A tubing string release apparatus includes a first mandrel configured to be fixed to an inner wall of a tubing string extended within a wellbore, the first mandrel defining a telescope chamber and a first port that facilitates fluid communication into the telescope chamber, a second mandrel slidably arranged against the first mandrel and defining a second port, and a telescoping cylinder arranged within the telescope chamber and including a telescoping base releasably coupled to the tubing string at an aperture defined in the tubing string, and a telescoping piston releasably coupled to the telescoping base. The telescoping base is advanced radially outward through the aperture when a pressure within the tubing string is increased to a first pressure, and the telescoping piston is advanced radially outward through the telescoping base when the pressure within the tubing string is increased to a second pressure greater than the first pressure.

A rheological lock apparatus includes a fluid chamber formed within a housing between a pair of seals. The fluid chamber contains a rheological fluid. An inner surface of the housing has a first plurality of splines projecting into the fluid chamber and extending longitudinally along a longitudinal dimension of the chamber. A driveshaft extends axially through the chamber such that the pair of seals are sealed against the driveshaft. The driveshaft includes a second plurality of splines. A field generator is coupled to one of the driveshaft or the housing to generate a field through the rheological fluid during times when the housing is substantially immobile in a borehole.

Apparatus and methods for reducing differential pressure sticking of a drill string stuck against a sidewall of a wellbore by decreasing hydrostatic pressure around the drill string within the wellbore. Drilling fluid is displaced out of the wellbore by injecting a displacement fluid into an annulus defined between the sidewall and an exterior of the drill string, and pressure of the injected displacement fluid within the annulus is decreased by bleeding the injected displacement fluid out of the annulus.

Techniques for determining properties of a spotting fluid include positioning a member of a test apparatus into a prepared mudcake sample at a specified depth, the mudcake sample associated with a drilling fluid and including a specified thickness; circulating a flow of the spotting fluid to contact the prepared mudcake sample in a test cell; soaking the prepared mudcake sample in the spotting fluid for a specified time duration; subsequent to the specified time duration, detecting a force exerted on the member relative to a displacement distance of the member from the specified depth in the mudcake sample during removal of the member from the mudcake sample; recording, with the test apparatus, the detected force relative to the displacement distance; and determining, with the test apparatus, one or more properties associated with the mudcake sample based on the recorded force relative to the displacement distance.

A downhole tool for use within a wellbore extending into an underground formation includes a wellbore wall disengaging assembly having a tubular string defining a longitudinal axis, and a plurality of longitudinal blades forming a retractable sleeve around the tubular string, the retractable sleeve having a substantially contiguous inner profile in a closed position, and wherein the retractable sleeve is actuated based on an internal pressure in the tubular string proximate to the downhole tool. A method of disengaging a downhole tool from a wall of a wellbore extending into an underground formation includes lowering a wellbore wall disengaging assembly, the assembly comprising a tubular string defining a longitudinal axis, and a plurality of longitudinal blades forming a retractable sleeve around the tubular string, the retractable sleeve having a substantially contiguous inner profile in a closed position, and actuating the retractable sleeve.

A slip cover for downhole logging tools to prevent the tools from becoming lodged during extraction and a method of retrieving a lodged logging tool in a wellbore are disclosed. In some implementations, the slip cover may include a generally cylindrical polymeric sleeve having an inside diameter greater than an outside diameter of a generally cylindrical well logging tool to which the sleeve is to be applied and having one or more perforations disposed therein.

A slip cover for downhole logging tools to prevent the tools from becoming lodged during extraction and a method of retrieving a lodged logging tool in a wellbore are disclosed. In some implementations, the slip cover may include a generally cylindrical polymeric sleeve having an inside diameter greater than an outside diameter of a generally cylindrical well logging tool to which the sleeve is to be applied and having one or more perforations disposed therein.

A drilling system includes a drilling rig, and a drill string extended from the drilling rig and into a wellbore and including a plurality of sections of drill pipe connected end to end and a drill bit arranged at a distal end of the drill string. At least one section of the drill pipe includes an outer surface and a plurality of raised features extending radially outward from the outer surface.

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 vorticesone clockwise and one counter-clockwisewhere 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.

An apparatus for controlling tool face and methods of use with a torque generator connected to a drill string for drilling linear and nonlinear subterranean bore segments. In some embodiments, the apparatus and methodologies of use comprise a tool controller having an outer housing independently rotatable from and extension conduit extending therethrough and forming an annulus therebetween. The tool controller may provide for a first fluid pathway for allowing a bypass portion of fluids to flow through the torque generator, and a second fluid pathway through the annulus for allowing a torque generator portion of fluids to flow through the annulus. In some embodiments, at least one fluid flow restrictor may be provided within the annulus to controllable cause a cascading reduction in torque generator fluid pressure as it flows through the annulus, allowing high resolution tool face control over a larger (and tunable) range of drill string speed (rpm) set points.