansion cone. The expandable liner includes an upper tubular body, a lower cone housing having an outer diameter greater than the upper tubular body, a eutectic alloy layer surrounding a circumference of the upper tubular body, and a bottom packer and a top packer extending around the upper tubular body and positioned around opposite ends of the eutectic alloy layer. The expansion cone has a cone body provided in the lower cone housing and a heater provided around an outer surface of the cone body.

Abstract: A downhole assembly includes: a shape-memory article; and a deployment control element adjacent the shape-memory article, the deployment control element having a body and a seal element that forms an enclosure together with the body, the deployment control element further including an activation fluid disposed in the enclosure, wherein the body, the seal element, or both of the deployment control element is degradable in the presence of the activation fluid.

Abstract: The invention concerns a blasting system (1) configured for explosive material charging in a borehole (3). The system (1) comprises a detonator support device (5) configured to be inserted into the borehole (3) by means of a charging hose (7); a main body (9) of the detonator support device (5) comprises a channel (8) oriented along a main body centre line (CL) extending along the borehole extension during said explosive material charging; an openable cover device (14) covering the channel (8) is configured to come into contact with the charging hose (7) in motion for pushing the main body (9) along the borehole (3), wherein the charging hose (7) in motion is configured to open the openable cover device (14) whilst a stopping arrangement (13) stops the main body (9). The invention also concerns a method of explosive material charging in a borehole (3) by means of the blasting system (1).

Abstract: A method for expanding a two-stage expandable liner hanger includes expanding a first section of an expandable tubular having the first section and a second section. The first section includes one or more anchoring ribs. The method further includes expanding the second section of the expandable tubular after cement is pumped into the expandable tubular.

Abstract: The present invention relates to a downhole assembly for permanently sealing off a control line controlling a well component of a well tubular metal structure prior to plug and abandonment of a well having a top, comprising a first part of a tubular line, a second part of the tubular line, a downhole closure unit arranged between the first part and the second part of the tubular line and comprising a first element comprising a first opening, a second opening and fluid communication channel between the first opening and the second opening, the first opening being arranged closer to the top than the second opening, the first opening having a first connection to the first part of the tubular line, and the second opening having a second connection to the second part of the tubular line, wherein the first element has a first outer shape in a first state in which the fluid communication channel is open and a second outer shape in a second state in which the fluid communication channel is closed, the second shape be

Abstract: A method and an apparatus for sealing perforations or cracks found in an oil well casing. The apparatus includes a hydraulic cylinder with an oil supply section at one end and a rod at another end, a cylindrical liner at least a portion of which is a malleable metal and a receiver; and a frusto-conical wedge being disposed at a lower end of the liner and fixedly connected to the rod. The method includes lowering the apparatus into the well casing and increasing hydraulic pressure to the hydraulic cylinder sufficient to pull the frusto-conical shaped wedge into the liner providing sufficient lateral force to force sufficient liner material into the perforations or cracks of the well casing to seal the well casing wall.

Abstract: A downhole method for preparing and/or providing isolation at a predetermined position in an existing well includes inserting a downhole tool comprising a bit on a projection part in a first well tubular metal structure, positioning the downhole tool opposite the predetermined position, separating an upper part of the first well tubular metal structure from a lower part of the first well tubular metal structure, moving the downhole tool along the longitudinal extension in the upper part to a second position, and separating a first part of the upper part of the first well tubular metal structure from a second part of the upper part of the first well tubular metal structure, thus providing an uncased opening between the second part of the first section and the second section.

Abstract: A method for assembling a liner system including disposing from an uphole end of the liner a first slip subsystem, disposing from the uphole end of the liner a seal, and disposing from the uphole end of the liner a second slip subsystem.

Abstract: A patching construction method using a hydraulic variable-grade expansion tool for blocking during drilling is provided, which includes a conversion joint, a supporting central pipe, a supporting ring, an expansion pipe, pressure gradient piston subs, double female thread connection subs, T-shaped limiting subs, a tapered centering sub, double male thread central shafts, split supporting subs, an expansion cone, a piston sub with male and female threads, a T-shaped ball compressor, a lower U-shaped pressing sleeve, a ball-seat fixing sleeve, a reciprocating spring, a sealing ball seat, a sealing ball, a tapered guide sub, etc.

Abstract: A valve arrangement is for a downhole apparatus having a tubular body having first and second ports in a wall thereof. The valve arrangement comprises a valve member that comprises a first port associated with the first port of the tubular body; and a second port associated with the second port of the tubular body. The valve arrangement is configurable to be locked in a first configuration with the tubular body, such that the first port is closed and the second port is closed. The valve arrangement is configurable to be locked in a second configuration with the tubular body, such that the first port is open and the second port is closed. The valve arrangement is configurable to be locked in a third configuration with the tubular body, such that the first port is closed and the second port is open.

Abstract: A lead-free pinscreen imprint device for retrieving at least one imprint of a topmost surface of a fish located in a wellbore may include a housing with a central aperture that extends along a section of a central axis thereof. The lead-free pinscreen imprint device may include a pinscreen portion disposed in the housing. The pinscreen portion may include various pins that are disposed along a vertical axis that is parallel to the central axis. The pinscreen portion may include an imprint surface that faces in a downward direction and a scanning surface that faces in an upward direction. The lead-free pinscreen imprint device may include a three-dimensional (3D) laser image scanner disposed in the housing at a location that is immediately above the pinscreen portion. The 3D laser image scanner may be configured to scan the scanning surface and identify any depth changes in the scanning surface.

Abstract: A method of sealing a well having a casing wall comprises transporting a camera into the casing wall making a visual recording by visually recording perforations, microfractures or other breach type damages of the wall and vertical location thereof on the wall. Selecting a vertical location for sealing the well, the vertical location being determined from the visual recording. Transporting an expandable sealing device being made of an expandable metal and a hydraulic cylinder attached to the sealing device by a shear pin into the well. Expanding the sealing device to engage the casing wall such that a gas seal is made between the sealing device and the casing wall, the sealing device being expanded through engagement by the hydraulic cylinder.

Abstract: A hanger system including an expandable liner, an expandable first slip subsystem disposed about the liner, an expandable second slip subsystem disposed about the liner, a seal disposed about the liner and between the first slip subsystem and the second slip subsystem, and an expandable lock ring disposed about the liner and against one of the first slip subsystem or the second slip subsystem. A method for lining a borehole including running a liner system into a borehole, landing the liner system in a liner hanger, expanding the first slip subsystem simultaneously with a portion of the liner, expanding the second slip subsystem simultaneously with another portion of the liner, and sealing the liner to the liner hanger between the first slip subsystem and the second slip subsystem with the seal. A borehole system including a borehole in a subsurface formation, a casing in the borehole, and a liner system.

Abstract: Apparatus and associated methods relate to pre-completion skin repair of releasably isolated wellbore perforation clusters. In an illustrative example, a completion method includes dividing a target portion of a wellbore casing into N distinct portions. For each distinct portion, a wireline bottom hole assembly (BHA) may be positioned, for example, in a most downstream unperforated portion. The selected portion may, for example, be releasably fluidly isolated from downstream perforation clusters, and a new perforation cluster may be generated. A non-particulate skin-repairing fluid may, for example, be pumped from uphole until a breakdown pressure of a geological formation surrounding the wellbore is exceeded. The BHA may, for example, be operated to reestablish fluid communication before moving to a next portion. After repeating the process in the N distinct portions, for example, the BHA may be removed prior to final wellbore completion.

Abstract: A segmented cone expansion ring and expansion system including the ring, the ring including a plurality of segments each segment of the plurality of segments having opposing load walls, each load wall including one of a projection or a recess receptive of the projection, the projection having a neck portion and a rounded anchor portion and the recess having a rounded geometry and a set of dimensions complementary to the projection and that defines a clearance fit for the projection within the recess. A method for expanding a tubular member including introducing the expansion system a tubular member and loading the load walls of the plurality of segments of the ring while not loading the projections and recesses of the plurality of segments. A borehole system including an expansion system disposed within the borehole.

Abstract: Swellable packer assemblies, downhole packer systems, and methods to seal a wellbore are presented. A swellable packer assembly includes a mandrel and a sealing material disposed about a portion of the mandrel, where the sealing material is formed from a material that radially expands from the mandrel in response to fluid exposure. The swellable packer assembly also includes a cover that is initially disposed about a portion of an outer surface of the sealing material, where the cover prevents the sealing material from being exposed to fluid while the cover is positioned about the portion of the outer surface of the sealing material, and a pressure-actuated piston configured to shift from a first position about the mandrel to a second position about the mandrel, where the sealing material is exposed to fluid after the pressure-actuated piston shifts from the first position towards the second position.

Abstract: An open tip downhole expansion tool incudes a frustoconical member having a base and a tip, the member having a radially outer zone and a radially inner zone and having an axial length extending from the base to the tip; an outer compliance area in a material of the member along a length of the radially outer zone; and an inner compliance area in a material of the member along a length of the radially inner zone, the outer and inner compliance areas being located at different positions along the axial length of the frustoconical member, the outer and inner compliance areas each causing the frustoconical member to present a first resistance to deformation when the compliance areas are in a first condition and a higher resistance to deformation of the frustoconical member when the compliance areas are in a second condition.

Abstract: A method for configuring a logging module for logging sensors deployment based on a sensing data acquisition objective includes selecting a tool body, selecting at least one type of sensor, and selecting at least one type of roller. The method also includes incorporating the at least one selected type of sensor onto the at least one selected type of roller to provide at least one sensor roller, and mounting the at least one sensor roller into a compressible mounting assembly provided in the tool body to provide the logging module.

Abstract: A string includes a pipe that is connected to an expansion mechanism and a retrieval tool that is connected to the pipe above the expansion mechanism. The retrieval tool includes a carrier that can selectively latch on an expandable liner and one or more actuators. The retrieval tool can ensure latching of the carrier while the expandable liner is above the Blow-out Preventer. The retrieval tool can prevent accidental latching of the carrier on the expandable liner during the expansion of the liner. By manipulating the pipe, the retrieval tool can force the carrier's release from the expandable liner.

Abstract: Automated flowline leak sealing can be implemented as a flowline sealing tool assembly. A sealing sleeve is configured to be positioned within a flowline with a circumferential leak. The sealing sleeve includes a pair of ends configured to be positioned on either side of the circumferential leak. A pair of sealing elements are attached to the pair of ends, respectively, and are configured to seal the pair of ends to an inner wall of the flowline on either side of the circumferential leak. A deployment tool includes a hollow cylinder configured to be inserted into and retracted from an inner volume defined by the sealing sleeve. The deployment tool is configured to activate the pair of sealing elements to seal the pair of ends to the inner wall of the flowline on either side of the circumferential leak in response to being retracted from the inner volume.

Abstract: A pressure rated well annulus fluid expansion storage device that is capable of managing pressure variation within a well annulus by removing or adding fluid to the well annulus. The well annulus fluid expansion storage device includes an annulus fluid expansion unit containing a well annulus fluid and a working fluid, the annulus fluid expansion unit further includes a moveable partition maintaining the working fluid and the well annulus fluid in separate chambers, a working fluid storage tank that stores the working fluid, an adjustable pressure control valve that maintains a pressure of the working fluid, a working fluid pump that feeds and pressurizes working fluid from the working fluid storage tank into the annulus fluid expansion unit, a check valve that allows flow of working fluid from the working fluid storage tank to the annulus fluid expansion unit, and a flow line for receiving and discharging well annulus fluid.

Abstract: A casing patch system comprising a base tubular with two anchor/seals coupled to the base tubular and an expansion tool comprising two expansion devices positioned such that upon expansion of the first anchor/seal, the second expansion device engages the second anchor/seal, which allows reduction of the expansion forces due to sequential expansion and reduces the length of the displacement necessary for setting the casing patch, eliminating the need for resetting the thruster, which allows deployment and setting of the casing patch on a wireline. In another embodiment, the expansion device comprises two swages coupled to a shaft at a distance between them approximately equal to the length of the anchor/seal.

Abstract: Liner hangers and methods of use. An example method includes positioning a liner hanger in a wellbore; the liner hanger comprising: two sealing elements disposed on the exterior of the liner hanger and having a void space therebetween, and a pressure reducing metal element disposed between the two sealing elements. The method further includes trapping a wellbore fluid in the void space; wherein the wellbore fluid thermally expands in the void space creating an annular pressure in the void space; and reducing the annular pressure by materially altering the pressure reducing metal element.

Abstract: Swell packers comprising swellable metal sealing elements and methods for forming a seal in a wellbore are provided. An example method includes providing a swell packer comprising a swellable metal sealing element; wherein the swell packer is disposed on a conduit in the wellbore, exposing the swellable metal sealing element to a brine, and allowing or causing to allow the swellable metal sealing element to swell.

Abstract: A method for drilling a borehole includes selecting a lower pressure limit and an upper pressure limit for a drilling fluid at a drilling location in the borehole. In addition, the method includes activating a pump to circulate the drilling fluid down a drill string and up an annulus disposed about the drill string. Further, the method includes operating the pump to maintain the drilling fluid at the drilling location at a pressure between the upper and the lower pressure limits. Still further, the method includes deactivating the pump to stop circulating the drilling fluid up the annulus. The method also includes sealing the drilling fluid in the annulus at a selected time after deactivating the pump and maintaining the pressure of the drilling fluid at the drilling location between the lower and the upper pressure limits.

Abstract: This disclosure provides an expansion joint apparatus that has a releasable coupler that holds the tool in a locked position for run-in purposes. Once in position, the releasable coupler can be activated to release a tubular housing from an outer mandrel located within the tubular housing to allow for independent movement between the tubular members comprising the expansion joint apparatus.

Abstract: There is provided a sandscreen joint (110) capable of providing zonal isolation. The ends of the portion of the (110) are capable of extension on activation of the sandscreen (110), including transition areas (135), which are coated with an elastomer sleeve (134). On activation of the sandscreen (110), the sleeve (134) is pushed out into contact with the bore wall and serves to isolate the zone on one side of the activated sleeve (134) from the zone on the other side of the sleeve (134). Thus, the provision of the sleeve (134) on the activated sandscreen (110) may prevent fluid from flowing axially along the bore between the bore wall and sandscreen. This may serve to protect the weave at the transition area (135), preventing axial flow through the transition areas (135).

Abstract: An apparatus deploys and retrieves a wear bushing in a wellhead during the same trip, such as when using a bottom hole assembly for drilling. Arms in the form of pistons, levers, dogs, etc. can be moved between retracted and extended conditions on the apparatus using actuations from remote communications. When extended, the arms engage inside the wear bushing or inside an adapter disposed in the bushing. When retracted, the arms lie within the exterior of the tool to avoid wear and damage when the drillstring is used for drilling or other operations. During deployment, the bushing supported on the extended arms is seated in the wellhead. The arms are then retracted through remote activation, and the bottom hole assembly is run further downhole. During retrieval, the retracted arms are extended through remote activation and engage in the bushing so the drillstring can lift the bushing from the wellhead.

Abstract: A downhole patch setting tool for expanding a patch over a distance of 10+ metres in a well, has a top and a tool body having a bore, an outer face, a first end and a second end, the second end being arranged closer to the top than the first end, the bore at least extending from a first bladder assembly to a second bladder assembly, an expandable metal patch, the first bladder assembly and the second bladder assembly creating an annular space therebetween, the expandable metal patch having an inner diameter in an unexpanded condition, the tool body having a first and second openings, providing fluid communication between the bore and the first bladder assembly and the second bladder assembly to allow pressurised fluid to expand the bladder assemblies, and a valve arrange to control passage of the pressurised fluid from the bore to the annular space.

Abstract: Methods for positioning an expandable metal sealing element in the wellbore. An example method includes an expandable metal sealing element having a reactive metal and disposed in a location. The method further includes actuating a washout prevention element, contacting the expandable metal sealing element with a fluid that reacts with the reactive metal to produce a reaction product having a volume greater than the reactive metal, and allowing the washout prevention element to prevent at least a portion of the reaction product from flowing away from the location.

Abstract: A well completion assembly and method including apparatus for setting a liner hanger, screens and liner within a wellbore, performing an acid treatment and cementing a liner in a single trip.

Abstract: The present invention discloses an expandable liner hanger system comprising a central pipe and an expandable pipe, with an expansion cone provided therebetween the central pipe and expandable pipe in a way that the expansion cone is movable along the central pipe, so that the expandable pipe is expanded; wherein, the expansion cone comprises an expansion cone seat move along the central pipe, and an expansion cone sleeve fitted over the expansion cone seat, the connection between the expansion cone seat and the expansion cone sleeve is configured in a way that the expansion cone sleeve can move upward together with the expansion cone seat along the central pipe so that the expandable pipe is expanded, and the central pipe can drive the expansion cone seat to disengage from the expansion cone sleeve.

Abstract: Non-planar shearing auxetic structures, devices, and methods are provided herein. In some embodiments, a non-planar shearing auxetic structure can include a mathematically compact surface with an auxetic pattern of repeating unit cells. The shearing auxetic structure can have a contracted configuration and an expanded configuration, and, when in the compact configuration, can be configured to move to the expanded configuration while generating a net shear on the surface. Shearing auxetic structures can have handedness and, in some embodiments, multiple handed shearing auxetic structures can be joined to create rigid or semi-rigid composite structures, e.g., by arranging differently-handed structures concentrically wherein two or more structures lock against each other. Handed shearing auxetic structures can also provide actuators to convert rotation or other motion to translation, volume expansion, bending, twisting, etc. These structures have many applications, e.g.

Abstract: A well completion assembly and method including apparatus for setting a compliant screen assembly and a liner within a wellbore in a single trip.

Abstract: High power laser systems, high power laser tools, and methods of using these tools and systems for opening up damaged wells and for cutting, sectioning and removing structures objects, and materials, and in particular, for doing so in difficult to access locations and environments, such as offshore, underwater, or in hazardous environments, such as nuclear and chemical facilities. And, high power laser systems, high power laser tools, and methods of using these systems and tools for providing rock-to-rock plugs for decommissioning of wells.

Abstract: An apparatus deploys and retrieves a wear bushing in a wellhead during the same trip, such as when using a bottom hole assembly for drilling. Arms in the form of pistons, levers, dogs, etc. can be moved between retracted and extended conditions on the apparatus using actuations from remote communications. When extended, the arms engage inside the wear bushing or inside an adapter disposed in the bushing. When retracted, the arms lie within the exterior of the tool to avoid wear and damage when the drillstring is used for drilling or other operations. During deployment, the bushing supported on the extended arms is seated in the wellhead. The arms are then retracted through remote activation, and the bottom hole assembly is run further downhole. During retrieval, the retracted arms are extended through remote activation and engage in the bushing so the drillstring can lift the bushing from the wellhead.

Abstract: An expandable liner is used to re-complete a wellbore for a re-fracturing operation. The expandable liner may be used to cover the old perforations and provide a larger bore after expansion. The larger bore allows the new completion perforations and fracturing operation to be more easily achieved. In one embodiment, the expandable liner may have a rib disposed around an outer diameter of the expandable tubular, wherein the rib is configured to form a seal with the outer tubular.

Abstract: A casing patch includes a tubular that comprises a first end and a second end opposite the first end, each of the first end and second end comprising an expandable wedge that is deformable into a wellbore casing; and a locating profile formed onto an inner surface of the tubular between the first and second ends.

Abstract: A to be expanded tubular (4) can be locked to a previously installed host casing (2) using a self energizing top anchor (SETA) tool. This SETA tool has an anchoring section with a set of anchoring slips (1), and a centralizer which is connected to the body of the anchoring section. The anchoring slips (1) engage the host casing (2) once an expansion cone (3) presses the tubular against the shoulder of the centralizer. The SETA tool is further provided with a guide nose (7) to which a force transmission sub (8) is connected.

Abstract: Expandable tube members that are fabricated from a composite material that includes a structural plastic, which structural plastic includes phase change materials that undergo a permanent expansion upon exposure to wellbore conditions. This permanent expansion of the structural plastic causes the expandable tube member to expand radially and/or longitudinally without the use of an expansion tool. The expandable tube member can be used to control fluid loss, patch wells, stabilize a formation in a wellbore, enhance flow, provide sand screening, and repair damaged pipes, casings, or liners.

Abstract: An expandable device comprising a plurality of expandable cells. The cells may be bistable cells or other types of cells that are expanded from a contracted position towards an expanded position. Additionally, the cells may be combined with locking mechanisms to hold the structure in an expanded position.

Abstract: A hybrid push and pull method for expanding a tubular in a wellbore utilizes an expansion assembly with a sealed and another, optionally expandable, cone, wherein during at least part of the expansion process the sealed cone is moved up through the tubular by a combination of push and pull forces and the push force is generated by pumping fluid at an elevated pressure into a space between the bottom plug and the expansion assembly. This allows staged expansion of the tubular in a hard rock formation and/or of a tubular surrounded by a hardened cement lining and/or of a pair of partially overlapping nested tubular ends.

Abstract: A system includes a wear bushing retrieval tool. The wear bushing retrieval tool an annular main body configured to be disposed about a tubular string, a plurality of locking dogs, wherein each locking dog of the plurality of locking dogs is pivotably coupled to the annular main body, a first axial securement feature coupled to the annular main body, and a second axial securement feature coupled to the main body, wherein the first and second axial securement features are configured to cooperatively axially capture a coupling of the tubular string when the annular main body is disposed about the tubular string.

Abstract: A liner hanger seals with casing string 8 having mill scale and supports a liner 98 within a well. The liner hanger includes a tubular anchor 48 and a tubular expander 40. The tubular anchor 48 may be positioned in the casing string 8 using an inner mandrel 10. An actuator assembly 6 forcibly moves the tubular expander 40 into the tubular anchor 48, expanding the tubular anchor 48 to grippingly engage the expanded tubular anchor 48 against the casing string 8 and to form a circumferential seal between metal sealing elements 52 on the tubular anchor 48 and the interior wall of the casing string 8. The metal sealing element 52 is oversized to provide rigidity, heat shrunk onto the tubular anchor 48, and abrasively dressed to remove excess material prior to installation of the liner hanger.

Abstract: A liner having an outer surface coated with a fluid absorbing coating is cladded to a tubing string by inserting the folded liner into the tubing string and then unfolding the liner against the tubing string. The liner may be a long single thin foil corrosion resistant liner coated with a sticky glue and a hygroscopic and/or other fluid absorbing coating to absorb fluid pockets trapped between the tubing and liner and inhibit corrosion and leakage of, the elongate tubing string.

Abstract: The disclosed embodiments include a method, apparatus, and computer program product for determining a suitable casing design for a well. For example, one disclosed embodiment includes a system that includes at least one processor and at least one memory coupled to the at least one processor and storing instructions that when executed by the at least one processor performs operations for receiving historical data associated with previously drilled wells; in response to a determination that the historical data associated with previously drilled well is relevant to the well, generating a first set of casing designs using a probabilistic approach and generating a second set of casing designs using a combination approach that combines the probabilistic approach with a deterministic approach; and selecting a suitable casing design from a resulting set of casing designs.

Abstract: A surgical access system facilitates access to a surgical site within a patient's body through an incision in the body. Surgical access systems can have at least one retention member and a fluid transportation member configured to deliver fluid to a surgical site or to remove fluid from a surgical site. In some embodiments, a surgical access device irrigates a surgical site to reduce surgical site infections and removes fluid from the surgical site to increase a physician's visibility into the surgical site.

Abstract: An expandable device comprising a plurality of expandable cells. The cells may be bistable cells or other types of cells that are expanded from a contracted position towards an expanded position. Additionally, the cells may be combined with locking mechanisms to hold the structure in an expanded position.

Abstract: A setting tool for hanging a tubular string includes: a mandrel having an upper portion and a lower portion for extending into the tubular string; a housing connected to the mandrel upper portion; and a bonnet. The bonnet is: for receiving an upper end of the tubular string, disposed along the mandrel, and linked to the housing. The setting tool further includes: an actuator for stroking the bonnet relative to the mandrel and the housing, thereby setting a hanger of the tubular string; an electronics package in communication with the actuator for operating the actuator in response to receiving a command signal; and a latch. The latch is: connected to the mandrel lower portion, operable between an extended position and a retracted position, for being restrained in the retracted position by being disposed in the tubular string, and extendable by being removed from the tubular string.

Abstract: Perforations in an existing borehole are covered with an expandable clad or elongated tubular that is expanded on location with the expansion equipment then removed. The clad is made of a disintegrating material such as a controlled electrolytic material known as CEM and is expanded into position to cover the existing perforations. One or more plugs are run in with perforating guns and the plugs set with the guns moved away from the set plug and fired to make new perforation. After each new perforation is made a ball is delivered to the plug to isolate a portion of the well and the new perforations are treated such as in a fracturing or another operation. Over time or with exposure to well fluids or temperatures the clad disintegrates and the original well drift diameter is regained so that subsequent production or injection is not impeded.