US1673616A - Method of and device for cementing wells - Google Patents

Description

`Tune l2, 1928.

A. BOYNTON METHOD OF AND DEVICE FOR CEMENTING WELLS 2 Sheets-Sheet l INVENTOR 75o f/vlO/V, mf@

ATTORNEYS iblflfl w Fild oct. l1, 1925 Patented June I2, 1928.

UNITED STATES ALEXANDER BOYNTON, OF SAN ANTONIO, TEXAS.

METHOD OF AND DEVICE FOR CEMENTING WELLS.

Application led October 1, 1925.

This invention relates to improvements in devices for cementing well casings and is especially designed for use where a plurality of oil sands are to be protected against cavings, the down flow of water or the like,

by means of cementation.

Heretofore in the art it has been proposed to carry out the cementation of wells by the use of a process wherein the cementA was l spaced from the mud fluid by mean's of two wooden plugs. In this old process, the well casing is first let down upon the bottom of the well in order to find the bottom, and then picked up a few inches in order that l the pump may set up circulation. Just at this point in the process difficulty is not infrequently encountered since it is not always possible to pick up the casing. After the casing has been picked up a bottom plug is inserted, then the cement vis pumped into the casing and on top of the cement a top plug is placed. The mud fluid is then pumped in on top of the top plug until the bottom plug strikes the bottom of the well. The

i5 casing having been picked up, say six inches from the bottom as above described, and the bottom plug being say twelve inches long, the'pump will, of course, stall when the bottom plug strikes the bottom of the well.

50 Then the casing is picked up again to a point say six inches above the top of the ottom plug and the pump is started again and run until the top plug strikes the bottom plug. The casing is apt to stick or as freeze at any time. If the casing could not be picked up the second time, the cement is trapped and must be'gremoved. The pump again stalls when the top plug strikes the bottom plug, because gthc top plug is about 40 twelve inches long, and as just stated, the casing has been picked up to a point six inches above the top; of the bottom plug. When the top and bpttom plugs come together as stated, the cement is all outside of 46 the casing. Then the casing is lowered to the bottom. Sometimes, however. it cannot be lowered. If no trouble is encountered in picking up the casing twice as set out and then letting it down again, this process 50 works all right unless one or both of the plugs should stick to the casing. Serious diiiiculty has been encountered due to the plugs sticking. rlfhe plugs are made of wood, and the kind of wood of which the u plugs are constituted varies. Different `collapses it.

Serial No. 59,887.

kinds of wood expand to different degrees, but all plugs expand more or less when exposed to the mud fluid, and the amount of expansion depends not only upon the character of the wood, but also upon the moisture contained in the wood at the time the plugs are used. Moreover, sticking of the plugs results not only from swelling and expansion, but may also be caused by any imperfection in the casing, such as dents, slivers or bends. Frequently casings become distorted from great outside pressure, and it is not uncommon in deep wells to have the casing collapse when great pressure of water or mud fluid on the outside comes against the casing and bends it or partially Not only must the quality of wood and its moisture content be always observed with care, but the greatest care must always be used to accurately caliper the plugs to the proper diameter in order to avoid sticking of the plugs if too tight on one hand and the leaking by of cement if too loose on the other hand. For these reasons it has been found that the process heretofore proposed in the art is very often unsatisfactory.

The object of the invention is to provide a device of this character which does not involve the necessity of raising or lowering the well casing, and which does not involve the use of wooden plugs or any other kind of plugs that may expand and stick or become lodged against dents or other imperfections in the pipe.

A further object of the invention resides in the provision of a device having these advantages and capacities, and which is readily controllable by the operator for the purpose of easily and effectively carrying out the successive cementation of the well casing at oints above the various oil yproducing san s.

A still further object is to provide a device of this character which 1s simple and durable in construction, reliable and effective in operation and easy and comparatively inexpensive to manufacture and employ.

Other objects and advantages reside in certain novel features of the construction, K

arrangement and combination of parts as will be hereinafter more fully described and particularly pointed out in the appended claims, reference being had to the accompanying drawin forming a part of this specication, an in which :--l

Figure 1 1s a view artly in section and partly in elevation il ustrating the device constructed in accordance with the present invention.

Figure 2 is a fragmentary view and vertical section showing portions of the device illustrated in Figure 1.

Figure 2 further illustrates the device shown in Figure 1.

Fi re 3 is a sectional view on line 3 3 of Figure 2.

Figures 4 and 5 are detail views of the cementing tool.

Figure 6 is a detail view showing another form of the diierential float signal and valve.

In the drawings, the well hole is designated at W and the formation shown has a plurality of oil producing sands designated at S and S.

The well casing is designated generally at 1 and has perforated liners 2 and 3 opposite the sands S and S. Above each of the oil producing sands, nipples 4 are incorporated in the well casing and have dia metrically opposite perforations 5 controlled by the rubber sleeve valve 6 snugly fitting the nip les and held in place by a relatively smallupper retaining cup 7 and a relativel large lower retaining cup 8 threade onto the nipple. The sleeve valve 6 is provided with discharge openings 9 angularly spaced apart from the perforations 5 of the nipples.

The present invention proposes the use of a cementing tool designated generally at 10 which is suspended by a string of tubing from above the well and which may be vertically adjusted in any suitable way. The cementing tool has an upper section designated generally at 11 and a lower section` designated generally at 12 connected by a slipl joint designated generally at 13. The slip joint 13 has cooperable shoulders 14 and 15 formed on the sections'll and 12 respectively, so that when the cementing tool is raised, the section 12 will also be raised. However, when the cementing tool is lowered so far as to permit the lower end of the same to rest on the bottom of the well, the section 12 being supported on the bottom of the well remains stationary, and the section 11 will move down somewhat into the section 12. This permts discharge openings 16 in the section 11 to be brought into re 'stry with discharge openings 17 in the section 12. At all other times, however, discharge openings 16 and 17 are out of re 'stry.

e section 12 has a perforated cylinder or nipple 18 incorporated therein and on etch si e of the perforations of the cylinder 18, rubbers 19 are provided, the rubbers 19 being expanded by the internal pressure exerted through opening 20 on the inner face of the rubbers and being held against axial displacement and reinforced and protectedbv retainin elements 21. As shown in dotted lines in 1igure 5 the intermediate ortion of the rubbers 19 may be expandedpbut the ends are held against expansion and within the retaining elements or cups 21 by virtue of the provision of reinforcing and holding wires 19, the wire 19 being imbedded in the rubbers 19 as shown. The lower end of the section 12 is open and is provided with a dart valve 22 equipped with a spring 23 designed to hold the dart unseated except when the pump is running, the pressure at such times closing the dart valve and sealing the lower end of the ceinenting tool.

Above the perforated nipple 18 of the cementing tool a valve seat 25 is fixed on the section 12, and with this valve seat 25 a differential float valve and signal 26 is cooperable. As shown in Figure 6 the difierential signal and valve 26 may consist sim ly of a ball of either rubber, hard wood, al oy of aluminum and lead, or of any material provided only that its specific gravity is less than that of the cement mixture and greater than that of the mud fluid, so that the ball will sink in the mud fluid and will float on the top of the cement mixture.

In the event it should be found diflicult to make a combined signal and valve with a specific gravity of this character it may be preferable to use the form of combined signal and valve shown in Figure 2 and which comprises a ball B made up of any hard noncompiessible metal or alloy or other substance such as guttapercha or an allo of aluminum and any other light Sofit metal. A handle H is rigidly and securely connected to the ball B and is constituted of white ine or any other soft wood or similar su stance. The handle H is shellacked or painted to prevent it from absorbing water and thereby changing its specific gravity while under the great fluid pressures existing in the lower regions of the well. This type of combined signal and valve may be readily varied to cause it to have the exact specific gravity required under the prevailing conditions. The problem is always to use a combined signal and valve of such specific gravity that it will float in the cement and yet sink in the mud fluid used to force the cement down into place. In modiying the combined valve and signal shown in Figure 2 to cause it to have these rop erties it is placed in the cement whic has been mixed in the cement mixing box on the derrick floor. The point at which the handle H becomes submerged is marked. The handle H is then cut olf slightly above this mark. It is to be understood that the ball till B is always of a specific gravity heavier than the cement. Cement is usually mixed and used at a specific gravity of about 1.7. The specific gravity of ball B should therefore be about 1.75 so that it will barely sink in the heavier cement. The correct specific gravit-y to cause the signal ball to float safely m any cement mixture is then determined as described by cutting off the handle just above the point at which it sinks in the cement mixture. In this way the combined valve and signal may be readily adapted to the different cements and different mixtures of the same with water and sand in order to compensate for the varying s cie gravities of such cement mixtures. L ewise the combined valve and si al is adapted for use with the mud luirfsn reduced by different wells and different fields and which also have varying specific gravities.

The well casing is provided just below each sleeve valve 6 with a laminated packing or sealing member 27 consisting of washers cut from belting or other suitable material and held in place by retaining rings 28. Above each laminated packing member 27 a Mother Hubbard packer 29 is provided and consists of a tubular structure of fabric having its lower end secured to the well cas ing by means of a wrapping 30 of wire and having its upper end open and located o posite the intermediate perforations of t e sleeve valve.

With this arrangement in cementing wells, the cementing tool is first lowered into the well down to a position opposite the lower perforated liner 3. The pump is then started and circulation is established. At this time cement has not been pumped into the tool and the ump circulates the mud fluid. Then with the pump still running the cementing tool is raised into the imperforate well casing, whereupon the pump stalls and remains stalled until the rforated c linder 18 of the cementing tool 1s opposite t e perforations of the lower nipple 4 when the pump again starts, since circulation again may be established through the perforations of the lower nipple 4 and out through the valve 6. The operator now knows that the cementin tool is in position to carry out cementation for the protection of the lower sands. The cement is'now pum ed in until the desired amount has been p aced above the bottom sand. This amount is determined by calculating the contents of cement mixing box and of the drill stem or pipe used in the cementing process. en enough cement has been pum ed out of the box on the dex-rick :door to rep ace all of the mud fluid which the drill stem will hold, then the operator knows that the cement is going out around. the casing. The operator knows how much cement he wants to go out at this point. When that amount has been pumped from the cement box, he is ready to raise the cementing tool to the next place to be cemented. The cement that has been pumped down through thev tool passes out through the perforations of the cylinder 18 and out through the lower rforated nipple 4, the sleeve valve 6 permitting the cement to How out, but preventing it from flowing back. In locating the next place to be cemented, the operator raises thestool until the perforated cylinder 18 is op osite the upper liner 2. This can be rea ily known since with the pump working, circulation will be had over a vertical adjustment of ten to fifty feet. With the cementing tool known to be'opposite the upper perforated liner, the operator continues to raise the cementing tool, with the pump working, until the pump stalls, and with the pump stalled the operator still raises the tool until circulation is again established when it is. apparent to the operator that the perforated cylinder 18 is opposite the upper perforated nipple 4. When the perforated cylinder 18 is opposite the perforated nipple 4, an adjustment of the cementing tool a few feet either way will stall the pump.

The dart with a spring under the ball seat to hold the dart unseated except when the pump is running is a desirable feature. If cavings should slip into the well through perforations the same will be washed out by the pump. Under such circumstances, the perforations in the sli valve will also function. The spring un er the dart also provides drainage for the cementing pipe or drill stem as the same is slowly being withdrawn from the well, remembering always that any vigorous action from the pump will promptly seat the dart and allow no cement to escape past it. If at any time the operator should carelessly raise the cementing pipe too fast, so that the escaping fluid should seat the dart, he can get the dart unseated again and thereby provide drainage for the pipe by lowering the same a joint or two until the level of the fluid inside the cementing pipe and outside of same equalize. At that point the spring under the dart ball will again unseat the dart. Whereupon, the operator resumes the withdrawal. The importance of having the cementing pipe drain back into the well lies in the fact that if the mud fluid is withdrawn from inside the casing before the cement has set outside the casing, too great a strain would be exerted upon the rubber cylinder. The weight of a thousand feet of liquid cement might blow holes in the rubber cylinder opposite the holes in the perforated nipples and thus allow the cement from the outside to come back to the inside of the casing. The mud fluid must not be withdrawn from the inside of the casing until the cement hai set outside the casing.

ion

With the perforated cylinder 18 opposite the upper perforated nipple 4 the cement is again pumped into the cementing tool and on top of the cement the ball 26 is placed. The pumpl is then again connected up and started and mud Huid is pumped down on top of the cement until the valve 26 seats on the seat 25, whereupon the ump stalls. The cement is held in the position by the action of the valve 6 and sealing members 27 and packers 29. The tool may then be withdrawn from the well since the cementation of the several sands has been completed.

By lowering the drill to the bottom of the well to cause the discharge openings 16 and 17 to register, the drill may be drained and after having been drained of the cement it may be conveniently used as a washing tool. This is a feature which is particularly advantageous should some of the upper sands be inadvertently cemented.

The 'purpose of the slip valve and joint 13 is to wash out the tubing through which the well was cemented, after the cementing process has been completed. If the tubing should be withdrawn from the well immediately after the signal ball struck and without being washed out, there would be a considerable amount of cement left upon the inner wall of the tubing because the mud Huid in its downward course does not overcome the tendency of the cement to adhere to the tubing. The major part o the cement is, of course, thrust downward and out through the cementing tool. The slip valve is provided in order that the tool ma be lowered to the bottom of the well whlch opens the slip valve, and then by vigorously applying the pump the tubing is thoroughly cleaned of cement. which would otherwise SLL and foul the tubing. As soon as the cement has been washed out of the tubing, the tubing and cementing device are withdrawn from the well. Signal ball 26 is removed, then if any fear is felt that too much cement has been pumped out at any particular horizon, that is, enough cement to rise up on the outside of the casing to seal off all or part of the sand next above, the cementing tool which now, by removin ball 26, is converted into a washing tool, is lowered to each producing horizon where there is fear that cement might be opposite the pay formation. The washing tool is then raised and lowered in the perforated section of the liner opposite each pay formation. The construction of the washing tool is such that the sealing members of the same cause all of the discharge from the pump to be forced through a limited section of the liner as the washing tool is raised and lowered with the pump applied. In this manner any cement which may have risen to too high a level will be Washed out of the well. This process of flushing out the producing horizons after the cementing job has been Lezama finished is the safest and proper practice because there is no way of tellin just how much cement will be required to fi l the space between the wall and blank section of the liner, between pay formations.

The approxlmate amount of cement required to fill the space between two producing horizons is determined by measuring the amount discharged from the cement box on the Hoor. This is necessarily inaccurate and not capable of exact determination. Therefore, it is always best to make sure and have enough, even if the cement is forced up upon the sand above. This emphasizes the importance and demonstrates the necessity for going back into the well with the washing tool and washing each sand after the cementing process has been finished. The only difference between the cementing tool and the washing tool is the signal ball 26 and the seat 25. In order to convert the cementing tool into a washing tool, it is. as stated, only necessary to remove the ball 26. The seat 25, of course, does not prevent the device from functioning properly as a washing tool so long as ball 26 is kept away.

It is to be understood that the signal ball 26 is not inserted until the cementing tool has been raised to the uppermost level where cement is to be pumped out. When this uppermost level has been reached and all of the cement which it is desired to place into the well has been pumped into the tubing, then the tubing is unscrewed on the derrick floor and the signal ball is placed upon the top of the cement. The tubing is then screwed together again and the pump started and run until the signal ball 26 becomes seated upon the seat 25. It is unnecessary to use the signal ball on the lower horizons because the operator knows by calculating the displacement in the cement box, the amount of cement that has been forced out of the ce menting device at each horizon. The purpose of the signal ball is to stall the pump when the last of the cement has passed out of the tubing, If it were not for the signal ball giving notice when all of the cement has passed out of the tubing, mud fluid would continue to o out and the cement might rise above the point where it was desired to place the cement.

As has been pointed out above the cementing tool may be withdrawn to the upper sand without swabbing the well or raising the fluid by expansible members 19 of the cementing tool due to the action of the spring 23 since this spring holds up the dart valve when the cementing tool is being withdrawn from the well. It should be noted that substantially this same result is achieved even ar the ball 26 has seated upon completion of the cementation of the upper sand.

It is true that after ball 26 seats, no fluid can drain back through the tubing, but the fluid on the outside of the tubing will not be Withdrawn from the well by expansible members 19, because expansible members 19A will not expand as the tool is being Withdrawn after ball 26 has seated for the reason that no fluid pressure can pass by ball 26 and be communicated to the inside of eX- pansible members 19. After ball 26 has seated, all fluid except the comparatively small amount contained in the tubing will drain past expansible members 19. In this manner no great amount of fluid is withdrawn from the well after the upper sand has been cemented.

What I claim is:

1. A device for cementin Well casing above the several sands of t e Well, comprising valve controlled outlets in the casing above each of the sands, and a cementing tool shiftable in the Well casing and having an outlet adapted to selectively cooperate with the outlets in the casing, said tool having expansible packing means on each side of this outlet, said tool having a valve seat above its outlet and a float ball valve cooperable with said seat.

2. A device for cementing well casing above the several sands of ythe Well, comprising valve controlled outlets in the casing above each of the sands and a cementing tool shiftable in the Well casing and having an outlet adapted to selectively cooperate'with the outlets in the casing, said tool having packing means on each side of this outlet, said cementing tool including adjustable sections and having draining openings selectively registerable in one adjustment of the sections.

3. A device for cementing wells includin a casing having a plurality of perfora nipples, a rubber sleeve valve fitted on each perforated nipple and having imperforate portions closing the perforations of the ni ples, and also having perforations angular y spaced from the perforations of the nipples, retaining cups cooperable with each sleeve valve, and a shiftable cementing tool within the casing adapted to be selectively registered with the nipples of the well casing.

4. A device for cementing Well casing above the several sands of the well, comprising valve controlled outlets in the casing V above each of the sands, and a cementing tool shiftable in the Well casin and having an outlet adapted to selectife y cooperate with the outlets in the casing, said tool hav ing packing means on each side of this outlet, and valve means at the lower end of the cementing tool adapted to normally remain open and close with a certain pressure within the tool.

5. The herein described method of. cementin a well having a casing including a plura ity of perforated liners and valve controlled outlets above the liners which consists in using a shiftable cementing tool in conjunction with a pump, in aligning the tool with the lowermost perforated liner, in establishing circulation through the tool and liner while the tool is aligned with the liner, then raising the last-named tool tnrough the well casing thereby stalling the pump until the tool is aligned with the lowermost valve outlet of the casing whereupon circulation is resumed, in pumpin cement throu h the tool While the tool is a ed with the owermost valve control out et and in similarly cementing the liners above the lowermost liner.

ALEXANDER.- BOYN TON.

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