Rotating control device having a partition seal assembly

A rotating control device (RCD) which partitions the rotating speed of an inner barrel relative to a rotary and stationary seal via a roller bearing assembly. The roller bearing assembly causes the rotary seal to rotate at near half the speed, or portion of the speed thereof, of the inner barrel. Alternatively, a rotary seal assembly is rotatable by frictional contact with the inner barrel, and a stationary seal assembly is in frictional contact with the rotary seal assembly to prevent the rotary seal assembly from rotating at the same speed as the inner barrel. The speed differential between the inner barrel and the rotary seal, as well as between the rotary seal and the stationary seal is reduced by nearly half, which reduces wear and increases performance life of each seal.

BACKGROUND

Field of the Disclosure

Embodiments of the present disclosure generally relate to a rotating control device (RCD) of use in a drilling operation. More specifically, embodiments of the present disclosure relate to an RCD having a partition seal assembly that increases seal performance and life.

Description of the Related Art

Drilling a wellbore for hydrocarbons requires significant expenditures of manpower and equipment. Thus, constant advances are being sought to reduce any downtime of equipment and expedite any repairs that become necessary. 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.

Rotating control device (RCD) technology has become an important tool for lowering drilling costs and increasing well productivity, especially in many hard-rock areas and mature oil and gas fields. Lower drilling costs are achieved primarily by faster penetration rates, reduced non-drilling time, and reduced mud volume requirements associated with underbalanced drilling.

RCDs are used as diverters on a wellhead or riser and are to be used with annular and ram blow out preventers, and thus have the ability to seal off pressure from a wellbore with or without tubulars in the wellbore. RCDs provide a rotating seal that allows drilling to proceed with the wellbore under pressure. RCDs create a pressure-tight barrier within the wellhead or riser that enables the containment and diversion of returning fluids, thus forming a line of defense against drilling hazards, such as kicks and shallow gas. RCD's permit closed-loop drilling, which offers environmental, cost, and safety benefits. In the past, wellhead pressure was typically limited to a few hundred PSI. Today, however rotary drilling operations are continued with as much as 2,500 PSI peak wellhead pressure while gas-cut fluid is circulated to the surface.

Rotary seals typically rely on a hydrodynamic film or a self-lubricating material. However, it is well known that the life span of rotary seals within RCD systems is relatively short mainly due to higher pressure and velocity (PV) conditions, and continual operations which cause the rotary seals within the RCD to break down rapidly. The greater the differential pressure and the higher the speed required both cause more stress on the rotary seal. Furthermore, reduced film thicknesses and increased friction lead to rotary seal failure. As such, the life of the rotary seals is relatively short and unpredictable. Furthermore, there is a trend in RCD equipment for higher pressure and higher speeds.

During the drilling operation, drill pipe or tubulars are axially and slidably moved through the RCD of a wellhead or riser. The axial movement of the drill pipe along with other forces experienced in the drilling operation cause wear and tear on the bearing and rotary seal assemblies of the RCD, and the rotary seal assemblies subsequently require repair. Typically, the drill pipe or a portion thereof is pulled from the RCD, and the bearing and rotary seal assembly in the RCD is then released. Thereafter, an air tugger or other lifting means in combination with a tool joint on the drill string can be used to lift the bearing and rotary seal assembly from the RCD. The bearing and rotary seal assembly are replaced or reworked, installed into the RCD, and the drilling operation is then resumed.

Therefore, what is needed in the art is a new and improved apparatus for improving rotary seal life. More specifically, what is needed in the art is an improved RCD apparatus for increasing rotary seal performance.

SUMMARY

In one embodiment, a rotating control device comprises an inner barrel; an outer barrel; a roller bearing assembly disposed between the inner barrel and the outer barrel, wherein the roller bearing assembly is rotatable by rotation of the inner barrel; a rotary seal assembly coupled to the roller bearing assembly; and a stationary seal assembly disposed adjacent to the rotary seal assembly.

In one embodiment, a rotating control device comprises an inner barrel; an outer barrel; a roller bearing assembly comprising an inner ring, an outer ring, a cage, and a cage insert disposed between the inner and outer rings, and wherein the roller bearing assembly is coupled to the inner barrel; a first seal coupled to a first seal carrier, wherein the first seal carrier is coupled to the cage insert of the roller bearing assembly; and a second seal coupled to a second seal carrier.

In one embodiment, a rotating control device comprises an inner barrel; an outer barrel; a rotary seal assembly disposed between the inner barrel and the outer barrel, wherein the rotary seal assembly is rotatable by frictional contact with the inner barrel; and a stationary seal assembly disposed between the inner barrel and the outer barrel, wherein the stationary seal assembly is in frictional contact with the rotary seal assembly to prevent the rotary seal assembly from rotating at the same speed as the inner barrel.

DETAILED DESCRIPTION

FIG. 1illustrates a rotating control device (RCD)100for use in a riser string during a drilling operation. The RCD100may be a rotary fluid sealing structure and is usable with a land or sea based drilling platform comprising one or more of a wellhead, a riser, motors, pumps, a rotating drill string, a hoisting structure, and a means for circulating drilling fluid. The RCD100creates a pressure tight barrier within a wellhead or riser that enables safe fluid containment and diversion against drilling hazards.

The RCD100includes an outer barrel102disposed between a first end104and second end105. The RCD100further includes a top sub103disposed adjacent the first end104of the RCD100, and a bottom sub107disposed adjacent the second end105of the RCD100. The top sub103and the bottom sub107may guide, position, and/or centralize a drill string when being raised and lowered through a wellhead or riser. The top sub103and the bottom sub107may include seals configured to direct fluid around the RCD100and/or prevent fluid from entering the RCD100.

FIG. 2illustrates a top view of the first end104of the RCD100ofFIG. 1. In some embodiments, the first end104of the RCD100may be a top end. Drill pipe, or other tubulars, may be inserted into the RCD100via the first end104such that the drill pipe is lowered from the first end104via the top sub103to the second end105. The RCD100permits the drill pipe to move axially and slidably through the RCD100while rotating. During a drilling operation, the RCD100may seal against the drill pipe being lowered through the RCD100to prevent drilling fluid and hydrocarbons from flowing up through a wellhead or riser and out onto the rig floor in an uncontrolled manner.

FIGS. 3 and 4each illustrate a different cross-sectional view of the RCD100ofFIG. 1. As shown, the RCD100includes an inner barrel106that is rotatable by the top sub103relative to an outer barrel102. The outer barrel102may be fixed in place when the RCD100is installed in a wellhead or riser. During operation, a drill string is inserted into the first end104, moved through the top sub103, inner barrel106, and bottom sub107, and out of the second end105, while continuously rotating with the top sub103and the inner barrel106relative to the outer barrel102. To maintain a seal between the inner barrel106and the outer barrel102, the RCD100includes at least a first seal110and a second seal112as further shown and described with respect toFIGS. 5 and 6.

The first seal110and/or the second seal112form a seal between the rotating inner barrel106and the stationary outer barrel102. The first seal110and/or the second seal112may comprise an elastomeric compound. As such, the first seal110and/or the second seal112may comprise a rubber material, a phenolic material, or any other material suitable for sealing during drilling operations. In some embodiments, the first seal110and/or the second seal112may be a mechanical seal and/or may comprise a metal material, a steel material, a carbide material, and/or combinations and mixtures thereof.

The RCD100further includes a roller assembly150disposed between the outer barrel102and the inner barrel106. The roller assembly150may rotate and/or guide the movement of the inner barrel106relative to the fixed outer barrel102such that the drill string is moved through the top sub103, the inner barrel106, and the bottom sub107. The RCD100may also include a compensation system152, such as a pressure compensation system configured to maintain a positive pressure on the RCD100seals.

FIG. 5illustrates an enlarged view of region5ofFIG. 3, andFIG. 6illustrates an enlarged view of region6ofFIG. 4. In addition to the first seal110and the second seal112, the RCD100includes a bearing assembly108. In some embodiments, the bearing assembly108is a roller bearing assembly.

The bearing assembly108is disposed between the outer barrel102and the inner barrel106. The bearing assembly108may comprise a metal material (for example, steel), a ceramic material, or any other material suitable for drilling operations. The bearing assembly108is coupled to the inner barrel106. The inner barrel106is rotatable at a first rotational speed, such as by rotation of a drill string disposed through the RCD100. As such, the bearing assembly108is rotatable by the inner barrel106. The bearing assembly108is rotatable by the inner barrel106upon rotation of the inner barrel106.

The inner barrel106may be coupled to a first sleeve member115. The first sleeve member115may be disposed adjacent the inner barrel106and between the inner barrel106and the outer barrel102. The first sleeve member115may have a length parallel to the length of the inner barrel106. Furthermore, the first sleeve member115may be coupled to an inner ring114of the bearing assembly108. In some embodiments, the first sleeve member115may be coupled to the inner ring114via a link member117. In an alternate embodiment, the link member117may be omitted and the first sleeve member115and the inner ring114may be shrunk fit around the inner barrel106.

The bearing assembly108includes an inner ring114, an outer ring116, a cage118, and a cage insert120. The cage118is disposed between the inner ring114and the outer ring116. Furthermore, in some embodiments, the cage118includes a plurality of roller bearings122disposed between and in contact with the inner ring114and the outer ring116. In some embodiments, the cage118includes a plurality of slots to secure the roller bearings122. The plurality of roller bearings122may be disposed in the plurality of slots, such that, in some embodiments, each slot comprises at least one roller bearing122. As such, the cage118and the plurality of roller bearings122may each be independent pieces.

Each roller bearing122may comprise a metal material. Furthermore, each roller bearing122may be coated with a non-metal material, for example, a rubber material or a phenolic material.

As the inner barrel106is rotated in a first direction, for example a clockwise direction, the inner ring114is also rotated in the first direction by the inner barrel106. As such, the inner barrel106and the inner ring114are rotated at the same first rotational speed. Rotation of the inner ring114in the first direction at the first rotational speed causes each individual roller bearing122of the bearing assembly108to rotate about its own axis in a second direction, for example, a counter clockwise direction and roll along the inner surface of the outer ring116. The roller bearings122, as a group, rotate at a second rotational speed. The second rotational speed of the plurality of roller bearings122is less than the first rotational speed. In some embodiments, the second rotational speed of the plurality of individual rollers is nearly half of the first rotational speed of the inner barrel106and the inner ring114. Although each individual roller bearing122rotates in the second direction, the plurality of roller bearings122revolve about the inner barrel106in the same first direction but at nearly half of the first rotational speed, or portion thereof.

The cage118of the bearing assembly108rotates with the plurality of roller bearings122at the second rotational speed, which is less than the first rotational speed. In some embodiments, the second rotational speed is nearly half of the first rotational speed. The cage insert120is also disposed between the inner ring114and the outer ring116and coupled to the cage118. In some embodiments, the cage insert120is coupled to the cage118by a pin mechanism124so that the cage insert120is rotated at the second rotational speed via the bearing assembly108.

In some embodiments, the RCD100further includes a second sleeve member130. The second sleeve member130is disposed between the first seal110and the inner barrel106. The second sleeve member130may be coupled to the inner barrel106. The second sleeve member130may be configured to minimize wear of the first seal110as the inner barrel106and the first seal110rotate relative to each other. Alternatively, the first seal110may be in direct contact with the inner barrel106.

The RCD100further includes a first seal assembly101aand a second seal assembly101b. The first seal assembly101amay comprise the first seal110and a first seal carrier128that supports the first seal110. The second seal assembly101bmay comprise the second seal112and a second seal carrier126that supports the second seal112. One or more thrust and/or radial bearings109may be positioned between the first seal carrier128and the outer barrel102. Furthermore, in some embodiments the radial bearings109may be enclosed in a race. In some embodiments, the radial bearings109may be supported within the race and/or within a support ring such as an inner ring and an outer ring and/or a head screw. In some embodiments, the head screw may be an extra wide head screw. Extra wide head screws may further be used to preload the radial bearings109.

In some embodiments, the first seal assembly101amay be a rotary seal assembly in that the first seal110and the first seal carrier128rotate relative to the inner barrel106and the outer barrel102. The first seal110and the first seal carrier128are disposed between the outer barrel102and the inner barrel106and coupled to the roller bearing assembly108. In particular, the first seal carrier128is coupled to the cage insert120of the bearing assembly108by a pin mechanism140as shown inFIG. 6. As such, the first seal110is rotatable at the second rotational speed relative to the inner barrel106via the bearing assembly108.

The second rotational speed of the first seal110is less than, for example near half of, the first rotational speed of the inner barrel106. By rotating the first seal110at the second rotational speed, which is less than the first rotational speed of the inner barrel106, the speed differential between the first seal110and the inner barrel106is reduced, such as by near half. In some embodiments, the speed differential between the first seal110and the inner barrel106is reduced, and the reduction in speed may be dependent upon the bearing assembly108. For example, in some embodiments, the speed may be reduced by 60% or 70%, while in other embodiments the speed may be reduced by 40% or 30%, although other reductions are contemplated. The reduction in speed between the first seal110and the inner barrel106reduces wear on the first seal110, which results in longer seal life.

In some embodiments, the second seal assembly101bmay be a stationary seal assembly in that the second seal112and the second seal carrier126remain stationary relative to the inner barrel106and the outer barrel102. The second seal112is coupled to the second seal carrier126and seals against the first seal carrier128. In some embodiments, a support unit154may be disposed between the second seal carrier126and the outer barrel102to support the seal assemblies101a,101band seal off the upper end of the outer barrel102.

Since the first seal carrier128rotates at near half (or a portion) of the speed of the inner barrel106, the speed differential between the first seal carrier128and the stationary second seal assembly101bis also near half (or a portion) of the speed of the rotation of the inner barrel106. The reduced speed between the first seal carrier128and the second seal112also reduces wear on the second seal112, which results in longer seal life. The RCD100as described above partitions the rotating speed of the inner barrel106relative to the first seal110and the second seal112via the roller bearing assembly108, which lengthens the life of each of the first seal110and the second seal112.

FIG. 7illustrates an alternate embodiment of the embodiment shown inFIG. 3. As shown inFIG. 7, the cage insert120, the pin mechanism124, and the pin mechanism140are omitted. In such an embodiment, the first seal assembly101amay be driven by seal friction formed against the inner barrel106. Specifically, the friction between the first seal assembly101aand the inner barrel106causes the first seal assembly101ato rotate rather than driving the first seal assembly101aby the bearing assembly108as described above.

The rotation of the inner barrel106may cause the first seal assembly101ato rotate through frictional contact between the inner barrel106and the first seal assembly101a. However, frictional contact between the first seal assembly101aand the second seal assembly101bmay prevent the first seal assembly101afrom rotating at the same speed as the inner barrel106. Therefore, the relative speeds of the inner barrel106and the first seal assembly101amay be split in some proportion, thereby reducing speed without any coupling to the bearing assembly108. As such, the first seal assembly101ais driven by seal friction with rotation of the inner barrel106at a reduced speed.

Benefits of the present disclosure include that the lifetime and performance of the first seal110and the second seal112is enhanced (e.g., nearly doubled) as the speed differential between the first seal110and the inner barrel106(as well as between the first seal carrier128and the second seal112) is reduced. In some embodiments, the speed differential between the first seal110and the inner barrel106(as well as between the first seal carrier128and the second seal112) is reduced by nearly half. The use of proven seals with known pressure and velocity limits permits the first seal110and the second seal112to nearly double performance life as the velocity factor is reduced by approximately fifty percent. Furthermore, no external pressure containment devices and/or external or internal lubrication systems are required to lengthen the lifespan of the seals as in prior RCD systems.

While the foregoing is directed to certain embodiments, other and further embodiments may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.