A wiper dart includes one or more wiper elements disposed about a mandrel, each wiper element comprising a wiper cup that extends radially outward and rearwardly relative to the mandrel, and a nose assembly coupled to the mandrel. A drive element is disposed about the mandrel and includes a shoe and a cup coupled to the shoe. The cup extends radially outward and rearwardly from the shoe and exhibits a maximum diameter less than or equal to a maximum diameter of the one or more wiper elements, and the shoe provides at least one of axial and radial support to the cup.

A wiper dart includes one or more wiper elements disposed about a mandrel, each wiper element comprising a wiper cup that extends radially outward and rearwardly relative to the mandrel, and a nose assembly coupled to the mandrel. A drive element is disposed about the mandrel and includes a shoe and a cup coupled to the shoe. The cup extends radially outward and rearwardly from the shoe and exhibits a maximum diameter less than or equal to a maximum diameter of the one or more wiper elements, and the shoe provides at least one of axial and radial support to the cup.

A downhole borehole cleaning apparatus (10) for recirculating drill cuttings contained in a downhole borehole is provided and has a body (10) having an outer surface for contacting downhole fluid containing said drill cuttings, the downhole fluid comprising a certain pressure within the downhole borehole (16). The body (10) has a pair of bearing surfaces (30U; 30D) spaced apart along the longitudinal axis of the body (10), and the pair of bearing surfaces (30U; 30D) comprise substantially the same maximum outer diameter (d1) which is greater than the maximum outer diameter of the rest (14) of the body (10). Each of the pair of bearing surfaces (30U; 30D) comprises a substantially constant and un-interrupted diameter (d1) around its whole outer circumference for at least a portion of its longitudinal length; this forces all of the drilling fluid to pass around that maximum outer diameter. The outer surface of the body (10) further comprises a low pressure generation means (50) located in between the two longitudinally spaced apart bearing surfaces (30U; 30D) for generating a region of lower pressure in the downhole fluid within that region compared to the said certain pressure. A method of cleaning a downhole borehole is also described involving miming in a work string comprising a downhole borehole cleaning tool (10) into a borehole to be cleaned, and permitting or arranging for relative movement to occur between the downhole borehole cleaning tool (10) and fluid located in the annulus (15) in the borehole (16) whereby drill cuttings are recirculated.

A downhole borehole cleaning apparatus (10) for recirculating drill cuttings contained in a downhole borehole is provided and has a body (10) having an outer surface for contacting downhole fluid containing said drill cuttings, the downhole fluid comprising a certain pressure within the downhole borehole (16). The body (10) has a pair of bearing surfaces (30U; 30D) spaced apart along the longitudinal axis of the body (10), and the pair of bearing surfaces (30U; 30D) comprise substantially the same maximum outer diameter (d1) which is greater than the maximum outer diameter of the rest (14) of the body (10). Each of the pair of bearing surfaces (30U; 30D) comprises a substantially constant and un-interrupted diameter (d1) around its whole outer circumference for at least a portion of its longitudinal length; this forces all of the drilling fluid to pass around that maximum outer diameter. The outer surface of the body (10) further comprises a low pressure generation means (50) located in between the two longitudinally spaced apart bearing surfaces (30U; 30D) for generating a region of lower pressure in the downhole fluid within that region compared to the said certain pressure. A method of cleaning a downhole borehole is also described involving miming in a work string comprising a downhole borehole cleaning tool (10) into a borehole to be cleaned, and permitting or arranging for relative movement to occur between the downhole borehole cleaning tool (10) and fluid located in the annulus (15) in the borehole (16) whereby drill cuttings are recirculated.

A hydraulically actuated Jack And Pull (JAP) tubular expansion tool string comprises: an annular non-return valve arranged in the wall of the JAP string, which allows mud to flow from a surrounding annulus into the bore of the expansion tool string when the pressure in the bore of the tool string is lower than that in the annulus; a second non-return valve arranged in the JAP string below the annular valve which allows fluid to move down only; wherein during the cycling of the jack the annular non-return valve is continuously open and the second non-return valve cycles with the jack movement to inhibit curing of cement in the expansion tool string.

A hydraulically actuated Jack And Pull (JAP) tubular expansion tool string comprises: an annular non-return valve arranged in the wall of the JAP string, which allows mud to flow from a surrounding annulus into the bore of the expansion tool string when the pressure in the bore of the tool string is lower than that in the annulus; a second non-return valve arranged in the JAP string below the annular valve which allows fluid to move down only; wherein during the cycling of the jack the annular non-return valve is continuously open and the second non-return valve cycles with the jack movement to inhibit curing of cement in the expansion tool string.

A device and method of repairing a damaged portion of a seal bore interconnected in a tubing string, where the device can include a chamber, a piston positioned within the chamber, and a filler material contained within the chamber. A force applied to the piston can cause the piston to move within the chamber, which can cause at least a portion of the filler material to be expelled from the chamber, with at least a portion of the expelled filler material filling a recess in the damaged portion of the seal bore, thereby repairing the sealing surface of the seal bore.

A device and method of repairing a damaged portion of a seal bore interconnected in a tubing string, where the device can include a chamber, a piston positioned within the chamber, and a filler material contained within the chamber. A force applied to the piston can cause the piston to move within the chamber, which can cause at least a portion of the filler material to be expelled from the chamber, with at least a portion of the expelled filler material filling a recess in the damaged portion of the seal bore, thereby repairing the sealing surface of the seal bore.

An instrumented wiper dart configurable at the wellsite comprising any combination of a sealing member, a sensor sub, an electronics package, and a communication system; wherein the sealing member is cylindrical in shape, releasably coupled to the wiper assembly, and configured to sealingly engage the inner surface of a workstring. The sensor sub is release releasably coupled to the wiper assembly, and includes one or more sensors to measure a property of the wellbore environment. The electronics package is releasably coupled to the wiper assembly, configured to receive one or more data sets from the sensor sub, and transmit one or more data sets to the communication sub. The communication sub is configured to transmit the one or more data sets; and wherein the instrumented wiper plug is displaced down the workstring in response to a volume of fluid pumped from surface.

An instrumented wiper dart configurable at the wellsite comprising any combination of a sealing member, a sensor sub, an electronics package, and a communication system; wherein the sealing member is cylindrical in shape, releasably coupled to the wiper assembly, and configured to sealingly engage the inner surface of a workstring. The sensor sub is release releasably coupled to the wiper assembly, and includes one or more sensors to measure a property of the wellbore environment. The electronics package is releasably coupled to the wiper assembly, configured to receive one or more data sets from the sensor sub, and transmit one or more data sets to the communication sub. The communication sub is configured to transmit the one or more data sets; and wherein the instrumented wiper plug is displaced down the workstring in response to a volume of fluid pumped from surface.