US2358679A - Mud dispersion apparatus - Google Patents

Description

Sept. 19, 1944. v. B. zAcHER 2,358,679

MUD DIsPERsIoN APPARATUS Filed July'e, 1942 l 2 sheets-sheet 2 ATTORNEY vPatented Sept. 19, 1944 2,358,679 q n DISPRSIONLAPARATUS 'i s V emplication only r6, 194,2, seminal-49,901.

(Oliila-'o 12 claims.

. My invention relates to an apparatus,` for laccomplishing the dispersion offlocs formedin'drill-f ing muds during use.

This application is a continuation in .part of my pending application Serial No.' 337,411, led

May 27, 1940.

In the operation of modern day drilling. ofoil.

wells, the practice is to force down through fthe drillpipe a mud mixture which serves :to lubricate the bit, assist in the cutting, and alsoto carry thecuttings out of the well. There .areother ad.- vantages inherent in theuse of drilling mud, such vas supporting the walls of the ghole, sealing o porous formations, cooling thebit, etc.l YBecause of the many functions it must perform, itis .essential to keep the mud in the best Vviscous condition for the ilarticular job Vat hand; i L In the past, by one means or another to bereferred to later, the drilling fluid has been trea'ted in an eiort to give it the Viscosity yield. strength l or gel strength most conducive toits beingpumped down the drill pipe. The body of mudmoving upwardly in this mile or two mile drill pipe ,pas-

sage is .sometimes called the slug flow. Y n; z- Y After the drilling fluid has passed down the dil-,ill pipe and has lubricated the bit, picked `up the mile or, two mile passage around thefoutside of. the drill pipe, it has changed considerablyinrits phys'- ical make-up. It has much .greater viscosity `or stiffness than when it was originally introduced into the drill pipe on its Vdown trip; and-asgit emerges from the top of the jwell it is usuallyzt'hen in no condition to be recirculated without retreatment. Y v

This retreatment of the mud mustjta-ke-fcareofV l may be employed during the drilling period. ,Such

mixing machines are typified jby the Sonsthagen Patent No. 1,363,368. Also`my invention istofbe distinguished from devices which relate to the problem of freeing the mud slug'f-rom entrappedgas by means of paddlesoperating at 4200 RQP. in a vacuum chamber as .taught bythe .Henst Patent No. 2,142,270. Each of the abovedevices wouldbe used on a drilling `job when the-particular problem they relate to is encountered. ,However, neither takes the place-offor Woulddowhat my device and method does in'regard topthe. par:- ticular and different problem- "i-it deals with,

namelylchopping theviocs .which Vhave formed inthe'mud f. s 1

Upon-emergency from '.topio'futhe well the mudai's overi'lowedinto a ditchby way of anoverowfpipef Itis njotaiuncommon for the Viscosity ,ofthisfslugxilowtoibe'so great as to plugthe over- -ilowpipezandcause themud to Aspl'll over the well head finto the cellar.: ,The high` viscosity .of .this slug ow :also malresitdiiicult to move :it in the `ditch on-its ,wayltov the yarious treating devices, .such asmentioned` above-and eventually back into vthedrillpipe.y f y L Y.

@condition of high Viscosity (yield strength)V .of

the.:drilling mudzcan interfere as muchas any :other'factor with; satisfactory drilling progress.l

Thefoccula-tion which often produces Athis high rviso.osity,v gives `the fluid .a fluilinessand lightens it sopthat-pump troublesgfollowv ,In addition to this -lthe-.highyiscosity cuts down the rapid flow of the :llidsthrough theLbi-t holes ,in the bottom ,of the :Welland robs the fluid "of :its hydraulicking jet `Yllll; ing'making the hole; Todaymuch ,reliance lplaced on `thesupplementaryi cuttingY effect of this-fast flowllgmud being rejected `fromgthe bit hOIlBS.. Y 'Y Y In the past,-` in orderfto reduce'theviscosity 0'1 gel-s *length ofthe mud, resort has vbeen :had to :to disperse a `fiocculated condition.

chemicals Still another method has been to employ large pumdpsto lift the ,mudginto riflle towers, from' r,iivhic-lf1itjturnblesover ya seriegof steps, the tendeny being-to reduce its. viscosity or gel strength. Eachof .the-above schemes is very costly, requiring expensive pumping equipment or chemicals, and lgives .only .an apnroximateresultfas contrasted ,with the Positiveresults offemploying my'fmethod apparatusx l Y l 1; have found? that/@hopping blades, located ear `the .bottom of. the fdithfad-iaent the'- Outlet from the well, if.. operated atk a 'will transform :the thick vslug flow into v4an easy flowing dril1in`g`iluid." Exactly ,Why this fshould be the caseI have not been ableto ascertain and therefore I` advance` the following explanations withv the understanding thatv subsequent experiwell casing, lnfioving at'A the rate ofaboutY oneinile' passage up the mileY or two 5anlhoury during Y'its miles of well hole, theparticles tend to' occul'ate, that is, theyftend-to attract eachother and grow growth in particlesize of these elements, the vis- `very highspeed, Y

pears that as each layer of flocs is chopped orv j sheared from the face of the advancing nmud stream, they are thrown into a vortex, where their affinity is further broken. They appear to come before they move out of this vortex. The'- mud beyond the vortex is very much reduced in viscosity, the vflocs are broken up, and it is'ready'to" .be treated for gas removal as suggested by Henst No. 2,142,270, ifA that is a problem on `the par-` ticular wellbeing drilled. w 1

It is, therefore, one of the objects of Vmyvinven- Ytion to provide'anapparatuscapable of dispersing Athese flocs, so that `the mud can moveV on, down the ditch', and receive any lfurther treatment for other conditions to be.overcome' before it lstarts downthe well-tubing on another trip.

- ,Another object of my invention is to provide novel apparatus capable of dispersing these flocs, without impeding the continuous*movementv of mud in the ditch, and where necessary,'giving a 'sufficient-...propelling force to thertreated mud to Vkeep it moving and to prevent it from overflowing the casing head or the ditch. The mechanism exerts .extremelyY littleaction to force mud V.downV ditch, and, in effect, really does little morethan allow flow Yto be unimpeded. The free; flowing tendency down ditchisfof -course, mostly caused bythe reduced' viscosity as wouldV be expected.

Another object of my invention isto' provide an apparatus by which one lor morelvery high speed choppers establish a shearing or chopping face in the mud stream from which the mudis 'chopped oi in thin layers Aby the rapidly rotating knives or choppers and the chopped off portion -is throWninto-'what might be describeda's va vortex. In a sense, it is ones by means of the-high 'speed operation which vchops or shears, and then throws the dispersed making little: ones out offbig llocs into the'vo'rtex `from which they emerge tinto the mud stream,

Other objects of myinventionwill appear from the description and drawings yas I have notat-V tempted above to state them all. Nor is this K description intended'aslmore thantfullfcompli- Yunder the influence of the chopper several times cosity or stiffness of the mud rises perceptibly.

Fig. 2 is a view in side eievation, partially in cross-section, showing details of construction;

Fig. 3( is a view in end elevation taken on the line III-III, of Fig. 2;

Fig. 4 is a view in side elevation, partly in crosssection, showing a modied form of apparatus;

Fig. 5 is a similar view of another modication;

Fig. 6 is a view in side elevation, partly in crosssection, showing another modification. Y VIn .the drawings, numeral I0 indicates the well casing whichmay or may not extend to the bottom of the well, depending upon the formations encountered and the depth of the well. In any event, it is suflciently tight to provide a conduit for returningto the surface the drill fluid or mud introducedin the drilling operation. 'Ihe drill pipe VII extends to the bottom of the well and v at its lower end is secured the bit or drilling tool (not shown) and down through its center is cir- "c'ulated the drilling fluid or mud for purposes already pointed out. As. this drilling fluid emerges'from the top of the well casing I0 it overflows into pipe I2 and .thence to the mud ditch I3 through a suitable pipe I4.

, I prefer to fabricate my apparatus asa unitary structure, adapting it for ready placing in and YIemoval'fro'm ditch. I3. The apparatus includes -the housing .I6 and suitable bulkheads I5 with hinged'wings Ia.N The llatter serve to guide the `mud through housing. I6 where it is treated. After the ,mud is treated in housing I6 it is conducted through suitable ditches tothe pit from which it is pumped down the drill pipe. Before the mud reaches the pit it may be passed through yscreens which remove the cuttings, shale and any other hard'particles'which it carried to the surface, and it mayy pass through a device like Henst No.r2,l42,2-70 for gas removal treatment.

The chopping or shearing apparatus employed 'in mymethod of reducing the viscosity or gel strength ofthe thickened mud, comprises one'or.

'more choppers 20, A2| arranged to rotate in casing -I6- nearthe-bottom of Yditch I3, where they may be operated at veryrhigh speed. They may have :an inclined .face to impart aV slight imlpelling effect.` Preferab1y,'they are'mounted on a shaft or shafts set atan angle less than 90 with respect to ditchA I3 so that the net effect will be to impart Vmovement,`or at least not to impedeY movement,

of vthe mud down the ditch. Y

VInYFig.- 2, chopper shaft 22 is mounted at an ."angle of 172 in relation to the floor of the ditch.

ance with R. S. Sec. 4888,` requiring the explanation of one mode of applying the invention, which compliance vdoes notlimit the invention `tothe illustrative embodimentexcept. as required by the appended claims. j p Y.

In the drawingsare shown several Vformsof apparatus for practicingmy method." It is ob.- vious thatv otherehang'es Vcould be made inthe apparatus and still .practice themerthod, and it is not my intention to limit the apparatus Vexcept 'as required by the appended claims.Y

In' the drawings, in which similar.. reference numerals referto likelparts: g f

` Fig. 1 is an isometric view of a portionV of a `well `near the surfaceshowing the apparatus ofm .invenionmminiedm the mudcivch;

I' vlIi'lFig's. 4, 6 it is mounted at an angle of 60. Thev preferable range seems to be '75 to 60. In devices like Fig. 5, the shaft 22 may be substantially parallel with the floor of ditch I3.

/I have vobtained very fine resultsV- from using 'a -pairofchoppers 2li-and 2I mounted on shaft'22 whichis carried in suitable anti-friction bearings arranged in housing 25.V A motor 26 or other fsuitable drivingY meansgmayY be employed Vfor roftating shaft 272. l

The chopper 20 Ais rigidly secured to shaft 22 with its impeller faces set at an angle of 2022 Vfrom a `plane perpendicularto the axis of the shaft. In ohegdevice tested, .the Vdiameter of this chopperwas about 51/2 to 6'.; The imlpeller faces vwere4 set so that upon rotation .of shaft 22 the mud was deflected downwardly in a general direction toward the right h and' end of housing I6. Chopper 2| was`also rigidly mounted on shaft y l22 and had its impellerfaces Vset at an angle of `15-1f7`fro'n`i 'a plane'perpendicular to the axis of -the shaft. It was of slightly-smaller size than Achopper 20, being from 5 to 451/2" in diameter;

to housing vortex created by the-impellers.

Theimpeller' faces were 'set in a direction opposite to the corresponding faces of chopper'20 lso that uponrotation of shaft 2 2 they impelled the mud in an upward direction or counter to the direction imparted by :chopper 20. Being of 'a smaller size and with the blades set at a lesser angle than chopper'Zll, the latter was the predominant one of the pair and assisted movement of the mud down the ditch. .In relation to 'direction of rotation the set of the impelling faces on the choppers is' `suchthat they .act like a knife or chopper and lift or throw the severed ocs away from the point of cutting. For example,

in Fig 3 the shaft would rotatecounter-clock- Wise looking down the shaft from the motor end.

It is preferable in aplural chopper apparatus, in order to interfere as little as possible with downstream movement of 'mud through casing I6, to havethe larger or more effective chopper arranged in an upstream-position in relation to the less elective chopper. It is to be understood that the effectiveness of a chopper may be varied by changing its diameter or by the angular set on the impelling face, etc., consequently, when I use the term morereiective impeller, I am not necessarily referring to one with a larger diameter.

'fective in 'b'reaking up the noos, presumably by za"shaving, chopping, or shearing action com,- bined with a throwing or `impelling of the severed portions. away Afrom eachother in a vortex, so thatfthey do not -re-.unite to reform the larger floc, in which form it emerged with -the'slug flow from the well. Y f As stated earlier, the high velocity of the chop.- per blades moving adjacent the face ofthe slowly advancing mud appears to have the same ef.-

' fectas if the flocs were placed on a chopping f blockY andthen chopped with a .keen knife at The shaft housing 25 is welded or otherwise secured at 66 to housing |6.- The latter is per- -forated at 21 to vpermit entry of shaft 22 with a slight clearance.

In the drawings is 'shown a hopper 23g-fitted I6 at 24, preferablydirectly above the By means of valve controlledby rod 3| threaded in web- 32 the hopper contents (usually chemicals) canfbe fed into housing I6 in the quantity desired. The choppers'20, 2I will cut the chemicals intothe mud. f

The whole'unit may besecurely vmounted in fditch I3 with vbulkheads I5 resting securely on the! bottom, by mean'sof co11ar'29' to which is attached horizontal angle member 34 adapted to 'rest on or be securedto the top of the trough sides. Upon looseningthis collar 29 Ysupporting arm 34 can be brought to rest on the top edges of ditch I 3. A- gate-35 is mounted to slide in a Y slot 36 in the downstream end of housing I6. A spring 3ft-holds it in any selected position.v By

use of` gate 35 a 'good working level of mud in fhousing I 6`-can be assured.

The modification shown inF'ig. ioliiifers from Fig. 2v only in respectV to the tilt to' shaft 2,2 and @arrangement of choppers 20Qand2l. In Fig. 4

the mud movement is itoltheright and chopper 2| is arranged to be more effective'than chopperV 2 0, so thatthefnet effect isy for the chopped mud to emerge from thel vortex ,withY a slightdirectional movement downstream; Shaft' 22 slopesto the right, preferably at an angle Vof 60 to` 75 to the bottom of ditch I3'.

lThe modification shown in Fig. 5 employs ltwo Vchoppers 2l), ZIarranged on shaft 22 which vmay Vproject in fromupperjendwall 'III of ditch I3 or 'be rotated by other suitably'mounteddrive Mud movement is to the right. ChopperZIl is prefer#r ably slightly more effective than chODDeI 2l, al-

-though it need-not be as lthe sheared off ocs entering and then emerging from kthe lvortex will 1 tend to travel downstream with thefgeneral vmud movement.V i The modicationshown in Fig. 6 is substanhigh'velocity The face .of the advancing mud stream seems to hold the flocs, while the blades -chopthem off. vThe mud is chopped, then it is thrown intoand out of the vortex. This action is Lto be distinguished frommixing ormoving a fluid.l with a propeller. Inmy device and method there is: no particular speed up in movement of the mud in ditch I3.

The purposerof my device is not to move the mud in ditch I3. If the choppers acted like a mixer or screw feed pump they would speed up mud movementalong ditch I3 to at least twice its normal rate. Thiswouldgbe bad because it would scavenge the ditch above thel choppersand prevent submerged operation for the choppers. y

Because V,of the above,the matter `of-'velocity or* speed of rotation of the chopper or choppers is important and gives my new result. This veloci-ty can be determined on'the following basis. -Selectthe normal and desired: volume and rate of movement of mud in ditch`V I32-V SelectV the speed most satisfactoryfor shaft22l and divide it bytwo. Then calculatev from these'factors the size and pitch of an-impeller face which would move the mud in ditch I3 at the desired normal rate with shaft 22 turning at vhalf speed. With such an impeller face operated at normal instead of half speed, one is usually assured of obtaining sufficient velocity to avoid pumping'on the-one hander cavitationvon the other, and to obtain the desired chopping action.- Thisis given as an example and not with the idea that doubling theimpeller speed is'the critical speed.

It is a speed which does appear to give good -re- Asults.

` The` important thingis to vhaverthespeed of shaft 22 and the .chopper or choppers of a size and angular setA on their impellingr faces such that these faces lose most of their zpumping im- Ypeiling function in favor of the chopping or` ishearingfunction of the choppers..V ,The top limit Y on the speed range should bejust belows'the point ability.V of the" chopper-impell'ersto create a vor- .tex or vortices as vthey throwoff the chopped noos. For-example, the thickness `of layer chopped from the face of the advancing. mud

wall.-onreachrevolutionis only a fraction of the thickness oflayer that would vbe peeledo'if .if

-tially like the one rin Fig. 2, 'except thatfchoppers l 20, 2I` are'made of equal eiiectiveness. l The devices just described are particularly ef` the "device were being' used=as a.,mixer or as a Dump to move the mud in ditch I3;

I have found the devices shown in Figs. 2, 4, 5 and 6 .t'oibe particularly efficient; The chopperimpellers are seti tol produce impinging Vvortices ofthe :severed particles. This apparently vcreates 4i 2. In amud floc dispersing a 'maximum zone of turbulence and impingement in housing I6 so that very, little mud escapes the chopping` treatment. y

I have tried in Fig. 2 to illustrate what paths the highly viscous untreated mud takes and how the chopper-impellers act on it. The dotted lines 40 and 50 indicate roughly the innermostfaces orboundaries of the untreated mud slug as it movesup into position, and the arrows 4| and 57| indicate its general direction of movement into the chopping zone. .The high speed of rotation of choppers 20 and 2|, coupled with the high viscosity of the untreated mud, results in a chopper causing the mud above chopper 20 and below chopper 2l to take the form substantially of the profile of the edge of the chopperblades. vIt is something'like a vortex or whirlwind. On each rotation the choppers cut or sever a thin layer of this highly viscous mud wall and throw or impel these .severed particles in the general direction of the arrows 42 and 52 to form a vortex. These severed particles are not ,only thrown toward each other, but are also subject to a centrifugal action in the vortex which, judging from the results obtained, effects a thorough deflocculation vof the mud. There is every indication that the flocs which enter the vortex are passed through the choppers several times before they are thrown out and move downstream.

Because the larger chopper-'impeller 20 is set y.

to act in the downstream direction, the net effect is for the deflocculated mud to be assistedin its movement in that direction.

While to illustrate my invention I have described apparatus having a single shaft 22, it is obvious that a shaft for each chopper might be employed as the means for rotating the choppers. f

`What I claimis:

1. An apparatus for mechanically dispersing a fiocculated colloidal system in a mud'slu-g moving slowly in, aditch, means including a shaft set at an angle to the axis of said ditch, means for supporting said shaft operatively in said ditch, means for rotating said shaft, a plurality of chopper-impeller means secured to said shaft in spaced apart relation along the axis of saidshaft,- a portion of said chopper-impeller means having their ,impeller surfaces arranged at anglesY to throw flocs chopped from said mud slug into the area between them.

apparatus adapted to operate submerged in a ditch fullof a slow Yrnovingmud slug, the combination of a frame,

a shaft set atan angleA to the axis of said ditch, means for rotating' said shaft at high speed, a chopper and impeller on said shaft and a second ,chopper and impeller on said shaft spaced apart from the other, the impelling surfaces on said choppers being disposed so as to throw the 4severed mud i'locs toward each other.

l' 3. A mud treating device comprising a'frameY for positioning over a mud ditch, a vshaft rotatably supported by the frame, said shaft being downwardly inclined from the frame in the di-A extending fromthe frame into the mudV ditch at anangle less than a right angle to the axis of said ditch, means for imparting rotation to the shaft, and a pair of oppositely set mud cutting and impelling members secured spaced apart along the shaft adjacent the lower end thereof, the member farthest downstream being smaller than the other member. Y

5. A mud treating device comprising a frame, for positioning with respect to a mud ditch, a shaft rotatably supported by the frame, said shaft being-inclined in relation to the bottom of theditch and extending from the frame into the mud ditch, means for imparting rotation to the shaft, and a pair of oppositely set mud cutting and impelling members secured spaced apart along the shaft adjacent the lower end thereof, the member4 farthest downstream being smaller than the other member. Y

6. A mud treating ,device comprising a frame for positioning withl respect to a mud ditch, a shaft rotatably supported by the frame, said shaft being inclined in relation to the bottom of the ditch and extending fromV the frame into the mud ditch, meansv for imparting rotation to the shaft, and a pair of oppositely set mud cutting and impelling members secured spaced apart along the shaft adjacent the lower end thereof, whereby upon rotation of said shaft two zones of oppositely directedV and severed mud will be produced. f '7. A mudv treating device comprising a ditch chamber having an inlet and outlet through which mudV is free to flow, a drive shaft mounted in saidv chamber in a position inclined tothe verticalin the direction from which the mud enters said chamber-,means for rotating said shaft, a pair` of severing and impelling means secured to said shaft, spaced apart vertically thereon, with their Yrespective impelling surfaces oppositely set, and in which the uppermost of said severing means is madewith a more effective impelling surface Y l Y 8. A mud `treating' device'comprising a-ditch chamber having an inlet and outlet through which mud'is free to flow, a drive shaft mounted in said chamber in la position slightly inclined to the vertical in the direction from which -the mud enters said chamber, means for rotating said shaft, a pairpof severing meansy with impelling surfaces secured to said shaft, spaced apart vertically thereon, Vwith theirA respective impelling surfaces oppositely set, and in which Vthe uppermostofsaid'severing means is made with a more effective impellinglsurface.

, 9. Amud treating device comprising a ditch chamber havingan inlet and outlet throughwhich Y mudiis free to'flow, a drive shaft mounted in rection of mud flow in the ditch, means for im- Avparting rotation to theV shaft, and a 'pair of oppositely set mud cutting and impellingimembers secured vspaced apart along'the shaft Vadjacent the lower end thereof, the lowermost member being smaller than the other member.V y f ;fl. A mud treating device comprisinga frame for'positioning with respectfto a mud ditch, a shaft rotatably supported by Saidchamber in apositionslightly inclined to the Verticah means'for rotating said shaft, a Vpair of severing means vwithl 'impelling surfaces secured to l'said shaft, spaced Vapart Vvertically thereon, with .their respective s' impelling surfaces oppositely set, and in which the severing means farthest' upstream is made with a more effective impelling surface.v g' Y I 10. A mud treating device comprising a ditch chamber Yhaving aninlet and outlet through which Vrnud.is free to iiow by gravity, a drive shaft mounted in said'chamber inclined in relation to Y the bottom of said ditch, means for rotating said theframe, said-.shaft VVV shaft,y a pair of Ysevering meanswith impelling surfaces secured to said shaft,'spaced apart axially thereon, with their respective impelling surfacesoppositely set,

11. Apparatus for rendering circulated viscous drilling mud suiciently less viscous to permit of it being recirculated, comprising a conduit for the passage of said mud, upstream and downstream sets of radially disposed blades in said conduit and having oomminuting edges, said upstream and downstream blades being twisted, and means inclined in relation to the axis roi" said conduit to rotate said blades at speeds sufliciently high to subject said mud passing thereby to very fine commuting action and in such a manner as to cause said upstream twisted blades and said downstream twisted blades to oppose each other.

12. Apparatus for rendering circulated viscous drilling mud suiiciently less viscous to permit of cause said upstream twisted blades and said downstream twisted blades to oppose each other, said upstream set of blades having a greater forwarding eiect on said mud than said'downstream set of blades. I n

VERNON B. ZACHER.

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