Abstract: A method for detecting an influx and/or loss of circulation in a wellbore, comprising measuring a condition in the wellbore using a downhole sensor; determining that a positive displacement pump is shut off or turned on; predicting pit volume and/or gas concentration at a plurality of time points after the positive displacement pump is shut off or turned on using the measured condition in the wellbore prior to the positive displacement pump is shut off or turned on, wherein the measured condition correlates with the pit volume and/or gas concentration; measuring pit volume and/or gas concentration at the plurality of time points; comparing the predicted and the measured pit volumes and/or gas concentrations at the plurality of time points; and producing a warning signal if the difference between the predicted and the measured pit volumes and/or gas concentrations is greater than a pre determined value.

Abstract: A rotary tool for operation within an underground borehole or within tubing in a borehole has a tool body and at least one sensor-containing unit attached to the tool body and positioned to contact the conduit wall. The sensor-containing unit includes an exterior portion to contact the borehole or tubing wall and one or more sensors is located in a cavity between the exterior portion and the tool body. The sensor-containing unit may be formed from the exterior portion, an attachment portion for attachment to the tool body, and one or more connecting portions extending between the attachment and exterior portions, with the sensor-containing cavity between the attachment and exterior portions. Possible rotary tools include drill bits, reamers, mills, stabilizers, and rotary steerable systems.

Abstract: A rotary tool for operation within an underground wellbore or within tubing in a wellbore has at least one force-sensitive element attached to the tool body and positioned to contact the conduit wall, wherein the force-sensitive element comprises an outer portion to contact the wellbore or tubing wall, at least one connecting portion which is more compliant than the outer portion and through which the outer portion is connected to the tool body, and at least one sensor responsive to force on the outer portion transmitted through the force-sensitive element to the tool body. The sensors may resolve forces into measurable forces on three axes. Possible rotary tools include drill bit, reamer, mill, stabilizer and rotary steerable system for a drill bit.

Abstract: A downhole cutting tool which may be a reamer or a mill has a rotary tool body with at least one block which carries hard-faced cutters and projects or is extensible from the tool body. A radially outward facing part of the cutter block defines a channel for fluid flow which extends generally axially along the cutter block. The channel is configured such that at least the rotationally trailing edge of the channel extends along the block in one or more directions which are inclined relative to the tool axis. This reduces or avoids the amount of channel edge parallel to the tool axis and thereby mitigates whirling and/or or vibration.

Abstract: A method is provided for controlling a managed pressure drilling system. The method comprises providing a fast system interpretation model for the operation of the managed pressure drilling system, obtaining real-time measurements from one or more sensors regarding the operation of the managed pressure drilling system, using the measurements to calibrate the fast system interpretation model for the managed pressure drilling system in real-time and using a predictive controller to run the calibrated fast system interpretation model to a time horizon in the future.

Abstract: Tubing in a borehole is removed using a rotary milling tool comprising a plurality of elements projecting from or extensible from the body of the tool. The elements are distributed azimuthally around the tool body. The elements comprise cutters to remove material from the tubing and outward facing guide surfaces for sliding contact with an inner surface of the tubing. As the tool is rotated and advanced, forward cutters contact the inner surface removing material from the tubing and exposing a renewed interior tubing surface with a diameter swept out by the cutter. The outward facing guide surfaces extend the same distance from the tool body as the forward cutters producing a sliding contact with the newly created inward facing surface. Further cutters, disposed behind the outward facing guide surfaces, with respect to motion of the tool through the tubing, remove the remaining portion of the tubing.

Abstract: A rotary cutting tool, which may be a reamer for enlarging an underground borehole or a mill to remove tubing by cutting into the inside wall of the tubing, has a plurality of cutter assemblies distributed azimuthally around a longitudinal axis of the tool, wherein each cutter assembly includes a supporting structure bearing a sequence of cutters which extends axially along the tool with leading surfaces facing in a direction of rotation of the tool. The cutters of each sequence are positioned at a plurality of circumferential positions such that no more than three cutters of the sequence are aligned on any line parallel to the longitudinal axis of the tool. In an overlapping arrangement, a plurality of cutters in the sequence may have a leading face circumferentially behind the leading face but ahead of the trailing end of at least one other cutter.

Abstract: A reaming tool for enlarging an underground borehole comprises a plurality of cutter assemblies distributed azimuthally around a longitudinal axis of the tool, wherein each cutter assembly includes a supporting structure bearing a sequence of cutters which have hard surfaces exposed and facing in a direction of rotation of the tool. The outer surface of the support structure on each cutter assembly includes zones which each face towards an end of the assembly and is configured such that as it extends circumferentially relative to the tool axis in the direction opposite to rotation of the tool, it also extends away from an end of the assembly.

Abstract: A reamer for enlarging an underground borehole comprises a plurality of cutter assemblies distributed azimuthally around a longitudinal axis of the tool, and each cutter assembly comprises a supporting structure and a plurality of hard faced cutters (211-216) embedded therein with a hard face of each cutter exposed and facing in a direction of rotation of the tool. Each cutter assembly includes at least one outward-facing gauge surface (220), at a radial distance from the tool axis which aligns the gauge surface with the radially outer extremity (218) of at least one cutter. This gauge surface (220) extends (221) in the direction of rotation circumferentially ahead of the extremity of the exposed face of the aligned at least one cutter. It may meet the side of the assembly at a curved (222) or bevelled (342) edge and may also extend back from the exposed face of the cutter.

Abstract: A downhole rotary tool for comminuting tubing in a borehole comprises a tool body and a plurality of cutting assemblies projecting from or extensible from the tool body and distributed azimuthally around a longitudinal axis of the tool body. Each cutting assembly comprises a supporting structure and a plurality of cutters with cutting surfaces of hard material. The rotating tool is advanced into initial contact with the tubing to commence milling axially along the tubing and then advanced further to continue milling the tubing, At least one cutting assembly has material which is softer than the hard faces of the cutters and is positioned to contact the tubing at the initial contact and delay contact between at least one hard surfaced cutter and the tubing.

Abstract: The operation of rotary equipment carried on elongate structure such as coiled tubing extending into a borehole from the Earth's surface is carried out by providing at least one optical fibre extending downhole to the rotary equipment from the surface, using optical time domain reflectometry to operating the optical fibre as a distributed vibration sensor while the rotary equipment is in operation, and thereby observing vibration created by the rotary equipment.

Abstract: A method is provided for determining a discharge coefficient of a managed pressure drilling choke/valve as a function of valve opening position. The method comprises: a flow of air/gas through the choke/valve; measuring a velocity of the air/gas flow at an inlet of the choke/valve; and measuring a pressure drop of the air/gas flow across the choke/valve.

Abstract: A drilling system that includes a drill bit that drills a bore through rock. A shaft coupled to the drill bit, wherein the shaft transfers rotational power to the drill bit. A housing that receives at least part of the shaft. A rotary steering system that controls a drilling direction of the drill bit. The rotary steering system includes a steering sleeve that couples to and uncouples from the housing to control a drilling direction of the drill bit.

Abstract: A directional drilling system that includes a drill bit that drills a bore through rock. The drill bit includes an outer portion of a first material and an inner portion coupled to the outer portion. The inner portion includes a second material.

Abstract: A reamer for enlarging an underground borehole comprises a plurality of cutter assemblies distributed azimuthally around a longitudinal axis of the tool. Each cutter assembly comprises a supporting structure and a plurality of hard faced cutters secured therein with a hard surface of each cutter exposed and facing in a direction of rotation of the tool and extending radially outwards from the tool axis to a radially outward extremity. These cutters are arranged in a sequence extending axially along the tool. In contrast with convention a1 cutter assemblies, the supporting structure comprises at least one radially outward-facing surface which is positioned to follow behind the leading face of at least one cutter as the tool rotates and which is aligned with the radially outer extremity of the cutter at the same radial distance from the tool axis. Thus the surface area available to contact the borehole wall and stabilize the positioning and motion of the rotating reamer is enhanced.

Abstract: A reaming tool for enlarging an underground borehole comprises a plurality of cutter assemblies (251, 252, 253) distributed azimuthally around a longitudinal axis of the tool, wherein each cutter assembly comprises support structure bearing a sequence of cutters (211-214) with leading surfaces facing in a direction of rotation of the tool and the sequence of cutters extends axially along the tool from an axial end (202) of the tool with the cutters positioned at radial distances from the tool axis which progressively increase as the sequence extends away from the axial end of the tool. The cutter assemblies include guiding structure (261-264) which is positioned circumferentially ahead of the leading faces of cutters of the sequence on the assembly.

Abstract: A reaming tool for enlarging an underground borehole has a plurality of cutter assemblies distributed azimuthally around a longitudinal axis of the tool. First, second and possibly more cutter assemblies each have an axially extending length comprising supporting structure bearing a sequence of cutters which have hard surfaces facing in a direction of rotation of the tool and are distributed axially along the length. A plurality of the cutters on the second cutter assembly are at axial positions relative to the tool which are intermediate between axial positions of the cutters on the first cutter assembly. Cutters on further assemblies may also be at intermediate axial positions. Cutters in the overall plurality of sequences are positioned at radial distances from the tool axis which increase as axial distance from an end of the tool increases.

Abstract: A bell nipple for use in an offshore wellbore operation comprising an upper tubular member and a lower tubular member connected telescopically via a slip joint, one or more pistons at the level of the radial plane which is defined by the lowest point of the side outlet and each substantially not axially movable relative to the lower tubular member, wherein the total cross sectional area of the one or more pistons is substantially the same as the cross sectional area of the slip joint less the cross sectional area of the drillpipe. The one or more pistons in the bell nipple provides passive heave compensation in the system, so that the flow rate of drilling fluid measured along the flowline is free from perturbation due to heave during offshore operations.

Abstract: Monitoring one or more items of equipment associated with a borehole or other conduit. A sensor system includes a vibration sensor for sensing vibrations at one or more sensor locations associated with one or more items of the equipment and/or the borehole or other conduit. A processing system processes the sensor information to determine a characteristic of the operation of the one or more items of equipment and/or the borehole or other conduit.

Abstract: An expandable reamer for a borehole has a plurality of support elements (202) distributed around a central axis of the tool with cutters (234, 236) and stabilising pads (250) on the support elements, arranged such that at least one of the support elements comprises at least one region comprising cutters and at least one support element comprises a stabilising pad having a front surface positioned to face the wall of the borehole. The reamer includes drive mechanism for expanding the support elements (202) radially outwardly from the central axis. The support elements differ in the presence or axial positions of stabilising pads (250) thereon such that at least one support element differs from at least one other support element in the presence or axial position of at least one stabilising pad. This arrangement allows the stabilising pads to be positioned at or close to full gauge, thereby reducing vibration.