Abstract: A method according to one or more aspects of the disclosure includes actuating a slip device to grip a tubular extending through a bore, the slip device has an upper set of slips spaced axially above a lower set of slips and the actuating includes radially moving in unison the upper and the lower sets of slips from an open position to an extended position gripping the tubular.

Abstract: An improved seal disposed at an interface of a main body of an inner drilling riser tie-back connector (ITBC) and a subsea wellhead is provided. The seal comprises a main body portion formed of a pair of opposed inwardly projecting fingers having a saw-cut profile at their ends and an outwardly projecting lever arm disposed adjacent to and at an outward angle to one of the opposed inwardly projecting fingers.

Abstract: A wellhead capable of steering fluid flow to minimize contact with equipment in the wellbore comprises a central bore and a plurality of side bores coupled to injection ports. The plurality of side bores comprise a rifled internal surface having a circular or helical configuration into which fluids can be injected. The side bores intersect with the central bore at a mixing chamber, which also comprises a rifled internal surface. By injecting fluids into the wellbore through these ports, the operator can create a vortex utilizing the full capacity of the wellhead while minimizing contact with any wireline equipment.

Abstract: There is provided a wellhead assembly that includes a production well, a first valve, process equipment, a transport pipe for transporting fluid away from the wellhead assembly, and piping fluidly connecting the production well to the first valve, the process equipment, and the transport pipe. The first valve is located between the production well and the process equipment, and there is a fall in the piping between the first valve and the transport pipe such that when the first valve is closed liquid will drain from the first valve into the transport pipe under the action of gravity. There is also provided a method of draining the wellhead assembly, an arrangement for depressurising the wellhead assembly using a service line and a method of depressurising the wellhead assembly.

Abstract: In one system, there is an emergency pipe stroker tool, wherein the emergency pipe stroker tool is configured to act as a first mechanical barrier for a well. Further, there is an emergency quick disconnect tool in communication with the emergency pipe stroker tool, wherein the emergency quick disconnect tool comprises a connector assembly and a fluid conduit in communication with the well, and further wherein the connector assembly is configured to simultaneously detach from the well and to seal the well. Further still, there is a cement retainer in communication with the emergency quick disconnect tool and the emergency pipe stroker tool, wherein the cement retainer is configured to act as a second mechanical barrier for the well, wherein, the emergency pipe stroker tool, the emergency quick disconnect tool, and the cement retainer act in coordination to seal a well while establishing the multiple mechanical barriers.

Abstract: A first aspect of the invention provides a gas or oil well tubing having an annular packer mounted thereon, wherein the annular packer is formed from an eutectic alloy. By prefabricating the annular packer on the tubing it can be placed in situ from the outset and thus can be active by melting at any time to form a eutectic seal quickly and easily. An annular packer with by-pass conduits is also provided to enable cement to be pumped past the annular packer when it is in situ. The annular packer is further provided with conduit clearance means to clear cement from within the conduits.

Abstract: A plug is provided that includes a mandrel, a sealing element, a slip and ramp assembly, a lock ring, at least one antirotation device, and a lower ball standoff. The slip and ramp assembly have linear and radial angles allowing a mandrel wall that is thin when compared to the overall diameter of the mandrel. The sealing element is configured so that when set additional pressure from the surface increases the sealing ability of the sealing element. Antirotation devices are provided to assist in mill out. Lock ring is provided to keep the slips in their set position and a further configured so that additional downward forces increase the locking ability of lock ring. A lower ball standoff is provided so that in the event of reverse flow a ball from below is prevented from lodging within the plug and is held at the lower end of the plug were standoffs are provided to allow fluid flow around the ball.

Abstract: This invention relates to a sealing apparatus, system and method for use in a well pipe. The apparatus has a mandrel arranged around a centre axis through the apparatus, a radially movable gripping device arranged around the mandrel, a radially movable packer element arranged around the mandrel, and an axially movable activation device designed to set up axial forces for activating the apparatus. The apparatus also includes a radially movable centralizer arranged around the mandrel for centring the apparatus. The activation device being operatively connected to the gripping device, the packer element and the centralizer for the respective activation and radial movement of each, via power transmission of axial forces, between retracted, passive positions and expanded, active positions relative to the centre axis of the apparatus.

Abstract: A degradable downhole isolation tool for use in hydrocarbon well completion. The tool sets and isolates zones for fracking, and then degrades without leaving residual parts and without milling or introducing a new degrading fluid. The plug's mandrel and other parts are a solid polymer which hydrolyzes in aqueous downhole fluid to produce an acid which degrades degradable metal slips and other metal parts. The plug's seal may be degradable metal pedals or split rings. The plug is delivered to the well site as an interchangeable parts kit for adaption to the well's requirements.

Abstract: Methods for treating and restoring zonal isolation in a subterranean well involve the use of a well treatment tool that may drill one or more holes in casing and inject a treatment fluid that may seal cracks or fissures in the cement sheath behind the casing. Microannuli may also be sealed. The treatment fluids may be solids free or in the form of suspensions containing solids having a particle size between 1 nm and 100 nm.

Abstract: The present invention relates to a downhole valve system (1) for controlling inflow of a fluid from and to a formation (100), comprising a casing (2) having an inner surface (3), an outer diameter (ODc) and an inner diameter (IDc), and a cross section (Ac) defined by the inner diameter, the casing comprising a plurality of valves (4, 4a, 4b, 4c)arranged spaced apart from each other for controlling the flow of the fluid to and from the formation through the casing, and a plurality of autonomous operating adjusting devices (5) each controlling one of the plurality of valves and each autonomous operating adjusting device comprising a body (6) having an outer body diameter (Db) and a body cross section (Ab), the plurality of autonomous operating adjusting devices being fastened inside the casing in order to allow the fluid to flow between the outer body diameter of the body of the autonomous operating adjusting device and the casing.

Abstract: A fluid flow control device serving as an inflow port from a fluid reservoir (R) to the interior of a production pipe (S) is in the form of a housing (3b, 3c, 3d, 3e, 3f, 3g, 3h, 3i, 3j, 3k, 3l). The housing has a primary flow path (18) and a secondary flow path (19). The secondary flow path is in fluid communication with a chamber (B) in which is arranged an actuator (5) for a valve device (4), the valve device arranged to open and close the primary flow path. At least one flow restrictor (1,2) is arranged in the secondary flow path, the flow restrictor arranged to provide a pressure to chamber (B) sufficient to actuate the valve to an open position when the fluid flowing through the secondary flow path is oil, and a pressure sufficient to actuate the valve to a closed position when the fluid has a viscosity and/or density less than oil.

Abstract: A multiplier sleeve has a releasable seat coupled to a dog within the slidable sleeve allows a single sized ball, dart, or plug to actuate several sliding sleeves. Upon actuation by properly sized ball the ball, slidable sleeve, seat, and dog move downward where the dog is no longer supported allowing the seat to move within the slidable sleeve to a point where the seat is no longer supported thereby releasing the ball. With the slidable sleeve moved downward the port or ports in the sliding sleeve is exposed. A staged port and piston assembly inserted into the ports maintain pressure within the tubular assembly to allow the ball to move through and actuate the targeted sliding sleeves.

Abstract: A frac plug for use in a plug and perf arrangement to within a wellbore. The frac plug includes a central mandrel and locking portion which can be set within the wellbore. A bypass port is disposed through the central mandrel and is unblocked to fluid flow during setting of the plug assembly. Thereafter, the central mandrel is axially shifted within the set locking portion to block fluid communication across the frac plug.

Abstract: A rotating ball valve assembly includes a rotatable ball element. The rotatable ball element includes a first side portion, a second side portion, and a central passage. One of the first and second side portions includes first and second outwardly projecting pin elements. A sliding sleeve assembly includes a sliding sleeve member having a first guide track with a first force reducing profile associated with the first outwardly projecting pin element and a second guide track having a second force reducing profile associated with the second outwardly projecting pin element. The sliding sleeve member is shiftable relative to the first and second tubular members to selectively pivot the rotatable ball element between an open orientation and a closed orientation.

Abstract: The present disclosure relates to a sleeve fracturing assembly including a composite sleeve and an opening tool. The composite sleeve and the opening tool can automatically engage with each other via teeth-shaped members arranged thereon so as to open the composite sleeve. The present disclosure further relates to a sleeve fracturing device, which includes a plurality of composite sleeves and opening tools, wherein each composite sleeve and opening tool can achieve unique engagement. The present disclosure still further relates to a method of using the sleeve fracturing device.

Abstract: A device for removing and preventing paraffin by using electric heating generated from skin effect-based natural gas electricity and an application thereof are disclosed, and the device comprises a natural gas collection portion, a natural gas electricity generation portion and a device for removing and preventing paraffin by using electric heating powered by the natural gas electricity generation portion; the natural gas collection portion is used to collect and separate natural gases discharged from a wellbore; the natural gas electricity generation portion generates electricity with natural gases. The power source required by the electric heating of the steel armored cable of the present invention comes from the natural gas electricity generation portion, and the air source required by the natural gas electricity generation portion can be obtained directly from the associated gases extracted from an oil well.

Abstract: A well system includes a work string extendable into a wellbore, and a pump that pumps a fluid into an annulus defined between the work string and the wellbore. A flow-activated motor is coupled to the work string and has a housing that receives the fluid pumped into the annulus. The flow-activated motor further includes a driveshaft rotatably positioned within the housing and a plurality of rotor vanes coupled to the driveshaft, wherein the driveshaft rotates as the fluid flows through the housing and impinges on the plurality of rotor vanes. A rotating agitator tool is coupled to the driveshaft such that rotation of the driveshaft correspondingly rotates the rotating agitator tool. The rotating agitator tool engages and loosens debris in the wellbore while rotating, and the debris is entrained in the fluid and flows through the flow-activated motor and subsequently to a surface location for processing.

Abstract: A completion system and method for intelligent control of multilateral wells. A completion deflector defines a hollow interior that is fluidly coupled with a uphole tubing and downhole main completion strings. Hydraulic, electric, and/or fiber-optic communication line segments extend between the uphole end and downhole end of the completion deflector for providing power, control or communications between the surface and production zones associated with the main wellbore. The communication line segments are located outside the completion deflector interior and may be located within longitudinal grooves formed along the exterior wall surface of the completion deflector. A self-guided, wet-matable connector is provided at the uphole end, which connects the both interior flow path and communication lines, and which may allow connection at any relative radial orientation. The uphole end of the completion deflector has an inclined upper surface for deflecting various tools and strings into a lateral wellbore.

Abstract: A casing deployment apparatus includes a processing resource with a signal pattern recognition engine unit (420), a tubular measurement unit (404) and a decision unit (416). A first sensor input (402) and a second sensor input (406) are attached to the pattern recognition unit (420) and receive first sensor data and second sensor data corresponding to first and second time-varying sensor signals. The pattern recognition unit (420) analyzes a characteristic of the first sensor data to determine whether the characteristic is substantially consistent with a first expected characteristic of the first sensor data associated with deployment of casing in a borehole. The tubular measurement unit (404) analyzes a characteristic of the second sensor data in order to determine whether the characteristic is substantially consistent with a second expected characteristic of the second sensor data associated with the deployment of the casing.

Abstract: A drilling module is for radial drilling in a well and an anchoring module is for use in a well tool. The drilling module has a piston for receiving a drill for the radial drilling, and for displacing the drill in a radial direction towards a wall of the well and a cylinder for receiving and guiding the piston. Both the piston and the cylinder are guide-free and of a non-circular shape, at least in a portion, to prevent relative rotation between them. The anchoring module has an extent in the axial direction of the well. The anchoring module includes a displacement device arranged to push against a portion of the wall of the well to press the anchoring module against an opposite portion of the wall of the well. The displacement device is oblong in the axial direction of the anchoring module.

Abstract: A method and system for treating a wellbore, where an additive casting having energetic material and a treatment substance is deployed downhole, and then the energetic material is reacted so that it releases the treatment substance into the wellbore. A perforating system is used to initiate the reaction of the energetic material. An example of the energetic material includes a propellant that generates gases which urge the treatment substance into openings in sidewalls of the wellbore, such as perforations or fractures. One embodiment of the treatment substance includes a crystalline anhydrous acid.

Abstract: A variable frequency drive system and a method of controlling a pump driven by a motor with the pump in fluid communication with a fluid system is provided. The method includes monitoring a pressure in the fluid system, monitoring and adjusting an operating frequency of the motor to maintain the pressure at a pressure set point, and, based on the monitored operating frequency, causing the pump to temporarily boost the pressure in the fluid system to a temporary boost set point for a first time period. The method also includes determining whether the temporarily boosted pressure in the fluid system stays above the pressure set point for a second time period and causing the pump to enter a sleep mode when the temporarily boosted pressure stays above the pressure set point through the second time period.

Abstract: An exemplary method of controlling an artificial lift system may include monitoring, via a downhole phase change sensor, for an indication of steam breakthrough, determining the occurrence of a steam breakthrough event based on the indication of steam breakthrough, and adjusting one or more parameters of the artificial lift system based on the determination. One example system for controlling an artificial lift system may include a downhole phase change sensor configured to monitor for an indication of steam breakthrough and a processing system configured to determine the occurrence of a steam breakthrough event based on the indication of steam breakthrough and adjust one or more parameters of the artificial lift system based on the determination.

Abstract: Industrial machines and methods of operating the same. One method includes receiving, with an electronic processor, a current value of a parameter of an industrial machine during operation of the industrial machine and comparing, with the electronic processor, the current value of the parameter to a stored value of the parameter to determine whether the industrial machine is unlevel. The method also includes, when the industrial machine is unlevel, autonomously, with the electronic processor, changing a position of at least one of a plurality of jacks to level the industrial machine, wherein autonomously changing the position of at least one of the plurality of jacks includes at least one selected from a group consisting of extending the at least one of the plurality of jacks and retracting the at least one of the plurality of jacks.

Abstract: Systems, apparatus and methods are described for purposes of initiating a response to detection of an adverse operational condition involving a system including a drill rig and an inground tool. The response can be based on an uphole sensed parameter in combination with a downhole sensed parameter. The adverse operational condition can involve cross-bore detection, frac-out detection, excessive downhole pressure, a plugged jet indication and drill string key-holing detection. A communication system includes an inground communication link that allows bidirectional communication between a walkover detector and the drill rig via the inground tool. Monitoring of inground tool depth and/or lateral movement can be performed using techniques that approach integrated values. Bit force based auto-carving is described in the context of an automated procedure.

Abstract: Provided in some embodiments are systems and methods for transient-pressure test of an oil reservoir water injection well system. Embodiments provide for determining a fracturing injection rate for the well, setting a test injection rate preferably below the fracturing injection rate, conducting a stabilized injection of water into a wellbore of the well at the test injection rate for a prescribed period, and conducting a fall-off test including shutting-in the well for a prescribed fall-off period, and acquiring test data indicative of fluid pressure in the wellbore of the well during the injection and the fall-off periods. Embodiments also provide for generating a model prediction, comparing the model to the test data to determine whether it is a match for the well, and associating the parameter values with the well, including the severity and the location of the shallow damage, if the reservoir model is a match.

Abstract: A system may include a downhole tool conveyable into a wellbore on a conveyance, and a plurality of sensing devices positioned at a distal end of the downhole tool to emit wave energy in an axial direction within the wellbore. At least a portion of the wave energy are reflected by one or more wellbore hazards and received by the plurality of sensing devices. The system further includes a data acquisition system communicatively coupled to the downhole tool to receive and process reflected wave energy and thereby identify the one or more wellbore hazards.

Abstract: An assembly for receiving telemetry signals from downhole equipment is located at a top end of a drill string above a drill rig floor. The assembly may be configured to receive multiple types of telemetry signals, for example, two or more of electromagnetic telemetry, mud pulse telemetry and drill string acoustic telemetry signals. The assembly may comprise a cap comprising a coupling and an end separated by an electrically-insulating gap region. The end of the cap may be connected to a grounding system for the drill rig.

Abstract: Systems, methods, and computer-readable media for channel estimation in mud pulse telemetry based on a preamble waveform. A system located at a first location of a wellbore can receive, from a second device located at a second location of the wellbore, a signal including a Golay preamble waveform and data symbols. The Golay preamble waveform can be based on Golay complementary codes. Based on a measurement associated with the signal, the system can then detect the Golay preamble waveform in the signal. Next, the system can estimate a characteristic of a communication channel between the first location and the second location based on the detected Golay preamble waveform.

Abstract: Systems and methods for digital signal processing are provided. A method includes mapping a symbol in a pulse sequence by using a pulse width and a pulse start in the symbol, reading a message using a symbol value for each symbol in a string of symbols, and modifying a drilling configuration according to the message. A device configured to perform the above method is also provided.

Abstract: Disclosed herein are systems and methods for determining properties of subsurface formations, such as for oilfield applications. The methods can comprise calculating a Gibbs free energy of the subsurface formation using a parameter of the subsurface formation. The methods can further comprise determining the property of the subsurface formation using the Gibbs free energy of the subsurface formation. The methods can, in some examples, further comprise selecting an enhanced oil recovery technique for the subsurface formation based on the calculated property of the subsurface formation. In some examples, the enhanced oil recovery technique can comprise low salinity water injection.

Abstract: A system for increasing the detecting degradation of a wellbore. The system comprises a computer memory configured for storing computing instructions and a processor operably coupled to the computer memory. The system comprises a sensor operably coupled to the computer memory and is configured to determine the presence of at least one chemical species indicative of degradation of the wellbore in a fluid exiting the wellbore. Methods of monitoring a wellbore for corrosion or other degradation of one or more components of wellbore equipment are disclosed as are methods of increasing the lifetime of a wellbore.

Abstract: A pick assembly comprising a holder body, a strike body, a base body attachable to a drive mechanism, and an interference assembly comprising at least one interference member. The holder body comprises a head portion and a shaft depending from the head portion. The strike body comprises a super-hard strike tip. The head portion and the strike body are cooperatively configured such that the strike body can be attached to the head portion, the strike tip being exposed for striking a body to be degraded when in use. The base body comprises a base bore. The base bore, shaft and interference assembly are cooperatively configured such that the shaft can be secured within the base bore, the interference member disposed between the shaft and the bore. Frictional interference between the shaft, interference assembly and base bore is sufficient to prevent rotation of the shaft within the base bore in use.

Abstract: A system and methods are disclosed for providing the location of a tunnel boring machine (TBM) by establishing of a plurality of known locations or “monuments”; from these monuments located at least on, over or within the TBM's start point, known in the art as a “pit”. The present invention provides among other things an integrated navigation system that provides real-time parametric guidance information to the TBM, relative to the tunnel origin, past course and current trajectory, while simultaneously employing a non-contact measuring system in concert with said origin and course information for the final provision of an as-built map of tunnel dimensions and centerline.

Abstract: The purpose of the present invention is to provide a scroll fluid machine, the reliability of which is ensured and which can be manufactured with high productivity. The present invention provides a scroll fluid machine comprising: a stationary scroll having a spiral wrap upstanding therefrom; an orbiting scroll provided facing the stationary scroll and orbiting; a casing provided outside the orbiting scroll; a drive shaft for causing the orbiting scroll to orbit; an orbiting bearing for transmitting the rotational movement of the drive shaft to the orbiting scroll; and a plurality of rotation prevention mechanisms for preventing the orbiting scroll from rotating. The scroll fluid machine is characterized in that: the rotation prevention mechanisms have crankshafts and also have crank bearings for supporting the crankshafts; and the gap between each of the crankshafts and the corresponding one of the crank bearings is set to be greater than the gap between the drive shaft and the orbiting bearing.

Abstract: A steam turbine having a cooling option, in which steam is taken from the flow channel, the steam cooling the thrust-compensating intermediate floor, being mixed with a small amount of live steam and being returned to the flow channel. A method cools the steam turbine, wherein steam is extracted from the high-pressure region and is fed to a space between the thrust-compensating partition wall and inner casing, wherein steam from the space between the thrust-compensating partition wall and the inner casing is fed via a first cross feedback passage to the high-pressure region.

Abstract: The present disclosure is directed to an improved system and method for repairing a bend in a turbine blade of a turbine of a gas turbine engine. The system includes an articulating guide configured to fit into an access port of the turbine. The articulating guide includes a proximal end and a distal end. The system also includes a repair tool configured at the distal end of the articulating guide. Further, the repair tool is configured to fit over the turbine blade. Thus, the repair tool is configured to bend the turbine blade to an unbent position while the turbine blade is secured within the turbine.

Abstract: A damper seat for a ring damper that redirects axial loads and is disposed within a gas turbine engine with at least one disk rotatable about a rotational axis and having a disk neutral axis extending radially from the rotational axis.

Abstract: A component stage for a turbomachine includes a component section. The component section includes a flowpath surface at least partially exposed to a core air flowpath defined by the turbomachine, when the component stage is installed in the turbomachine. The component further includes a plurality of sequentially arranged riblets on the flowpath surface, the plurality of sequentially arranged riblets customized for an anticipated location of the flowpath surface within the turbomachine by defining one or both of a non-uniform geometry or a non-uniform spacing.

Abstract: An axial-direction passage, a forced vortex passage, a first blade array passage, and a second blade array passage are formed in a rotor shaft of a turbine. Cooling air from an air extraction port of a compressor flows through the axial-direction passage which extends in an axial direction. The forced vortex passage is connected to the axial-direction passage and extends outwards in the radial direction relative to an axial line from a connecting portion between the forced vortex passage and the axial-direction passage. The first blade array passage is connected to an end portion on the outer side in the radial direction of the forced vortex passage and guides cooling air to a first blade row among a plurality of blade rows. The second blade array passage is connected to an end portion of the forced vortex passage and guides cooling air to a second blade row.

Abstract: A turbine blade with an internally cooled turbine blade airfoil, in which a hollow space is divided by rib elements in at least one cooling channel carrying a coolant, wherein a recess of material, which is arranged next to at least one rib element on a turbine blade airfoil wall, is embodied such that tensions occurring within the turbine blade airfoil can be reduced in a region surrounding the at least one rib element.

Abstract: An apparatus and method for an airfoil for a gas turbine engine includes a trailing edge cooling circuit utilizing a plurality of trailing edge ejection holes. The ejection holes can include a circumferentially radiused inlet, a converging section, a metering section, and a diverging section to improve airfoil cooling as well as castability.

Abstract: A turbine airfoil for a gas turbine engine includes a pressure sidewall extending along a spanwise direction, and from a leading edge of the airfoil towards the trailing edge of the airfoil. The turbine airfoil additionally includes a suction sidewall also extending along the spanwise direction, and from the leading edge towards the trailing edge. The pressure sidewall and suction sidewall define a cooling air cavity therebetween, and one or both of the pressure sidewall and suction sidewall define a trailing edge cooling channel extending from the cooling air cavity substantially to the trailing edge. Additionally, one or both of the pressure sidewall and suction sidewall include a plurality of pressure drop members extending partially into the trailing edge cooling channel for reducing an amount of cooling air flowing therethrough from the cooling air cavity.

Abstract: An apparatus for an impingement hole for an engine component of a gas turbine engine includes an impingement baffle. The impingement baffle is spaced from an impingement surface and includes a plurality of impingement holes for providing an impingement flow to the impingement surface. The impingement holes can have an angled upstream edge such that an inlet has a greater cross-sectional area than an outlet. The walls of the impingement holes can have a hood to provide a higher shear flow content to minimize dust accumulation on the impingement surface.

Abstract: A method and apparatus for an airfoil in a gas turbine engine can include an outer surface bounding an interior. At least one flow channel can be defined among one or more full-length and partial-length ribs to further define a cooling circuit within the airfoil. The cooling circuit can have at least one tip turn at the partial-length rib, having at least on fastback turbulator disposed at least partially within the tip turn.

Abstract: An airfoil for a turbine engine having first and second radially extending cooling chambers separated by a radially extending rib in which rows of crossover holes pass through the rib and fluidly coupling the first and second chambers.

Abstract: The present disclosure is directed to a rotor blade for a gas turbine engine. The rotor blade includes a platform having a radially inner surface and a radially outer surface. A connection portion extends radially inwardly from the radially inner surface of the platform. An airfoil extends radially outwardly from the radially outer surface of the platform to an airfoil tip. The airfoil includes a leading edge portion and a trailing edge portion. The platform, the airfoil, and the connection portion collectively define a cooling circuit extending from an inlet defined by the connection portion to one or more outlet passages at least partially defined by the trailing edge portion of the airfoil. At least one of the one or more outlet passages include an entrance and an exit radially inwardly offset from the entrance.

Abstract: A flowpath component for a gas turbine engine includes a first platform including a vascular engineered lattice structure, a body extending from, and supported by the first platform. The body is configured to at least partially span a flowpath in an installed position and the vascular engineered lattice structure including at least one purge air inlet, and at least one spent air outlet.

Abstract: A turbine assembly with a hollow aerofoil having a main cavity with an impingement tube, insertable inside the main cavity for impingement cooling of an inner surface of the main cavity, and a platform at a radial end of the hollow aerofoil, and a cooling chamber for cooling the platform arranged relative to the hollow aerofoil on an opposed site of the platform. The cooling chamber is limited at a first radial end by a wall segment of the platform and at an opposed radial second end from a cover plate. The impingement tube extends in span wise direction through the cooling chamber from the platform to the cover plate and restricts a sub-cavity of the main cavity. The wall segment includes an entry aperture for a cooling medium to enter from the cooling chamber of the platform into the sub-cavity of the hollow aerofoil.