US2659438A - Means for cementing wells - Google Patents

Description

Nov. 17, 1953 s. B. SCHNITTER MEANS FOR CEMENTING WELLS 4 Sheet 's-Sheet 1 Filed Aug. 16, 1946 INVENTOR.

Sylvester B. Schnilzer fig ATTORNEY 7 wawwwn 4 Sheets-Sheet 2 Nov. 17, 1953 s. B. SCHNITTER MEANS FOR CEMENTING WELLS Filed Aug. 16, 1946 .QM W'M WI 17, 1953 s. B. SCHNITTER MEANS FOR CEMENTING WELLS 4 Sheets-Sheet 3 Filed Aug. 16, 1946 .S'ylvesferfl Sclm iitl' INVENTOR.

BY ML,

ATTORNEY NOV. 17, 1953 5 SCHNH-TER 2,659,438

MEANS FOR CEMENTING WELLS Filed Aug. 16, 1946 4 Sheets-Sheet 4 JNVEN TOR.

ATTORNEY Patented Nov. 17, 1953 UNITED STATES PATENT OFFICE 2,659,438 MEANS FOR. CEMENTING WELLS Sylvester B. Schnitter, Dallas, Tex., assignor to L. L. Rector, Tarrant County, Tex.

Application August 16, 1946, Serial N 0. 690,969 7 Claims. (Cl. 166-1) This device is primarily intended for the cementing of casing or pipe strings, commonly used in bored holes-penetrating the earths strata.

tendant damaging effects on the slurry. 7

In short, at the very point and placewhere it is most desired that firmness be maintained by in place, the former methods for attempting closure have lessened the pressure; and the very was weakened and made non-dependable. In the former systems, at the time of the aforesaid pressure reduction designed closure, there was an appreciable reversal of movement in the slurry after above the ports.

In my method the devices.

important porti-and-strata-sealing that was sought after, by the cementing operation,

It is of no little consequence that no satis--' factory and absolute-closure of the discharge ports seal inside nor after they have functioned.

The instant invention is designed to afford both inside and outside seals; and when used there a disruption of the integrate is no chance of plug within'the area of my cementing In light of this specification, there'w'ill be found among the objects of my invention, the following:

(a) A method for cementing pipe in any well by discharging slurry at alevel, or successively" (b) A method for cementing to prevent a gyrating action charged slurry; and to prevent such slurry about the vertical pipe in any well Within the disany spiraling of in* a meeting and contacting of opposed flows, at a point'clo'sely adjacent to and beyond thepo'int of discharge.

((2) a meth'odfor cementing pipe in any well at two levels'without time lapse 'betweenthe first sh'o'e placement and the subsequent cem enting collar discharge of slurry; and either procedure being elective by the operator, based on physical conditions encountered.

(e) A method for cementing pipe in any well, wherein a volume of slurry is maintained between a pair of collapsible cementing plugs, prior to discharging the slurry from the casing; and in which no amount of slurry is permitted at any time to pass through the primary plug preceding the slurry.

(f) A method for cementing and immediately re-cementing pipe in any well by discharging slurry from casing below and across and above a selected level of precarious characteristics (hereinafter described); and which slurry placement is followed, in immediate succession, by a second discharging slurry from casing, below and across and above the same selected level of precarious characteristics, the whole operation resulting in the complete integration of all cement placed.

(g) A method for cementing pipe in any well in which is employed hydraulically operated means for opening the terminal ports of the cementing collar; and other hydraulically operated means, for closing and sealing the terminal ports of the cementing collar.

(h) A method for cementing pipe in any well employing activated means to provide egress from the casing; and employing other activated means to shut-off such egress; and further employing still other activated means to permanently seal-off such egress from the casing, and analogically and conversely shutting off all subsequent ingress thereto.

(z') A method for cementing pipe in any well, employing means for closing and sealing the terminal ports of the cementing collar to be accomplished within pressure therein, being the same pressure at which the slurry is finally discharged through the terminal ports; such pressure-balancing within the area precluding any variation of pressure, the action of which is damaging to slurry in place.

(9') A method for cementing pipe in any well, in which the final pressure developed by the pump on the casing may be retained, or released, wholly or in part, without any damage to the slurry in place.

(is) A method for the interval pipe in any well, plugs, whereby the terminal ports of a cementing collar, unopened for any reason whatever prior to the drilling out of the cement in the casings, may be effectively sealed against leakage from within and from without the casing; and which sealing does not require an after-cementing operation of any nature.

(I) In the cementing of wells, a cementing collar provided with port means which, when opened, will permit a reversal of the direction of flow of the well fluid, if required for any purpose whatever.

(m) A port-carrying collar capable of such flexibility of use and operation that it may be made to provide a single means for closing and sealing the discharge ports; or to carry a plurality of different means for such purpose; when provided with plural means, one such may eifect temporary closure of the ports, and another effect permanent closure and sealing.

(n) A port carrying collar provided with means for opening ports, and other means for closing ports, operation of the collar being so simple that it may be safely and effectively used by untrained labor and yet result in most dependable operation.

My method and my device, and its construction, operation and use, is illustrated in the accompanying drawings, which disclose a satisfactory and preferred form of my device. It is to be understood, however, that I can practice my method effectively and satisfactorily with devices which incorporate and use the same, notwithstanding that such devices may be in forms and arrangement somewhat different from the structures illustrated in the accompanying drawings; and such departure from the structures delineated will not depart from the spirit and essential principles of my method.

In the accompanying drawings:

Fig. I is a partially sectionalized elevation of a typical installation of a pair of my cementing collars carried by casing in place below the earths surface, to provide three-stage cementing, through the shoe and the collars.

Fig. 11 is a partially sectionalized elevation of a typical cementing collar, before the cementing operation is performed.

Fig. III is a partially sectionalized elevation of a cementing collar, connected to and above a casing which carries a collapsible cementing plug with rod extending into the collar to carry a trip member; and in which the terminal port discs have been dislodged.

Fig. IV is a partially sectionalized elevation of a cementing collar in which the baflles have been forced to lower position, closing the sleeve passage.

Fig. V is a partially sectionalized elevation of a part of the collar in which discharge flow dispersal mechanism is disclosed.

Fig. VI is a partially sectionalized elevation of a typical collapsible cementing plug.

Fig. VII is a partially sectionalized elevation of a cementing collar carried by and below a casing in which a collapsible plug is provided with a rod extending into the collar to carry a trip "member.

Fig. VIII is a partially sectionalized elevation, comparable to Fig. VII except that the sliding sleeve has been forced downwardly into final position, sealing the terminal ports.

.Fig. TX is a plan view of the structure shown in Fig. V, taken along the line 9-9 thereof.

Fig. X is a sectionalized elevation of a trapping collar, in which the collapsible plug shown in Fig. VI has been trapped.

Fig. XI presents schematic drawings depicting seven stages in the disposition of parts of my device at various steps in plural cementing operations.

Fig. XII is a partially sectionalized view of the tapered wall of the collar and a modified form of the tapered wall of the sleeve.

In the drawings the various parts and elements of structures employed in the practice of my method and in the construction and operation of devices required thereby are indicated by numerals; and numeral l indicates the earth's strata; and the numeral 2 identifies the bored hole of a well, whether it be an oil well, a gas well, a water well or other. The surface casing foundation 3 supports the machinery used in drilling operations; and the well casing 4 has been lowered into the drilled hole to the desired depth, usually to a point near the bottom of the hole 9.

In Fig. I a typical string of casing is in place, and carries upper cementing collar 5, lower cementing collar 6, trapping collar 1 and a conventional shoe 8; these members being disposed casing 4;

the internal diameters of the bafiie devices in each such cementing collar. The lowermost collar carries movable bailles having a smaller diameter than that of the baiiies in the cementing collar of the greatest diameter.

The arrangement heretofore indicated, and

particularly that depicted in Fig. I, is intended together with the conventional shoe 8, to eiTect a dual cementing operation. Further typical cementing collars are simply added to the string of casing at the several levels where further cementing is to be done.

Referring noW The upper sub is provided with female top threads l2, which comprise companion threads for attachment to threads at the end of a length of casing.

shoulder IS on the sleeve locking sub IS, the latter being used as a connector for attaching sub H to body 28.

Sub II is provided with male bot-tom threads 14, to engage female threads I! on the sleeve locking sub l5. Sub ll is provided with an inner bore l5, which has a diameter similar to the bore of easing A which carries the cementing collar.

Sleeve locking sub I6 is provided with a series of horizontally disposed female serrations 18. These are preferably slightly rounded so that their indentations may more easily mate and form locking engagement with complementary male serrations 56 in the top of movable sleeve 55.

The sleeve locking sub I6 is provided with a square shoulder 20 for horizontal locking and I 6 v, frictional engagement to a similar mating surface 36 on the upper face of the body 28. This when the after the connected to subs l6 and 2-5, and which houses most of the operating mechanism of the cementcollar (5 or 5) of which it is a part.

There are shearing screws 29 passing through the walls of body 28, and-through the wallv of sleeve "5 and into the wall of the upper baflle 85, so constructed and disposed that whenthis baiiie is moved downwardly these screws ,are

Also'when the sleeve fiiiis-movedidownwardly (an operation subsequent to the -moveca: ed to the body-28. Through the twallof there are provided :terminal ports: 32-, the final discharge ,ofvtheyflow stream from within cementing collar5 or EyilfltO them by forcing discs 3i3-0ut 0f position.

Discs 5i! may be kept inzplace until the stage is reached which requires their t meanwhile 'theyr may be removably attached to the body 2'8 by some suitable ferrous or'non ferrous compound, or they may be yieldablyiand temporarily'fused in position and inattachment .to the bodyrszt. bythe use of suitable fusiblezinaterial; and whatever materialis so used the same is indicated: by numeral 3!.

There face of this wall and into certain key Ways or milled'grooves .73 provided in the external face of movable sleeve 555. "These grooves will allow very limitedvertical these keys, the sleeve may not rotate orturn, because of the pressure of these keys.

These provisions for keys and grooves-are required, because whenever a cementing operation and 55- in positions and grooves 13, the sleeve 55 might have a tendency to turn within the body 28, and this would render it impossible, or at least difficult, to drill out the cement. In this connection it is to be noted also that the baffles, which are employed to receive force for movi'rigthe sliding sleeve, must themselves be made of drillable material. They will be drilled out, along with the cement acoumulated and hardened within the cementing collar.

Some suitable bonding or fusing material 34 is employed to hold and maintain keys 33 in proper place and position. These keys may be made of any irregular shape. For instance, they may be made square, orrectangular or hexagonal, etc. Two of them will be sufficient; and they must be lined up perfectly with the groove 13. For this reason, among others, it is desirable that keys 33 be set exactly in their proper places and depths, and welded firmly there. This practice is recommended, notwithstanding that the keys may be threaded in place, if such operation is found desirable by the manufacturer. In any event, a suitable aperture 42, of proper shape and contour, is made through the body wall 28 to receive and .hold keys 33.

:slightly smaller diameter than the bore 40 of the upper part of this body. This arrangement is 'made because of the fact that, between these two .bores, there is a tapering bore 39 which is prefer- :ably arranged to extend an equal distance above and below body terminal port 32. This tapering bore is accurately finished and made to gradually increase in diameter as it extends upwardly. The degree of the tapering is small; and it is provided. to afford a final resting place for a wall section of complementary inclination (that is of wedgelike inclination) on the outside of the sliding sleeve. The taper on this sleeve is indicated as at 54; and between these two tapered and complementary surfaces there will eventually be made a locking and wedging and mating contact, to effect final and permanent engagement between sliding sleeve 55 and body 28.

Body wall 28 terminates at its lower end in square shoulder 4|, which will lock in frictional engagement with a complementary shoulder 46 in lower sub 45.

This lower sub is carried by the lower end of body 28; and it is provided with male threads 41 on its upper end; and these threads find engagement with the companion threads 31 of body 28. The internal bore 48 of the lower sub corresponds in diameter with the bore of the casing 4, to which it is attached through the use of female threads 49. The shoulder 50, constituting the upper face of lower sub 45, has a special function in that it fixes the farthest limits of the movement of slidable sleeve 55 in its downward progress; and the squared end 14 of this sleeve finally comes to rest on this shoulder. This shoulder prevents any undue stress which may otherwise come about between the tapered faces 39 and 64; and it is so positioned as to prevent any wire drawing or other damage of the tapered faces. Such irregularity or deformity would be undesirable, and may be the occasion of leak between these faces, if allowed to occur.

The movable sleeve 55, having the form of an elongated cylindrical member mounted within the bore of body 28, of a typical cementing collar, is an item of major importance in the use and operation of this device. Its general structure and appearance is indicated in Figs. 11, IV, VII and VIII. Its internal diameter is constant, being substantially that of the casing 4, which carries the cementing collars 5 and 5. However, its external diameter is greater at the top of the sleeve than at the bottom; and the sleeve is fixed within the body 28 of the collar in an initial position, from which it will be moved downwardly later to be wedged into its final position, sealing and closing body terminal ports 32, as will be hereinafter pointed out in detail.

Below serrations 56 the outer wall of the sleeve is provided with undercut 51, horizontally disposed, and made to lessen the cross section of the sleeve wall, the better to provide spring action when serrations l8 and are disengaged (upon the downward movement of the sleeve), and also to allow the upper wall of the sleeve to spring into position after its downward movement. This springing recoil may be provided for by a pre-set expansion of the top of the sleeve outwardly, to a slightly greater diameter than its normal original diameter; and this pre-set expansion may extend through and to a point slightly below the section of the sleeve carrying serrations 56.

There are vertically placed slots 58 through the end of the upper side wall of sleeve 55, so arranged as to facilitate the disengagement of the serrations 56 and i8. These slots terminate in lower enlargements 18, which are provided to further lessen the material in the wall of the sleeve in the vicinity of the pre-set expansion, so that spring action may better be accomplished in such area of the sleeve wall.

The upper outer wall 59 of the sleeve has a diameter closely approximating that of the upper inner bore 48 of body 28, so that the sleeve may fit closely within this body, and yet be allowed to move downwardly therein when sufficient force is exercised therefor.

The diameter of the lower bore of the body 28 is less than the diameter of the upper bore of this body; and a complementary construction will be found in the sleeve itself, because the latter must eventually move downwardly within this body. The external diameter of the lower part 12 of the sleeve member therefore closely approximates the internal diameter of the lower bore of the body 28.

The tapered wall section 64 of the sleeve, so made to provide a wedgelike member, to fit tightly against the tapered section 39 of the wall of body 28, when the sleeve is forced into its lowermost position.

Above the tapered section of the sleeve one or more grooves 6| may be machined around the outer diameter of the sleeve; and these grooves carry resilient material formed to provide sealing rings 60. Sealing rings are thus arranged to prevent the passage of iiuid between the wall of body 28 and the wall of the sleeve member.

One or more sealing rings 68 may be arranged below the tapered section of the sleeve, comparable to sealing rings 69. Such a lower ring may be carried in a horizontally disposed groove 69, which is comparable, except for size, with groove 6|. It is good practice to place a pair of these rings above the tapered section of the sleeve, and another pair of such rings below such section.

A plurality of shear screws 61 holds the lower baflle 96 to the sleeve, until this baffle is moved from its place of original position in the sleeve; and in such movement the screws are sheared in response to force placed thereagainst.

Within the bottom end of the sleeve there is provided a baffle stop H0, which is a short cylin- -.operation, port and this straight bore drical ring of drillable material; and it isprovided with external thread-s Hi for engagement with companion threads l-l'ia in the inner wall of the sleeve. This baflle stop fixesthe limit of the downward travel of lower bafile 86; and this baffle is provided with a lower face HM which will come to rest on upper face N2 of the bailie stop. It is to be noted that the internal bore 76 of the lower part of the sleeve is the same as the inside diameter of easing 4.

The sleeve is provided with passageways E 7; and these areinitially aligned with terminal ports 32, which are arranged through the wall of the both/.28.

Passageways ii are closed before any actual cementing is done. Therefore, this :baifie must be moved downwardly to openthe passageways; and the lower baffle is thus moved bythe action of hydraulic force (as will be hereina-fter explained) but even at this point in the 32 remains sealed with disc .30 for a time; and the latter must be forced outwardly by hydraulic pressure from Within the cementing collar. After the yielding of disc 30 the "casing flow stream canandwill flow through :passageway '17, andfce discharged out of port 32 into the open hole'z, of the well surrounding casing 4.

Within the upper section of the sleeve there is provided upper baiile 35, which is a short cylindrical member of drillable material. The outside wall face at of the upper baille has a diameter equal to that of the internal diameter of the sleeve, over the inner wall of which this baille may be made to slide downwardly. In its initial position (before sliding downwardly) the outer wall of the upper bailie lies against the inner wall ofthe sleeve, aids the keeping of engagement between the serrations and i8.

Sealing rings carried in grooves87 are disposed about the circular periphery of upper ba-flie .85 and of lower baflie 95 to prevent the passage of fluidbetween the outer walls of these baiiles and the inner face of the sleeve before and after and during the movement or" these hafiles.

The lower shoulder as of upper bafile 85, and the upper shoulder i of lower baille common horizontal plane, so that these'bafiles remain inclose contact while in their initial'position; and also after their final movement.

At the very top of the upper baiile 65, there is a straight vertical bore 93, which is slightly less in diameter than the diameter There is a tapered bore 92 in by lower baffle .96

terminating in straight bore .5! of this baflle. There is a straight bore It! in lower :bafile 96;

is of the same diameter as the straight bore Si in theupper baiile. There is a tapered bore E33 in the lower baflle 96, and it ends in the straight vertical bore M2 of this battle.

The tapering of bores 82 and E63 within bafiies and $6 is not relied upon to provide or assist passage of collapsible plugs. These'plugs, on the other hand, have inherent characteristics and design allowing them to conform to retaining .Walls and pass through openings having smaller measurements than the that the angle of inclination of From the foregoingrdescription ofthe several elongated whe baffle it Will received by both the her 56.

her 96 :is sufficient it sageways through these baflies presents angpen- ,ingofgrea-ter diameter at the top of the copper 'bafile iand1an opening of considerably less 1diameter at the bottom of the lower bathe 96-; and the tapered walls of these baffles will furnish lodgmentor resting places for certain trip members, which are designed to receive hydraulic other membersof'thisclass) In Fig. 1H :it will be noted thattrip member 1H5 has:an.-extension device or rod I to gitSflllldST/Sidi? and to the collapsible cement- ;ing plug 5 I 1 below, so that areiixedon thelopposite ends of this rod.

snug {fit (in passing downwardly through the easing and will collapse inwardly and become passing through cementing colla-rscfiiandzfi.

:In speakingofthe plug i H as being collapsible, it;is to :be understood that what is meantis that such member has the capacity to take on the irregular shapeof anyopening or passage through which it-may be forced to capable of springing back to its former shape.

' Trip member Hi5 is not collapsible; and When it fi ds lodgment :upon the internal taper of a receive-the full force of the hydraulic pressure'exerted upon it from above.

It is :to @be noted that baffle -96 because of hydraulic pressure exerted 1H; and thereafter this pressureis -member H5 and the mem- When such -.pressure on member H5 and memfind its own direction,

rection not desired; and this It must be borne in mind that all of the baflles indicated in this specification, and all of the trip members, of which H is typical, and all of the rod members, such as H6, and all of the collapsible plugs, such as III or I34 or I45, must be made of drillable material. That is to say, the drilling bit must be able to cut them away, along with any cement around them, after the cementing job is done. This is done because, when the work of cementing is finished, there must be a free and unobstructed conduit or passageway through all of the cementing collars employed, not less in diameter than the bore of the casing 4.

Trip member I corresponds in general structure, appearance and function to member I I5, except that member I20 is larger and will come to rest upon the inclined wall 92 of upper baffle 85. It is to be noted also that member I20 is connected to a rod-like or tubular member I46, extending above it; and this last is fastened to collapsible plug I45. VII and VIII.)

In Fig. IV will be found a special trip member I2I, which is not connected to any rod or tube structure (such as I I8 or I46) nor is it connected to any collapsible plug. It is made of drillable material, having such shape and size as will allow it to come to rest upon the inclined wall I03 of the lower baffle, blocking and closing the passageway within this baflle. This special trip member is employed only when it is found debe a lapse of time after the completion of the first and lowest cementing level, and before the beginning of cementing operations at a second and upper level. This particular member may be used in place of the combined members H5, H6 and III, in second level cementing operations; and when so used the trapping collar 1 is not used in the casing string. Therefore, member I2I is an alternate for use in second level cementing operations. However, it is a requisite in third level cementing operations, and in other cementing operations above the third level. The trip member I2I is simply dropped into the casing fluid at its surface; and then it is allowed to gravitate to its final position.

In the discharge of the flow stream from body terminal ports 32, after they have been opened, as hereinabove explained, it should be evident that such flow stream can be allowed to fix and without the intervention of any means for conditioning the direction of the flow; and it is true that my apparatus may be used without any such means. There may be physical conditions under which it may not be found practical to provide such means on the outside of the cementing collar, because the inclusion of such means will increase the overall diameter of the tool. Whenever such means may not be employed advantageously, for this or any other reason, my standard cementing collar, without such means, may be used. However, there are reasons for the provisions of such means; and it is recommended that such means be used whenever possible. Otherwise, the discharge of a high velocity flow stream, directly out of the ports, may cause a cutting action on the walls of the drilled hole of the well. In any such cut-away section of the wall, the slurry coming from the ports may find escape in a dimay result in channeling (an evil hereinabove discussed, which is to be avoided if possible). Also, the dislodged portions of the stratum forming the wall of the (See Figs.

named member well bore may become intermingled with the slurry introduced, and result in an impairment of the strength of the latter.

Therefore, I employ special dispersal means for controlling and regulating the direction and velocity of the flow from the terminal ports, and to effect uniformity and complete integration in the discharged slurry as it is being placed.

Such means may take many forms; and a typical form of such means is disclosed in Figs. V and IX, wherein there are several runways, arranged to communicate with the terminal ports; and these runways constitute conduits. For purpose of greater clarity the vertically disposed runways are called shank runways, of which members I28 and I25 are typical; and the oblique runways, which are inclined from the vertical, are called arm runways, of which I26, I21, I29 and I30 are typical.

Shank runway I28 receives flow at its lowermost end, and discharges flow, from its uppermost end, into communicating arm runways. Shank runway I25 receives flow at its uppermost end, and discharges flow, from its lowermost end, into communicating arm runways.

In a typical arrangement there will be found a pair of oppositely disposed shank runways I28; and likewise there is a pair of oppositely disposed shank runways I25.

Each arm runway is so positioned and inclined as to have a companion arm runway disposed at the same angle and arranged to discharge flow in the exact opposite direction of the flow from the arm runway first mentioned. Each. arm runway has a cross-sectional area slightly less than one-half of the cross-sectional area of its communicating shank runway.

The net result of such an arrangement is to create initial turbulence, and to prevent undesired channeling. The velocity of the flow of two opposing streams meeting between the outlets of opposed arm runways is dissipated; and the turbulently intermingled flow stream resulting from a combination of these opposite forces will then proceed to the points of least resistance, and completely fill the area about the cementing collar. Such an arrangement and operation will make and produce a far more homogeneous placement of a slurry mass than may be had without such means. Uniformity in the density of this mass in the discharging area is a most desirable objective indeed; and my structure and method have been found to fully effect such objective.

The structure immediately hereinabove discussed is more than means for deflecting the flow leaving the discharge ports in the cementing collar. It has all the advantages of a baffle or a deflector; but it has far greater advantages than either, in that the dissipation of the velocity of the discharge stream is effected; and an orderly and uniform integration and placement of homogeneous slurry results. Also there can be no cutting away of the walls of the surrounding earths stratum as a result of high velocity discharge.

While the device illustrated in Figs. V and IX may have the construction therein shown, it is to be noted that instead of tubular members for the runways there may be used rectangular channels, or conduits of any desired shape. For instance, a flattened or elliptical tube may be employed, or an arc of a tube may be employed. The conduits must be finally built and securely fastened together and well attached to the body :13 2.8 of the cementing collar. For this purpose the use of welding i3! is ideally suited. However, conduits may be fashioned .as a. part of the body itself.

It should be obvious, of course, that the special dispersal means, which I have just .described, may be employed as an attachment to a conventional shoe '8 which is placed on the lower end of the casing near the bottom of the hole. Also, it may be attached about the wall of a simple length of easing which has been previously provided with suitable discharge ports, so that these ports may communicate with my dispersal means In other words, such means may be used in connection "with my cementing collar 55 or 5; Or :it may be used in connection with any suitable perforated pipe employed for flow, delivery and placement of fluid. When so used the same advantages will be found as are hereinabove clai nod for its use with my cementing collar.

The collapsible cementing plugs herein referred to, of which that shown in Fig. VI is typical, may be made in a variety of shapes and sizes; and the one illustrated is merely a preferred form. It is required that the plug be made of resilient material, because it must be collapsible. Perhaps the best material for such use is rubber, natural formula used to produce the rubber should result in a composition of relatively soft and yielding nature, yet capable of withstanding considerable abrasive action.

Typical plug 136 is made with a hollow interior 33. A solid top I32 may be provided with a bevelled side wall 13m. The plugs are usually made with a solid top, because they can be used without any connection or attachment thereto. When it is desired to attach rod I H? or we to the plug, a suitable hole may be drilled through the top, at its center, to receive such rod or tubular member; and such place with nuts and lock washers.

These plugs are used to shut off, space, or segregate fluids of the same or different characteristics. For instance, when a plug is placed, there may be found above Or" normal character, or slurry.

In order to more effectively separate the fluids lying on either side of the plug, special arrangements have been made to produce a substantial seal. Among these are horizontal wipers 13-5. They are in fact lips which extend from the hollow core of the plug outwardly to fit closely the bore of a casing string.

Circumferential wipers are preferably arranged on the plu in two between the groups. This recess I31 within the wall of the plug, which lessens the thickness of the cross-section of the resilient material forming the wall in that area. It is particularly in this area that the plug reacts responsively to effect partial collapse and elongation, when it is required to suffer deformity in passing through restricted openings.

Between each pair of horizontal Wipers I35 there are arranged diagonal wipers I 36, which reinforce the former; and these diagonal members also closely fit the bore of the casing string.

Receding or dished ribs 138 are arranged below the lowermost horizontal wiper, and they extend toward the base of the plug. Such ribs limit the tendency of the lower wiper to separate from the wall of the casing as a result of great pressure upon the top of the plug. My construction prevents the undesirable deformation of greater deflection of the bottom wipers;

space constitutes a member may be fastened in l,

or below it Well fluid .1

groups, with a space iii) Through the bottom of the vided a plug port 139 The plug so used is not equipped M5, or other condoes not carry trip member H5 or any other trip member.

The collapsible in the bottom of entire flow sufilciently large size as debris, such as drill bit stream; and they are of not to retain fiow stream cuttings or other foreign materials.

The trapping collar assembly 1 is provided with cylindrical body 156 which carries upper female threads 15'! and lower female threads I58 to engage companion threads on the ends of upper and lower casing 4.

Below the end of upper casing is further provided with internal threads l5!) to engage. external threads 51 on the drillable bushing 562. This bushing also is provided with female threads 153 for engagement with male threads 565011 the upper end of the perforated trapping collar nipple l 64.

Internal bore I56 of this perforated nipple is 4 the body I56 of smaller diameter than that of the casing 4. However, its diameter is greater than the straight bore I02 of the lower baille 96 and greater than the straight bore 9I of the upper baffle 85.

Perforated nipple I64 is provided with a perforated bottom I68. The bottom of this nipple may be closed by causing V -shaped segments thereof to be cut out of the end wall of a straight nipple; and the remaining segments may be heated and turned inwardly to substantially close the nipple and form its bottom. After being thus formed the segments are welded together to strengthen the bottom wall.

The trapping collar body I56 is provided, in its mid-section, with internal and horizontally disposed serrations I60 which supply anchorage and bearing for the concrete fill I69 which is tamped and embedded below bushing I62 and behind the wall of nipple I84, so as to strengthen and support these last two named members. It is to be noted that this concrete and the bushing and the perforated nipple are all made of drillable meterial, and can be cut away by the drill bit when desired.

Operation The steps by which my method may be employed in a typical cementing operation around the casing of a well, in successive stages, so that cementing can be done at three levels in succession, can be better understood by referring to Fig. XI of the drawings, where typical members, which may be employed in the method, have been indicated, especially with reference to the relative locations of these several members at various intervals of time.

Fig. X1 is a schematic or diagrammatic arrangement, designed more to illustrate the steps employed, and the order thereof, then to delineate the details of any of the mechanism therein indicated.

In the schematic arrangement of Fig. XI there are seven views, marked from A to G, inclusive; and the letters of the alphabet indicate by their usual sequence the sequence of the seven steps carried out from the beginning to the ending of a typical cementing operation of three stages.

In each of the views in Fig. XI there are indicated a casing string 4, upper cementing collar 5, lower cementing collar 6, trapping collar 1 and a conventional shoe 8.

Certain operative elements of the cementing collars are indicated by the numerals given them earlier in this specification, though no attempt is being made to detail such elements in Fig. XI. Also indicated are collapsible cementing plugs I34, III and I45, as used in the views or steps; and there is a free ball or trip member I2I, unattached, which is first introduced in view F and appears also in view G. In the latter view there is an extra and uppermost cementing plug I45 carrying a rod or tube I46 so as to connect it with a typical trip member IZQa, and the only difference between the upper member IZUa and the lower member I in view G is that the former is larger in diameter.

The direction of the flow stream is indicated by appropriate arrows in the views of Fig. XI. The progressive employment of the members in- XI is as follows:

The casing string 4 is lowered into the bored this string is placed in the to receive the shoe 8, the trapping collar 1, cementing collar 6 and cementing collar 5, in the order named; and these members are spaced in the string the required distances so that they will thereafter function at the predetermined levels at which cementing, and operations incident thereto, are required to be performed.

The level around shoe 8 and above is to be cemented first, and this is called first stage cementing. The level around collar 6 and above it is to be cemented next; and this is called second stage cementing. The level around collar 5 and above is to be cemented last; and this is called third stage cementing.

The vertical distances between these three cementing stages is fixed at the discretion of the operator; and they may be such that the cementing from any lower stage may continue upwardly to and overlap the cementing in the next upwardly succeeding stage; or it may not, as physical conditions may require or good practice dictate.

It is customary practice to carry out fiuid circulation for a requisite period to determine that the casing and the discharge ports from the shoe are fully open and that the fluid flows evenly behind the casing to the surface source. When cementing operations are commenced there is no obstruction to the flow stream in the casing nor in the bored hole area surrounding the casing. This is the situation in view A.

In Fig. XI the moving well fluid is indicated by single pointed arrows and the moving slurry by double pointed arrows.

Next, in view B, cementing slurry has been introduced into the casing until it has been forced by the pump through shoe 8 and upwardly around the casing. The operator knows the cubic content of the desired fill behind the casing; and only such quantity of slurry has been placed through the shoe. On top of that slurry an independent and unattached collapsible plug I34 was previously introduced into the flow stream and forced downwardly by the action of the pump, until it came to lodgment in or above trapping collar I. The operator determines the quantity of well fluid to be introduced above the plug I34, by computing the cubic contents of the casing per foot thereof. He uses that volume necessary to fill the casing bore from trapping collar 1 to cementing collar 6. When all of such volume has been pumped above plug I34, then collapsible plug I I1 is placed in the flowstream. The relation, therefore, between collapsible plug I34 and collapsible plug I I1, within the casing string, is that vertical distance between trapping collar I and cementing collar 6.

This stated relation provides for the simultaneous arrival, or nearly so, of plug I34 at trapping collar I, and plug III (with extension IIS and trip member H5) at the cementing collar 6. During this operation, and until plug I I1 and its trailing member I I5 are finally lodged in collar 6, there continues to be stream circulation through trapping collar I, notwithstanding that plug I34 is or is not in trapped position, as disclosed in Fig. X. This arrangement is made to compensate for any over or under measurement of the volume of fluid required for spacing between cementing collar 6 and trapping collar I. At any rate, when trip member H5 is stopped by baffle 96, the first stage cementing operation has been completed.

When trip member I I5 is nested in lower bafile 95, as shown in view C, then the pump pressure, and its increase applied thereabove, will cause this baffle to be driven downwardly, shearing screw 61, and opening sleeve passages I1 to the introduction of fluid.

.plug II? and below plug I45. P

I carrying with it sleeve:

.ing, as indicated in view E.

' This is done I? .Thiscexposesfor: the firstztimei theiports ;32 ,sand

menting collar 6, as indicatedinviewssC and'D. Slurry for this purpose has been introducedabove The'xvolumefof slurryifprfthe second stage op- -eration; which 1 is introduced 'into 't'he casingtbe- "tweentplugs' I I1 and:'I45,tis again at thefcontrol and discretion of the'pperator, .in 'exactlythe same-manner as hereinbefore':explained in the determination of the r-volume: of 'slurryiintroduced into the casing forthei'first stage. rwellrfiuid sis pumped a'boveplugl45.

' The pressure of the pump continues to force downwardlyplug I (above'which'is typical'iwell fluid) and the slurry KbEIOWthiS plug isfforc'ed outwardly through ports-32, until trip emember I20 isrnested in upper bafrle85. .Con'tinuingpre'ssure, WithfltSlHCIfGELSB, will move 5111115 I upper bafiie downwardly, shearingscrew #29 .which 'hel'd -.the

' upper "bafile 85 :to the v sleeve :andcthe rupper *ba'flie 85' isdrivenover sleeve:passageul'l 'closing it.

Continuing pressure from above swine-further l 45 :and :trip ;member 55 .to have-sheared segmented scrcw 29, andireleased-serrations lock on the sleeve). "Thisicloses dischargeeports s2 drive downwardly the plug 1withyavery-tight wedging action, rasexplained in a detail earlier in this :specificatio It'isito be .wellxunderstood that thelpressure below-upper baflie85, tripxmember I 29 andzsleeve 55,- has not been changed, despite =theincrease of pressure above rte-move ithese membersdown- Wardly.

This then completes thesecond'stage cement- Ihecompletion of second'stage cementingis indicated by -the;pressure rise on the pump at-the surface. It willbe :noted that the operation to cementthe first second stage is that-ofthercontinuous method.

- The third stage cementing operation --is then begun. The final pressure-on theweasing, which completed the second -stage operation, having been released, --the trip-member -I-2-I is then dropped into theicasing to-fgravitate in the swell fluid. A sufiicient timeil-apse is-a'llowed toenable trip member I2I to fall toits -tapered mating point .injlower bafile a6, in cementing .collar--5.;

Then the pump pressure =is-applied to the casing; and this will cause .lower .ba'flle 9.5to be driven Ldownwardly, shearing screw 67.; after which sleeve passages I? are opened to the introduc'tion of fluid. This exposes the ports 32 for the first time, and also their closing discs '3fl ;an'd'-increased pump pressure will expel the latter. Thereafter, fluid at the third cementing stage is discharged throughcementin'g co1l'ar'5.

It is customary to carry out fluid circulation through cementing 'collar '5 for a requisiteperiod.

to ascertain "if the fluid in th'e circulation streamlhas retained all of=its desiredscharacteristics of weightand viscosity during :the time lapse in which it was not moving. I The cementing slurry isnext introduced into the casing. The volume of slurry is iagain--de terminedby the operator for the'fill desired behind the casing. When this proper amount of slurry has been introduced into the casing, collapsible plugME, withextension 446 and trip member 120a, is introduced intothe casingv above the slurry. I Well fluid is .introducedinto-the:cas-

ing above plug I45.

the trip membera-trip member a :and

stage -=cementing-, having a: the second and-third stage operations, is that -of ,practice, the primary slurry discharging. The above described practice,

-of such length that ondary collapsible -therein.;;. and-the The pressure :of -:the pump continues to :force plug M5- downwardly; and the slurry-.below:-; this plug is forced outwardlysthroughsportsa32,-until I2Darisnesteddn-upperbaflie 85.

which held .upper baiile- .85 to rtheas-l'eeve 55; and

the upper bafiie is-driven-.over.-sleevepassage I1,

Continuing pressure on'the oasingwill further drive downwardlythe plug 5 I45 and trip Jmember -Again=-itis toibe understood, despite thepressure. increase. -in.-the 1 area above upper baiile-*85, sleeve 55,- there is .no change of pressure in the area below these mem- This latter pressure :is constant with the sleeve :55 :move to .provide closure and seal. p

.This third stage cementing-completion is indicated bythe pressure rise-on the:pump?atthe surface. vThe method outlined for this-third time lapse between the intermittentmethod, It will be seen that I may confine slurrybetween a pair-ofcollapsible plugs,- duringitsmovecasing string slightly above the-shoe, This cementing behindicasing.

s For this-practice, the.primarycollapsibleplug I TyWith trip member 1|. I5, precedes ithe slurry;

rand the-secondarycollapsible plug I 45, with trip member I 20, :followsthe slurry. These'respective members open .-the-. cementingcollar to discharge "thezslurrmand close the cementing collar to .prewent 'furthendischarge.

:Itwill be .noted that-in such practice, no slurry finds passage through fracture of aprimary plugtwere itdisposed .with- '50 mnfiningthe slurry betweena pair-of' collapsible plugs-both of designof-plug I 34,:during the slurry movementwithin racasing string, so as: to discharge the slurry through the shoe; :In .such

pump at the surfaceto employing identical collapsible plugs 134 .to confine slurry .both .theprimary and secplugs could become trapped .fiow stream would continue and when so past the secondary plug through added openings provided on the longer trapping collar nipple for this purpose.

In my method employing the cementing collar in multi-stage cementing, it will be noted that the second stage cementing does confine the slurry between a pair of collapsible plugs in continuous cementing practice.

Conditions and circumstances may occasionally be found in which my cementing collar, with ports open, may be used to receive fluid into the casing from the well bore. Whenever it shall have been determined that such situation is to be met, then my cementing collar is placed on the casing string, at the desired level; and this collar is so placed without having any port discs; that is, the ports are open when the collar is placed; and no baffles are carried within this collar.

This stripped collar is so used whenever it is desired that any fluid be caused to flow from the well bore into the collar. The following are indicated as examples of such use.

(A) Water or well fluid may be forced downwardly through special means ployed to cause the flow to be discharged out of the shoe at the bottom of the casing, and into the well bore, from which it may return into the casing through the open ports of my collar.

(B) Slurry may be caused to flow in the same manner, and be received back through the ports of my collar, into the casing, for the purpose of cementing a lner therein.

When either of the operations indicated (A) or (B) above are carried out, it will be necessary to provide within the casing an auxiliary, or secondary and smaller, string of pipe, extending from the earths surface to a point well below my collar; and such auxiliary conduit is indicated by the word means under the heading (A) immediately above. Such auxiliary means is sealed to and retained within the easing, at a point below my collar, in the conventional manner, or in such manner ator may elect. In any event when the fluid or slurry (as the case may be) returns from the well bore into my collar it will fill the region within my collar immediately about the auxiliary string, ing. Incidentally, during fluid returning into the casing opened collar, will allow for the this operation, the through my sampling of such fluid, to determine whether it be oil or other fluid. I

In the employment of the sliding sleeve member within any collar to be used in my method, a modification may be made in the outer ta pered wall section of this sleeve, if desired. This modification is indicated in Figure XII, where in a series of circumferential grooves 64a may be provided. Within these grooves there is space in which may be accommodated any minor foreign materials to lar. This construction will then provide a numwhich will more effectively In the event it should be desired, the sliding sleeve in my device may to include only such structure and design in the sleeve as will be found in the upper part thereof above the passageways through its walls; constructed no passageways are needed. Also my sleeve may be made in two which may be emunder as the operand pass upwardly within the casbe found between the tapered faces of the sleeve and of the wall of the c01-- be shortened and made Y Cal 29 pieces, by dividing it on a horizontal line at or below the base of the inclined side wall of the sleeve; and when thus made in two pieces they may be joined together by the use of threads, or other means of joinder.

I claim:

1. In apparatus for cementing pipe in a well bore, a collar provided with ports through its walls; a slideable cylindrical sleeve disengageably carried within said collar and having passageways through its walls, said sleeve being pro vided with an internal shoulder, the said ports and passageways being initially in communication; a lower bafile disengageably secured in the sleeve and initially closing the passageways; means for disengaging the lower baffle and for moving it downward into a position of support by the shoulder to open the passageways; an upper baflie disengageably secured in the sleeve above the lower bailie; means for disengaging the upper baffle from the sleeve and for moving it downward into engagement with the lower baffle to close the passageway and for disengaging the sleeve from the collar to move it downward to close the ports.

2. In apparatus for cementing pipe within a well bore, a collar provided with ports through its walls; serrations on the inner wall of the collar; a slideable cylindrical sleeve carried within the said collar and provided with passageways through its walls, said sleeve having complementary serrations on its outer wall disengageably attached to the serrations on the collar, the sleeve being so placed as to align its passageways with said ports when the serrations are engaged; moveable means disengageably attached within the sleeve for opening the passageways; moveable means disengageably attached within the sleeve for closing the passageways; means to disengage the first named moveable means and move it downward to open the passageways; means to disengage and move the second named moveable means downward to close the passageways; and pressure actuated means for disengaging the serrations and sliding the sleeve downwardly to close the ports.

3. In apparatus for cementing pipe within a well bore, a collar adapted to be incorporated in a string of well casing so as to form a part thereof and having discharge ports through its walls said ports being in communication with the well bore when disposed therein; a slidable sleeve arranged within the collar and provided with passageways through its walls; a movable annu lar baffle disengageably attached within the sleeve in position to initially close the passageways and adapted to open the passageways when moved downwardly; and means to disengage the bafile from the sleeve and move same downwardly to open the passageways.

4. In apparatus for cementing pipe within a well bore, a collar adapted to be incorporated in a string of well casing so as to form a part thereof and having discharge ports through its walls said ports being in communication with the well bore when disposed therein; a slidable sleeve arranged within the collar and provided with passageways through its walls; and a movable annular bafile disengageably attached within the sleeve in position to initially close the passageways and adapted to open the passageways when moved downwardly; means to disengage the baffle from the sleeve and move same downwardly to open the passageways; the outer wall of the baflie being provided with sealing rings to frictionally engage the walls of the sleeve.

5. In apparatus for cementing pipe within a well bore, a collar provided with cylindrical walls, having a plurality of discharge ports therethrough; a slideable cylindrical sleeve disengageably attached to the inner wall of said collar, and provided with passageways through the walls, the ports and passageways being initially in communication, the sleeve being so constructed as to close the ports when it is moved downwardly within the collar; means for moving the sleeve downwardly in the collar to close the ports; and the inner wall of the collar being provided with a tapered area, and the outer wall of the sleeve being provided with a tapered area, the two said areas being complementary and so arranged and constructed that they will effect wedgelike frictional engagement when the sleeve is forced downwardly.

6. In apparatus for cementing pipe within a well bore, a collar provided with cylindrical walls, having a plurality of discharge ports therethrough; a slideable cylindrical sleeve disengageably attached within the collar, and provided with passageways through its walls, the ports and passageways being initially in communication the sleeve being so constructed as to close the ports when it is moved downwardly within the collar; means for moving the sleeve downwardly in the collar to close the ports; and the inner wall of the collar being provided with a tapered area, and the outer wall of the sleeve being provided with a tapered area, the two said areas being complementary and so arranged and constructed that they will effect wedgelike frictional engagement when the sleeve is forced downwardly, the beveled area of the sleeve being provided with a series of circumferential grooves.

7. In apparatus for cementing well pipe within a well bore, a cementing collar provided with cylindrical walls having a plurality of discharge ports therethrough; a slideable cylindrical sleeve disengageably attached to the inner wall of said collar and provided with passageways initially in communication with said ports, said sleeve being so constructed that when it is caused to move downwardly within the collar it will close the ports; means for disengageably attaching the sleeve in the collar; a moveable cylindrical lower bafi'le within said sleeve disengageably attached to the walls thereof and so arranged as to initially close said passageways and so constructed that it will open the same when moved downwardly; means for disengageably attaching the lower baille to the sleeve; a longitudinal passage extending through the lower bafile; a movable cylindrical upper bafiie within said sleeve disengageably attached to the walls thereof and initially arranged above said passageways and so constructed that it will close the same when it is moved downwardly; means for disengageably attaching the upper loathe to the sleeve; a longitudinal passage extending through the upper bailie; a trip ball arranged to enter the lower baiile and being of such size that it will not pass through the lower baille so that it will cause the disengagement and downward movement of said baille in response to pressure exerted within the pressure exerted within the well pipe from above; and stop means carried by said sleeve and so sleeve to close the ports.

SYLVESTER B. SCHNITTER.

References Cited in the file of this patent UNITED STATES PATENTS 2,435,016 Pitts Jan. 27, 1948

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