Abstract: A flow conveyed plugging device for use in a well, the device can include a body, and one or more lines extending outwardly from the body, each of the lines having a lateral dimension that is substantially smaller than a size of the body. A method of plugging an opening in a well can include deploying at least one flow conveyed plugging device into the well, the flow conveyed plugging device including a body and, extending outwardly from the body, at least one of the group consisting of: a) one or more fibers and b) one or more lines, the flow conveyed plugging device being conveyed by flow in the well into sealing engagement with the opening. Another flow conveyed plugging device can include a body, and fibers extending outwardly from the body. The flow conveyed plugging device degrades and thereby permits flow through an opening in the well.

Abstract: A method for use with a subterranean well can include releasing flow conveyed plugging devices into the well, each of the plugging devices including a body and, extending outwardly from the body, at least one of lines and fibers, and the plugging devices blocking flow through respective openings in the well. Another method can include perforating a zone, releasing a set of flow conveyed plugging devices into the well, each of the plugging devices including a body and, extending outwardly from the body, at least one of lines and fibers, the set of plugging devices blocking flow through respective perforations in the zone, perforating another zone, releasing another set of the flow conveyed plugging devices into the well, and the second set of plugging devices blocking flow through respective perforations in the second zone.

Abstract: A system can include an annular restrictor connected in a tubular string. The annular restrictor restricts flow through an annulus formed between the tubular string and a wellbore. Restriction to the flow through the annulus biases the tubular string into the wellbore, and fluid in the wellbore displaces into the tubular string and/or a formation penetrated by the wellbore. A method can include connecting an annular restrictor in a tubular string, and flowing a fluid through an annulus formed between the tubular string and a wellbore, thereby causing a differential pressure across the annular restrictor, the differential pressure biasing the tubular string into the wellbore. Another method can include connecting an annular restrictor in a tubular string, flowing a fluid through an annulus, thereby biasing the tubular string into a wellbore, and then causing the annular restrictor to no longer restrict flow through the annulus.

Abstract: A circulating valve assembly can include a valve controlling flow between an interior and an exterior of the assembly, another valve controlling flow between sections of a flow passage extending through the assembly, and an actuator that both opens one valve and closes the other valve in response to each of multiple positive pressure differentials from the interior to the exterior. A system for use with a well can include a circulating valve assembly controlling flow through a tubular string and a well tool connected in the tubular string downstream of the assembly. In one configuration of the assembly, the flow passes through the well tool. In another configuration, the flow passes from the tubular string to an annulus external to the tubular string, with the flow substantially bypassing the well tool. The assembly cycles between the configurations in response to alternating increases and decreases in the flow.

Abstract: A circulating valve assembly can include a valve controlling flow between an interior and an exterior of the assembly, another valve controlling flow between sections of a flow passage extending through the assembly, and an actuator that both opens one valve and closes the other valve in response to each of multiple positive pressure differentials from the interior to the exterior. A system for use with a well can include a circulating valve assembly controlling flow through a tubular string and a well tool connected in the tubular string downstream of the assembly. In one configuration of the assembly, the flow passes through the well tool. In another configuration, the flow passes from the tubular string to an annulus external to the tubular string, with the flow substantially bypassing the well tool. The assembly cycles between the configurations in response to alternating increases and decreases in the flow.

Abstract: A well system can include a well tool with a retarder chemical. The retarder chemical is released from the well tool into an annulus and retards setting of cement therein. A method of retarding setting of cement at a location in an annulus can include releasing a retarder chemical from a well tool connected in a casing string, after the cement is placed in the annulus. A well tool can include a valve that controls fluid communication via a port between an exterior of the tool and a flow passage extending through the tool, an annular recess, and a dispersible annular exterior component received in the recess. Another well tool can include a valve that controls fluid communication between an exterior of the tool and a flow passage extending through the well tool, an internal chamber, and a retarder chemical in the chamber.

Abstract: A fibrous plugging device for use in a subterranean well can include a body having fibers and a retainer material. The retainer material retains a shape of the body. A system for use with a well can include a fibrous plugging device conveyed by fluid flow in the well. The fibrous plugging device includes a body comprising multiple fibers. The fibrous plugging device engages an opening in the well, and thereby seals off the opening. A method for use with a well can include flowing a fluid through the well, thereby conveying at least one fibrous plugging device including a body having multiple fibers, and the fibrous plugging device sealingly engaging an opening in the well, thereby substantially preventing flow through the opening.

Abstract: A method of controlling flow in a well can include a device introduced into the well being conveyed by flow in the well, and the device having a plurality of fibers extending outwardly from a body. A well system can include a flow conveyed device conveyed through a tubular string by flow in the tubular string, and the flow conveyed device including a body with a plurality of fibers extending outwardly from the body. A flow conveyed device for use in a well can include a degradable body, and a plurality of fibers joined to the body, each of the fibers having a lateral dimension that is substantially smaller than a size of the body.

Abstract: A method of controlling flow in a subterranean well can include a device introduced into the well being conveyed by flow in the well, the device comprising a material selected from poly-vinyl alcohol, poly-vinyl acetate and/or poly-methacrylic acid. The material may degrade in the well. A system for use with a well can include a flow conveyed device conveyed through a tubular string by flow in the tubular string, and the flow conveyed device including a material selected from poly-vinyl alcohol, poly-vinyl acetate and/or poly-methacrylic acid. A flow conveyed device for use in a subterranean well can include a body and a degradable material extending outwardly from the body, the degradable material being formed as a film, tube or filament.

Abstract: A flow conveyed device for use in a well can include a body and a plurality of lines joined to the body, each of the lines having a lateral dimension that is substantially smaller than a size of the body, and each of the lines including fibers. A method of controlling flow in a well can include a device introduced into the well being conveyed by flow in the well, and the device including a plurality of lines extending outwardly from a body. Each of the lines may include fibers. A system for use with a well can include a flow conveyed device conveyed through a tubular string by flow in the tubular string, the flow conveyed device including a body with a plurality of lines extending outwardly from the body, the body including at least one knot.

Abstract: A method of controlling flow in a well can include a device introduced into the well being conveyed by flow in the well, and the device having a plurality of fibers extending outwardly from a body. A well system can include a flow conveyed device conveyed through a tubular string by flow in the tubular string, and the flow conveyed device including a body with a plurality of fibers extending outwardly from the body. A flow conveyed device for use in a well can include a degradable body, and a plurality of fibers joined to the body, each of the fibers having a lateral dimension that is substantially smaller than a size of the body.

Abstract: A method of controlling flow in a well can include a device introduced into the well being conveyed by flow in the well, and the device having a plurality of fibers extending outwardly from a body, the fibers being retained by a retainer. A well system can include a flow conveyed device conveyed through a tubular string by flow in the tubular string, and the flow conveyed device including a body with a plurality of fibers extending outwardly from the body. A retainer can at least partially enclose the device. A flow conveyed device for use in a well can include a body, and a plurality of fibers joined to the body, each of the fibers having a lateral dimension that is substantially smaller than a size of the body.

Abstract: A valve assembly can include a longitudinal flow passage, a first longitudinal section of the flow passage having less flow area than a second longitudinal section of the flow passage, and a valve that permits flow in only one direction through the flow passage, the valve including a closure member. In an open position, the closure member can be disposed between the second flow passage section and a chamber in fluid communication with the first flow passage section. A method can include connecting a valve assembly in a tubular string, the valve assembly including a valve that permits flow in only one direction through a longitudinal flow passage of the valve assembly, and flowing fluid in the one direction through the tubular string, thereby displacing a closure member of the valve to an open position and preventing displacement of the closure member toward a closed position.

Abstract: A valve assembly can include a longitudinal flow passage, a first longitudinal section of the flow passage having less flow area than a second longitudinal section of the flow passage, and a valve that permits flow in only one direction through the flow passage, the valve including a closure member. In an open position, the closure member can be disposed between the second flow passage section and a chamber in fluid communication with the first flow passage section. A method can include connecting a valve assembly in a tubular string, the valve assembly including a valve that permits flow in only one direction through a longitudinal flow passage of the valve assembly, and flowing fluid in the one direction through the tubular string, thereby displacing a closure member of the valve to an open position and preventing displacement of the closure member toward a closed position.

Abstract: A well system and associated method can include an acoustic generator which can be used to excite a formation with acoustic waves transmitted from the acoustic generator. Another well system and associated method can include an acoustic generator which can transmit acoustic waves into cement surrounding a casing. Another well system and associated method can include an acoustic generator which can be used to transmit acoustic waves into an annulus surrounding a well screen during or after a gravel packing operation. Another well system and associated method can include an acoustic generator which can be connected in a drill string in close proximity to a drill bit, with the acoustic generator transmitting acoustic waves into a formation ahead of the bit.

Abstract: A well completion method can comprise, in a single trip into a wellbore, the following steps being performed for each of multiple zones penetrated by the wellbore: abrasively perforating the zone with a tubing deployed perforating assembly, fracturing the perforated zone with flow from surface via a well annulus, and then plugging the fractured zone with a removable plug substance, the perforating assembly displacing in the wellbore while the fractured zone is being plugged. Another well completion method can comprise, in a single trip into a wellbore, the following steps being performed for each of multiple zones penetrated by the wellbore: perforating the zone using an abrasive perforator, then displacing the perforator in the wellbore away from the earth's surface, then fracturing the zone, and plugging the fractured zone with a flowable plug substance.

Abstract: A vortex-controlled variable flow resistance device ideal for use in a backpressure tool for advancing drill string in extended reach downhole operations. The characteristics of the pressure waves generated by the device are controlled by the growth and decay of vortices in the vortex chamber(s) of a flow path. The flow path is designed to produce alternating primary and secondary vortices—one clockwise and one counter-clockwise—where the primary vortex is stronger and produces higher backpressure than the secondary vortex. This in turn generates alternating weak and strong pressure pulses in the drill string. The weak pulses may be barely perceptible so that the effective frequency of the pulses is determined by the stronger primary vortices.

Abstract: A well system can include a well tool with a retarder chemical. The retarder chemical is released from the well tool into an annulus and retards setting of cement therein. A method of retarding setting of cement at a location in an annulus can include releasing a retarder chemical from a well tool connected in a casing string, after the cement is placed in the annulus. A well tool can include a valve that controls fluid communication via a port between an exterior of the tool and a flow passage extending through the tool, an annular recess, and a dispersible annular exterior component received in the recess. Another well tool can include a valve that controls fluid communication between an exterior of the tool and a flow passage extending through the well tool, an internal chamber, and a retarder chemical in the chamber.

Abstract: This application is directed to a pressure balanced mud motor and a method of using the mud motor. The mud motor includes a power section to rotate a passageway housing and propel fluid through a passageway disposed in the passageway housing. The mud motor also includes a drive shaft assembly that allows for easy replacement of parts.

Abstract: Tools and methods for abrasively cutting downhole pipes and casing. The tools and methods are ideally suited for situations where the pipe to be cut or perforated is positioned partly or wholly inside another pipe and damage to the outer pipe must be avoided. The jet nozzles are positioned at a non-normal angle to the target surface to reduce the jets' effective cutting distance. While pumping the abrasive fluid, the jets are supported at a selected radial distance from the target surface so that within a predetermined operating time the jets will cut or perforate the inner pipe but leave the outer pipe substantially intact. The tool may be rotated with a motor to perform cutoff operations or held in a fixed position for perforating.