Abstract: A safety valve for use in a subterranean well can include a housing assembly having a flow passage extending longitudinally through the housing assembly. An outer diameter of the housing assembly is eccentric relative to the flow passage. A well tool can include a magnetic coupling between magnet devices. One magnet device includes a series of magnets which are unequally spaced circumferentially about the other magnet device. Another safety valve can include a longitudinally extending flow passage, a closure device which selectively permits and prevents flow through the flow passage, and an outer diameter which is eccentric relative to the flow passage.

Abstract: A fluid isolating pressure equalization in a subterranean well. A well system includes a well tool including a chamber therein containing an electrical assembly in a dielectric fluid, and a pressure equalization apparatus including a flowpath having opposite ends. One end is connected to the chamber, and the other end is connected to a source of another fluid. The flowpath extends alternately upward and downward between the opposite ends. A pressure equalization apparatus for use with a well tool in a subterranean well includes multiple spiral wraps of a tube. A flowpath in the tube extends in opposite directions in respective successive wraps of the tube.

Abstract: A method of actuating a valve in a well can include storing energy as a result of a differential pressure across a closed closure device of the valve, and releasing at least a portion of the stored energy while opening the closure device. A valve for use in a well can include a closure device, a biasing device, and an actuator which stores energy in the biasing device in response to a pressure differential across the closure device. A well system can include a tubular string, and a valve which controls fluid flow through the tubular string. The valve may include a closure device and an actuator which actuates the valve at least partially in response to a pressure differential across the closure device.

Abstract: A pressure equalization apparatus can include separate longitudinal bores which form a continuous flowpath, the flowpath alternating direction between the bores, and the bores being interconnected at opposite ends thereof. A well system can include a well tool with a chamber therein containing an assembly in a dielectric fluid, and a pressure equalization apparatus including a flowpath having one end connected to the chamber, and the other end connected to a source of a another fluid, the flowpath extending in opposite directions between the flowpath ends through multiple separate bores. A method of installing a well tool can include attaching a mandrel to the well tool, then lowering the well tool at least partially into the well suspended from the mandrel, and then securing a pressure equalization apparatus to the mandrel, a flowpath of the apparatus being connected to a chamber of the well tool containing an assembly.

Abstract: A method of actuating multiple valves in a well can include applying a pressure cycle to the valves without causing actuation of any of the valves, and then simultaneously reducing pressure applied to the valves, thereby actuating the valves. Another method can include releasing a locking device of each valve which prevents actuation, and then reducing pressure applied to the valves, thereby actuating the valves. A valve can include a port which provides for fluid communication between an exterior and an interior of the valve, a closure member which selectively permits and prevents fluid flow through the port, the closure member permits flow through the port in response to a decrease in a pressure differential from the interior to the exterior of the valve, and a locking device which prevents displacement of the closure member, the locking device being released in response to mechanical force applied to the locking device.

Abstract: A safety valve for use in a subterranean well can include a housing assembly having a flow passage extending longitudinally through the housing assembly. An outer diameter of the housing assembly is eccentric relative to the flow passage. A well tool can include a magnetic coupling between magnet devices. One magnet device includes a series of magnets which are unequally spaced circumferentially about the other magnet device. Another safety valve can include a longitudinally extending flow passage, a closure device which selectively permits and prevents flow through the flow passage, and an outer diameter which is eccentric relative to the flow passage.

Abstract: A circulation control valve can include first and second valve devices and at least one opening which provides fluid communication between an interior longitudinal flow passage and an exterior of the valve. Fluid communication can be provided through each of the first and second valve devices in response to application of a respective one of first and second pressure differentials applied across the corresponding valve device via the interior longitudinal flow passage. Fluid communication in any direction through the opening may be permitted in response to application of the first pressure differential to the first valve device. Fluid communication through the opening may be prevented in response to application of the second pressure differential to the second valve device.

Abstract: A magnetically coupled safety valve with satellite outer magnets. A safety valve includes a housing having multiple chambers extending longitudinally in a pressure bearing wall of the housing, and multiple magnetic devices, each of the magnetic devices being reciprocably disposed in a corresponding one of the chambers. Another safety valve includes multiple first magnetic devices, a second magnetic device magnetically coupled to the first magnetic devices, with the first magnetic devices being circumferentially spaced apart and encircling the second magnetic device. Yet another safety valve includes a housing having a pressure bearing wall, and multiple magnetic devices, each of the magnetic devices being reciprocably disposed in the housing wall, and each of the magnetic devices being completely surrounded by the housing wall.

Abstract: A method of actuating a valve in a well can include storing energy as a result of a differential pressure across a closed closure device of the valve, and releasing at least a portion of the stored energy while opening the closure device. A valve for use in a well can include a closure device, a biasing device, and an actuator which stores energy in the biasing device in response to a pressure differential across the closure device. A well system can include a tubular string, and a valve which controls fluid flow through the tubular string. The valve may include a closure device and an actuator which actuates the valve at least partially in response to a pressure differential across the closure device.

Abstract: A circulation control valve includes an opening between the valve exterior and an interior passage, an internal closure device for permitting and preventing flow through the opening, a valve device initially preventing flow through the opening, and an internal chamber. The valve device opens upon application of a pressure differential between the passage and the exterior to thereby permit communication through the opening, and the closure device displaces upon a second pressure differential between the passage and the internal chamber to thereby prevent communication through the opening. Another valve includes first and second valve devices.

Abstract: A circulation control valve. A method of controlling circulation flow between an interior flow passage of a tubular string and an annulus external to the tubular string in a subterranean well includes the steps of: interconnecting a valve in the tubular string, the valve including at least one opening for providing fluid communication between the interior flow passage and the annulus; applying an increased pressure to the interior flow passage while fluid communication through the opening between the interior flow passage and the annulus is prevented, thereby permitting fluid communication through the opening between the interior flow passage and the annulus; and then applying another increased pressure to the interior flow passage while fluid communication through the opening between the interior flow passage and the annulus is permitted, thereby preventing fluid communication through the opening between the interior flow passage and the annulus.

Abstract: A downhole pressure barrier (100) operatively positionable in a subterranean well. The downhole pressure barrier (100) includes a housing (102) having a flow passage (122) formed therethrough. A plug member (124) that is positioned within the flow passage (122) selectively prevents flow through the flow passage (122) and allows flow through the flow passage (122) responsive to contact with an activating agent. At least one retainer assembly (130) supports the plug member (124) within the housing (102). The retainer assembly (130) selectively prevents communication between the activating agent and the plug member (124). An activating assembly including a combustible agent (164) that is positioned between the retainer assembly (130) and the plug member (124) is operable to create a communication path through the retainer assembly (130) upon combustion of the combustible agent (164) to allow communication between the activating agent and the plug member (124).

Abstract: A circulation control valve. A method of controlling circulation flow between an interior flow passage of a tubular string and an annulus external to the tubular string in a subterranean well includes the steps of: interconnecting a valve in the tubular string, the valve including at least one opening for providing fluid communication between the interior flow passage and the annulus; applying an increased pressure to the interior flow passage while fluid communication through the opening between the interior flow passage and the annulus is prevented, thereby permitting fluid communication through the opening between the interior flow passage and the annulus; and then applying another increased pressure to the interior flow passage while fluid communication through the opening between the interior flow passage and the annulus is permitted, thereby preventing fluid communication through the opening between the interior flow passage and the annulus.

Abstract: A fluid isolating pressure equalization in a subterranean well. A well system includes a well tool including a chamber therein containing an electrical assembly in a dielectric fluid, and a pressure equalization apparatus including a flowpath having opposite ends. One end is connected to the chamber, and the other end is connected to a source of another fluid. The flowpath extends alternately upward and downward between the opposite ends. A pressure equalization apparatus for use with a well tool in a subterranean well includes multiple spiral wraps of a tube. A flowpath in the tube extends in opposite directions in respective successive wraps of the tube.

Abstract: A safety valve with a flapper/flow tube friction reducer. A safety valve for use in a subterranean well includes a closure assembly, an operating member which engages the closure assembly, and at least one of the closure assembly and the operating member including a friction reducing device which provides rolling contact between the closure assembly and the operating member. Another safety valve includes a flapper which rotates about a pivot relative to a seat, a flow tube which engages the flapper to rotate the flapper, and a friction reducing device which with rolling contact biases the flow tube toward the pivot when the flow tube engages the flapper. Yet another safety valve is described in which at least one of the flapper, the seat and the flow tube has a friction reducing device attached thereto which provides rolling contact between the flapper and the flow tube, or between the flow tube and the seat.

Abstract: Electrically operated well tools. A well system includes a well tool positioned in a wellbore. The well tool includes an actuator and an operating member displaceable to operate the well tool. The actuator includes a series of longitudinally distributed electromagnets, in which current is controllable in a predetermined pattern to thereby variably control longitudinal displacement of the operating member. In another well system, the operating member is displaceable between opposite maximum limits of displacement to operate the well tool, and an electromagnet is operative to displace the operating member to at least one position between the opposite maximum limits of displacement. In a method of operating a well tool, the well tool is operated by controlling current in a series of longitudinally distributed electromagnets of an actuator in a predetermined pattern, thereby causing corresponding longitudinal displacement of an operating member.

Abstract: A formation isolation valve for underbalanced drilling applications. A system for operating a formation isolation valve includes the valve interconnected in a casing string. An assembly displaces through the casing string, thereby causing the valve to open prior to the assembly reaching the valve. An operating system includes a well tool with an actuator positioned downhole. A device for causing the actuator to operate the well tool is also positioned downhole remote from the actuator. A method of operating a well tool includes the steps of: positioning the well tool in a well, the well tool including an actuator; positioning a power source for the actuator in the well; and at a downhole position remote from the actuator, causing the actuator to operate the well tool.

Abstract: A safety valve with extension springs. In a described embodiment, a valve for use in a subterranean well includes a closure member having open and closed positions. A structure displaces to cause the closure member to displace between the open and closed positions. A biasing device has a length which decreases as the structure displaces to cause the closure member to displace toward the closed position.

Abstract: A circulation control valve includes an opening between the valve exterior and an interior passage, an internal closure device for permitting and preventing flow through the opening, a valve device initially preventing flow through the opening, and an internal chamber. The valve device opens upon application of a pressure differential between the passage and the exterior to thereby permit communication through the opening, and the closure device displaces upon a second pressure differential between the passage and the internal chamber to thereby prevent communication through the opening. Another valve includes first and second valve devices.

Abstract: A circulation control valve. A method of controlling circulation flow between an interior flow passage of a tubular string and an annulus external to the tubular string in a subterranean well includes the steps of: interconnecting a valve in the tubular string, the valve including at least one opening for providing fluid communication between the interior flow passage and the annulus; applying an increased pressure to the interior flow passage while fluid communication through the opening between the interior flow passage and the annulus is prevented, thereby permitting fluid communication through the opening between the interior flow passage and the annulus; and then applying another increased pressure to the interior flow passage while fluid communication through the opening between the interior flow passage and the annulus is permitted, thereby preventing fluid communication through the opening between the interior flow passage and the annulus.