Filter assembly with vibration feature

Abstract

A filter assembly is provided having a resilient member connected between an upper member and a lower section, wherein the resilient member enables the filter screen to vibrate relative to the upper member. A centralizing member is positioned above the filter screen having a diameter greater than the filter screen, wherein the filter screen is a cylinder having a plurality of filter apertures formed therein, and wherein the filter apertures extend substantially parallel to the central axis.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates in part to devices and methods used in oil and gas drilling operations to diffuse aggregations of lost circulation materials (LCM) which are used to resolve lost circulation and fluid losses, and more particularly to such devices which include elements for breaking down larger masses of LCM during the diffusion step and which can be further agitated and dislodged by vibration imparted to the diffuser.

2. Prior Art

When drilling oil and gas wells, under proper conditions during the drilling process, drilling fluids and drill cuttings are circulated away from the drill bit into the annulus around the drill stem and brought to the surface. Such drilling fluids are also important for providing hydrostatic pressure to prevent formation fluids from entering into the well bore, keeping the drill bit cool and clean during drilling, and suspending the drill cuttings while drilling is paused and when the drilling assembly is brought in and out of the hole. Because proper circulation is critical to the drilling process, any lost circulation is a significant problem that must be overcome for drilling to recommence.

Lost circulation is the partial or complete loss of drilling fluid or cement slurry to the formation during drilling or cementing operations or both. Lost circulation can be brought on by natural causes, such as naturally fractured formations or unconsolidated zones, or induced causes, such as when the hydrostatic fluid column pressure exceeds the fracture gradient of the formation and the formation pores break down enough to receive (rather than resist) the fluid. When lost circulation occurs, it typically results in the new expenditure of time and mud or cement, adding substantially to the overall cost of a well.

The consequences of lost circulation can be as little as the loss of a few dollars of drilling fluid, or as disastrous as a blowout and loss of life. If the amount of fluid in the well bore drops due to lost circulation (or any other reason), hydrostatic pressure is reduced, which can allow a gas or fluid which is under a higher pressure than the reduced hydrostatic pressure to flow into the well bore. Another consequence of lost circulation is dry drilling. Dry drilling occurs when fluid is completely lost from the well bore without actual drilling coming to a stop. The effects of dry drilling range from as minor as destroying a bit to as serious as major damage to the well bore requiring a new well to be drilled. Dry drilling can also cause severe damage to the drill string, including snapping the pipe, and the drilling rig itself.

Lost circulation material (LCM) is the collective term for substances added to drilling fluids when drilling fluids are being lost to the formations downhole. Commonly used LCM types include fibrous (cedar bark, shredded cane stalks, mineral fiber and hair), flaky (mica flakes and pieces of plastic or cellophane sheeting) or granular (ground and sized limestone or marble, wood, nut hulls, Formica, corncobs and cotton hulls). The LCM, in combination with other fluids with increased viscosity, are used to fill fractures and heal the loss zone quickly.

As the LCM is delivered to the loss zone, accumulations and aggregations of the LCM can occur which may obstruct the necessary flow of fluids to the site. Therefore, it is desirable to prevent such obstructions by diffusing such aggregations or “clumps” as early and as quickly as possible. Given the nature of some types of LCM and their tendency to aggregate into such clumps, one solution is to cause such clumps to contact diffusing members placed into the fluid path, but while not substantially decreasing the proper fluid flow during the healing process of the loss zone.

In addition to diffusion near the loss zone, there is also a need for diffusion of LCM clumps that form as the fluids are delivered through the drill pipe at the rig floor, as well as diffusion of LCM clumps which may form after leaving the mixing tank where the LCM is added to the drilling fluids. Furthermore, once drilling operations are concluded, the diffuser can also be deployed in various locations for diffusion in completion and workover operations.

A further need exists for diffusers and filters to enable a lower part of the assembly to move or vibrate relative to the upper part of the assembly, where such vibration can assist in the disintegration and dislodgement of LCM and other solids through the assembly. The present invention provides an effective means of accomplishing this objective through the use of a resilient member connecting the upper and lower parts of the diffuser or filter.

SUMMARY OF THE INVENTION

Therefore, it is an object of the present invention to provide a diffuser assembly having an upper member mountable within the conduit and having a fluid inlet port, and a lower section having a diffuser screen. A resilient member is connected between the upper member and the lower section, wherein the resilient member enables the diffuser screen to vibrate relative to the upper member. A plurality of diffusing members are positioned below the resilient member, wherein the diffusing members are oriented relative to a central axis of the diffuser screen. A centralizing member is positioned above the diffuser screen having a diameter greater than the diffuser screen. The diffuser screen is a cylinder having a plurality of diffuser apertures formed therein, the cylinder including a bottom cap having a fluid exit port; and wherein the plurality of diffusing members extends substantially parallel to the central axis.

Another object of the present invention is to provide a diffuser assembly wherein a first set of diffusing members is mounted at a first selected height along the central axis of the diffuser screen, and wherein a second set of diffusing members is mounted at a second selected height along the central axis of the diffuser screen.

Another object of the present invention is to provide a diffuser assembly wherein the diffusing members are mounted to the diffuser screen such that the diffusing members protrude internal to the diffuser screen.

Another object of the present invention is to provide a diffuser assembly wherein the diffusing members are mounted to the diffuser screen such that the diffusing members protrude external to the diffuser screen.

Yet another embodiment of the present invention is to provide a diffuser assembly wherein the resilient member is adapted to permit the lower section to move relative to the upper member in response to mud flow changes, pressure changes, and other solids mass movement.

Another object of the present invention is to provide a diffuser assembly that can be positioned in different locations, including within a downhole carrier sub inside a well bore, within a drill pipe at the rig floor, or within a conduit in fluid communication between a mixing tank and the rig floor.

BRIEF DESCRIPTION OF THE DRAWINGS

For a further understanding of the nature, objects, and advantages of the present invention, reference should be had to the following detailed description, read in conjunction with the following drawings, wherein like reference numerals denote like elements.

FIG. 1 shows a side sectional view of a carrier sub, such as a stabilizer or other type of downhole sub, containing a preferred embodiment of a diffuser screen of the present invention.

FIG. 2 shows a side view of the diffuser screen of FIG. 1.

FIG. 3 shows a bottom view of the diffuser screen of FIG. 1.

FIG. 4 shows a top view of the diffuser screen of FIG. 1.

FIG. 5 shows a perspective view of the diffuser screen of FIG. 1 depicting the screening cylinder having internal cutters.

FIG. 6 shows a perspective view of the diffuser screen of FIG. 1 without the screening cylinder to better depict the placement of the internal cutters.

FIG. 7 shows an alternate embodiment of the diffuser screen having external cutters and a lower slotted screening cylinder.

FIG. 8 shows a bottom view of the diffuser screen of FIG. 7.

FIG. 9 shows a top view of the diffuser screen of FIG. 7.

FIG. 10 shows a perspective view of the diffuser screen of FIG. 7 depicting the screening cylinder having external cutters.

FIG. 11 shows a perspective view of the diffuser screen of FIG. 7 without the screening cylinder to better depict the placement of the external cutters.

FIG. 12 shows a further alternate embodiment of the diffuser screen having external cutters and a lower screening constructed from vertical rods.

FIG. 13 shows a bottom view of the diffuser screen of FIG. 12.

FIG. 14 shows a top view of the diffuser screen of FIG. 12.

FIG. 15 shows a perspective view of the diffuser screen of FIG. 12 depicting the screening cylinder having external cutters.

FIG. 16 shows a perspective view of the diffuser screen of FIG. 12 without the screening cylinder to better depict the placement of the external cutters.

FIG. 17 shows the diffuser deployed within a stabilizer.

FIGS. 18A and 18B show retrievable and nonretrievable diffusers deployed within a section of drill pipe at the rig floor.

FIG. 19 shows the diffuser deployed within a conduit between a drilling fluid mixing tank and the rig floor.

FIG. 20 shows a preferred embodiment of a diffuser assembly having external diffusing members, and including a resilient member to permit vibration between the upper and lower members.

FIG. 21 shows an alternate embodiment of a diffuser assembly having internal diffusing members, and including a resilient member to permit vibration between the upper and lower members.

FIG. 22 shows a preferred embodiment of a filter assembly having a resilient member to permit vibration between the upper and lower members.

FIG. 23 shows an alternate embodiment of a filter assembly having a resilient member to permit vibration between the upper and lower members.

DETAILED DESCRIPTION OF THE INVENTION

Before the subject invention is further described, it is to be understood that the invention is not limited to the particular embodiments of the invention described below, as variations of the particular embodiments may be made and still fall within the scope of the appended claims. It is also to be understood that the terminology employed is for the purpose of describing particular embodiments, and is not intended to be limiting. Instead, the scope of the present invention will be established by the appended claims.

In this specification and the appended claims, the singular forms “a,” “an,” and “the” include plural reference unless the context clearly dictates otherwise. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood to one of ordinary skill in the art to which this invention belongs. Unless otherwise specified herein, all materials of construction are preferably steel resistant to the corrosive effects common in oil and gas production environments. As used herein the term “conduit” shall mean any tubular member into which the diffuser 1 or filter can be installed for the purpose of allowing LCM-containing fluid to flow through the conduit and be broken apart, or diffused, by the diffuser 1. Non-limiting examples of conduits may be a carrier sub, drill pipe, stabilizer, or other tubular member such as shown in the figures.

Turning now to the figures, a preferred embodiment of the present invention is shown in FIGS. 1-6 as a diffuser assembly 1 comprising a diffuser 2 adapted to reside within a conduit in the form of a carrier sub 3, having an upper mounting member 4 mountable within the carrier sub 3 and having an fluid inlet port 5, and a lower section having a diffuser screen 6. As shown in more detail in FIGS. 4 and 6, a plurality of diffusing members 7 are removably attached to the diffuser screen 6, wherein the diffusing members 7 are radially oriented relative to a central axis 8 of the diffuser screen 6. The diffuser screen 6 is a cylinder having a plurality of diffuser slots 9 formed therein and a bottom cap 10 having a fluid port 11.

In the embodiment shown in FIGS. 1-6, the diffuser assembly 1 further includes a plurality of centralizing members 16 adjacent to the diffuser screen 6, wherein each of the centralizing members 16 extends between the mounting member 4 and the bottom cap 10. The three centralizing members 16 serve to keep the diffuser screen 6 centered within the carrier sub 3. It should be understood that the centralizing members 16 can take a wide range of structural forms which accomplish the purpose of centering the diffuser screen 6 within the carrier sub 3.

As shown best in FIG. 6, with the cylindrical diffuser screen 6 removed for clarity, each of the plurality of diffusing members 7 includes a diffusing edge 12 (which may be a sharp edge, or which may be non-sharp but sufficient to separate clumps of LCM and other solids), and a mounting flange 13, and wherein the mounting flange 13 is adapted to matably engage one of the plurality of diffuser slots 9 of the diffuser screen 6. In a preferred embodiment, a first set 14 of diffusing members 7 is mounted at a first selected height H1 along the central axis 8 of the diffuser screen 6, and a second set 15 of diffusing members 7 is mounted at a second selected height H2 along the central axis 8 of the diffuser screen 6. In this embodiment shown in FIGS. 1-6, the diffusing members 7 are mounted to the diffuser screen 6 such that the diffusing edges 12 are internal to the diffuser screen 6. It should be understood that each individual diffusing member 7 may reside in any slot 9 to provide a varied and irregular pattern of diffusing members 7 on the diffuser screen 6. However, it is believed that having organized sets of diffusing members 7 at selected heights may provide more consistent separation of LCM aggregations during the diffusion of the fluid through the diffuser assembly 1.

As best shown in FIG. 6, the diffuser assembly 1 further includes a bottom diffusing device 17 extending from a post 19 affixed to the bottom cap 10 internal to the diffuser screen 6, wherein the diffusing device 17 includes a plurality of radially disposed edges 18 similar to the diffusing members 7 positioned above the diffusing device 17. The diffusing device 17 essentially serves as a third stage diffusion step in addition to the first and second set 14, 15 of diffusing members 7, prior to the fluid 20 exiting the diffuser screen 6 through fluid port 11.

In an operational configuration, fluid 20 flows through the carrier sub 3, such as a stabilizer or other type of downhole or surface sub, and into the inlet port 5 of the mounting member 4. Any LCM aggregations or clumps in the fluid 20 pass against the diffusing edges 12 of diffusing members 7, and are separated into smaller portions to collect within the diffuser screen 6, while the fluid 20 can exit the diffuser screen 6 through diffuser slots 9 and the fluid port 11.

The preferred embodiment described above, as well as the alternate embodiments described below, are effective for diffusion of a wide range of fluids and materials, including oil and water based muds, barite drilling muds, cement, all drilling fluids, spotting acids for break-up of limestone formations, blended materials mixed in blending tanks, breakup of larger masses of carbide bombs, and any other “cake balls” mud clumps, LCM, cement, and the like that form in the string or from poor blending.

In an alternate embodiment shown in FIGS. 7-11, a similar diffuser assembly is configured to allow the flow of fluid 20 such that LCM aggregations are caused to contact diffusing members 24 positioned external to the diffuser screen 21, and where LCM too large for the diffuser slots 9 is collected on the outside of the diffuser screen 21. A mounting member 22 (similar to mounting member 4) includes an inlet port 23 for entry of fluids 20. The fluid 20 is then diverted by a cone-shaped diversion member 25 attached to a bridge 26 inside mounting member 22 and disposed between the fluid inlet port 23 of the mounting member 22 and the diffuser screen 21.

As shown best in FIG. 11, with the cylindrical diffuser screen 21 removed for clarity, each of the plurality of diffusing members 24 includes a diffusing edge 27 and a mounting flange 28, and wherein the mounting flange 28 is adapted to matably engage one of the plurality of diffuser slots 9 of the diffuser screen 21. In this embodiment, three sets of diffusing members 7 are mounted at selected heights along the central axis 8 of the diffuser screen 21, similar to the arrangement seen in FIG. 6.

As shown in FIGS. 7-11, the diffuser assembly 1 further includes a lower filter element 30 attached below the diffuser screen 21, wherein the lower filter element 30 is constructed from a slotted cylinder. A bottom cap 31 is attached to the bottom of lower filter element 30, and which includes a fluid exit port 32. A further embodiment is shown in FIGS. 12-16 that is identical to the embodiment of FIGS. 7-11, except for the lower filter element 30, which is constructed from vertical rods 33.

As shown in FIG. 17, the diffuser assembly 1 is deployed within another type of conduit in the form of a stabilizer 40, which supports the bottom hole assembly (BHA) in the well bore in order to avoid unintentional sidetracking or vibrations, and ensures the quality of the hole being drilled.

As shown in FIGS. 18A and 18B, the diffuser assembly 1 is deployed within a section of drill pipe 50 at the level of the rig floor 52. Note that in FIG. 18A, the diffuser screen 6 includes a retrievable neck 51, as is common in the art, that enables retrieval of the diffuser by conventional fishing tools. FIG. 18B includes an opening as shown in FIG. 5 and elsewhere herein. In this operation, the diffuser 1 is installed in the drill pipe 50 while drilling fluids containing LCM are pumped into the well bore during drilling. As the drill string moves deeper into the well bore and another section of drill pipe 50 is needed, the diffuser 1 is removed, and the next section of drill pipe 50 is position near the drill string at the rig floor 52. Before the next section of drill pipe 50 is connected, the diffuser 1 is re-installed into the existing string of drill pipe 50, and the new section of drill pipe 50 is then threaded onto the drill string, after which the drilling and fluid flow can be restarted. Thus, any clumps of LCM that enter into the drill pipe 50 are diffused by the diffuser 1.

As shown in FIG. 19, the diffuser 1 is deployed within a conduit 60 between a drilling fluid mixing tank 61 and the rig floor 52. Tank 61 may be a fixed tank, or it may be a mobile tank located on a vehicle such as a truck or other vessel. The left side of FIG. 19 depicts the arrangement in a partial exploded view, while the right side of FIG. 19 depicts a fully assembled view with typical valves, hoses, and connectors to enable fluid flow from the mixing tank 61 to the rig floor 52. Pumps 62 are deployed in-line with the hoses from the mixing tanks 61 to move the drilling fluids from the mixing tanks 61 through the diffusers 1 or filters, as applicable. Thus, any clumps due to poor mixing and/or LCM accumulation that exist when the fluid leaves the mixing tank 61 can be diffused by the diffuser 1 prior to arriving at the rig floor 52.

As shown in FIG. 20, another embodiment 70 of a diffuser assembly depicts a diffuser having external diffusing members 24 (as explained above with respect to FIG. 7-11), and including a resilient member 71 to permit vibration between the upper and lower members 72, 73. Specifically, the upper member 72 includes a mounting member 22 (similar to mounting member 4) which includes an inlet port 23 for entry of fluids. The lower member 73 includes the diffuser screen 21 and the plurality of diffusing members 24 as explained previously, but is separate from the upper member 72, and connected to the upper member 72 by a resilient member 71. Thus, the lower member 73 is permitted to move along the central axis 8 relative to the upper member 72 by the resiliency of the resilient member 71. The resilient member 71 may be a coiled metal spring, wherein one end of the spring is welded to the upper member 72 while the opposite end of the spring is welded to the lower member 73 after insertion into a hole formed at the top of the conical member 25. Various alternatives to the coiled metal spring may also be used, as long as those alternatives enable functionally equivalent operation, i.e. vibratory movement of the lower member 73 relative to the upper member 72.

In this configuration, the resilient member 71 is adapted to permit the lower member 73 to move relative to the upper member 72 in response to a number of downhole events, including mud flow changes, pressure changes, and other solids mass movement. Those events will cause the lower member 73 to move in response to those forces, and in doing so, will cause further and more forceful contact between the clumps of LCM and other solids passing through the diffuser, further aiding in separation, disintegration, and dislodgement of those solids, and leading to more efficient and effective diffusion.

The presence of resilient member 71 also provides another advantage of flexibility during the step of lowering and inserting the diffuser assembly into a conduit, such as a carrier sub 3. For example, because the lower member 73 is connected to the upper member 72 by the spring, the lower member 73 can be bent slightly away from the upper member 72 through the resiliency of the spring, thus facilitating the insertion operation until the diffuser assembly is properly seated in the conduit.

With respect to the spring constant for the resilient member 71, one of ordinary skill should be able to determine the proper range of the spring constant (and the related physical characteristics of the spring) to permit the desired vibration, but while keeping the upper member 72 and the lower member 73 from contacting each other. For example, it is important to prevent undesirable “hitting” between the upper and lower members 72, 73, because such hitting may affect the function of other pulsers and signal equipment in the downhole environment that monitor downhole conditions and processes. With the exception of the resilient member 71 and its function, this embodiment of FIG. 20 is otherwise similar in function to the embodiment shown in FIGS. 7-11.

FIG. 22 shows an embodiment 80 of a filter assembly that is similar to the embodiment of FIG. 20, but without the diffusing members 24 attached to the lower member 73.

FIG. 21 shows another embodiment 90 of a diffuser assembly depicting a diffuser having internal diffusing members 7 (as explained above with respect to FIG. 2-6), and including a resilient member 91 to permit vibration between the upper and lower members 92, 93. In this embodiment, the upper member 92 includes a portion that is slidably and telescopingly disposed within a slightly larger internal diameter of the lower member 93. Thus, the lower member 93 is permitted to move along the central axis 8 relative to the upper member 92 by the resiliency of the resilient member 91. As explained above with respect to the embodiment 70 shown in FIG. 20, the resilient member 91 may be a coiled metal spring, wherein one end of the spring is welded to the upper member 92 while the opposite end of the spring is welded to the lower member 93. Various alternatives to the coiled metal spring may also be used, as long as those alternatives enable functionally equivalent operation, i.e. vibratory movement of the lower member 93 relative to the upper member 92.

In this configuration, the resilient member 91 is adapted to permit the lower member 93 to move relative to the upper member 92 in response to downhole events, including mud flow changes, pressure changes, and other solids mass movement. Those events will cause the lower member 93 to move in response to those forces, and in doing so, will cause further and more forceful contact between the clumps of LCM and other solids passing through the diffuser, further aiding in separation, disintegration, and dislodgement of those solids, and leading to more efficient and effective diffusion.

FIG. 23 shows an embodiment 100 of a filter assembly that is similar to the embodiment of FIG. 21, but without the diffusing members 7 attached to the lower member 93.

As explained above with respect to the other embodiments disclosed herein, the diffusers and filters of FIGS. 20-23 are not limited to application for downhole use within a carrier sub 3, as shown in FIG. 1. Rather, they are equally suitable for use in other environments where diffusion and filtration are required, such as the stabilizer of FIG. 17, deployment within a section of drill pipe 50 at the level of the rig floor 52 as shown in FIGS. 18A and 18B, and deployment within a conduit 60 between a drilling fluid mixing tank 61 and the rig floor 52 as shown in FIG. 19.

All references cited in this specification are herein incorporated by reference as though each reference was specifically and individually indicated to be incorporated by reference. The citation of any reference is for its disclosure prior to the filing date and should not be construed as an admission that the present invention is not entitled to antedate such reference by virtue of prior invention.

It will be understood that each of the elements described above, or two or more together may also find a useful application in other types of methods differing from the type described above. Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention set forth in the appended claims. The foregoing embodiments are presented by way of example only; the scope of the present invention is to be limited only by the following claims.

Claims

1. A filter assembly, comprising: (a) a filter adapted to reside within a conduit, having an upper member mountable within the conduit and having a fluid inlet port, and a lower section having a filter screen;(b) a resilient member connected between the upper member and the lower section, wherein the lower section is substantially below the resilient member, and wherein the resilient member enables the filter screen to vibrate freely within the conduit relative to the upper member; and(c) a centralizing member above the filter screen having a diameter greater than the filter screen;wherein the filter screen is a cylinder having a plurality of filter apertures formed therein, the cylinder including a bottom cap having a fluid exit port;wherein the filter apertures are oriented relative to a central axis of the filter screen; andwherein the plurality of filter apertures extends substantially parallel to the central axis.

2. The filter assembly of claim 1, further including at least one centralizing member adapted to centralize the filter assembly within the conduit.

3. The filter assembly of claim 1, wherein the filter assembly is positioned within a downhole carrier sub inside a well bore.

4. The filter assembly of claim 1, wherein the filter assembly is positioned within a stabilizer.

5. The filter assembly of claim 1, wherein the filter assembly is positioned within a drill pipe at a rig floor.

6. The filter assembly of claim 1, wherein the filter assembly is positioned within a pipe in fluid communication between a mixing tank and a rig floor.

7. The filter assembly of claim 1, wherein the resilient member is adapted to permit the lower section to move relative to the upper member in response to mud flow changes, pressure changes, and other solids mass movement.