US2374169A - Means for cementing between multiple sands - Google Patents

Description

F 1 8; 7. ALEXANDER BOY/VTO/V,

Filed Oct. 14. 1941 ATTORNEY.

Patented Apr. 24, 1945 MEANS FOR CEMENTING BETWEEN MULTIPLESANDS Alexander Boynton, San Antonio, Tex.; Sida S. Martin executrix of said Alexander Boynton,

deceased Application October 14, 1941, Serial No. 414,956

4 Claims.

My invention relates to means for cementing between multiple sands of oil and gas wells.

The principal object is to provide new and simple means for cementing between and above the several producing formations of a well.

Another object is to enable the operator to determine, with great accuracy, the exact places where cement will be left in the well.

In carrying out the cementing between sep-' arate sands, I employ a special tool attached to the lower end of the drill stem or tubing. This tool has two expansible members adapted to be expanded by pump pressure and I perforate the nipple between these expansible members, so that cement pumped downward through the drill pipe will be forced out through openings in the casing, each of these openings being governed by a yieldable valve normally held closed by the pressure of drilling mud around the casing and which valves are adapted to be opened by pump pressure transmitted through the drill stem. A removable valve, which may be dropped through the drill stem, is adapted to close the opening through the lower end of the special cementing tool and another removable valve, which is of such specific gravity that it will float on cement and will sink in the drilling mud, is employed to stall the pumps each time the proper amount of cement has been discharged through the tool, in order to accomplish the several cementing operations. In this connection, I employ another special tool for recovering the aforementioned valves Fig. 4 is a cross section on the line 4-4, Fig. 2. Fig. 5 is an outside view ofthe wire shields. 'Fig. 6 is a frontal elevation of the check valve spring.

Fig. 7 is a vertical section through a portion of one of the valve assemblies, the screws and valve being shown uncut.

Method In order to prevent the aforestated harmful effects of drilling mud upon the producing sands, I employ (1) clean water to wash the sand before cementing the well. (2) Then I fill the annular space between casing and sand with heavy mud charged with sand sealing substances, and (3) after the preceding operations, I apply cement slurry charged with similar sand sealing sub- I stances adapted to form miniature valves which whenever the cementing tool should be raised to another place where cement is to be discharged through the casing, or where mud or water is to be pumped through it in order to force surplus cement out of the well.

To prevent cement from penetrating the producing formations, I first Wash clean the exposed surfaces of these formations, after which operations I introduce liquid cement into the well'bore surrounding the casing, the cement being charged with valve-like sand sealing substances which are adapted to adhere to the sticky film and which will be forced to close all pores in the sand by pressure of the cement which thus will be excluded from sealing the sand against subsequent flow of production into the well. A small portion of the cement will contact the sand for only a few minutes during the cementing operation, the sand sealing substances in the cement bein precautionary during these few minutes.

The first of said operations is accomplished by pumping a few barrels of clear water rapidly ahead of the heavy mud.

The second operation consists of following the wash water with enough sand seal charged heavy mud to cover the sand and support the cement above it.

The third operation is to place the cementing tool above the sand and pump in cement slurry, thoroughly charged with mica flakes and ground rubber, the latter varying from dust to particles somewhat larger than the largest pores of the sand which is being protected from intrusion of the cement.

The finer particles of the rubber being more numerou than the flakes of mica, will be drawn out of the cement slurry and will close the small pores in the sand. Larger particles of the rubber will be drawn ,into the larger pores and the mica flakes will be forced over all pores which the ground rubber failedto close. Of course, some of the mica flakes will be preceded by the particles of rubber in'contacting the pores of the sand.

Under such circumstances, the rubber particles leaks out through the sand.

It is preferable to mix a larger proportion of ground rubber in the first one-fourth of the cement than in the remainder thereof. The proportion of mica flakes may be the same throughout.

Satisfactory results ordinarily will be obtained by employing a mixture of two to five per cent ground rubber and five to ten per cent mica flakes, the rubbercontent being increased ten to fifteen per cent in the first one-fourth of the slurry, it being understood that these proportions relate to volume and are subject to wide variations.

The cement will set within a few hours after being pumped into the well. The particles of rubber will be dissolved soon thereafter by the hydrocarbons. The mica flakes, being larger than the pores of the sand, will flow out of the well with the first production. The original interstices of the producing sand thus are left unobstructed by the one-way valves of ground rubber and mica flakes which stand on guard over the sand during the time of danger to its and leave thereafter.

The means In Fig. 2, illustrating the cementing tool, the upper and lower expansible members 2, which may be of rubber, are received closely over the mandrel I which may be a steel casting having the discharge openings Ic formed between its retainer cups Ia, The upper and lower expansible members 2, which are adapted to be expanded by pressure acting upon their inner surfaces from within the mandrel I via the lateral openings lb, have their proximate tapered ends closely received within the retainer cup Ia of the man- .these shields being received closely within the retainer cups Ia and 5 and being imbeddedpartially within the exterior surfaces of the expansible members 2, proximate their ends.

The cylindrical tapered ends of the expansible members 2 form hermetic contact with the retainer cups to and 5 whenever the members 2 are expanded against the well casing H (see Fig. 1) by pressure from within them and while so expanded the wires 3 protect the expansible members from being abraded unduly by the casing as the cementing tool is raised or lowered. The shields 4 provide that the ends of the wires are free and that the expansible members can never become impinged upon them to thereby impair their movements in yielding to the pressure which expands the members 2.

The swaged nipple l, secured upon the-lower end of the mandrel I, has its lower portion of reduced diameter adapted to receive the shell It with such as clearance all around it. This shell, having the depending central extension Mb somewhat smaller than the restricted opening lb through the nipple I, has formed upon it the valve I 40 adapted to engage the seat Ia formed within the nipple 1. h The connection member 8, having the restricted circular axial opening 81) somewhat larger than the external diameter of the shell I4, has threaded connection with the mandrel l and with the tool joint 9 which, in turn, has similar connection with the drill pipe I0.

The shell II, shown to be identical with the other shell I4, has the axially depending rod Ila over which the washers or fioat units I2 may be received closely. The lower member of these washers is formed into the valve I2a adapted to become engaged upon the seat 8a formed within the connection member 8. These washers and the valve member, being of slightly larger diameter than that of the shell II and having small clearance within the tool joint 9, are secured upon the depending rod Ila by the nut I3. The shell LI and the other members assembled upon it will be referred to as the float valve assembly and the valve seat 8a as the float valve seat. The washers I2 and the valve I2a may be of hardened rubber, gutta percha or the like, and the float valve assembly should be of such specific gravity that it will float upon the cement slurry used to cement the well and that it will sink in the mud fluid employed to force the cement down through the drill pipe or tubing. Several of the washers or float units I2 are employed in order that the float valve assembly may be made to have the correct specific gravity.

The shell II and its extension IIa being metallic and, consequently, being of greater specific gravity than that of the cement slurry, and the washers or float units I2' being of less specific gravity than that of the mud slurry, it is evident that the specific gravity of the assembly can be decreased by adding washers, or that its specific gravity may be increased by decreasing the number of these Washers.

The float valve assembly designated generally by the numeral II, and the shell I4 upon the valve I40 are adapted to pass through the drill pipe I0 and the tool joints therein and to engage upon their respective seats in a manner that will be explained.

The shell It has the intruding pins I6 secured upon it by means of the welds Ilia. The shell II has the intruding pins I5 secured upon it by the welds I5a. A suitable fishing out or catching and releasing tool, such as is set out in my Patent #2,250,463, issued July 29, 1941 may be employed to fetch out the float valve assembly and the shell I i, the lateral openings II!) of the shell I I and the similar openings I4a of the shell I4 being provided that the fishing tool may force mud or cement slurry out of the shells.

In Fig. 7, which illustrates the simple valve mechanism employed in the well casing in conjunction with the cementing tool shown in Fig. 2, the nipple 2I, adapted to be joined threadedly into the well casing H, has the lateral openings 21, each having its outer portion expanded into the valve seat 2Ib which is engaged normally by the valve I8 having the short shank IBc which may be secured within the central opening I91) of the fiat spring I9 by the weld l8b. Proximate its ends, this spring has the slots I9a within which the smooth shanks 20a of-the screws 20 have slight clearance. These screws are secured within the nipple 2i at such distance apart that the proximate ends of the slots I9a are in close proximity to the screws, in order to maintain the valve IS in position at all times to re-engage its seat after being disengaged therefrom, The slots I9a extend somewhat beyond the screws, in order that the spring will be permitted to contract slightly as the valve is forced open, it being understood that the spring is installed so as to transmit seating force to the valve.

The discharge nipple 22, being adapted to be joined into the casing string, has the protecting shell 22a housing the spring and valve and has such clearance with them as to' allow the valve to be opened.

It is apparent that the valve l8 may be dispensed with if the nipple 2| be provided with a smooth fiat external surface adapted to engage the spring itself, which thus can be converted into a valve at its place of engagement over the opening 2|a.

A plurality of such valves as the one illustrated in Fig. 7 may be installed upon each of the nipples 2|, as appears i Fig. 1. The valves so installed operate as check valves which; permit fluid from within the casing to be forced by them, but prevent fluid from the annular space surrounding the casing from entering the casing. The assembly of valves upon each nipple 2| will be referred to as the valve assembly.

In Fig. 1, the well casing I1 is shown positioned centrally within the well bore "a, the

valve assemblies 42, 43, 44, 45, and 46 being positioned so as to provide that the annular space surrounding the casing may be filled with cement slurry in such manner as to; protect each of the producing formations, as will be explained. Such formations will be referred JtO as sands! The casing shoe 23, connected upon th lower valve assembly installed upon it are adapted to.

. gage the well casing l1.

The valve He now will be dropped through the drill stem or pumped down. When it engages the seat la, the expansible members 2 will be expanded by the pump pressure and will en- The pump will stall, unless the expansible members are on either side of the lateral openings 2|a through the nipple 2| of the valve assembly 46. If the pump stalls,

' raise or lower the drill stem until the pump starts.

Then proceed as follows: (1) Pump a few barrels of clear water through the drill stem in order to wash clean the exposed surface of the nonend of the casing, has within it the c0nrete'24 having the central opening 24a and having he be drilled out upon completion of the well and provide, in the meantime, that fluid ,Within the well bore exterior of the casing will be excluded i y from the casing while, at the same time, fluid may be pumped through the casing.

It being understood that the cement slurry may be charged with ingredients such as have been previously mentioned in this specification, it will be understood further that the sands 30, 34, and 38 are productive and, consequently, that the annular spaces 3|, 35, and 39 are to be left free of cement while the cement is setting between the sands. The formations 32, 36', and 40' being unproductive and apt to carry water or unwanted gas, are to have their respective adjacent annular spaces filled with the cement 33, 31, and 4 I, while heavy sand seal treated mud in the annular spaces 3|, 35, and 39 support the cement above them. I

Operation Just before cementing the well, enough heavy and seal treated mud will be pumped through the casing to fill the annular space 3| between the casing and the productive formation 30. This mud should be as nearly as possible of the same according to the plan stated in the preceding paragraph, the cementing tool illustrated in Fig. 2 will be attached to the drill stem or tubing and lowered to the position where the expansible members 2 will be one above and the other below the valve assembly 46, it being understood that the valves Ho and Me are not employed as yet.

productive formation 32. The water will pass out of the drill stem and into the annular space between the casing and the well bore Ila via the slots Ic of the member I, the lateral openings 2|a of the nipple 2| (opening the check valve I8) and the annular space between the nipple 2| and the sh'ell22a. This path will be followed, of course, by allpump fluid forced through the cementing tool."-., (2) Pump into :the drill stem enough sand seal charged cement slurry to fill the annular space between the non-productive formation 32 and the casing. (*3) Place the float valve assembly H on top of the cement and pump down the cementuntil the pump stalls. The valve l2a will be engaged then upon the float valve seat 8a, as shown in Fig. 2. (4) Remove the float valve assembly H and the valve Me by means of a special tool such as was previously mentioned, these members being removed in ord'r that pressure may equalize on both sides of the expansible members when the drill stem is (5) Raise the drill stem until the cementing tool has its expansible members 2 posi-,

raised.

tioned on either side of the valve assembly '45.

This .position of the expansible members can be v enough heavy sand seal charged mud to remove any surpluscement from the exposed surface (of the sand 34.

(7) Remove the valve- I40 and the valve assembly 44.

The formations 38', and 40 may be cemented in the same manner as was specified for cementing the formation 32; thereby placing the cement where indicated at 3, 31, and 4|; while the spaces 3|, 35, and 39 are left clean of cement, but charged-with sand seal ladened heavy mud, as stated. v

It is apparent that all fluid pumped through the valve assemblies will beheld by them outside of the casing while the cement sets.

Another important feature of this cementing meansis that the tendency of cement slurry to settle before it sets is retarded very much by the ,enlarged shells 22a of the nipples 22 if the mud employed to fill the annular space below the cement should be much lighter than the cement.

After the cement sets, the casing may be perforated opposite the several sands by employ 1 ing any one-of several tools for the purpose which are adapted to be operated by the drill stem. Gun perforations, being intended primarily to penetrate through the cement which heretofore was left in the sands and between them and the casing, need not be employed in wells cemented by this means, because with this practice no impervious substances are left between the casing and the productive formations and no cement is permitted to penetrate the sands.

I claim:

1. In a means for cementing casing in well bores, a float valve assembly comprising: a shell; 3, depending rod thereon; a valve on said rod; float units upon said rod and between said valve and shell, said units being of proper specific gravity to cause said assembly to sink in mud fluid and float on cement slurry; and means on said shell for being engaged by a fishing-out tool.

2. A cementing tool for use in cementing a casing in place in a well extending through multiple sands, said tool comprising: a tubular mandrel formed with discharge openings intermediate its extremities; expansible means on each side of said openings for establishing a seal between said mandrel and casing; a drill pipe; 2. connecting member secured to the upper end of said mandrel and having a passage provided with a valve seat of a lesser diameter than the internal diameter of the drill pipe; a Joinder means between said drill pipe and said connecting member and having a passage of a greater diameter than the diameter of the valve seat in said connecting member; a nipple secured to washers and a valve positioned on said rod, said assembly being arranged to be dropped from the surface through the drill pipe to seat on the valve seat of said connecting member; and a valve having a shell and a depending extension and being constructed to be dropped, before said float'valve assembly, through said drill pipe, said joinder means and said connecting member into said nipple to seat on the valve seat of said nipple, said last named depending extension, when the valve is seated, projecting out beyond the outer end of said nipple.

3. The tool of claim 2 wherein the shells are perforated.

4. The tool of claim 2 wherein the shells have inwardly projecting pins for engagement by a suitable fishing-out tool.

ALEXANDER BOYNTON.

Images