Abstract: A connector tool is used to direct fluids from a lifting assembly into a bore of a downhole tubular. The connector tool includes a body having an upper end and a lower end. The upper end is configured to be coupled to the lifting assembly, and the lower end is configured to be coupled to the downhole tubular. A telescopic engagement assembly is coupled to the body and configured to selectively extend and retract a seal assembly disposed at a distal end of the connector tool with a proximal end of the downhole tubular. A pump is coupled to the lifting assembly such that rotational movement from a component of the lifting assembly directs fluid to extend and retract the telescopic engagement assembly.

Abstract: A drilling rig system for obtaining high trip rates separates the transport of tubular stands in and out of their setback position into a first function, delivery and retrieval of tubular stands in well center position as a second function; and the functions intersect at a stand hand-off position where tubular stands are set down for exchange between tubular handling equipment. A drilling rig has a tubular delivery arm that vertically translates the mast in a non-conflicting path with a top drive. The tubular delivery arm is operable to deliver tubular stands between a catwalk, stand hand-off, mousehole, and/or well center positions. An upper racking arm moves tubular stands between a racked position in the racking module and a stand hand-off position between the mast and racking module. An upper support constraint stabilizes tubular stands at the stand hand-off position.

Abstract: A bow-spring centralizer (6) includes bow springs (5), moving collars (11) secured to each end of each bow spring, and interlocked stop collars (10). Extendable collars (8) may each be formed of a moving collar (11) movably interlocked with a stop collar (10). The centralizer (6) may optionally be formed from a tube cut using a laser to create two extendable collars coupled by bow springs. Each extendable collar may include heads integrally formed on extensions protruding from a collar (stop collar or moving collar). The heads may be generally rectangular, arrow, or teardrop-shaped head or some other shape. Each head may be slidably captured within a chamber on the interlocked collar (moving collar or stop collar). The extensions of each interlocked tubular member define the outer walls of the chamber in which a head of the interlocked tubular member is slidably captured.

Abstract: Undertaking a wellbore operation while monitoring wellbore pressure with stationary pressure sensors coupled to tubing extended within the wellbore and thereby generating downhole annulus signals in real-time. The wellbore pressure is also monitored at or near a surface location during the wellbore operation with surface pressure sensors that generate a measured wellhead pressure. The downhole annulus pressure signals are received at an outer loop controller that provides a desired wellhead pressure based on a difference between the real-time downhole annulus pressure signals and a desired pressure setpoint. The measured and desired wellhead pressures are received with an inner loop controller that provides command signals based on a difference between the measured and desired wellhead pressures. The command signals are received by flow control devices that adjust a backpressure within the wellbore based on the command signals.

Abstract: In accordance with embodiments of the present disclosure, system and methods for controlling borehole pressure in a MPD system to compensate for heave effects on a drilling rig are provided. The systems and method described herein involve calculating and implementing set points for two or more MPD system components in real time. These MPD components that are controlled via the dynamic set points may include a choke, a backpressure pump (BPP), a rig pump diverter (RPD), a continuous circulation device, one or more mud pumps, a pressure relief system, or some combination thereof. By calculating and providing these set points in real-time during various well and drilling operations, non-productive time, well control events, and costs to remedy issues resulting from improper pressure levels within the borehole may be mitigated or avoided.

Abstract: A method for monitoring a well bore during drilling operations, particularly with respect to a fluid gain and/or fluid loss event. Monitoring the well bore may be accomplished by monitoring an incoming flow rate of the fluid into the wellbore. The fluid return line from the well bore may carry drilling fluid from the well bore to a mud gas separator located downstream from the well bore. Changes in at least one parameter of the mud gas separator may be monitored. The changes to the at least one parameter of a mud gas separator may be compared to the incoming flow rate of the fluid. Discrepancies between the changes and the incoming flow rate may be indicative of a fluid gain or fluid loss condition.

Abstract: A fluid transfer device for use in wellbore drilling includes at least one pressure vessel having a fluid port at a bottom thereof for entry and discharge of one of a working fluid or a power fluid and a fluid port at a top thereof for entry and discharge of the other of the power fluid or the working fluid. The pressure vessel has a barrier fluid between the power fluid and the working fluid. Valves are coupled to the power fluid port for selective introduction of the power fluid into the at least one pressure vessel. Valves are coupled to the working fluid port such that the working fluid is constrained to flow in only one direction.

Abstract: An anchor member comprises a substrate; and at least one insert secured to the substrate and extending outwardly from an outer surface of the substrate. The insert is configured for engagement with another member. In an embodiment, the insert comprises a shell at least partially defining an empty core. Alternatively, the insert comprises an inner portion and an outer portion disposed on the inner portion; the inner portion comprising a soft material which comprises one or more of the following: a low carbon steel or an aluminum alloy; and the outer portion comprising the soft material and a hard material and having a gradient in the weight ratio of the soft material to the hard material, the hard material comprising one or more of the following: an intermetallic compound; a ceramic; a hard steel; or a titanium alloy.

Abstract: A latching dog includes a dog body, at least one engagement arm protrudes from an outer radial surface of the dog body in a transverse direction, and at least one retention fin protrudes from the dog body in a longitudinal direction. The at least one retention fin maintains the latching dog engaged with a housing surface to keep the latching dog at a desired axial and/or rotational position while milling the housing and latching dog.

Abstract: A debris catcher and system is provided for removing debris from fluids such as in wellbore stimulation operations. A generally tubular housing axially supports a tubular screen inside a housing bore. Debris-laden fluid flows from an intake end of the housing axially into the bore of the screen and exits screen openings radially into an axially elongated flow annulus formed between a tubular wall of the screen body and the housing bore. Debris is retained in the upstream portion of screen body and clean fluid, in the annulus, returns downstream of the screen for exit out a discharge end of the housing. The screen is removably installable to the housing.

Abstract: A system of cleaning a portion of the casing prior to a plugging operation may include a centralizer, a first radially extendable cutting tool, a second radially extendable cutting tool, a preliminary extendable cleaning tool, and a fluid jet cleaning tool. In a preferred embodiment a centralizer, a radially extendable cutting tool, and a fluid jet cleaning tool are run into a wellbore where the radially extendable cutting tool cut the window through the inner production tubular and the fluid jet cleaning tool removes the remaining's cement and other debris allowing a plug to be placed within the window. In another embodiment a centralizer and a first extendable cutting tool may be run into the well where a small window is cut and then the centralizer first extendable cutting tool are removed from the wellbore. A centralizer, a second extendable cutting tool, and a fluid jet cleaning tool a run into the wellbore.

Abstract: A methodology and apparatus for cutting shape(s) or profile(s) through well tubular(s), or for completely circumferentially severing through multiple tubulars, including all tubing, pipe, casing, liners, cement, other material encountered in tubular annuli. This rigless apparatus utilizes a computer controlled, downhole robotic three-axis rotary mill to effectively generate a shape(s) or profile(s) through, or to completely sever in a 360 degree horizontal plane wells with multiple, nested strings of tubulars whether the tubulars are concentrically aligned or eccentrically aligned. This is useful for well abandonment and decommissioning where complete severance is necessitated and explosives are prohibited, or in situations requiring a precise window or other shape to be cut through a single tubular or plurality of tubulars.

Abstract: A core barrel assembly for a drill string comprising a core barrel, an inner tube assembly removably positionable within the core barrel, and a mechanical shock inducement mechanism for inducing at least one shock, and preferably a plurality of shocks, in the inner tube assembly. This induced shocks help reduce occurrences of blockage of core samples entering the inner tube assembly in fractured or brittle rock formations.

Abstract: A Christmas tree and a method of completing a well in a standard wellhead. The tree is presented as separately deployable upper and lower portions with the master valves contained in the lower portion so that they are located below the wellhead housing to lower the height of the tree while increasing well safety and integrity. The upper master valve is bi-directionally sealing to allow for pressure testing, removing the requirement for tubing hanger plugs.

Abstract: A wellbore control device includes a housing defining a throughbore which can receive a tubular, a first gate with a first hole, and a second gate with a second hole. The first gate and the second gate are supported by the housing and and can perform a movement transverse to the throughbore between an open position and a closed position. The movement of the first gate and the second gate from the open position to the closed position splits the throughbore into an upper portion and a lower portion, the upper position and the lower positing being completely separate from each other. The first hole and the second hole are aligned substantially co-axially with the throughbore in the open position. A part of at least one of the first hole and the second hole remains aligned with the throughbore in the closed position.

Abstract: A stripping element for rotary flow control diverters used in the oil and gas industry can include a stiffening member formed of a first harder material than a deformable member formed of a second softer material over-molded to the stiffening member. The stiffening member can include apertures that provide for the second softer material of the deformable member to be displaced through the apertures when a pipe of a drill is displaced through the stripping element. The stiffening member can include multiple members that stiffen the deformable member to prevent the deformable member from bending into the stripping element when a pipe of a drill is displaced through the stripping element. The multiple members can be displaced out in a direction away from the pipe of the drill when the pipe of the drill is displaced through the stripping element to prevent the stripping element from being compromised.

Abstract: Methods and apparatus are provided for cementing a liner. In one embodiment, the method includes releasing a dart behind a cement; landing the dart in an activation seat; increasing pressure to activate a liner hanger; further increasing pressure to release the dart from the activation seat; landing the dart in a plug; and increasing pressure to release the dart and the plug. In one embodiment, releasing the dart from the activation seat comprises deforming the dart.

Abstract: A system includes an annular packer assembly configured to be positioned within an outer annular barrel. The annular packer assembly includes a packer having a radially-inner surface configured to contact an inner annular barrel and a radially-outer surface, and the packer extends axially from a first end to a second end. The annular packer assembly also includes a piston assembly configured to move axially relative to the outer annular barrel to deflect the second end of the packer radially-inwardly into an annular space between the inner annular barrel and the outer annular barrel to seal about the inner annular barrel.

Abstract: There is disclosed an improved frac plug apparatus for setting a plug in a downhole. In an embodiment, the apparatus comprises an inner cone shaped member having a first end and a second end, the inner cone shaped member having a generally increasing outer diameter from the first end; an expandable outer sleeve having a first end and a second end, the first end of the expandable outer sleeve adapted to receive the first end of the inner cone shaped member and the second end of the expandable outer sleeve having a plurality of fingers joined at their tips at predetermined break points; wherein, upon receiving the first end of the inner cone shaped member further into the expandable outer sleeve, the fingers of the expandable outer sleeve are adapted to break at their tips at their predetermined break points and expand outwardly to engage a surface of the downhole.

Abstract: Autonomously conveyable and actuatable wellbore completion tool assemblies and methods for using the same, comprising: an onboard controller and location sensing device, a plurality of adaptable perforation sealing devices comprising a primary sealing portion and at least one secondary sealing portion extending radially outward from the primary sealing portion to form a secondary seal in the perforation; an autonomously actuatable transport member for supporting the plurality of adaptable sealing devices during conveyance of the tool assembly within the wellbore, and an on-board controller configured to send an actuation signal to actuate at least release of the plurality of adaptable perforation sealing devices from the transport member, wherein the tool assembly comprises a friable material and self-destructs within the wellbore in response to a signal from the on-board controller that affects self-destruction.

Abstract: Methods of formulating a cement slurry for use in a subterranean salt formation, including methods for formulating a cement slurry capable of providing long-term zonal isolation within a subterranean salt formation. The methods also take into account the effects of treatment fluids on the cement slurry, such as drilling fluids, spacer fluids, flush fluids, or other relevant fluids used to perform a subterranean formation operation.

Abstract: Pump-through standing valves, wells including the pump-through standing valves, and methods of utilizing a pump-through standing valve to deploy a downhole device are disclosed herein. The pump-through standing valves include a valve body, a standing valve at least partially formed within the valve body, and a flow-through valve at least partially formed within the valve body. The standing valve includes a standing valve fluid conduit and a standing valve flow control device. The flow-through valve includes a flow-through valve fluid conduit and a flow-through valve flow control device. The wells include a wellbore, which extends within a subterranean formation, a wellbore tubular, which extends within the wellbore, and the pump-through standing valve, which is operatively attached to the wellbore tubular.

Abstract: A safety valve system for a subterranean well includes a central body with a central body profile and a supporting body having a supporting profile shaped to support the central body profile. An outer diameter seal circumscribes the central body to seal between the central body and the supporting body. An inner diameter seal is located within a central bore of the central body to form a seal between the central bore of the central body and a cable that extends through the central bore. An annular fluid flow path extends through the safety valve system axially past the outer diameter seal and the inner diameter seal. A valve assembly is moveable between an open position where fluid can flow through the annular fluid flow path, and a closed position where fluid is prevented from flowing through the annular fluid flow path.

Abstract: A method of oscillating a pressure in a borehole is provided that includes determining a hydraulic diffusivity, using injection tests, in a borehole, calculating a pressure field using an appropriately programmed computer at a proximal distance to the borehole using a first forced oscillation result in a porous media, calculating a flow rate at the proximal distance from the borehole by multiplying a gradient of the pressure field by a measured permeability and dividing by a viscosity of a fluid under test, computing, using the appropriately programmed computer, a volumetrically averaged flow rate by integrating a square of the flow rate over a volume around the borehole, outputting a value of an angular frequency for which the volumetrically-averaged flow rate is maximum, and operating a pump at a second forced oscillation according to the angular frequency on the fluid under test, where an increase in permeability around the borehole is provided.

Abstract: A whipstock assembly for emplacing and orienting a whipstock within a wellbore. The whipstock assembly includes a whipstock, an anchor sub for securing the whipstock within the wellbore and a locating tool which is releasably secured to the whipstock. The locating tool includes a tool body with an inclined contact face and a hook which extends radially outwardly from the tool body. The hook is shaped and sized to engage a lower end of the casing exit window to align and orient the whipstock with the casing exit window.

Abstract: A process for removing hydrate formations from a flowline includes connecting a manifold to the flowline, passing an inert gas across a pair of inlets of the manifold so as to create a reduced pressure across the pair of inlets that is less than a pressure of a fluid in the flowline, opening a valve between the pair of inlets and the flowline so as to expose the pressurized fluid in the flowline to the reduced pressure across the pair of inlets, disassociating hydrates in the flowline by exposure to the reduced pressure across the pair of inlets, and flowing the fluid and the disassociated hydrates from the flowline into the outlet of the manifold and outwardly of the manifold through at least one of the pair of inlets.

Abstract: A downhole system can include multiple sub-components of a downhole debris separator assembly that is modular. The system can also include multiple couplers arranged on or among the sub-components of the multiple sub-components. Each of the couplers can connect with others of the couplers in different combinations to form respectively different configurations of the downhole debris separator assembly.

Abstract: There is a switch sub adapter configured to connect a switch sub to a perforating gun assembly. The switch sub adapter includes a body having first threads that connect to the switch sub and second threads that connect to the perforating gun assembly; a first internal chamber formed at a first end of the adapter; a second internal chamber formed at a second end of the adapter; a conduit connecting the first internal chamber to the second internal chamber; and a dart having a tip part located in the conduit and a base part located in the second internal chamber.

Abstract: According to an aspect a deformable member is provided, wherein the deformable member is configured for use in a ballistic transfer module. The ballistic transfer module includes the deformable member, a booster holder, a booster and a detonating cord. A method of initiating one or more percussion initiators of a perforating gun assembly using the ballistic transfer module and deforming the deformable member is also provided.

Abstract: An electrical submersible pump system include an electric submersible pump coupled to a lower end of a production conduit extending into a wellbore, the production conduit in fluid communication with a discharge of the electric submersible pump and with a well conduit extending to the surface. A bypass conduit is nested inside the production conduit and is in fluid communication with the discharge. The check valve is opened when flow is established in the annular space and is otherwise closed. The bypass conduit extends for a selected distance above the discharge. The bypass conduit has a plurality of selected diameter apertures through a wall of the bypass conduit to enable flow into the annular space.

Abstract: The present disclosure relates to a particularly effective well configuration that can be used for single well cross steam assisted gravity drainage (SW-XSAGD) wherein a single well has multiple injection sections each separated by a production segment that is completed with passive FCDs to control steam flashing.

Abstract: Methods for the recovery of geological hydrocarbons from hydrocarbon reservoirs include injecting a low molecular weight oil soluble hydrocarbon compound and an electron acceptor into a reservoir, which enter a region of the reservoir comprising a microbial culture capable of metabolizing the low molecular weight hydrocarbon compound and the electron acceptor, thereby promoting flow of geological hydrocarbon.

Abstract: Wellbore tubulars including selective stimulation ports (SSPs) sealed with sealing devices and methods of operating the same are disclosed herein. The wellbore tubulars include a tubular body that defines a tubular conduit and a plurality of selective stimulation ports. Each selective stimulation port includes an SSP conduit and a sealing device seat. The wellbore tubulars further include a plurality of sealing devices. Each sealing device includes a primary sealing portion that is seated on a corresponding sealing device seat and forms a primary seal with the corresponding sealing device seat. Each sealing device also includes a secondary sealing portion that extends from the primary sealing portion and forms a secondary seal between the primary sealing portion and the corresponding sealing device seat. The methods include methods of stimulating a subterranean formation utilizing the wellbore tubulars.

Abstract: A dynamic monitoring system for dynamically monitoring injection operations on wells by determining the extent of fracturing using downhole pressure measurements. The system comprises a downhole pressure gauge, means to transmit data from the downhole pressure gauge to surface and a surface data acquisition unit wherein, on inducing a pressure change in a wellbore by an injection operation, the downhole pressure gauge records a pressure trace as data, the data is transmitted to surface at a first sampling frequency, the data is stored in the surface data acquisition unit and fracture length is calculated from the stored data to indicate extent of fracturing. Sampling frequencies are outside the known operating ranges.

Abstract: A method for stimulating a natural gas formation, comprising injecting a liquid cryogen and a proppant into a natural gas formation.

Abstract: The disclosure provides fracturing methods having advantage over current fracturing methods. The disclosed fracturing methods can change the fracture gradient of the downhole subterranean formation. For example, one or more of the fracture gradients of the low and high stress zones of the downhole subterranean formation can be changed. Furthermore, in relation to current practices, the methods can decrease the extent and/or degree of fracturing within low stress downhole formations and increase the degree of fracturing within high stress formations.

Abstract: A tool assembly for performing a wellbore operation including an actuatable tool, a location device, and on-board controller are together dimensioned and arranged to be deployed in the wellbore as an autonomous unit. The actuatable tool, such as a perforating gun having associated charges, perforates a wellbore along a selected zone of interest. The location device, such as casing collar locator, senses the location of the actuatable tool based on a physical signature provided along the wellbore. The on-board controller or micro-processor is configured to send an activation signal to the actuatable tool when the location device has recognized a selected location of the tool based on the physical signature. The tool assembly further includes a multi-gate safety system. The safety system prevents premature activation of the actuatable tool.

Abstract: According to the claimed method, fracturing fluid is injected into a well containing a plurality of perforated intervals to create, and facilitate the propagation of, a hydraulic fracture in at least one of the perforated intervals; then, the suspension containing insoluble degradable material, oppositely charged polyelectrolytes and/or their precursors is injected into the well; at the same time, a degradable viscous phase, non-miscible with fracturing fluid, is formed from the oppositely charged polyelectrolytes and/or their precursors; a degradable plug is formed in at least one of the perforated intervals, fracture, or wellbore; diversion of the fracturing fluid flow to the next perforated interval is provided with subsequent plug degradation in at least one of the perforated intervals, fracture, or wellbore within the required time.

Abstract: A subsea reservoir pressure maintenance system, including: a subsea chemical storage unit; a seawater intake and treatment system that takes in seawater and chemically treats the seawater with a chemical stored in the subsea storage unit, wherein a first subsea seal-less pump transfers the chemical from the subsea chemical storage unit to the seawater intake and treatment system; a second seal-less subsea pump that boosts pressure of the chemically treated seawater received from the seawater intake and treatment system; and a water injection manifold that receives the chemically treated seawater at the boosted pressure and injects the chemically treated seawater into a seabed.

Abstract: A drilling apparatus including plurality of subsystems, each subsystem includes a subsystem controller, one or more sensors, and one or more actuators. Each subsystem controller is configured to determine a local subsystem state from measurements received from the one or more sensors and further configured to receive global state estimates and updated control strategies. Each subsystem controller is configured to send command signals to one or more actuators based at least in part on the local subsystem state, global state estimates, and updated control strategy. A method and system for coordinating the control of a plurality of drilling subsystems during drilling operations is provided. A method of drilling subsystem controller decision-making based on a co-player inference playing strategy is further provided.

Abstract: A system and method for operating a mud motor in a wellbore. The method includes running the mud motor into the wellbore. A threshold rate of a pressure increase over time is selected. A rate of a pressure increase over time is measured across the mud motor in the wellbore. A flow rate of a fluid being pumped into the wellbore is varied when the measured rate is greater than or equal to the threshold rate.

Abstract: Fluids produced from a fractured subterranean formation may be monitored by pumping into the well a fracturing fluid which contains a tracer. The method may be used to monitor produced hydrocarbons as well as produced water. The tracer may also be used in a sand control, frac pack or acid fracturing operation. The tracer is a component of a composite where it may be immobilized within a matrix (such as an emulsion) or porous particulate, onto a support or compressed with a binder into a solid particulate. The tracer may be slowly released from the composite.

Abstract: Systems and methods are provided for determining a cure state of cement in a wellbore. A drill device can be used to drill cement in a wellbore. Contact between the drill device and the cement can cause friction or heat, which can produce a gas. A gas detector can be positioned near a wellbore for detecting an amount of gas and a type of gas produced by contact between the drill device and the cement in the wellbore. The cure state of cement in the wellbore can be determined based on the amount of gas and the type of gas detected.

Abstract: A system can include a current source electrically connected to casing in a wellbore, and a sensor including a monitoring electrode, a potential difference between the casing and the electrode resulting from current applied by the current source, and the potential difference indicating an impedance of a substance in an annulus external to the casing. A method can include positioning sensors spaced apart along a casing in a wellbore, each of the sensors including an electrode in electrical contact with a substance in an annulus, inducing current in the casing, and measuring a potential difference between the casing and the electrode at each sensor. Another system can include a current source, the current source being electrically connected to casing in a wellbore, and a sensor including a monitoring electrode and an electro-optical transducer that converts a potential difference between the casing and the electrode into strain in an optical waveguide.

Abstract: An assembly for use in subsurface drilling includes a downhole probe supported by a locking mechanism with a bore of a drill string section. The probe comprises a first spider and a second spider at the uphole and downhole sections of the probe. The locking mechanism secures the probes in the bore against axial and rotational movement relative the drill string section.

Abstract: A position determination system and a method for position detection within a wellbore are disclosed. A radioactive tag may be disposed within the wellbore. One or more scintillating optical fibers may be longitudinally disposed along a drill string, wireline, or the like, and run into the wellbore. A detector system is coupled to the optical fiber(s). A scintillating optical fiber emits short, bright flashes of visible light whenever exposed to the gamma radiation. When a scintillating flash is measured, it may be determined that the optical fiber is located within proximity to the radioactive tag. The amplitude of received pulses may be used to estimate where in the optical fiber scintillating events are occurring. By providing a second optical fiber coupled to a scintillating optical fiber, a time delay between received pulses may be used to indicate where along the scintillating optical fiber scintillation events are occurring.

Abstract: In one aspect, an electromagnetic (EM) telemetry device is disclosed including an EM telemetry circuit capable of transmitting a pulsed high power EM telemetry signal, wherein the high power EM telemetry signal has a peak or average pulse power of about 20 W to about 2000 W.

Abstract: An electromagnetic (EM) telemetry system with capacitive electrodes for use with downhole equipment is described. Embodiments of the EM telemetry system with capacitive electrodes include a downhole transceiver comprising an encoded signal transmitter, a downhole sensor disposed to monitor the downhole equipment, and an encoded signal receiver comprising one or more capacitive counter electrodes. The one or more capacitive counter electrodes receives a first encoded signal from the downhole transceiver, the encoded signal corresponding to a voltage measured between the counter electrode and a wellhead. A decoder and demodulator of the encoded signal receiver recovers information in the first encoded signal. A second encoded signal, which may include instructions for the downhole equipment, may be similarly encoded, modulated, and transmitted from the encoded signal receiver to the downhole transceiver.

Abstract: In a system (3) for the tracking of milling material (26), comprising a milling machine (1) for milling a section (28) of a ground pavement (29) in a milling operation, a truck (14) for loading and transporting away the milling material (26) removed during milling of the section (28) of the ground pavement (29), a deposition site (24) for depositing the milling material (26) transported away by the truck (14), a first detection device (18) for detecting data signals relating to the milling material (26), it is specified for the following features to be achieved: that a second detection device (20) detects position data of the deposition site of the milling material (26), wherein the first and the second detection device (18, 20) transmit the data signals (60) relating to the milling material (26) and the position data of the deposition site (24) to a documentation device (22) which links the position data with the data signals relating to the milling material (26).

Abstract: Rock bolts comprising an expandable tube having a longitudinally extending depression disposed between two curved outer portions of the tube, wherein the depression defines a channel having an opening defined between the two curved outer portions of the tube and the width of the opening is at least 10% of the width of the tube and/or a coating layer covers at least a portion of the expandable tube. Also, a method of manufacturing a rock bolt comprising forming an expandable tube comprising a longitudinally extending depression disposed between two curved outer portions of the tube, crimping a proximal end of the tube to form a crimped portion, and placing a sleeve around the crimped portion. Prior to crimping, a temporary spacer is placed in the channel in a portion of the tube adjacent to the portion of the tube that will be crimped.