US2662602A - Means for guiding, floating, and cementing well casing in bored holes - Google Patents

Description

S. B. SCHNITTER MEANS FOR GUIDING, FLOATING, AND CEMENTING WELL CASING IN BORED HOLES Dec. l5, 1953 2 Sheets-Sheet l Filed June 27, 1947 ttorneg Dec. 15, 1953 s. B. scHNlTTl-:R 2,662,602

MEANS FOR GUIDING, FLOTING, AND CEMENTING WELL CASING IN BORED HOLES Filed June 27, 1947 2 Sheets-Sheet 2 Snoentor Gttorncg Patented Dec. l5, 1953 MEANS FOR GUIDING, FLOATING, AND CE- MENTING WELL CASIN G IN BORED HOLES Sylvester B. Schnitter, Dallas, Tex., assignor to L. L. Rector, Tarrant County, Tex.

Application June Z7, 1947, Serial No. 757,452

(Cl. 16B- 1) 10 Claims. l

This application is concerned with means for guiding, oating and cementing well casing in bored holes; and it is particularly concerned with improvements in means to overcome the tendency to channel the cementing slurry through the Well uid and further to prevent the mixture of the cementing slurry with the well iiuid in the well pipe during the cen/renting operation.

Through the use of my invention, I have minimized the hazard of permitting inud cake deposits to remain in the Well bore, by providing a greater volume iiow` from the well casing to the well bore for wash purposes.

My invention eliminates the great expense entailed under the old practices, in that it is new unnecessary to use special pumping equipment in order to attain the required volume ilow through the casing, as is done with the prior methods and devices. Through the use of my invention I eliminate the aforesaid flow restrictions in the casing, such as have been used in the prior devices.

In my invention, where it is necessary to have a restriction in the casing to perform the functions of such restrictions in the casings as have appeared in prior devices, I have provided a Venturi form of iiow passageway.

By using the Venturi form of ow passage I have incorporated the following principle: When iiuid flows through a venturi its velocity rapidly increases from its entrance to the throat of the venturi, and decreases from the throat of the venturi to its outlet. The pressure is greatest at the entrance to the venturi, and at the outlet, and is least at its throat. The pressure lost at the throat of the venturi is almost entirely regained at its outlet. rthus, by passing the fluid through a Venturi-like pasu sage in the casing, almost the same amount of iiuid will be delivered through the well conduit, without increasing the pressure on the pumping equipment. This Venturi principle of flow passageway inside a well casing, during a cemen'ting operation, has not been used in the prior methods and devices for guiding and/or floating and/or cernenting Well casing in bored holes.

It is desirable that all duide employed during a well cenienting operation must be segregated from each other so far as it is possible to effect V such separation.

Such segregation of iuids can only be accomplished within the well pipe. My means as disclosed herein provide for segregaton of iiuids throughout the full length oi the pipe. My

means accomplishes a positive segregation between the fluids in the pipe; and no nuids pass through the segregating means, and substantially no fluids pass around them. Thus, I have, by the use of my means, eliminated the causes which generate the cement-mud ball mass formed in the casing in prior well cementing practice. This is of great importance.

In the use of small criiice ttings in the casing in prior devices used in cementing wells, as above described, the formation of cement-mud balls in the casing necessitated increased pumping pressure in order to force the mass formed by the cement-mud balls through the oricelike restrictions. By eliminating the formation ci the cement-mud balls in the casing in the use of my device, I can and do utilize the ordinary pumping equipment customarily used in well drilling practice. This results in extensive economies and much savings in equipment and costs.

By providing the means of my invention for segregating the well uids, the wash water is discharged from the well pipe in a free state, and the cementing slurry is likewise discharged from the well pipe in an uncontaminated state. Thus, the greatest possible benefit is derived from the wash Water and cementing slurry.

In prior cementing operations it has been the practice to disjoint the cementing head or surface fittings from the casing in order to inject the old style segregating means used as spacers between the fluids in the casing. The result of this practice has been that, while the surface ttings are disconnected, air is allowed to enter the casing. When this result occurs after the coniinng of the cementing slurry in the casing, the cementing slurry (being of greater density than the well iiuid ahead of it) will displace the well fluid and a void will be left at the top of the column of slurry. When the well head iitting is replaced, air will then be trapped in the void thus formed between the plug inserted and the cementing slurry. Thus, the air will be trapped between the column of iiuid below the plug and the column of uid above the plug. When pressure is applied to the plug above this ai pocket, the air, being of less density and viscosity than the cementing slurry ahead of it, will be compressed and will permeate into the cementing slurry and cause the formation of pockets or honeycomb-like recesses within the slurry, and thus weaken it. This is a most undesirable result fraught with grave consequences.

By the use of my device, I have overcome the introduction or air into the bore of the well pipe by induct.- all segregating means, desired for use in a cej enting operation, into the casing, under pressure, while the pump is in operation, and thus causing no stop-page of the flow stream. No voids result.

Among the objects to be attained by my invention are those indicated in the foregoing dissertation, and also the following:

l. To provide means for the floating and guiding of a string of casing into a well bore and to the desired level for the purpose o cementing the casing in the well bore.

2. To provide disengageable means within the casing which may be dislodged by other means so as tc provide substantially full casing area flow through the well pipe after the casing has been run to the desired level in the well bore.

3. To provide maximum area inside the well pipe for the iiow of nuid therethrough so as to reduce the well pumping pressure required and to increase the volume of flow of fluid through the weil circulating circuit.

4.. To provide and make effective the segre'fation of all iiuids in the well pipe during a cementing operation.

5. To provide valve means which move with the flow stream in the well pipe and operate to prevent the discharging of fluid from the well pipe, when desired; and such means further preventing the idowback of fluid into the well pipe after the discharge of the duid from the well pipe has taken place.

6. To provide a rigid segregating for segregating the fluids in the well pipe, which means has the capability of being deformed and reformed to the contour of the bore or passage- Way through the well pipe.

'7. To provide means for inducting all segre gating spacer means into the flow stream, inside the casing, while the casing is under pressure, and without interrupting the iiow oi iiuid through the well now circuit, during a cementing operation.

Other and further objects of my invention will become apparent upon the reading of the detailed specification which follows hereinafter.

My method and means for guiding, oating and cementing well casing in bored holes, and a suitable arrangement and construction of the parte thereof, and their operation and use, are illustrated in the accompanying drawings, which disclose a satisfactory and preferred form or my device.

It is to be understood, however, that I can practice my invention effectively and satisfactorily with various devices which incorporate use the same, notwithstanding that such devices may be in forms and arrangements som what different from the structuresillustrated in the accompanying drawings; and such departure from the structures delineated herein will not depart from the spirit and essential principles o my invention.

In the drawings:

Fig. I is a partially sectionalized elevation show ing several levels in a typical well about to be cemented, wherein my oat shoe and stall collar are carried by the casing in position in the bore hole, and wherein the cementing head is connected to the top of the casing above the earths snrface.

Fig. II is a partially sectionalized elevation. of certain levels of a typical well at the time or dislodging my float assembly from the iloat shoe by pressure operated trip means, and wherein a primary collapsible spacer plug is positioned in the cement head prior to its introduction into the well casing.

Fig. III is a partially sectionalized elevation ci a typical well with a volume of cementing slurry conned in the casing between a primary collapsible spacer plug and a top collapsible spacer plug, which latter plug carries a check valve.

Fig. IV is a partially sectionalized elevation oi a typical well wherein my cementing apparatus has been employed and wherein a volume of slur ry for cementing the casing in the bored hole has been discharged from the casing into the well bore, and wherein a check valve prevents further movement of fluids in the casing.

Fig. V is a partially sectionalized elevation my float shoe carried by and below the weil pipe, and wherein the shoe assembly trip ball is shown in the well pipe near its seating position.

Fig. VI is a partially scctionalized elevation oi my stall collar, connected above and below to the well casing, and or" my collapsible spacer plug, and of check valve.

Fig. VII is a partially sectionalized elevation of the upper portion of my cement head having an adapting liner positioned therein, and of my top collapsible spacer plug, and oi my check valve.

In the drawings, the various parts and elements of structures employed in the practice of my invention, and in the construction and op eration of devices required thereby, are indicated by numerals; and numeral l indicates the earths strata; and numeral 2 identies the lbore of a well, whether it be an oil well, a gas well, a water well or other type oi Well. In Fig. I the well casing 3 has been guided and floated into the drilled hole to the desired depth.

In Fig. I the typical well casing 3 carries the float shoe d, in which the float assembly l5 is positioned. A valve in the neat assembly i5 is a b-acls pressure check valve of a type such as has been heretofore used in floating and guiding Well casing into bored holes. In this construction well fluid may flow downwardly through the float shoe, but the lluid is prevented from flowing back into the casing through the float shoe.

During the time that the casing is being guided into the well bore by the defiecting action of the rounded sides of the shoe guide Ita, the well pipe acquires a 'floating buoya cy. The buoyant ball i8 inside the float assembly l5, is floated upward from its seat ld because the pressure of the fluid head on the outside of the casing is greater than the pressure of the iiuid head on the inside of the casing. The float ball l5 is retained within the float assembly l5 by means of rests or arms ita, which also form a seat for the ball, and such arms may be made integral with the float assembly l5.

In this float assembly 25 the valve ball it is caused to iioat during the time the casing is being guided into the well bore by reason of the fact that the speciiic gravity of valve ball t8 is less than the speciiic gravity of the well fluid. The area of the opening ib through which fluid may be discharged during the guiding and floating period is much smaller than the area of the bore of the casing. Consequently, by applying pres- .sure to the top of the casing, iiuid can be caused to discharge through the opening |312 in jet-like fashion, since the fluid is being forced from a large area through a small area. This effect is useful during the guiding and floating period. Should the casing encounter mud bridges or other mov 5 able restrictions in the well bore on its progress downward, liuid may be jetted through the opening ith, by puinp pressure from above so a's to wesh away the bridges or other restrictions.

A typical string of casing 3 also carries the stall collar li, which is placed on the casing above 'the float shoe il, at the desired level in the hole. 'The spaced relation between the stall collar 5 and the shoe fl of course determines the amount ci" cement-ing slur-ry to remain within the bore of the casing after the cementing operation is completed; and in norrnal practice such spacing customarily will 'not exceed 100 feet. This spaced relation between the stall collar and the shoe is determined by the choice of the operator.

Also pcsiticnedon the string of casing 3 is a cement head 5, which is disposed at the top ol' the casing above the earths surface. The cement head t and its appurtenant connections constitute the connecting means between the surface well pumps and the casing. By this cement head arrangement and connection, fluid may be pumped from the usual surface storage facilities, downwardly through the bore E of the casing, for discharge through the float shoe d into the bore 2 oi the well, and thence be directed upwardly behind the casing and returned to the said surface storage facilities. This entire ilow passageway, as above described, is commonly known as the well iiow circuit.

In this well flow circuit, a connecting fluid line 5e is caused to communicate with the cement head, and the bore of the casing by joinder to one opening or" the cross T53. The cross T9 is threade'ily connected to the top of the casing and fitted below the standard commercial plug valve l. The other Sc of cross TQ is shown in the drawings as being plugged, but such opening is adapted to receive connection with a con duit from the surface pumps if such connection be desired.

At the top or the cement head li is connected one end or" the flexible hose lil, the other end of which lexible hose is caused to communicate with the fluid line Se through valve l2, TIS and valve l i. 'Elexible hose it? also communicates with flow line i3d which is in turn connected to the surface pumps (not shown).

By this arrangement or manifold valves connected between the surface humos and the cen inenting head and casing, the flow of fluid into the casing can be directed and controlled. The when valve l i is in open position., while the coin inercial plug valve and valve l2 on the fle aole hose line are in closed position, the :duid pumped from the surface pumps is delivered to the bore of the casing without passing through the ce ment However, when valve l2 on the hex ible hose line, and commercial plug valve l, are in open position, while valve Il is in a closed position, the fluid pumped from the surn face pumps through flow line i3d is delivered to the bore of the casing by passing through the cement head. This flow control arrangement is an important part of ni invention, as will be demonstrated later in this specification.

While the assembly is positioned as shown in Fig. l, it may be desirable to wash and the well flow circuit, which is customary practice, before the cernenting operation. This done by manipulating the valve arrangement on the ceinenting head so that the well washing fluid will not pass through the cernenting head during this washing period, but will flow di rectly into the casing.

However, before the well washing operation begins the l'oat assembly l5 is dislodged from the float shoe fl so that there will be no restric tion in the float shoe during this operation. This is done by manually dropping the iloat shoe trip ball it into the bore of the well casing before the cement head t is placed into position thereon. rhis trip ball it, having a spen cie gravity greater than the well fluid, will gravitate to the bottom of the well casing bore until it reaches a closure seat il in the float assembly l5 of the float shoe rlihe closure seat Il is constructed or a tubular member having upper and lower tapered surfaces lla and llo respectively. The tubular member il is removably mounted in assembly lll by means of threads 45a. Taper ila provides a seat for trip ball itl. Taper lib provides a seat for float ball i8, while the casing is being floated into the well `riore to prevent baclziiow of fluid into the casing.

To facilitate the movement or trip ball it to its seating position it may be hastened in its progress to the bottom of the well casing by applying pump pressure to the casing through proper connections to the casing.

There is a plurality or" shearing screws le, passing through the wall of the tubular body 2S of the float shoe e, and into the wall of the oat assembly i5, so that assembly Eli is frangibly mounted in the shoe. After the trip ball IS has fornd lodgment on taper llc of closure seat Il, hydraulic pressure is applied by the surface pumps to the bore or" the casing to such an extent that the pressure applied to the trip ball l5 and assembly le will fracture the shearing screws i9 which permits the dislodgment and movement of the neat assembly downwardly in the body 2B and thus causes its ejection from the shoe into the bore of the well.

Were the float assembly l5 not elected from the oat 'shoe e, the ow of fluid through the well casing bore l would be greatly restricted, because it is obvious that the passage ich is much smaller in cross sectional area than the bore of the casing. However, after ejecting float assembly l5 from the oat shoe in the manner above described, the area of opening within the shoe through which the fluid is per mitted to iiow is substantially the same as the area in the well pipe. Consequentl', the volume of how through the unrestricted casing bore after electing the oat assembly is also greatly increased.

The oat assembly i5 is shown as partially dislodged in Fie. II by the action of pressure applied to the trip ball Eli, as above described. Float assembly i5 and tripping ball U5, L of greater specic gravity than the well f. will fall downwardly in the well bore after their dislodgrnent, as shown in Figures Ill and El?. Float assembly i5 and trip ball le are made of drillable material, which may be later drilled up, should the well drilling operation be carried to a depth beyond the initial subsurface positioning of the well pipe which cerneni d.

The float assembly and tripping ball made 'of aluminum, magnesium, plastic or a combination of same, or other materie drillable characteristic. By the ter. di is meant that these elements may be cut by the drill bit, along with any cement or materials around there. 'after the cernenting .ich is finished. Such drilling may be ecessary in order to provide a free and unobstructed passageway for the guiding and floating of a subsequent well pipe that may be later cemented in a deepened well bore. v

My invention, therefore, provides a well pipe bore which is free of all semi-closed iiow restrictions. It provides a free and unobstructed conduit or passageway for the movement oi cementing slurry or other iluids; and such passageway is substantially the same in cross sectional area as the bore of the casing.

After the well ow circuit has been Wash-circulated to the satisfaction i the operator, the collapsible plug Hl is placed in the cementing head Ei, as shown in Fig. II. This fluid segregating collapsible plug, and all subsequent uid segregating coilapsible plugs desired to be infected into the well casing, are positioned in the cementinor head Without interrupting the flow stream through the well circuit. Therefore, the introduction oi such plugs does not require the releasing of the pressure of the circulating pumps.

The plugs be positioned above the casing for introduction thereto by simply removing the hood or bonnet 2i from the cement head. The removal of the hood 2i may be accomplished by the withdrawal oi steel pins 22 from the openings 23 in the tie-down arms 25..

The tie-down arms are welded on the cuter periphery and at opposite sides oi the hood 2l, by means of welds Edo. The tie-down arms 2li are so positioned that they extend below the bottom of the hood in such a way as to permit the openings to align themselves with complemensteel pin openings 2E in the locking segments 2S. The locking segments 26 are welded to the cement head body 2'! by means of welds 26a. The tie-down arms 2d are thus pinned between the segments 2S.

When tl e pin openings in the tie-down arms and the pin openings 25 in the segments 25 are in alignment, the under surface 29 on the circumferential bottom rim oi the bonnet or hood 2l is shouldered on the upper surface 3G on the circumferential top rim of the cement head body 2T.

The removal of the tie-down pins 22 permits the bonnet or hood 2l of the cement head to be moved upv/'ardly and apart from the cement head body 2i. The bonnet or hood 2l may be moved upwardly by attaching a block and tackle (not shown) to the sling 2S positioned on the flexible hose ES.

After the bonnet 2i is removed the collapsible plug le may be placed in the cementing head the` bonnet may then be replaced, and locked in place. Of course, lle this operation is takplace, the pump not, is directed through valve il and flow conduit Se into the casing, and the valves l' and l? will be in closed position, so that iluid may not flow through the cementing head. Bleeder valve fil is provided on the flexible hose line lll for the purpose of releasing the pressure remaining in the cementing head after the new has been directed so as to by-pass the cementing head.

To make safe simple the detaching and attaching of the bonnet or hood 2i to the body 2i of the cementing head, the internal bore surface of bonnet 2l is made to provide an easy iit by slidable engagement With the outer wall 33 of the cement head body extension t4. In order to prevent fluid leakage between members 2l and il', grooves are provided on the inner side walls or" the bonnet 2l, in which grooves are placed resilient sealing rings te. Thus, during the time ings M.

that the pump flow is directed through the cement head, leakage from the head is prevented.

Since different diameters of casing may be encountered in cementing operations, it is necessary to make provision for the adaptation of the cementing head to this situation. It is also necessary to make diiierent diameters of collapsible plug l/-l so that it will fit different diameters of casings encountered in cementing wells. In Figures I, II and VII there is shown a liner or cylinder 3l which is slidably disposed within the bore of the cement head body 21. This liner 31 may be made of any thickness or it may be dispensed with entirely. In this way a cementing head may be made of a standard proportion and single size and yet be adapted to diiierent sizes of plugs i4 by the use of this variable thickness liner 31.

The means used for segregating fluids in my invention is the typical collapsible cementing plug |43. Plug Ma is of exactly the same construction as plug lll, and when plug I4 is described, such description will also apply to plug Elia.

This plug I4 is merely a preferred form, and may be made in a variety of shapes and sizes. This collapsible plug is made of resilient material, such as rubber, natural or synthetic, which has a yielding nature, and yet is capable of withstanding considerable abrasive action. This plug may be used to segregate any of the iluids used, or encountered, in the cementing operation, such as cementing slurry, Well fluid, water or other fluids.

The typical collapsible plug I4, shown in the drawings, is substantially in the form of a spool, having flanges 33 on the outer periphery thereof which produce sealing action when these ilanges are made to contact the walls of the bore 0f the well pipe. It has an irregular axial opening 39 which constitutes a hollow internal bore. At each end of the plug, ferrules 40 and Alia are inserted, and are retained inside oi the ends of the plug by means of rmly secured wire bind- The ferrules are provided with threads d2 on their inner surfaces, which threads provide attaching means for the closure member 43, extending member d4, or other members. A cork or other stopper may also be inserted in the end of the ferrule.

Before injecting the plug I4 into the well casing, the opening through ierrule Il@ is sealed by threaded engagement therein of closure plug 63, and the hollow bore 39 of the plug is filled with water or other non-compressible iiuid. To maintain the fluid within the plug while it is positioned in the cement head, and so that no air will be trapped therein, the lower ferrule :lila is sealed with the cork or stopper 0.5.

The plug I4 is so constructed that it may be deformed to the contours of the casing, or passageway in the casing, through which it is forced by pressure; and it will reform itself to the contours of the casing, or other passageway, after passing through any constriction in the casing. When the plug is deformed by being 'forced through a constriction, the sealing cork t5, which is used to retain the duid inside the plug, may be ejected from the plug by reason of the fluid pressure against it from inside the plug, so that the nuid inside the plug will be partially or Wholly discharged therefrom. After the constriction has been passed the plug reforms itself to its original shape.

Plug I 4, when confined under pressure, has

all of the attributes of a solid. It is made of resilient material, so that it may be elongatedV for passage through a restricted area, or it may be reduced in diameter by the ejection by pressure of iiuid therefrom, to pass such restricted. area. The rigidity of the plug is regained alter passing the restrictedL area. This so because a hydraulic suction built up inside the plug, which suction by the ejection by pressure of the plug when passing the restricted area. This hydraulic suction, acting in conjunction with the reilex action of the resilient material of which 'the plug is made, causes the plug to resume its original shape after p ing the restriction; and in reconorming itself, liquid from the surrounding area, equal volume to that discharged, will be drawn into the hollow space inside the plug by the force ol the layciraulic suction. Thus my plug, being of substantially rigid characteristic, notwithstanding its non-rigid elements, e-rective as means for substantially sealing oi and separating the contents of a well conduit, or other conduit, at whatever places or intervals may be desired.

ln Fig. Il is shown the collapsible plug i4 in position in the cement head preparatory to being inducted into the well casing by pressure applied by the surface pumps. This primary plug, as shown in Fig. II, is used for the purpose or spacing the cementing slurry which follows it and the well fluid which precedes it. This plug it is placed in the cement head in the manner hereinabove described while the well is being wash-circulated.

Alter the well has been waslncirculated to the satisfaction of the operator, Valve ii is closed and valves i2 and l are opened so that the flow circuit will be directed through the cement ing head Si.

The plug valve i has a central opening iii through the key et, which opening is shown in closed position in Figures I and II. When the valve key [lli is partly rotated by a wrench or other means, the valve opening it is caused to register with the lower opening ol the valve l, which leads into the casing, and opening it will then communicate with the interior of cementing head il, wherein plug is is positioned.

ln order to maire the valve l easier to open, there has been provided a by-pass between the lower part of the cement body i and the casing below the valve l. This bypass arrangement consists o a small diameter pipe connected with proper nipples, with a valve Si! thereon, which when opened, will allow the equalization of the pressure in cement head d and the casing below the valve rihus, the valve l will be sier to open when the pressures on each side or its closed key are equalized.

lifter the pumping flow is directed through the cement head in the manner hereinabove described, the pressure from the surface pumps is increased and plug lll is forced through the central opening it in valve l, and into the bore of the casing. The increased pressure from the pumps is necessary, because the opening 46 is of lesser diameter than the plug I4. The cork @5 may be forced out of ferrule opening lilla when plug Ill is forced through opening 46. The operator may tell when plug lll has passed the opening l5 by the pressure drop on the surface pump.

Alter the plug it has passed the valve l and has proceeded into the casing, the Valves l2 and l are closed (alter opening valve Il) so that the pumping flow will again by-pass the cement head 6. This is done in order that the bonnet 2| of cement head li may be removed in the manner hereinabove described for the placement therein oi collapsible plug lila, with its connecting extension fifi and check valve lil attached thereto; and this operation is performed without interrupting the pumping operation or without removing the cement head from its attached position on the casing string.

After the collapsible plug l@ has been forced by pressure into the Well casing, in the manner hereinabove described, the cenienting slurry or other well bonding material is pumped into the well casing through valve il and pipe tu, alter valves and l' are closed. This cementing slurry follows the plug le, and plug ill segregates the well fluid ahead of it from the cementlng slurry or other bonding material which follows it.

ln Fig. Ill the primary collapsible plug lit is shown at the bottom ol the well casing, and immediately above it in the casing is shown the cement slurry lll. Fhe volume ol' slurry introduced into the well casing is determined by the operator to suit the particular needs oi' the cementing job to be performed.

While the cementing slurry lil is being pumped into the well casing the hood 2i on the cement head ti is removed and collapsible plug lea is inserted into the cement head in the same manner that collapsible plug l was inserted therein. Plug la is exactly the same in construction as plug lil. Attached to the top or" collapsible plug lila is the checla valve 5i. The plug Ilia and check valve 5i are connected by means of the extension member lrl. Extension member is a rod which has threads on each end thereof so that it can be screwed into the check valve lil by means of threads ll in the lower end thereof, and the other end of the extension rod ifi can be screwed into the threads i2 on the inside or" the ferrule dit in the upper end of collapsible plug Illa.

when the desired amount of cementing slurry has been pumped into the well casing, valve il is closed, after opening valves l2 and. l, so that the pump flow will be again directed through the cement head li. Pressure is applied to the plug lila so that it is forced through the opening fili of valve l in the same manner that plug ifi was forced therethrough. rlhe valve hl, being of less diameter than the opening fili, will follow the plug ifea through the opening fili. rl'he plug Elia then segregates the cementing slurry lll from the well fluid, or other fluid, which follows the plug lila in the bore or the well casing.

After the plug ita and check valve 5l have entered the casing, valve il is opened and valves I2 and 'i are closed so that the pumping now will again oy-pass the cement head il.

Any number of spacer plugs may be injected into the well casing to segregate any number or any kinds or" iiuids, as may be required or desired, in the manner hereinabove described. These spacer plugs may be injected into the well casing without stopping the pumps and without interrupting the ilow through the well circuit.

In Fig. III the plug l is shown at the bottom of the casing after valve assembly i5 of float shoe Il has been ejected therefrom. Immediately above the plug ifi is the cementing slurry, and immediately above the cernenting slurry is the collapsible plug Isa with check valve 5l attached thereto.

.es the pressure flow is continued from the ll surface pumps, and the fluids continue to iiow in the well circuit, the plug I4 will be ejected from the bottom of the casing, as shown in Fig. IV, thus allowing the discharge of the slurry from the casing into the well bore.

As plug Ma progresses downwardly in the casing it will be pressure-collapsed through the stall collar 5 and will reconform itself to the walls of the casing bore below the stall collar 5. Check valve El, being attached to the collapsible plug 14a, will be forced to stopped position in the stall collar 5, thus building up pressure on the surface pumps and preventing the further flow of fluids within the well circuit.

Fig. V1' shows the check valve 5l in locked position in the stall collar with the collapsible plug Illa having passed the stall collar and conformed itself to the contours of the casing 3.

As shown in detail in Fig. VI, my stall collar 5 has a truncated inlet 52 and also has a truncated outlet 5t which inlet and outlet are joined at their smallest diameters by throat 54. This construction, as shown, forms a Venturi-like passage through the stall collar. The upper truncated inlet 52 also provides a seat and stop for the check valve 5i. The check valve 5l has a taper 52a near its upper end, which taper 52a mates with seat 52.

A groove is recessed into the inner surface of the truncated outlet 53, which groove extends downwardly with the vertical axis of the stall collar 5 from the smallest diameter of the said truncated outlet 53, and a top shoulder 55a is thus provided at the top of this recess 55. This Ven turi-like flow passage is constructed of a cylindrical tube 55, which tube is detachably engaged with the outer body 51 by means of threads 5S, which are made secure to complementary body threads 59.

The inner wall of the body 51 has a greater interior diameter below the threads 59 on body 51, which construction is so provided to permit an extremely easy and slidable t, when screwing the tube 55 to body 51, in assembling the stall collar 5.

At the lowermost point on the rim of tube 55 there is provided horizontal plane surface 6i to shoulder on a complementary horizontal plane surface 62, provided on the top rim of the stall collar extension nipple 63.

The extension nipple 53 is connected by male threads 64 to lower female threads $5 on the body 51. The bearing provided by the shoulders El and 52 is so constructed that the greatest possible support will be supplied to the tube 55 after it is mounted within the body 51. To further strengthen this support, extension nipple 53 is integrally attached by a suitable weld 56 to the lowermost point of the body 51. The extension nipple 63 has a male lower thread 61 for attachment to a complementary thread 63 within a coupling of the well casing string 3. It is to be noted that the bore S9 of the extension nipple s3 has the same diameter as the bore of the casing string 3, on which the stall collar is positioned.

As the collapsible plug lila progresses downward with the flow stream inside of the well casing, by reason of pressure applied by the surface pumps from above, it reaches the Venturi-like passage inside of the stall collar 5, and the pressure from the pumps deforms it and forces it through the throat 54 in the stall collar.

rihe operator will know when the check valve 5l reaches the stall collar by the sharp pressure rise on his pumps. When check Valve 5l reaches its seating position in the stall collar, it will be forced into locked position.

The check valve 5l is so constructed that the top thereof is tapered in such a way as to seat on the truncated inlet 52 of the stall collar tube 5S. It is made of some drillable material, preferably of aluminum, and is rigid enough that it will not be forced through the stall collar in the manner that collapsible plug Ilia is forced therethrough.

On the lower end of check valve 5E there is an expansible split ring '52, which is contracted when the lower end of the check Valve 5l is forced by pressure through the throat 54 of stall collar tube 55. When the split ring passes the shoulder 55a it will relax and snap into locking position in the groove 55. On the outer wall of the check valve 5l are sealing rings 53, which are for the purpose of preventing leakage of fluids around said check valve 5l after it has been locked in position.

When the check valve 5l is in locked position in the stall collar, it cannot be forced downward because the top thereof is firmly seated in the upper part of the stall collar tube 55, and it is prevented from moving upward because it is locked in position by the split ring 12 underneath the shoulder 55a.

When the check valve 5l is in such locked position, the surface pumps will be stalled, and the flow in the well circuit will be immediately stopped. Fluid is prevented from flowing back into the well casing through the stall collar when the pressure is released from the surface pumps, because the check valve 5l is prevented from moving upward by reason of its being locked in place by the split ring 12. Thus, there is provided an immediate shut-0H of fluid being discharged from the well casing, and an immediate shut-off of fiuid flowing back into the well casing. All fluid is then static.

The stall collar tube 5S, the check valve 5l and extension member ad are preferably made of a drillable material, such as aluminum, so that after the cement is set around the casing, these elements may be drilled out, for the purpose of producing oil through the casing, and also for the purpose of deepening the bore of the well, if so desired. Of course, the collapsible plugs I4 and Ilia, being made of rubber or other resilient material may be drilled out also.

When check valve 5| reaches the truncated opening 52, it is necessary to increase the pump pressure in order to force it into locked and seated position in the stall collar. This increased pressure, however, is not applied to any collapsible spacer plugs used in my method, because the pressure is absorbed by the check valve 5 and stall tube 56. The members 5l and 56 in effect constitute a baille to absorb the pressure from the pumps. This is important because the increased pressure, if applied lto the collapsible plugs, would cause their distortion and allow leakage around them, with the result that there would be some mixing of fluids segregated by the plugs. My device prevents such leakage and rmxing.

ln the function, operation and practice of my invention the string of casing is progressively made up as it is guided and floated into the well bore. The float shoe fl, with the valve assembly l5 mounted therein, is first mounted on the lower end of the first joint of casing. Then the stall collar 5 is placed in position between the rst joint of casing and the string of casing above it. This stall collar 5 may be placed at any interval along the casing as desired by the operator; but

13 in practice it is desirabley to space it a shortdistance above the float shoe d.

After the casing, with its appurtenant float shoe and stall collar, has been guided and floated into the hole to the proper depth, the trip ball lt is dropp to the casing and allowed to gravitate tou .d thel bottom thereof,V Trip ball MS is small enough to pass the throat '5ft or" the stall collar but it will come to rest on .the shoulder |'i in the ioat shoe i.

After this operation, the cement head which has already been assembled, with flexible hose l t attached thereto, is placed in position at the top of the casing t by means of a suitable casing oonnecting collar tu. The flow line i3d, from the surface pumps is conn-.cf f TlS. and then the cementing assembly is ready for operation.

The nrst step in ceinenting the casing in the Well is to wash-circulatc the hole. In order to have a full and unrestricted flow oi fluids through the well new circuit during this wash--circulating period, it is desirable to eject the valve assembly |55 from the float shoe l before this operation begins. The trip ball it has already come to rest on the taper or shoulder and when pressure is applied from the surface pumps through valve ll and now line da and thence through the cas ing fi, to the trip ball lli, the pressufe will cause shear screws i9 to be sheared or?, and then the valve assembly it will be ejected from the float shoe body Siti into the bore of the well, as shown in Figures Il, III and IV. There will then be an unrestricted passage through the casing bore for the circulation of Fluid through the well new cir cuit.

After the well has been wash-circulated to the satisfaction or" the operator, a collapsible plug |11 is put into the casing under pressure by directing the well flow circuit through the cement head Ei by opening valves i2 and l and closing valve il. Prior to this operation the collapsible plug ifi has been positioned in the cement head E by removing the bonnet 2| from the cement head il, placing the plug Hl in the head as shown in Figure II, and then replacing the bonnet 2i. This was done without interrupting the now in the well circuit, because during this operation the r'low has been directed through valve l i and flow line to. into the casing while Valves l 2 and "l were f closed.

After the collapsible plug it has been forced by pressure through the opening il of valve i and has proceeded into the casing below the cement head 5, then valves i2 and i are closed and valve opened so that the flow is again directed in such a way as to by-pass the cement head E. Without interrupting the continuity of flow the cementing slurry 'iti is pumped into the well cas-- ing behind the collapsible plug M.

While the cementing slurry is being run into the well casing, bonnet 2| on the cement head 6, is again removed and the collapsible` plug ita with check Valve 5| attached thereto is positioned in the cement head t, in the manner shown in Fig. VII. The bonnet 2| is replaced and, after a sufficient amount of cementing slurry has beerun into the well casing, valve ll is closed ai ter valves l2 and 7| are opened., so that the new will again be directed through the cement head t, and pressure from the surface pumps is applied to the collapsible plug Nia.

Collapsible plug Ma, carrying the check valve 5|, is forced by pressure through valve and into the casing in the same manner that plug |4- Was introduced into the casing. After plug Illa and check valve 5| have entered the casing, the flow is again directed through valve I| and flow line 5a into the casing, and the cement head 6 is bypassed by closing valves |2 and i.

The pumping is continued and plug lila, carrying check valve 5l, is forced through the casing with the well fluid. Plug ita acts as a spacer between cementing slurry l@ and the well uid behind plug ma, in the manner shown in Fig. III, wherein plug ma is shown during the time it is progressing downward in the casing, and plug i4 is at the lower end of the casing but not yet ejected.

As the flow continues on its path from the surface storage facilities through the pumps, through the casing, into the well bore, and upward around the casing and back to the surface storage facilities, the plug il will be ejected from the bottom of the casing and the cementing slurry 'm will be discharged into the well bore as shown in Fig. IV. IrEhe plug Hin is forced by pressure through the Venturi-like restriction inside of the stall collar 5, and valve 5| is forced into seating position in the stall collar 5, in the manner shown in detail in Fig. VI, and as has been described in detail hereinabove.

When Valve 5| is locked in position, it will cause the surface pumps to stall and the operator will immediately know that the cementing job has been completed, and he will stop the pumps and release the pressure thereupon. The valve 5| is locked by means of locking ring 'Eli so that it may not be forced upwardly in the casing by the iiuid head pressure of the cementing slurry outside of the casing, and will not allow the cementing slurry to llow back into the casing above the stall collar. Thus, there is an immediate and automatic stoppage of the now of fluid in the Well circuit, in both directions, when valve 5| is brought into locked and seated position.

The collapsible spacer plug il may be used for the segregation of any type or hind or nurnber of fluids used during a cementing operation; and as many or the plugs may be inserted into the well, in the manner hereinabove described, as may suit the convenience and desires of the operator.

After the cementing job has been completed, and the cement has set, the valve 5|, connecting member til, stall collar tube t5, plug it and plug Ma may be drilled out, in order to make the bore of the casing free of obstructions for the winning of production therethrough.

It is to be emphasized that the procedure outlined above for the practice o1 my invention is a continuous and uninterrupted operation. At no time during the cementing operation is the pressure released from the pumps until the ce inenting job is completed. During this procedure restrictions are removed from the well casing and there is provided a free, continuous and unrestricted flow or" fluids through the well casing to the greatest extent possible.

Various changes and adaptations may be made in the practice of my invention without departing therefrom. For instance, the central opening through the removable assembly i5, in iloat shoe ll, may be permanently closed by a plate, replacing the valve seating element il, which plate may be threaded or welded in place, across said opening. In this way trip ball may be dispensed with, and pressure applied diV rectly to the plate to eject assembly l5 from the shoe.

Also, the float assembly valve may be provided with a plurality of valve seats to accommodate a plurality of float balls, thus to make multiple check valves in this assembly when desired.

My invention as disclosed herein is primarily intended for the cementing of a string of casing at the lower end thereof. However, it is to be understood that my invention, and the method thereof, and the practice thereunder, may be used as the lower stage cementing step of a multi-stage cementing operation.

By multi-stage cementing it is meant that provision is made for the discharging of cementing slurry into the well bore in divided batches and at selected elevations or levels along the well pipe. A typical multi-stage cementing operation is disclosed in my co-pending application, Serial No. 690,969; and the present invention may be used with the system shown in said co-pending application.

To use the invention disclosed herein in a multi-stage cementing job, my stall collar and check valve unit would be eliminated and the float shoe only is used, which float shoe would be positioned for its customary function at the lower extremity of the well pipe. On the well pipe above the shoe, the multi-stage collar or collars would be positioned at the proper points.

rihe continuous flow and uninterrupted pumping, as is made possible by the instant invention, and the provision for the positive segregation of fluids during the cementing operation, and the elimination of dow restrictions in the Well casing, are particularly adapted for use in multi-stage cementing because it is desirable in such multistage cementing to segregate the various quantities of fluids used in the cementing operation and that there be continuous and unrestricted flow through the well pipe during the operation.

When the terms cementing slurry or slurry are used herein, the terms are meant to include any fluid of a cementitious nature used to bond well pipe in a bored hole, whether it be plastic, cement or other materials.

From the foregoing it is apparent that I have invented an apparatus for guiding, floating and cementing well casing in the bore of a Well wherein full and unrestricted flow of uids through the well casing is attained; there is continuous flow of fluid through the well ow circuit; as many and dierent kinds of fluids as may be desired in the cementing operation are segregated without stopping the flow of fluids through the Well flow circuit, and without releasing the pressure from the well casing; a positive and immediate closure of communication between the well casing and the bore of the well is attained by pressure, but which pressure is not applied to the fluid segregating media; with the result that the causes of costly cementing failures in the past have been eliminated, and a safe, speedy, positive and entirely dependable system introduced into the well cementing art.

I claim:

l. In a device for cementing well casing in the bore of a well, a collapsible plug made of resilient material having a circumferential surface on the outer periphery thereof engageable with the inner wall of the well casing when the plug is in normal undeformed condition, said plug having a hollow internal bore and being provided With an opening in each end thereof communieating with said bore, which openings are adapted to receive closure members; a non-compressible fluid occupying said hollow internal bore; closure members initially disposed in said openings so to confine said fluid, one of which closure menibers is adapted to be expelled from its opening whenever the plug is initially materially deformed by pressure applied thereto, whereby, some fluid may be expelled from the internal bore of said plug and some fluid may be drawn back into said bore when the plug assumes its original shape.

2. In a device for guiding, floating and cementing well casing in a bored hole, a tubular body adapted to form a part of a weil casing string; a detachable tubular member mounted Within the body, said tubular member being substantially Venturi-shaped, and having a recess at its lower end adapted to receive a relaxed split ring, and having a valve seat at its upper end; a valve head arranged to enter said member and rest on said seat to effect a valve closing the passage through the member; and a split ring carried by said head and arranged to expand into said recess and lock the valve in closed position.

3. In a device for guiding, floating and cementing well casing in a bored hole, in combination, a valve member comprising an elonga"ed cylindrical body having a taper at the upper end thereof; a split ring on the lower end thereof; a resilient collapsible spacer plug having a plurality of flanges on the outer periphery thereof and a hollow internal bore, and threaded openings in the ends thereof; and an elongated connector member adapted to join the body member with the collapsible plug by screwing one end thereof into the bottom of the body member and the other end thereof into one end of the collapsible plug.

In a device for guiding, noating and cementing Well casing in a bored hole, a tubular member having a tapered seat in its upper part and a shoulder in lower part, said member lelng arranged for incorporation within a string of casing; a valve member comprising an elongated cylindrical body having a taper at the upper end thereof adapted to mate with said tapered seat and thus provide closure of the well casing; a split ring arranged on the lower end of said body and adapted to relax underneath said shoulder at the time of closure of the well casing, and thus prevent the body from moving upwardly in the casing.

5. In a device for guiding, floating and cementing well casing in a bored hole; a string of casing; a float shoe carried on the lower end of said casing; a neat valve assembly frangibly mounted in said oat shoe and adapted to be ejected therefrom by pressure; a stall collar disposed on said string of casing in spaced relation with said shoe, the interior of said stall collar being adapted to receive and loci: in place a check valve to stop the iiow of fluids through casing string; a check valve adapted to seat and be locked in place inside said stall collar by pressure applied thereto; a plurality of collapsible spacer plugs adapted to provide segregation between the fluidsused in cementing the well casing in the bored hole, and adapted to move with the fluid inside the casing; a plug valve; a valved conduit; a cementing head having a removable hood thereon, said cementing head being adapted to communicate with the well casing through the plug valve and with fluid circulating pumps through the valved conduit; whereby said collapsible spacer plugs may be injected into the well casing without releasing the pressure from the fluids in the casing and without removing the cementing head assembly from the top of the casing; and means for admitting fluid under pressure into the well casing and around it.

6. In a device for guiding, floating and cementing a well casing in a bored hole, a resilient collapsible spacer plug having a hollow internal bore and being provided with an opening at each end thereof communicating with said bore and having a circumferential surface on the outer periphery thereof engageable with the inner wall of the Well casing when the plug is in normal undeformed condition; and insertable members closing said openings, one of which members is expellable by pressure of liquid contained in the plug when the plug is initially deformed.

7. In a device for cementing well casing in the bore of a well, a collapsible plug made of resilient material, said plug having a hollow internal bore and being provided with an opening at each end thereof communicating with said bore and having a circumferential surface on the outer periphery thereof engageable with the inner Wall of the well casing when the plug is in normal undeformed condition; and a closure member inserted in each such opening,

8. In a device for cementing Well casing in the bore of a well, a collapsible plug made of resilient material, said plug having a hollow internal bore and being provided with an opening at each end thereof communicating with said bore and having a circumferential surface on the outer periphery thereof engageable with the inner wall of the well casing when the plug is in normal undeformed condition; a closure member insertable in one of said openings and adapted to be expelled by pressure of liquid contained Within the plug when the plug is initially deformed; a closure member removably afliXed in the opening at the other end of said plug, said closure member providing a connector between said plug and a device to be conveyed thereby through a conduit.

9. In a device for guiding, floating and cementing well casing in a bored hole, a tubular body adapted to form a part of a Well casing string; a tubular member mounted Within the body, said tubular member having a recess at its lower end and adapted to receive spring actuated retainer means, and having a valve seat at its upper end; an imperforate valve head arranged to enter said member by hydraulic pressure and rest on said seat to effect a valve closing the passage through the member against the ow of fluid in either direction; and spring actuated retainer means carried by said head and arranged to expand into said recess and lock the Valve in closed position.

10. In a device for guiding, floating and cementing well casing in a bored hole, a tubular body adapted to form a part of a well casing string; a tubular member mounted within the body, said tubular member having a recess at its lower end adapted to receive a relaxed split ring, and having a valve seat at its upper end;

an imperforate valve head arranged to enter said member by hydraulic pressure and rest on said seat to effect a valve closing the passage through the member against the flow of fluid in either direction; and a split ring carried by said head and arranged to expand into said recess and lock the valve in closed position.

SYLVESTER B. SCHNI'ITER.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,011,484 Perkins et al Dec. 11, 1911 1,662,311 Hamer Mar. 13, 1928 1,735,330 McMahan Nov. 12, 1929 1,743,626 Shaver et al. Jan. 14, 1930 1,849,190 Jackson Mar. 15, 1932 2,107,327 Creighton Feb. 8, 1938 2,167,747 Dyer Aug. 1, 1939 2,196,652 Baker Apr. 9, 1940 2,196,657 Burt Apr. 9, 1940 2,236,987 Bechtold Apr. 1, 1941 2,286,126 Thornhill June 9, 1942 2,295,822 Armentrout Sept. 15, 1942 2,330,267 Burt et al Sept. 28, 1943 2,330,659' Anderson Sept. 29, 1943 2,352,744 Stoddard July 4, 1944 2,370,833 Baker Mar. 6, 1945

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