Abstract: A downhole apparatus comprises a casing string with a fluid barrier connected in the casing string. A degradable plug is positioned in the casing string above the fluid barrier. The degradable plug and fluid barrier define upper and lower ends of a buoyancy chamber in the casing string. The degradable plug may be degraded to leave an open bore through the casing string after the casing string is lowered into a wellbore.

Abstract: Switchable crossover tools can include a tool body and a rotatable chamber. The tool body includes a main tool path separable into uphole and downhole tool paths and an auxiliary chamber containing uphole and downhole annular ports. The rotatable chamber is located and rotatable within the auxiliary chamber and forming first and second auxiliary flow paths through the auxiliary chamber. The rotatable chamber is positionable between a conventional circulation mode and a reverse circulation mode. In the conventional circulation mode, the uphole and downhole tool paths are in fluid communication and the uphole and downhole annular ports are in fluid communication through the auxiliary chamber. In the reverse circulation mode, the uphole tool path is in fluid communication with the downhole annular port via the first auxiliary flow path, and the downhole tool path is in fluid communication with the uphole annular port via the second auxiliary flow path.

Abstract: A plug for displacing cement in a downhole environment comprising a seal surface having at least one profile. The seal surface, in response to applied pressure, creates a hydraulic seal with another device. The seal surface can be made of molded rubber and the profile formed thereon can be formed from the molded rubber and during the molding process. The profile can be a semicircular profile or multiple semicircular profiles. The profile or profiles can be one or more semicircular profiles and one or more line profiles. The plug can be a bottom plug and the seal surface can be an upstream seal surface and the other device can be a float collar. The plug can be a top plug and the seal surface can an upstream seal surface and the other device can be a bottom plug.

Abstract: A downhole tool. The downhole tool may include a tubular body and an inner sleeve that is slidable within the tubular body. The tubular body may include a port that allows fluid flow between a bore of the downhole tool and an area outside of the tubular body. The downhole tool may be sequentially positionable in a run-in position that blocks fluid flow through the port in the tubular body, then in an open position that allows fluid flow through the port in the tubular bod, and then in a closed position that blocks fluid flow through the port in the tubular body.

Abstract: A buoyancy assist tool has an outer case with a rupture disk assembly connected therein. The buoyancy assist tool defines the upper end of a buoyancy chamber in a well casing. A sleeve in the outer case traps the rupture disk membrane after it has ruptured to provide full bore flow through the casing.

Abstract: First fluid flows from a wellbore through a flow assembly and into a casing inserted into the wellbore. An optical cable is arranged on a bobbin attached to a bottom surface of the flow assembly. The optical cable of the flow assembly is released into the flow of the first fluid and is positioned downhole from the flow assembly by the flow of the first fluid. One or more signals are received via the optical cable. A determination is made that an annulus between the casing and a wall of the wellbore is filled with a second fluid based on the one or more signals. Flow of the second fluid is stopped based on the determination.

Abstract: Switchable cross-over systems, devices, and methods for cementing well walls. A switchable cross-over device includes a tool body, a flow sleeve, and a hydraulic sleeve. The tool body includes a main tool path separable into upper and lower tool paths and an auxiliary chamber containing upper and lower annular ports. The flow sleeve is within the auxiliary chamber and movable into a reverse circulation position by a plug traveling through the main tool path. The hydraulic sleeve is located within the main tool path and mechanically coupled to the flow sleeve. The hydraulic sleeve is movable into a conventional circulation position via pressure within the main tool path acting on the hydraulic sleeve.

Abstract: A system, method, and tool for controlling fluid flow in a wellbore. The system comprises a tubing string locatable in the wellbore and a crossover tool for enabling reverse circulation in the wellbore. The crossover tool comprises a tool body, a packer assembly, a drag block assembly, and a sleeve. The tool body comprises a bore in fluid communication with the tubing string and a valve located in the bore. The packer assembly is coupled to the tool body and creates a fluid barrier in the annulus formed between the tubing string and the wellbore. The drag block assembly engages the wellbore and resists axial movement. The sleeve is located in the tool body and axially moveable relative to the drag block assembly. The drag block assembly is coupled to the sleeve, and axial movement of the sleeve relative to the drag block assembly rotates the sleeve to control the valve.

Abstract: Switchable crossover tools can include a tool body and a rotatable chamber. The tool body includes a main tool path separable into uphole and downhole tool paths and an auxiliary chamber containing uphole and downhole annular ports. The rotatable chamber is located and rotatable within the auxiliary chamber and forming first and second auxiliary flow paths through the auxiliary chamber. The rotatable chamber is positionable between a conventional circulation mode and a reverse circulation mode. In the conventional circulation mode, the uphole and downhole tool paths are in fluid communication and the uphole and downhole annular ports are in fluid communication through the auxiliary chamber. In the reverse circulation mode, the uphole tool path is in fluid communication with the downhole annular port via the first auxiliary flow path, and the downhole tool path is in fluid communication with the uphole annular port via the second auxiliary flow path.

Abstract: Switchable cross-over systems, devices, and methods for cementing well walls are provided. A switchable cross-over device includes a tool body, a flow sleeve, and a hydraulic sleeve. The tool body includes a main tool path separable into upper and lower tool paths and an auxiliary chamber containing upper and lower annular ports. The flow sleeve is within the auxiliary chamber and movable into a reverse circulation position by a plug traveling through the main tool path. The hydraulic sleeve is located within the main tool path and mechanically coupled to the flow sleeve. The hydraulic sleeve is movable into a conventional circulation position via pressure within the main tool path acting on the hydraulic sleeve.

Abstract: A poppet valve having an elongated tubular housing and an internal bore. A flange extends within the internal bore supporting an interior tubular member. The interior tubular member itself has a central aperture and an inwardly protruding lip extending into the central aperture. A stem having collet fingers may be partially received in the central aperture of the interior tubular member. The collet fingers have a protrusion which is engagable with the inwardly protruding lip. A biasing element is provided biasing the stem toward a first position. An elastomeric seal may be disposed around the stem. When the stem is in a first position the elastomeric seal forms a fluid tight seal preventing fluid flow through the internal bore, and wherein upon application of a predetermined fluid pressure the stem transitions from the first position to a second position, whereby fluid flow is permitted through the internal bore.

Abstract: A system, method, and tool for controlling fluid flow in a wellbore. The system comprises a tubing string locatable in the wellbore and a crossover tool for enabling reverse circulation in the wellbore. The crossover tool comprises a tool body, a packer assembly, a drag block assembly, and a sleeve. The tool body comprises a bore in fluid communication with the tubing string and a valve located in the bore. The packer assembly is coupled to the tool body and creates a fluid barrier in the annulus formed between the tubing string and the wellbore. The drag block assembly engages the wellbore and resists axial movement. The sleeve is located in the tool body and axially moveable relative to the drag block assembly. The drag block assembly is coupled to the sleeve, and axial movement of the sleeve relative to the drag block assembly rotates the sleeve to control the valve.

Abstract: Switchable cross-over systems, devices, and methods for cementing well walls are provided. A switchable cross-over device includes a tool body and a flow sleeve. The tool body includes a main tool path separable into uphole and downhole tool paths and an auxiliary chamber containing uphole and downhole annular ports. The flow sleeve is within the auxiliary chamber and movable between conventional and reverse circulation positions. In the conventional circulation position, the uphole and downhole tool paths are in fluid communication and the uphole annular port is in fluid communication with the downhole annular port through the auxiliary chamber. In the reverse circulation position, the flow sleeve forms first and second auxiliary flow paths in the auxiliary chamber, the uphole tool path and the downhole annular port are in fluid communication via the first auxiliary flow path, and the downhole tool path is in fluid communication with the uphole annular port.

Abstract: A wellbore completion method comprising disposing a pressure relief-assisted packer comprising two packer elements within an axial flow bore of a first tubular string disposed within a wellbore so as to define an annular space between the pressure relief-assisted packer and the first tubular string, and setting the pressure relief-assisted packer such that a portion of the annular space between the two packer elements comes into fluid communication with a pressure relief volume during the setting of the pressure relief-assisted packer.

Abstract: Systems and methods for activating a down hole tool in a wellbore. A trigger is moveably positioned in the interior of a base pipe and includes a first end and a second, smaller end. The trigger is moveable between an unactivated position where a port in the base pipe is blocked and an activated position where the port is open. At least one latch member prevents movement of the trigger from the unactivated position to the activated position until a predetermined force is applied to the trigger. Increasing pressure in the interior increases a force differential between the first end and the second end. When the force differential is substantially equal to the predetermined force, the latch releases and allows the trigger to move from the unactivated position to the activated position, thereby opening the port to permit activation of the down hole tool.

Abstract: A wellbore completion method comprising disposing a pressure relief-assisted packer comprising two packer elements within an axial flow bore of a first tubular string disposed within a wellbore so as to define an annular space between the pressure relief-assisted packer and the first tubular string, and setting the pressure relief-assisted packer such that a portion of the annular space between the two packer elements comes into fluid communication with a pressure relief volume during the setting of the pressure relief-assisted packer.

Abstract: A wellbore completion method comprising disposing a pressure relief-assisted packer comprising two packer elements within an axial flow bore of a first tubular string disposed within a wellbore so as to define an annular space between the pressure relief-assisted packer and the first tubular string, and setting the pressure relief-assisted packer such that a portion of the annular space between the two packer elements comes into fluid communication with a pressure relief volume during the setting of the pressure relief-assisted packer.

Abstract: A wellbore completion method comprising disposing a pressure relief-assisted packer comprising two packer elements within an axial flow bore of a first tubular string disposed within a wellbore so as to define an annular space between the pressure relief-assisted packer and the first tubular string, and setting the pressure relief-assisted packer such that a portion of the annular space between the two packer elements comes into fluid communication with a pressure relief volume during the setting of the pressure relief-assisted packer.

Abstract: A magnetoresistive read head having a corrugated magnetoresistive layer wherein the corrugated section does not encroach on magnetic elements on either end of the magnetoresistive layer. The corrugations in the magnetoresistive layer stabilize the magnetization in the center region of the read head, while the magnetic elements stabilize the magnetization at the ends. By separating the two stabilization methods, unfavorable interactions between them is reduced.

Abstract: An apparatus and method for step-stabilization of giant magnetoresistive (GMR) based read heads are provided. With the apparatus and method, gratings or periodic structures are generated in the underlayer of the magnetoresistive (MR) sensor stack and the edges, or “steps”, in these structures are the magnetically active features. These “steps” are oriented approximately parallel to the desired bias direction and provide a restoring force towards the bias direction for any perturbations, whether intrinsic or extrinsic. In the case of a GMR sensor, where the easy axis is parallel to the permanent magnet set direction, these stabilizer steps are oriented parallel to the magnetization direction of the permanent magnets.