Patent Application
20250154847
The present invention relates to a rotating control device retaining mechanism for use in the oil and gas industry, more specifically used in managed pressure drilling operations.
When drilling for oil and gas, one encounters geological formations that have a narrower tolerance for changes in bottom hole pressure. Constant improvements are being sought to reduce any downtime of equipment and expedite any repairs that become necessary. A widely adopted solution to this problem is the so called ‘Managed Pressure Drilling’ (MPD). In this method of drilling, the annular space is closed to the atmosphere by means of a Rotating Control Device (RCD). Rotating equipment requires maintenance as the drilling environment produces forces, elevated temperatures and abrasive cuttings detrimental to the longevity of seals, bearings, and packing elements. An RCD is a pressure-control device used during drilling for the purpose of making a seal around the drillstring during its rotation and/or tripping in and out of a well. The RCD is designed to contain or divert hydrocarbons or other wellbore fluids and pressure and prevent their release to the atmosphere. The RCD diverts the fluid into a manifold equipped with a specialized choke that allows manipulation of the well's bottom hole pressure. Right before breaking a connection to add a new stand, the pumps are ramped down. At the same time, the dynamic component of the bottom hole pressure drops and needs to be compensated for, in order to maintain a near-constant bottom hole pressure.
In the oil and gas industry, it is paramount to ensure the safety of employees, a problem that may jeopardize employees' safety on a drilling rig is known as a “blowout”. When a zone of high geopressure is encountered during a drilling operation and the pressure exceeds the hydrostatic pressure exerted by the drilling mud, and the formation has sufficient permeability to allow fluid flow, then the formation fluid will move into the wellbore and displace the drilling mud. This is referred to as a “kick”; and if unchecked it will result in a “blowout” which is an uncontrolled release of crude oil and/or natural gas from an oil well Through the use of an MPD system which includes an RCD a kick can be safely controlled.
During drilling operations, the drill pipe or tubular is axially and slidably moved through the rotating control head. The axial movement of the drill pipe along with other forces experienced in the drilling operation, some of which are discussed below, causes wear and tear on the bearing and seal assembly and the assembly subsequently requires repair. Typically, the drill pipe or a portion thereof is pulled from the well and the bearing and seal assembly in the rotating control head is then released.
The internal sealing elements may be either passive or active. Passive sealing elements, such as stripper rubber sealing elements, can be fabricated with a desired stretch-fit. On the other hand, an active sealing element typically requires a remote-to-the-tool source of hydraulic or other energy to open or close the sealing element around the outside diameter of the tubular. An active sealing element can be deactivated to reduce or eliminate the sealing forces of the sealing element with the tubular. Several types of RCDs have been proposed with combinations of active and passive seals or sealing element, usually combining a stripper rubber sealing element and an active sealing element.
A tubular typically comprises sections with varying outer surface diameters. The passive and active sealing elements mentioned above must be designed to adapt to seal around all of the rough and irregular surfaces of the components of the tubular, drill pipe, tool joints, and drill collars.
The continuous movement of the tubular through the sealing element while the sealing element is under pressure causes wear of the interior sealing surface of the sealing element. When drilling with a dual annular sealing element RCD, the lower of the two sealing elements is typically exposed to the majority of the pressurized fluid and cuttings returning from the wellbore, which communicate with the lower surface of the lower sealing element body. The upper sealing element is exposed to the fluid that is not blocked by the lower sealing element. When the lower sealing element blocks all of the pressurized fluid, the lower sealing element is exposed to a significant pressure differential across its body since its upper surface is essentially at atmospheric pressure when used on land or atop a riser. The highest demand on the RCD sealing elements occurs when tripping the tubular out of the wellbore under high pressure.
Several components are used to control the fluid pressure. Typically, one or more blowout preventers (BOP) are mounted with the well forming a BOP stack to seal the well. In particular, an annular BOP is used to selectively seal the lower portions of the well from a tubular that allows the discharge of mud. In many instances, a conventional rotating control head is mounted above the BOP stack. An inner portion or member of the conventional rotating control head is designed to seal and rotate with the drill pipe. The inner portion or member typically includes at least one internal sealing element mounted with a plurality of bearings in the rotating control head.
The thrust generated by the wellbore fluid pressure, the radial forces on the bearing assembly and other forces cause a substantial amount of heat to build in the conventional rotating control head. The heat causes the seals and bearings to wear and subsequently require repair. The conventional rotating control head typically includes a cooling system that circulates fluid through the seals and bearings to remove the heat.
EP patent application 2 295 712 A2 teaches a rotating control apparatus, comprising: an outer member; an inner member having a first sealing element and a second sealing element; said inner member, said first sealing element and said second sealing element rotatable relative to said outer member; a first cavity defined by said inner member, said first sealing element and said second sealing element; and said inner member having a port to said first cavity. The first sealing element being inflatable to adopt the configuration of the drill string during operations and deflatable to allow the drill string to pass through the RCD when tripping in or out of the wellbore.
Canadian patent application CA 3,111,310 discloses a rotating control apparatus, comprising: —an outer member (RCD bowl); and—an inner member (bearing assembly housing); said outer member comprising: —a top surface defining an aperture adapted to accommodate the insertion and removal of the inner member; —an inner circular surface defining a cavity; —a side wall; —an outer casing; —a bottom surface adapted for connection with a mud cross; —at least two sealing members capable of moving between a closed position and an open position, where the at least two sealing members are adapted to sealingly engage and lock said inner member inserted inside said cavity when in a closed position and allowing said inner member to be inserted therethrough or removed from the inner member when the at least two sealing members are in the open position; said inner member comprising: —a first sealing element and a second sealing element adapted to sealingly abut against said inner surface of said outer member; said inner member, first sealing element and second sealing element being rotatable relative to said outer member.
A later filed application which led to U.S. Pat. No. 11,753,895 B2 discloses a multipurpose latch assembly (MPLA) for installation above the bore of a blowout preventer includes an annular sidewall extending between a top flange and a bottom flange and having an interior bore surface defining an interior bore. It states that a plurality of latching slots extend through the sidewall and a latching dog is slidably positioned in each latching slot. Actuators are connected to the latching dogs to extend and retract them through the latching slots.
Despite the existing prior art, there still exists a need for a robust retaining mechanism for RCDs which when in operation allows for quick and secure installation and removal of RCD sealing assemblies and accessories. Preferably, the proposed RCD retaining mechanism should also be operable and able to determine positional status remotely to improve operational productivity and increase the personnel's safety around the wellbore.
Accordingly, there is provided an RCD system comprising a retaining mechanism which allows for quick and secure installation and removal of RCD sealing assemblies and accessories into and from an RCD housing.
According to an aspect of the present invention, there is provided a rotating control device (RCD) assembly comprising a retaining system, comprising:
According to a preferred embodiment of the present invention, the bottom surface of the inner member abuts with the tapered landing profile of the outer member to establish said penultimate installation position, wherein said tapered landing feature providing an installation margin or window, negating the effect of an accumulation of material. Preferably, said tapered landing profile is also radiused.
According to a preferred embodiment of the present invention, each one of said at least two retaining members being actuated by a piston adapted to move the retaining member from the open position to the closed position. According to a preferred embodiment of the present invention, the retaining member assembly (ram block cylinder assembly) comprises: a cylinder housing, and a piston-rod arrangement.
According to a preferred embodiment of the present invention, cylinder housing comprises the means to move the retaining member (ram block) from a first position where the retaining member (ram block) is fully retracted within the outer member of the rotating control apparatus and a second position where the retaining member (ram block) is extended to a closed position into said main cavity.
According to a preferred embodiment of the present invention, when each one of said at least two retaining members is moved from said open position to said closed position, the top surface of the retaining member having a downward and inward tapered edge abuts on the upward and outward tapered edge of the circumferential slot of the inner member, causing the inner member to be driven axially upward to its final retained position.
According to a preferred embodiment of the present invention, when said at least two retaining members are in the closed position they effect a complete circular abutment with the cylindrical center section of the circumferential slot of the inner member.
According to a preferred embodiment of the present invention, when said at least two retaining members are in the closed position they affix the inner member in place and prevent any axial movement of said inner member within the primary cavity.
According to a preferred embodiment of the present invention, when said at least two retaining members are in the closed position, radial force is maintained to the inner member to restrict rotational movement of the inner member in relation to the outer member by frictional contact between the inner surface of said at least two retaining members and the cylindrical surface of the circumferential slot of the inner member.
According to a preferred embodiment of the present invention, when said at least two retaining members are in the closed position, radial force is maintained to the inner member to restrict rotational movement of the inner member in relation to the outer member by frictional contact between said retaining member top surface having a downward and inward tapered edge and the upward and outward angled upper face of the circumferential slot of the inner member and the retaining member bottom surface optionally, having an upward and inward tapered edge and the optionally downward and outward angled lower face of the inner member.
According to a preferred embodiment of the present invention, each one of said plurality of ram blocks are in the closed position in the absence of said inner member (i.e. with no inner member installed), each one of said at least two retaining members are mechanically interlocked with an adjacent retaining member to form a complete circular aperture which has a diameter smaller than the seal receiving diameters (said second diameter) of the outer member to protect these surfaces from contact by objects moving axially through the primary cavity of the outer member.
According to a preferred embodiment of the present invention, the piston/rod arrangement extends both inwardly and outwardly from the ram block cylinder assembly. Preferably, the cylinder housing includes an integral cavity adapted to accept a cartridge valve with load holding/locking functionality.
According to a preferred embodiment of the present invention, the means to move said retaining member are selected from the group consisting of devices adapted to impart linear movement comprising one or more of the following means of actuation: air-actuated; hydraulic; electrical; a wormgear or any other actuator adapted for this purpose.
According to a preferred embodiment of the present invention, the retaining member comprises a body and a concave front surface adapted to abut against the cylindrical surface of an inner member circumferential slot when in the closed position.
According to a preferred embodiment of the present invention, the ram block further comprises two side surfaces each of which having a protrusion and a cavity adapted for interlocking into a corresponding cavity and a corresponding protrusion of an adjacent retaining member.
According to a preferred embodiment of the present invention, the body of said retaining member comprises two opposite sides, a top, a bottom, and a seal which surrounds the retaining member body to provide a sealing engagement with an outer member secondary cavity to prevent fluid and solids migration between the wellbore and the cylinder chamber.
According to a preferred embodiment of the present invention, each one of said at least two retaining members further comprise a seal on said concave front surface.
According to another aspect of the present invention, there is provided a process of securing a sealing assembly or accessory inside a rotating control device assembly, said method comprising the steps of:
According to a preferred embodiment of the present invention, the circumferential slot, located above said bottom edge, comprising: a cylindrical center section does not comprise an upward and outward angled upper face adapted to abut with said retaining members when said at least two retaining members are moved from said open position to said closed position, but rather a straight edge preferably radiused, which is intended on abutting the top edge of the retaining member (ram block) and allowing the latter to lift the inner member to the final retained position. The upper face in the above embodiment may be less ideal but would be expected to work sufficiently well to achieve the purpose required from it.
Preferably, said cylindrical center section comprises a mid-point which, upon insertion of said inner member and abutment onto said tapered landing profile of said outer member, will be located in a position under a mid-point defined by said inner surface of said retaining member; and wherein, upon said retaining member being in a closed position and abutting against said cylindrical center section of said circumferential groove, said mid-point of said inner surface of said retaining member and said midpoint of said cylindrical center section of said circumferential groove will be in alignment.
According to another aspect of the present invention, there is provided a method of securing a sealing assembly or accessory inside a rotating control device apparatus, said method comprising the steps of
According to a preferred embodiment of the present invention, the bottom surface of the inner member engages with the tapered landing feature of the outer member to establish the penultimate installation position.
According to a preferred embodiment of the present invention, said tapered landing feature may also be tapered and radiused. Said tapered landing profile being to provide an installation margin or window, which would overcome the inevitable accumulation (i.e. build up) of material or debris which would, in turn, prevent proper alignment of the ram block with the circumferential slot on the inner member. In such a case, the ram blocks would be unable to properly close and would leave the inner member largely unsecured and prone to breaking or damage or simply be unable to perform the desired operation, negating the effect of a buildup of solid material.
According to a preferred embodiment of the present invention, each one of the plurality of ram blocks is actuated by a piston adapted to move the ram block from the open position to the closed position.
According to a preferred embodiment of the present invention, when each one of the plurality of ram blocks is moved from the open position to the closed position, the top surface of the ram block having an inward and downward tapered edge abuts on the outward and upward angled edge of the circumferential slot of the inner member, causing the inner member to be driven axially upward to its final sealing and retaining position.
According to a preferred embodiment of the present invention, when the at least two retaining members are in the closed position they effect a complete abutment with the cylindrical center section of the circumferential slot of the inner member. Preferably, when the at least two retaining members are in the closed position they lock the inner member in place and prevent any longitudinal movement from said inner member within the cavity.
According to a preferred embodiment of the present invention, when each one of the plurality of ram blocks are in the closed position, radial force is maintained to restrict rotational movement of the inner member in relation to the outer member by friction between the inner surface of the ram block and the cylindrical surface of the circumferential slot of the inner member.
According to a preferred embodiment of the present invention, when each one of the plurality of retaining members (ram blocks) are in the closed position with no inner member installed, the plurality of ram blocks are mechanically interlocked with each other to form a complete circular aperture which has a diameter smaller than the seal receiving diameters of the outer member to protect these surfaces from contact by objects moving axially through the central bore of the outer member which would normally be accomplished by the use of a bore protector, sleeve, or other means of protection.
According to a preferred embodiment of the present invention, the ram block cylinder assembly comprises the ram block, cylinder housing, and piston/rod assembly.
According to a preferred embodiment of the present invention, the ram block cylinder assembly comprises the ram block, cylinder housing, and integral piston/rod assembly.
According to a preferred embodiment of the present invention, said piston/rod assembly extends both inwardly and outwardly from the ram block cylinder assembly. The outward extension serves as a means to detect the open or closed position of the ram block cylinder assembly. The inward extension serves as a means of attachment of the ram block.
According to a preferred embodiment of the present invention, the cylinder housing comprises the means to move the ram block from a first position where the ram block is fully retracted within the outer member of the rotating control apparatus and a second position where the ram block is extended into the aperture defined in the outer member.
According to a preferred embodiment of the present invention, the cylinder housing includes an integral cavity adapted to accept a cartridge valve with load holding/locking functionality.
Preferably, the means to move the ram block are selected from the group consisting of devices adapted to impart linear movement. According to a preferred embodiment of the present invention, the device adapted to impart linear movement is selected from the group consisting of: pneumatic; hydraulic; electrical; a wormgear or any other actuator adapted for this purpose.
According to a preferred embodiment of the present invention, the retaining member (ram block) comprises a body and a concave front surface adapted to abut against the cylindrical surface of an inner member circumferential slot when in operation. Preferably, the ram block further comprises two side surfaces each of which having a protrusion and a cavity adapted for insertion into the cavity and protrusion of an adjacent ram block. More preferably, the body of the ram block comprises two opposite sides, a top and a bottom and a seal which surrounds the body to provide a sealing engagement with the ram block housing and prevent fluid and solids migration between the wellbore and the cylinder chamber. Preferably, a barrier fluid fills the cavity (i.e. space) formed between the ram block housing seal and the device adapted to impart linear movement to further prevent fluid and solids migration between the wellbore and the cylinder chamber. The cavity formed between the ram block housing seal and the device adapted to impart linear movement is externally connected to an accumulator to form a closed system which accommodates the variable volume of the cavity as the ram block is moved between open and closed positions. Even more preferably, the ram block further comprises a seal on its front surface.
According to a preferred embodiment of the present invention, the cavity formed between the ram block housing seal and the device adapted to impart linear movement is filled with a barrier fluid to further prevent fluid and solids migration between the wellbore and cylinder chamber. The cavity formed between the ram block housing seal and the device adapted to impart linear movement is externally connected to an accumulator to form a closed system which accommodates the variable volume of the cavity as the ram block is moved between open and closed positions.
The detailed description will be better understood in conjunction with the accompanying drawings as follows:
The cost of incorporating an RCD into a rig is meant to be offset by avoiding the consequences of not having one. Reducing the number of incidents and increasing the speed of drilling translates into lower costs for operators and owners alike. RCDs also allows operators to use lower mud weights in high-pressure environments, which reduces the costs associated with mud as well as the volumes of mud required. RCDs also allows the exploitation of reservoirs which may be very difficult to access. The use of RCDs also provides an effective means of managing drilling hazards, as they are intended to provide a gas-tight seal that protects operators, employees and the environment. RCDs are designed to divert toxic gas, such as hydrogen sulfide, away from the rig floor to protect personnel present on the rig. RCDs also prevent gas influxes from reaching above the blowout preventer and entering the riser creating serious safety hazard situations.
According to a preferred embodiment of the present invention as illustrated in
During the installation of a tool or passing a tubular through the RCD bowl (tripping in or out), the pistons moving the ram blocks are all actuated to move the ram blocks towards an “open” configuration where the inner surface of the ram blocks define a diameter inside the RCD which is at least as large or larger than the inner diameter of the RCD bowl. This allows the tool or tubular to move within the RCD bowl by minimizing the contact and friction against the high pressure radial seal bores and thus minimize the potential damage to the seals. The replacement of the high pressure seals remains the most common reason for the shutdown of operations and minimizing this occurrence directly translates in increased production and a decrease in operational costs.
According to a preferred embodiment of the present invention, the retaining members (or ram blocks) are present in such a way as to provide a good, robust interaction with the inner member nestled within the RCD bowl, i.e. inside the main cavity. Preferably, there are 6 ram blocks each of which is actuated by a piston. Consequently, there is a piston assembly for each ram block which provides the movement for the ram block.
According to a preferred embodiment of the present invention, the number of ram blocks is determined by the amount equipment allotted to operate the device. In some instances, it may be desirable to have fewer ram blocks and therefore, one could conceivably have only two ram blocks, each of which would cover half of the circumference of the tubular when in the closed position. Other embodiments may employ 3, 4, 5, 6 or even more ram blocks depending on the operating parameters such as sizing limitations.
By referring to
According to another preferred embodiment, the piston may only be partially recessed within the piston chamber to allow the ram block to be fully opened.
The ram blocks (the retaining members) can also be retracted to an open position in order to allow an oversized tubular or tool, such as a drill bit, to pass through the RCD, that would otherwise not be able to pass through the inner diameter created when the ram blocks are extended in a closed position.
As seen in
By referring to
By referring to
According to the illustrated embodiment in
By referring to
Referring to
Referring to
However, once there is then wellbore pressure applied from below the inner member, there is still the need for an impeding profile in the inner member to interact with the bottom edge of the ram blocks to prevent vertical axial upward movement of the inner member in the event that friction alone between the inner surface of the ram blocks and the cylindrical surface of the circumferential slot is not a reliable method of retaining the inner member.
Now referring to
As can be seen in
As seen in
According to a preferred embodiment, the outer member includes an integral cavity adapted to accept a cartridge valve with load holding/locking functionality. In the event of an absence of external hydraulic power the cartridge valve maintains ram block position and load bearing capacity in a fail locked condition.
According to another preferred embodiment, when in the closed position, the ram block not only supports the inner member located within the RCD bowl, but also forms a seal which is leak proof due to seals (not shown) on the inner face (27) of
According to the preferred embodiment illustrated in
The ram blocks of pair B (B1 and B2) can be seen to be extending from their housing (53 and 53′) but the protrusions (not labeled) can still be clearly seen on their sides. They are still considered to be independent from one another as they have no structural interaction, i.e. no interlocking of any kind between one another at this point. Their front surfaces (B1-27 and B2-27) extend beyond the outer member's inner circumference.
The ram blocks of pair C (C1 and C2) can be seen to be fully extended from their housing and their protrusions can no longer be seen on their sides. They are considered to no longer be independent from one another as they have structural interaction, there is interlocking between them as the protrusion of ram block C1 is fully inside the corresponding cavity found of ram block C2 at this point. Their front surfaces (C1-27 and C2-27) form a semi-circle as is expected when adjacent ram block are fully extended. To note, as can be seen, in the space between ram block C2 and ram block B1 the protrusion (91) located on ram block C2 has already started its insertion into the corresponding cavity located on ram block B1, there is a beginning of a structural interaction between these two adjacent ram blocks.
Also seen in
Connected to ram block C1 are the piston (87), piston plate (99) adapted to sealingly fit into the piston chamber (43). A pair of inner seals (94) and outer seals (96) located around the inner and outer walls respectively of the chamber to provide a seal to the piston (87) as it moves the ram block from a first “open” position to a second “closed” position upon actuation of the ram block (7). A large space (43) is seen in the chamber due to the movement of the piston and, correspondingly, the piston plate (99) to position the ram block C1 in a closed position. Looking at the piston chamber of ram block A1, one notes that the space is in front of the piston plate as the ram block is completely retracted within its housing. The inner seal and outer seals located on the piston are positioned to sealingly engage the front and back walls (respectively) of the piston cylinder chamber throughout the entire range of movement of a ram block.
The piston plate can be integrally mounted on the piston or assembled thereon. Preferably, located within a mid-section of the piston and adapted to fit within the piston chamber so as to abut against each of the internal surfaces of the piston chamber.
As would be understood by the person skilled in the art, the protrusion and cavities on the ram blocks can take many different types of shapes so long as they are adapted to fit into an adjacent ram block. A ram block having alternating protrusions and cavities (i.e. on one side the protrusion is at the top and on the other side of the ram block the protrusion is at the bottom) may be desirable as it allows one type of ram block to be used throughout the device. Alternatively, a ram block may have only one protrusion on one side and one cavity of the opposite side. Another alternative is that the ram blocks have no protrusion nor any cavities. Any number of possible alternatives are considered to be within the scope of this invention depending on the expected use and requirements.
Preferably, the ram blocks have a sealing element (29) (as seen in
According to a preferred embodiment of the present invention, the ram block assembly can be removed from the outer member by removing the bolts securing the assembly to the outer member and sliding the ram block out from its housing and disconnecting the hydraulic fluid inlet and outlet hoses.
As is understood by the person skilled in the art to which this disclosure is addressed, the sealing member described and disclosed in this description can take different forms but still be considered to be part of the inventive concept as described and illustrated herein. The embodiments described herein are to be understood to be exemplary and numerous modification and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the claims appended hereto, the invention may be practiced otherwise than as specifically disclosed herein.
