US1773941A - Method of and device for cementing wells - Google Patents

Description

Aug. 26, 1930. A. BoYNToN METHOD OF AND' DEVICE FOR CEMENTING WELLS s sheets-sheet 1 Filed ot. 1, 1925 INVENTOR AToRNEYs v @5o/vrom Allg. 26, 1930. A, BQYNTON 1,773,941

METHOD OF AND DEVICE FOR CEMENTING WELLS Filed Oct. l, 1925 3 Sheets-Sheet 2 @QQ Y www x ATTORNEYS y l (i f Aug. 26, 1930. A. BOYNTON METHOD oF- AND DEVICE FDR CEMENTING wELLs Filed Oct. l, 1925y 5 Sheets-Sheet INVENTOR /7Boy/v7'o/v,

WITNESSES 30 pump will, of course,

Patented Au'g. 26, 1930 PATENT oFF'lcE ALE-XANDER BOYNTON, OF SAN ANTONIO, TEXAS METHOD F AND DEVICE FOR CEMENTING WELLS Application led October 1, 1925. Serial No. 59,888.

This invention relates to an improved device for cementing oil, gas and water wells.

One of the principal objects of the invention is to provide a device of this character L'. which may be conveniently used to properly cement the well and which does not require the 'use of wooden plugs and barriers, or the raising and lowering of the well casing.

Heretofore in the art it has been proposed :e to carry out the cementation of wells by the use of a process wherein the cement was spaced from the mud fluid by means of two wooden plugs. In this old process, the well casing is first let down upon the bottom of the well 1n order to find the bottom, and then picked up a few inches in order 'that the pump may set up circulation. Just at this point in the process difliculty 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 is pumped into the casing and on top of the cement a top plug is placed. The mud fluid is then pumpedin on top of the top plug until the bottom plug strikes the bottom of the well. The casing having been picked up, say six inches from the bottom as above described, and thebotton. plug being say twelve inches long, the stall when the bottom plug strikes the bottom of the well. Then the casing is picked up again to a point say six inches above the to ofthe bottom plug and the pump is starte again and 'run until 85 the top plug strikes the bottom plug.

The casing is aptto stick or freeze at any time. If the casing could not be pulled up the second time, the cement is trapped and must be removed. The pump again stalls 40 when the top plug strikes the bottom plug,

because the bottom plug is about 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 v and bottom plugs come together as stated, the

cement is all outside of the casing. Then the casing is lowered to the bottom. Sometimes, however, it can not be lowered. If no trouble is encountered in picking up the casing twice as set out and then letting it 'down again, this process' works all right unless one or both of the plugs should stick in the casing. Serious difliculty has been encountered due to the plugs sticking. The plugs `are made of wood, and thekind of wood of which the plugs are constituted varies. Different kinds of wood expand to different degrees, but all plugs expand more or less when exposed to the mud fluid, and the amount of ex;I pansion 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.l

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 cas- 4 ing and bends it or partially collapses it. Not only must the quality of wood and its moisture content be always observed with care, but the lgreatest care must always be'used to accurately caliper the/plugs the proper diameter in order to avoid sticking of the plugs,

if too large, and leaking of cement past the plugs if too loose. For these reasons it has been found that the process heretofore proposed in the art is very often unsatisfactory.

The present invention avoids the dificulties and disadvantages of the old process lsince o plugs are used. At the same time the pres-` ent invention insures the proper application of the cement to the proper place .oplaces and the operator isaccurately advised when the cement'ation has been completed.

Other objects and advantages reside in certain novel features ofthe construction', ar rangement and lcombination of parts which will be hereinafter more fully described and Aparticularly pointed outin the appended Figure 2 is a view similar to Figure 1 but phase of the action of tion.

Figure 5 is a fragmentary view showing another embodiment of the invention.

Figure 5 is a view similar to Figure 5 and .illustrating the lower part of the apparatus shown in Figure 5.

' Referring to the drawings and more particularly to Figures 1 and 2, the numeral 1 designates the well casing. At its lower end the casing is provided with the ordinary casing shoe 2. Just above the casing shoe la perforated disc 3 is clamped in between the sections of the casing,'the p'erforations of the disc affording discharge openings 4. Centrally the disc 3 has a boss', and the boss and disc are provided with an axial guide opening 6 in which a valve stem 7 is fitted. The valve stem 7 has a head atv one end engaging the boss 5 and at its other end hasa head 9 providing anabutment for one end of a coil spring 10, the other end of the coil spring engaging a washer 11 on the underside of a Valve l2. The spring is tensioned to hold the valve 12 up against the under side of the plate 3 so that the valve closes the discharge opening 4 of the plate. The plate 3 may be made of soft brass or other suitable metal so that it may be drilled out after cementing has been completed. This assembly is commonly known as a back pressure valve.

A valve seat of wood, brass, or other suitable material is provided and has an outwardly directed annular flange 21 engaged andheld between the adjacent ends of the sections 16 and 17. The body of the valve seat 20 is preferably a driving fit in 'the cas- I .ing and for the purpose of further securing the valve seat in position transversely eX- tending openings may also be formedy in the valve seat and in the section 17 and these openings filled with babbitt 22. The valve seat 20 has a beveled valve facin 23 intermediate its ends, and the upper en is formed with a beveled guide surface 24. A differential float providing a combined signal and valve is designated at and is coo erable with the valve seat 20. Asshown in igures 1 and 2, 'this combined valve and signal-25 may be a ball or body of hard rubber, hard in view of the great difference in the specific gravity of the mud' fluid and of the cement,-

cement as usually mixed and used ranging from 1.67 vto 1.85 while the ordinary mud fluid ranges vfrom 1.10 to 1.20.

The embodiment of the invention shown in Figures 3 and 4 is identical'with that illustrated in Figures 1 and 2 except that a different means is provided for preventing back ilow of the cement and a somewhat different 4form. of signal and valve is employed, and that in addition to the 'elements shown in the embodiments illustrated in Figures 1 and 2, an imperforate barrier comprising a plate or disc D is fixed to the casing and obstructs the opening therethrough at a point a short distance above the shoe. The valve 12 and its associated structure are omitted in the forni ofthe invention shown in Figures 3 and 4 and in lieu of these parts a nipple 26 is incorporated in the string of casing and is provided with a number of diametrically opposite openings 27. Only two sets of openings 27 are provided and at one set is diametrically opposite the other. A sleeve valve 28 of rubber or other elastic material is fitted on the nipple 26 and has an imperforate portion 'covering the opening 27. The sleeve valve 28 is held in position by a relatively small upper retaining cup 29 and a relatively large lower retaining cup 30,l both cups being screw threaded on the nip le. As stated the sleeve valve 28 has imper crate portions covering the openings 27' but at points angularly spaced ninety degrees from the open- 4ings 27, the sleeve valve 28 is formed with discharge ports 31. The valve sleeve is preferably constituted of heavy rubber or other elastic material and is tensioned to snugly fit and firmly clamp the nipple 26. This valve, due to its elasticity, may be expanded when subjected to pressure within the nipple to permit fluid within the nipple to pass through vthe openings 27 in the space between the outside of the nipple 26 and the expanded or stretched valve 28 andout throughthe discharge port 31, but when subjected to outside pressure or to a pressure greater on the outside than on the in, the elasticity of the nipple will be aided by the greater outside pressure in forcing the imperforate portions of the nipple over the openings 27 thereby sealing the openings 27. In thisl way the valve 28 serves as a check valvel and effectively lprevents the' cement from running.

back into the casing as will be hereinafter more fully explained.

In Figures 3, 4, 5 and 5 a somewhat different form of combined valve and signal is employed and which comprises a ball B made up of any hard non-compressible metal or a alloy or other substance snch'as guttapercha or an alloy of aluminum and any. other light soft metal. A handle H is rigidly and securely connected to the ball or body B and is` cut off sli-ghtly above heavier than the cement.. Cement is usua may be readily varied constituted of white pine or any other soft wood or similar substance. 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 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 intoplace. In modifying the combined valve and signal 4shown in Figure 2 to cause it to have vthese properties it is placed in the cement which has been mixed in the cement mixing box on'the derrick floor. 'Ihe point at which the handle H becomes submerged is marked. The handle H is then this mark thus varying the material content. It is to be understood that the ball B is always of a specific gravily y mixed and used at a specific gravity of about 1.7. 'The specific gravity of therefore be about 1.7 5 so that it will barely sink in the heavier cement. The correct specific gravity to cause the signal ball to float safely in 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 different cements and different mixtures of the same with water and sand in order to compensate for the varying specific gravities of such cement mixtures. Likewise thecombined valve and signal is adapted forV use with the mud fluids .produced by dierent wells and different fields and which also have varying specific gravities.

with the anni nf the invention illustrated n in Figures 5 and 5 the combined signal and valve B, the valve seat 20 and the upwardly fitting spring closed valve 12 are all einployed in the well casing in substantially the same relation as 1 and 2 and hereinbefore described, except that these parts are positioned well up in the well casing since the arrangement sliownvin Figure 5 is designed specifically for use in cementing the so-called one string wells, that isthe-wells lwhich are'drilled in through the oil sands before they are cemented. In the arrangement shown nipple 35 is ineorporatpd in the well casing, the upper end of the .nipple 35 engaginof the perforated disc 3." At the lower end 0I the nipple an impe-rforate' barrier in the form of a brass plate 36 1s ixedly secured in the well casing.

With this embodiment of the invention it is essential to prevent the cementfrom flowing down between ball B should` that illustrated in Figures in Figure 5 a perforatedA the outside of the casing.A

and, the wall or formation ofthe well hole after it has been placed, and for this purpose laminated sealing members 37 are provided. The details of these sealing members 'form the subject matter .of a co-pending application, and here it is sufficient to note that-these laminated sealing members are designed to shear off the sha-le and other formation. defining the wall of the'well causing impaction of this slieared off material between the sealing members, whereby to prevent the ow'of cement down past the sealing members through the oil producing sands. The upper sealing member is slightly larger than the lower; otherwise the sealing members are identical.

In order to prevent down flow of the cement even though members should fail to fulfill their function, a bootleg packer 40 is provided and consists of a tubular structure of fabric mounted on the well casing just above -the sealing members-37, the lower end of the bootleg packer being fixed onthe well casing by a wrapping 41 ofrwire. The packer 40 enlarges towards itsv upper end and the Lipper end thereof is open and is located opposite the intermediate perforations of the nipple 35. The bootleg packer has its upper ready to receive the cement and check and stop the down flow of the same should conditions arise which would permit the cement to flow past the sealing members 37.

the laminated sealing open end always In all embodiments of the invention, they i the well casing, and the combined signal .-ball and valve -25 is placed on to of the fluid cement mixture where it will goat only partially submerged. The casinT is then connected to the pump and mud flbuid is pumped on top of the cement to force the cement down through the well and through the opening of the valve seat 20.

The course which the cement takes after being passed t rough the openin s of the ball valve seat depends on the em odiment of the invention which is employed. With the embodiment shown in Figures 1 and 2,' the cement,after passing through the openings in the valve 12 and out underneath the casin shoe 2. The valve 12 permits down How o the cement but prevents back flow thereof.

the ball valve seat, passes down past With the embodiment of the invention shown openings 27 'of the nipple and out through the openings 31. At this point it should be borne in min that the pump used to force the cement into the Well operates under a pressure of from three hundred to four hundred pounds per square inch, which insures the proper operation of the heavy rubber sleeve valve 28. Back flow of the cement into the well casing is prevented by the operation of the sleeve valve When practically all of the cement has been displaced from the Well casing the differential float which serves as a combined Y signal and valve will engage and snugly fit on the bevelled facing 23 of the valve seat 20 and the pump will stall, thereby indicating to the operator that thecement job has been completed. The cement cannot flow back into the casing and Where the cementation is carried out above the bottom of the Well, it cannot flow down between the outside of the well. casing and the wall of the well hole.

WithA this arrangement the Casin is not picked up, but after it is properly p aced in position it is left undisturbed, thus the proper cementation of the Well does not depend on the ability of the operator to manipulate the casing. No plugs are used and consequently no difficulty is encountered by virtue of swelling plugs. The relatively small combined signal and valve is well adapted to pass any obstruction, dents or imperfections 'in the well casing.

What I claim is:

1. A device for cementing Wells including a Vdifferential float having variable means whereby its specific gravity may be readily changed, and comprising a ball and a handle, said handle being adapted to be cut oi to vary the specific gravity of the assembl 2. A 'device for cementing Wells inclu ing a differential float having variable means whereby its specific gravity may be readily changed, comprising a ball of hard rigid substance and a wooden' handle.

ALEXANDER BOYN TON

Images