GB2431947A

GB2431947A - Insert for erosion protection

Info

Publication number: GB2431947A
Application number: GB0621544A
Authority: GB
Inventors: Mitchell Darwin Lambert; John Ravensbergen
Original assignee: BJ Services Co USA
Current assignee: BJ Services Co USA
Priority date: 2003-08-29
Filing date: 2006-10-31
Publication date: 2007-05-09
Anticipated expiration: 2024-08-27
Also published as: GB2431947B; GB0621544D0

Abstract

A downhole tool comprises a bottom hole assembly having a central opening therethrough and an insert having an inner diameter within the bottom hole assembly. The insert 70 is made of a hardened material to protect the bottom hole assembly from erosion as a fluid passes through the central opening and the insert. The insert 70 can be trumpet shaped and brazed or epoxied in place. The insert can be formed from discs or washers (figures 2 and 3) which define a passage of a throat. The hardened material can be polycrystalline diamond. The bottom hole assembly can be a nozzle, throat or diffuser.

Description

DOWNIIOLE OILFIELD EROSION PROTECTION

BACKGROUND OF TIlE INVENTION

Field of the invention

100011 ihe present invention relates to the cleaning of welibores in the field of oil and gas recovery. More particularly, this invention relates to a device adaptcd to improve the erosion performance of components utilized in the cleaning of solid particulate matter from a well. * *. * * . S... *5**

Description of the Related Art

* 100021 In the oil and gas industry, weilbores often become plugged with *:: sand, filter cake, or other hard particulate solids, which need to be removed * :...: periodically to improve oil production. Prior art methods for cleaning the *.* weilbore and the removal of these particulate solids include pumping a fluid from the surface to the area to be cleaned. To effectively clean the solids from the weitbore, the pumped fluids must return to surface, thereby establishing circulation. Therefore, the bottom of the hole circulating pressure must be high enough to support circulation but low enough to prevent teak off into the reservoir. In addition, the fluid must suspend and transport the solids. The fluid velocity and theological properties must support solids transport.

100031 It is known that the bottom hole pressure of a wcllbore declines as the reservoir matures, thereby complicating the wellbore cleanout. For example.

if the fluid being pumped into the wcllbore exits the work string (e.g., coiled tubing) at an excessive pressure, the fluid may enter the formation instead of returning to the surface with the sand particulates.

f0004j To overcome this problem, it is known to utilize gasification (e.g., by thc addition of nitrogen to the fluid) 10 decrease the hydrostatic pressure in the wellborc. Thus, the fluid may be pumped at reduced bottom hole pressures and circulation through the weHbore may be restorcd to transport the particulatcs to the surface. However, over time, the reservoir pressure may decline to a point * ** whereby gasification fails to result in consistent circulation of fluid to effectively * * * *..* * io remove the particulates.

* iaoos Reverse circulating is another method commonly used to increase * ***** the transport velocity of the fluid, especially when employing small diameter * tubing in large wcllbores.

0**SSS :. .: iooooi Yet another prior art method of removing the particulate solids in is the wcllbore where the bottomhole circulating pressure is a concern employs a jet pump, as described in U.S. Patent No. 5,033,545 to Sudol, issued July 23, 1991, incorporated by reference herein in its entirety. The jet pump is attached to a coiled tubing inside coiled tubing string (CCT). The power fluid is pumped down the inner string and returns, both the power fluids as well as the reservoir fluids, are taken up the coiled lubing coiled tubing annulus. The jet pump is designed such that reservoir fluids enter the pump at the bottom hole pressure (BHP). The jet pump then increases the pressure of the fluid pumping the fluids up the woric string with the solid particulates entrained in the fluids. Thus.

circulation is facilitated as the circulation no longer depends on BHP alone.

joooii Figure 1 shows an exemplary prior art jet pump apparatus (BUA) and method for effectively removing particulates such as sand from within a s welibore. The jet pump is particularly well suited for use with coiled tubing.

The following is a simplified summary of the operation of this apparatus and method. A jet pump 5 is shown within a weilbore. The jet pump 5 is attached to the bottom of CCT (not shown) via housing 6. In operation, fluid is pumped : *. down the inner coiled tubing (from left to right in Figure 1). The fluid enters the S...

o RHA and ported into the lower end ofjet pump 5 as shown by the arrows. As the *:1 fluid passes through nozzle I, the velocity of the fluid increases significantly, * : creating a jet stream. This increased velocity creates a low pressure that is felt at the entrance 7 to the jet pump 5. The Low pressure draws fluid and solid * .*.** * * particles into the jet pump. Subsequently weilbore fluids and solids contained *S i therein are entrained into the jot stream. The high-velocity fluid with sand particulates then enters the entrance end of the throat 100. As the fluid with the sand particulates continues to travel upward through the throat 100, the diameter of the throat increases, the velocity of the fluid decreases, and the fluid pressure increases.

-uoowt This method is commonly practiced with the use of coil-in-coil tubing, as described in U.S. Pat. No. 5,638,904 by Misseibrook Ct aL, issued June 17, 1997, incorporated by reference herein in its entirety.

iooo 11 has bcen determined that in some applications, the high-velocity impact of the sand-ladened fluids with the entrance of the throat causes excessive erosion in the high impact area 2. Other methods to remove particulate solids which utilize a nozzle, a throat, or a diffuser for entraining the sand-waler slurry s environment also experience excessive erosion. This erosion is generally most prominent at the nozzle, throat, or diffuser, as these arc the pinch points for the flow of fluid and are associated with higher velocity stTeamS.

ooao Erosion of the downhole tools may be exasperated when cleaning : ** particulates from deeper wells. 1)eepcr wells produce additional challenges for to the above-referenced procedure, as the deeper wells have increased hydrostatic * pressure and increased friction pressure. Thus, the coiled tubing operation must : incorporate higher pump output pressure and higher jet velocities in the nozzle and throat. For example, it is not uncommon for 8600 foot well to have 1000 * S p.s.i. bottom hole pressure, causing the flow velocity through the throat to be *5*S is between 200 and 600 feet per second. These higher particle laden jet velocities increase the erosion rate in the throat.

oou Thus, there is a need for a device for improving erosion perfonnance of devices used in the cleaning of a weilbore, such as nozzles, throats, or diffusers utilized downhole. The device should resist erosion ssociated with the high velocity jets of sand/water slurries generated when removing particulate solids, such as sand, from the welibore during well intervention or workover.

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tooui It is also known to decrease the erosion of the components of downhote tools by manufacturing the components of various materials, such as ceramics like TTZ stabilized zirconia, or 6% submicron tungsten carbide.

However, these prior ad methods fail to provide the desired level of erosion performance and may not be economically feasible with deeper wells (and the concomitant increase jetting velocities), as excessive erosion may still result.

Thus, there is a need for improving the erosion performance (i.e. decreasing the erosion) of components used in the cleaning of a wellbore when the components * *., are exposed to high velocity sand/fluid slurries. S...

SUMMARYOFTHE INVENTION * ..*

* toon, The invention relates to a device and method for improving the * ...** * . * ....: erosion performance (i.e. decreasing the erosion) of components of downhole * . * tools --e.g. nozzles, throats, and diffusers --used when removing particulate a..... * S

solids from the well bore. The invention may include an insert, e.g. for a throat of is a pump assembly to decrease erosion along the entrance, barrel, and/or diffuser of the throat.

iooi The insert may be comprised of a hardened material, such as a plurality of diamond disks, formed from platelets, which are brazed into one integral insert. The diamond disks may also be stacked next to each other and mechanically secured within the throat.

100151 In some embodiments, the device may be comprised of one or more washers, each of which may be formed from polycrystalline diamond (PCD) -diamond crystals in an encompassing cobalt matrix. These washers may be sequentially stacked within the component, such as a throat, and mechanically secured therein. Such PCD washers may be machined from commercially-available blanks of various sizes.

ooop Also disclosed is a device comprising an insert for a downhole tool, the insert being grown from diamond crystals. The diamond may bc grown on a mandrel. Once the mandrel is machined away, the resulting insert is trumpet shaped, and may have a flare. The trumpet may be affixed within the downholc tool via epoxy or brazing, for example. Further, the trumpet may be comprised * of a plurality of pieces, or may comprise an integral unit. S... S...

JD0)7J Once mounted within the downhole component, the inner surface * i,..: of the devices described herein may be polished along with the remainder of the *: inner surface of the downhole tool such as a throat to increase the surface finish, which further enhances erosion performance.

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ioos A method of using the devices mentioned above is also disclosed, S...

is as is a method of improving the erosion performance of downhole tools utilized in the removal of particulate solids from the welibore.

BRIEF DESCRIPTION OF THE DRAWINGS

ooio Figure 1 shows a cutaway view of a jet pump known in the prior art.

-20 100201 Figures 2A and 2B show an embodiment of the insert of the present invention comprising disks.

iceiri Figures 3A and 3B show an embodiment of the present invention comprising PCD washers.

0022j Figure 4A and 4B show an embodiment of the present invention comprising a diamond trumpet brazed into the throat.

10023, Figures 5A and 58 show an embodiment of the present invention comprising a diamond trumpet epoxied into the throat.

10024, While the invention is susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and will be described in detail herein. However, it should be understood that the invention is not intended to be limited to the particular : *** forms disclosed. Rather, the intention is to cover all modifications, equivalents * ..* io and alternatives falling within the spirit and scope of the invention as defined by the appended claims.

DESCRIPTION OF IIJLIJSTRATIVE EMBODIMENTS * .

0O25i Illustrative embodiments of the invention are described below as *..SS* * * ** **** they might be employed in the oil and gas recovery operation. In the interest of clarity, not all features of an actual implementation are described in this specification. It will of course be appreciated that in the development of any such actual embodiment, numerous implementation-specific decisions must be made to achieve the developers' spccific goals which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming, but would nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure. Further aspects and advantages of the various embodiments of the invention will become apparent from consideration of the

following description and drawings.

100261 Embodiments of the invention will now be described with reference to the accompanying figures. Dimensions described or shown are s intended for example only, as the invention disclosed herein is not limited thereto. The invention is particularly well suited for use in a throat for a downhole jet pump. Refening to Figures 2A and 2B, a throat 100 is shown comprised of three sections: the diffuser section 10, the barrel sectIon 20, and * ** ** 0 * the entrance section 30. The dilThser section 10 may comprise a 6 degree taper 0.*. * * *0

to therethrough, as shown. The throat 100 may be comprised of any hard'ned * : material suitable for downhole use, such as 6% cobalt tungsten carbide. Flow of 0*S*** * fluid during the cicanout procedure is from right to left (i.e. the surface is on the : left, and the obstruction being removed from the welibore is on the right).

101171 In this embodiment, the present invention includes an insert 40, comprised of a plurality of disks 50. In this embodiment, the disks 50 comprise pure diamond, which are brazed into one insert 40. Each disk may be laser machined from commercially-available pure diamond sheets. An example of the final dimensions of the disks are: 0.040" thick (1mm plus 0.0005" braze), having a 7mm (0.28") outer diameter and a 2.59 mm (0 102") inner diameter.

Alternatively, other sheet thickness could be used, for example diamond disks 1.2mm (0.047") or 1mm (0.039") thick may be utilized, separately or in combination to achieve a desired insert length.

00231 These diamond disks 50 are comprised of relatively pure diamond crystal (grown in platciet form), from suppliers of pure diamond, such as SP3 Inc., of Mountain View, California. The stack of disks may be brazed into a single insert 40 utilizing a high temperature process that uses, for example, a * braze such as Cusil ABA, which is comprised of copper, silver and 2% titanium.

The insert is then attached to the tungsten carbide throat using a low temperature process and a braze such as Incusil ABA (comprised of indium, copper, silver and titanium). As such, the resulting insert 40 has a higher surface hardness than * ** *:.. inserts of the prior art, thus improving the erosion-resistance of the insert 40. * I

o Also, the absence of binders avoids chemical interaction with other materials.

* Further, the thermal conductivity of diamond is higher than that for other prior art I.....

* materials used in the manufacture of the 100. In operations where the throat * erosion is being affected by an increase of the surface temperature, inserts 40 *..

U.s made of substantially pure diamond disks 50 may be preferable to inserts is comprised of other materials, 100291 The insert 40 is shown located primarily within the barrel section of the throat 100. In the illustrated embodiment, the insert 40 comprises a stack of twenty two disks 50. Fifteen of the disks 50 are shown within the barrel section 20 of the throat 100. In this embodiment, the insert 40 also protrudes into the diffuser section 10 of the throat 100. As shown in this embodiment, four disks 50 of the insert 40 protrude into the diffuser section 10 of the throat 100.

These four disks 50 may comprise an inner diameter having a 6 degree taper to match the internal diameter of the diffuser section 10, or these four disks 50 may l0 have a uniform inner diameter matching the inner diameter of the insert 40.

Further, the outermost diamond disk 50 abutting the diffuser Section 10 may comprise a chamfered outer diameter.

100301 The insert 40 may also protrude into the entrance section 30 of the throat 100. As shown, three disks 50 extend into the entrance section 30. As shown in Figure 2B, these three disks 50 may conform to the geornetiy of the entrance section 30 of the throat 100. In this example, the three disks 50 have a degree taper to match the taper of entrance 30. *

100311 The overall length of the insert may be varied according to the * S *..* o size of the throat 100, e.g. in this example, the overall length of the throat is

I 1.111

* 3.78" (96 mm), while the overall length of the insert 40 is 1.042" (26.5 mm). 5.111

* 100321 It should be noted the numbcr of disks 50 utilized to comprise 5:11 insert 40 of this embodiment may vary as well as the dimension of the disks 50.

* For instance, an insert 40 of this embodiment may also comprise 15 disks 1.2 mm thick and 4 disks 1 mm thick. Thus, the invention is not limited by a given number or dimension of disks 50.

i0033 In operation, (as described above with respect to Figure 1), the high-velocity fluid with sand parliculates enters entrance end 30 of the throat 100. The sand particulates then contact the insert 40, instead of directly contacting throat 100. As the diamond surface of the insert 40 is significantly harder than material of the throat, the erosion performance of the throat 100 is improved. The throat 100 having the insert 40 of the present invention is thus an improvement over prior art throats having no erosion-resistant insert.

100341 Figures 3A and 3B show another embodiment of the present invcntion in which the insert 40 comprises a plurality of washers 60. In (he embodimcn* shown in Figure 3A, three washers 60 are shown, although the number of washers 60 can vaiy depending upon the throat 100 being utilized and the desired performance characteristics of the insert 40. Washers 60 are preferably comprised of erosion-resistant polycrystalline diamond (PCD).

Commercial suppliers of PCD material include Thomas Wire Die, Ltd. of Ontario, Canada. These PCD washers may be formed from commercially-* ** available blanks, which are available in various shapes and sizes. The PCD io washers 60 may be comprised of crystals having, for example, 5, 25, or 50 **..*.

* micron diameter diamond crystals sintered into the matrix of cobalt. It has been S..... * S

found that the PCI) blanks may be machined into washers (60) more easily than * * S SSSI * pure diamond, by utilizing processes known to one of ordinary skill in the art **.* having the benefit of this disclosure, such as by EDM (electron discharge is machining). Additionally, these PCI) washers may be polished to further improve erosion resistance.

(00351 In this embodiment, it will he noted that each of the washers 60 may directly abut each other to form insert 40, i.e., no brazing material is present between the surfaces of the washers 60. To keep the PCD washers 60 in place within the throat 100, the washers 60 abut inner diffuser section 66. In this embodiment, inner diffuser section 66 is comprised of tungsten carbide. The washers 60 and thc inner diffuser section 66 arc located within sleeve 64, which may be comprised of stainless steel. Nut 62 is threaded on the outer body 64 of the throat 100 to secure the washers 60 within the throat tOO, as shown in Figure 3, thus, providing means for securing the inner diffuser section 66 and washers within the throat.

100361 It should be noted that once assembled, the entire inner surface of s the throat, i.e. the inner diameters of the entrance section 10, the insert 40, and the diffuser section 10 may be polished to remove any burrs or sharp edges, from the entrance section 10 through the length of the entire throat 100. This also : improves the erosion performance of the insert 40, as erosion is decreased with improved surface finish.

I 3l Returning to the embodiment of Figures 3A and 3B, washers 60 * ***** * may protrude within entrance section 30 of throat 100, as shown in detail in ***.* * * Figure 39. The PCD washer 60 within the entrance section 30 may have an inner * * diameter to conform to that of the entrance section 30, shown at a 30 degree taper S... * . *5**

in Figure 313. As shown, the insert 40 comprising of the PDC washers 60 does not enter the diffuser section 10 of the throat 100. However, as with the embodiment of Figures 2A and 213, a portion of the insert 40 may protrude within the ditThscr section 10 of throat 100, and have a tapered surface to conform to that of the diffuser section 10.

100381 Experimental results have been obtained for this embodiment of the present invention. Sand was removed from a simulated well. Simulated well conditions were 8600 feet deep, 1000 p.s.i. bottom hole pressure (BHP), and diffuser/throat flow velocity of (100 feet per second. The erosion of the entrance and barrel section of the throat 100 having the insert 40 of this embodiment of the pTesent invention with PCD washers 60 was compared to that of the prior art throat, which was made of 6% submicron cobalt tungsten carbide, after each throat had bcen exposed to similar conditions. A 12-fold improvement in erosion performance was noted with the use of the insert 40 having PCD washers 60.

s 100391 Ii should be noted that in another embodiment not shown, the insert 40 of Figure 2 (i.e. the plurality of pure diamond disks 50) may be assembled in a manner similar to the diamond washers of Figures 3A and 3B.

* That is, the diamond disks 50 may be stacked directly next to each other without the use of brazing material. (11 this embodiment, the diamond disks 50 are in secured within the throat 100 by inner diffuser 66 being within a sleeve 64, * secured by a nut 62, as described with respect to Figure 3A. This is *S** advantageous because the brazing material may be relatively soil, thus eroding ***.* * more quickly than the diamond, thus exposing the edges of the disks, which may **** * a a...

decrease erosion performance.

is 10o401 Now referring to Figure 4A and 4B, another embodiment of the present invention is shown. In this embodiment, insert 40 is comprised of an integral trumpet or tubule 70 having a flare 72. The trumpet 70 is comprised of a single piece of diamond that may be grown on a cone or mandrel to the desired size and shape using a plasma flame. After the diamond is grown on thc -20 mandrel, the mandrel may be machined Out to leave only the trumpet 70. The trumpet 70 may then be machined as necessary, to form flare 72, for example.

The resulting long, columnar crystals are oriented perpendicular to the flow direction, the crystals oriented perpendicular to the flow direction of the sand-laden fluid have superior erosion resistance as compare to crystals randomly oriented or oriented parallel to the flow direction.

100111 In the embodiment shown, the flare 72 of the trumpet 70 of the insert 40 extends into the entrance section 30 of the throat 100. The remaindcr of s the trumpet 70 may reside in the barrel section 20 of the throat 100. Although not shown as such, the other end of the trumpet 70 in another embodiment may protrude within the diffuser section 10 of throat 100.

ixi In this embodiment, the trumpet 70 is brazed within the throat. To facilitate this process, the throat 100 further comprises a braze feed path or hole * .** io 74 utilized to supply brazing material.

* : 110431 Referring to-Figure 5A and Figure 5B, another embodiment of the * : insert 40 of the prescnt invention is shown as a trumpet 80 having a flare 82. The * ...* * configuration of this embodiment is identical to that shown in Figure 4, with the I.. * * S...

exception that diamond trumpet 80 is epoxied within the throat 100, instead of being brazed within the throat 100 as shown in Figure 4. Thus, the throat 100 docs not require a braze Iced hole.

100441 Additionally, the trumpet 70 may be comprised of two sections in some embodiments. The trumpet may have a mouth having a larger inner diameter than the barrel section of the trumpet, the mouth being on the opposite 2U cnd of the trumpet than the flare, and extending into the diffuser section 10.

10045) Although various embodiments have been shown and described, the invention is not so limited and will be understood to include all such modifications and variations as would be apparent to one skilled in the art.

Specifically, although the disclosure is described by illustrating inserts for use with a throat, it should be realized that the invention is not so limited, and that the erosion-decreasing devices and methods disclosed herein may be equally employed on diffusers, nozzles, and the like exposed to high-vclocity flow of s tluidlparticulates downhole. * S. * S S *5SS * *

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Claims

CLAIMS

1. A downhole tool comprising: a bottom hole assembly having a central opening through it; and an insert having an inner diameter, within the bottom hole assembly, made of a hardened material to protect the bottom hole assembly from erosion as fluid passes through the central opening and the insert, wherein the insert is of diamond or polycrystalline diamond for protecting the tool from erosion as fluid enters a tapered opening of an entrance section and passes through the insert, and : *. the insert is in the form of (a) a plurality of discs or washers adjacent one * .. S another, or (b) an integral flared trumpet. * **S

2. The tool of claim I, wherein the bottom hole assembly is a nozzle or a diffuser. * .

3. The tool of claim I or 2, wherein the insert is in the form of a plurality of disks made of substantially pure diamond, brazed together to form the insert, each disk having **.

an inner diameter.

4. The tool of claim 2, wherein the insert further comprises a plurality of washers made of polycrystalline diamond directly abutting one another to form the insert.

5. The tool of claim 2, wherein the insert comprises an integral trumpet having a flare, the trumpet being comprised of grown diamond.

6. Adownhole tool, comprising: a bottom hole assembly having a central opening therethrough; and an insert having an inner diameter, within the bottom hole assembly, made of a hardened material to protect the bottom hole assembly from erosion as a fluid passes through the central opening and the insert.

7. The downhole tool of claim 6, in which the bottom hole assembly is selected from the group consisting of a nozzle, a throat, and a diffuser.

8. The downhole tool of claim 7, in which the insert comprises a plurality of disks made of substantially pure diamond, adjacent one another and brazed together to form the insert, each disk having an inner diameter.

9. The downhole tool of claim 7 in which the insert further comprises a plurality of washers made of polycrystalline diamond directly abutting one another to form the insert. * a. * . a a...

10. The downhole tool of claim 7, in which the insert further comprises an integral a...

trumpet having a flare, the trumpet being comprised of grown diamond.

* a.... a * * *

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