US3139142A

US3139142A - Apparatus for mixing fluids in a well

Info

Publication number: US3139142A
Application number: US142634A
Authority: US
Inventors: James P Chisholm; Joseph P Moran
Original assignee: Dow Chemical Co
Current assignee: Dow Chemical Co
Priority date: 1961-10-03
Filing date: 1961-10-03
Publication date: 1964-06-30
Anticipated expiration: 1981-06-30

Description

June 1964 J. P. CHISHOLM ETAL 3,139,142

APPARATUS FOR MIXING mums IN A WELL Filed Oct. 3, 1961 2 Sheets-Sheet 1 50 49 Y K K IN V EN TORS. James R 6/2 Ashe/m Joseph R Moran IQGENT June 1964 J. P. CHISHOLM ETAL 3,139,142

APPARATUS FOR MIXING mums IN A WELL 2 Sheets-Sheet 2 Filed Oct. 3, 1961 IN VEN TORS. James R C/wls/zo/m Joseph P. Mara/1 BY C. M 3

I96 E N T United States Patent 3,139,142 APPARATUS FOR MIXING FLUIDS IN A WELL James P. Chisholm and Joseph P. Moran, both of Tulsa,

(Eda, assignors to The Dow Chemical Company, Midland, Mich, a corporation of Delaware Filed Oct. 3, 1961, Ser. No. 142,634 4 Claims. (Cl. 156-224) This invention relates to an apparatus for moxing fluids and more particularly is concerned with a tool for mixing two fluids downhole in a well bore.

Many times in well treating operations it is desirable to mix fluids downhole in a well in order to take advantage of some feature of the mixing such as an exothermic or endothermic reaction, formation of a gel or precipitate, etc. Because of the length of time involved in placing such mixtures in a well after blending them on the surface, it is often impossible to get the mixture into the well at a predetermined place at a given time. Also, fluids which are safe to handle alone may produce mixtures which are dangerous to handle.

Heretofore, a preferred method of mixing fluids downhole in a well bore has been to pump one fluid down the well tubing and a second simultaneously down the annulus between the well casing and the tubing allowing these to come together at the end of the string of tubing. However, results obtained by this technique are not entirely satisfactory for many times only a small amount of intermingling of the fluids is found. This is especial- 1y true if the fluids have appreciable differences in density. The more dense fluid quickly settles and very often there is very litle mixing of the two fluids.

The tool of the present invention eliminates these problems and offers as its principal advantage a very satisfactory means for intimately mixing fluids downhole in a well.

It is another object of the present invention to provide a downhole mixing tool whereby materials that are safe to handle by themselves but which provide dangerous to handle mixtures can readily and safely be mixed in a well. It is a further object of the present invention to provide a tool whereby fluids can be mixed at a predetermined place in a well bore and at a predetermined time.

The foregoing and other objects and advantages will be apparent from reading the detailed description presented hereinafter in accordance with the accompanying drawings.

In the drawings:

FIGURE 1 is an elevation in section of a Well bore hole with the downhole mixing tool inserted therein.

FIGURE 2 is an enlarged section of the well bore hole of FIGURE 1 in the area of the tool.

FIGURE 3 is a sectional view of one embodiment of the tool of the present invention.

FIGURE 4 is a transverse section of the tool taken alone line 4-4 of FIGURE 3.

FIGURE 5 is a transverse section of the tool taken along line 55 of FIGURE 3.

FIGURE 6 is an exploded view of a conical check valve assembly used in the tool shown in FIGURE 3.

FIGURE 7 is an enlarged orthographic vertical section of a ball check valve assembly used in the tool shown in FIGURE 3.

In general the downhole mixing tool of the present invention comprises a tubular member which is attachable to the bottom of a well tubing and which can be slidably inserted into a second tubing of larger diameter positioned in a well bore. The bottom of the tool is attachable into a sealing means by which the annular space between the two strings of tubing is sealed off. The tubular member has a through passage the center axis of which coincides with the center axis of the tubing when it is attached thereto. The tubular member has check valves mounted in its internal through passage which valves define the top and bottom of a mixing chamber and are positioned so that a fluid can be moved down through the well tubing into the mixing chamber and out of the bottom of this chamber. In the area between the two valves which define the top and bottom of the mixing chamber, there are a plurality of check valves mounted in the wall of the tubular member through which a second fluid can be moved from the annular spacing between the well tubing and second larger diameter tubing into the mixing chamber.

In actual practice ordinarily the mixing tool is attached to the bottom of a string of small bore well tubing, com monly known in the well art as a macaroni string or macaroni tubing which in turn is positioned inside a larger diameter regular well tubing. These tubings in turn are placed in a cased or uncased well bore. Alternatively, the mixing tool can be attached to the bottom of the regular well tubing and the Well casing itself can serve as the second larger diameter tubing.

One embodiment of the downhole mixing tool of the present invention as shown in the figures comprises a two-membered hollow tubular unit 10.

The top member 11 of the unit 10 has an externally threaded collar 12 at its upper end whereby the tool is coupled to the bottom end of a macaroni tubing string (not shown). The member 11 at about its midpoint has a shouldered ring 13 projecting outwardly from the face 14 of the internal through passage 15. A ring-like valve seat 16 mating with the ring 13 is attached thereto by press fitting, welding or other conventional means. The valve seat 16 accepts the conical head member 17 of a check valve assembly 18. The valve head 17 has a cylindrical shaft 19 extending outwardly from the base 20 of the valve head 17. This shaft 19 has a diameter less than that of the base 20. A coil spring 21 is fitted over the end of the shaft 19. The other end of the spring 21 is fitted into a recessed shouldered opening 22 in the center of the top of a threaded spring retainer 23 which has been screwed into mating threads 24 cut into the face 14 of the lower end of passage 15 The spring retainer 23 is held secure by an open-center threaded retaining lock member 25, also screwed into the threaded portion of passage 15 until it fits tightly against the bottom of the retainer 23. Below the threads 24, the passage 15 of member 11 is widened and contains internal threads 26. The lower tubular member 27 has an externally threaded collar 28 at its top, the threads of which mate with threads 25 whereby the lower member 27 is joined tightly to the upper member 11. This member 27 has an internal passage 29 containing a shouldered ring 30 below its midpoint to which is aflixed a valve seat 31 the same as described for the top member 11. A second relief valve 18 having conical valve head 17, shaft 19, coil spring 21, spring retainer 23 and retainer lock nut 25 in fitted into the bottom portion of this member 27, the threaded members being screwed into mating threads 32 in the lower portion of the passage 29'. The section of passage 29 above the conical relief valve is the mixing chamber of the tool. Above the lower internal check valve 18 and valve seat 31 and below the threaded collar 28 a number of ball-type check valves 33 are placed in the sidewall 34 of member 27. These valves 33, as shown in the depicted embodiment of FIGURE 7 can be conventional Zerk type grease fittings, which are comprised of an externally threaded spring housing and ball seat 35, spring 36 and ball 37. Below the threads 32, the passage 29 is widened and contains internal threads 38 bywhich the tool is fastened to an externally threaded collar of a conventional seating cup 39.

"By changing the position of the spring retainer 23 and retainer lock nut 25 along the threaded portion 24 in the upper member 11 or along the threads 32 in the bottom member 27 of the tool the tension can be changed on the springs 21 thereby affording a means of varying the pressure required to open the relief valve 18 in each of the two

members

11 and 27 of the tool 10.

Also, if desired, a number of holes can be placed in the spring retainer 23 to facilitating fluid flow down through the lower part of passages and 29 although these are not essential to the performance of the tool.

Flat surfaces can be formed into opposite sides of the outside wall of each of the

members

11 and 27 as well as on the seating cup 39 for easy attaching of wrenches thereto when loosening or tightening the sections.

One embodiment of a well assembly into which th tool of the instant invention had been incorporated is shown in FIGURE 1. In this assembly a bell-shaped perforated member 41 was fastened as by welding onto the bottom of a well tubing 42. At a predetermined distance above member 41 a thick Walled nipple 43, i.e., a conventional seating nipple, was placed in the tubing 42. The tubing 42 then was positioned into a cased well bore in an earth formation and sand poured into the hole to fill the annular space between the hole and the tubing 42 to a point a short distance above the top of the bell shaped end member 41. The top member 11 of the instant tool was coupled to the bottom of a second string of smaller-diametered tubing 44, i.e. a macaroni string which fits inside the regular well tubing 42 leaving an annulaus 45 between the two sets of tubing. The bottom member 27 of tool 10 in turn is attached to the member 11 and a seating cup 39 attached to the bottom of member 27. -The seating cup can be of conventional 1 design, e.g. having a series of Teflon packing rings 46 around its periphery which provide a liquid restraining seal when in place in the seating nipple 43. Above the well the macaroni string 44 is packed off from the tubing 42 by a conventional stuffing box 47. A feed line 48 fitted with a check valve to prevent backward flow is attached to the tubing 42 communicating with the annular passage 4.5. feed lines with a check valve in each line and a common control valve 50 is attached to the top of the macaroni string 44.

In the embodiment shown in FIGURE 1, the bell shaped member 41 is shown resting on the bottom of a well. It is to be understood, however, that by use of packers and sealers, a well bore can be sealed off at any predetermined point and the tool then be utilized for treatment at or above the position.

The materials of construction to be used for the tool and the well tubing can be selected from any of a variety of structural materials that are resistant to attack by the chemicals being pumped and have the requisite strength for operation at the pressures involved. Stainless steels and other ferrous, chrome or nickel based alloys as conventionally used for well tubing and well assemblies have been found to be suitable.

In operation, a fluid is introduced under pressure into the macaroni, tubing 44 and passes through the coni cal relief valve 18 in the upper tool'member 11 into the mixing chamber of the tool. Simultaneously a second fluid is pumped down through the annulus 45 between the macaroni tubing 44 and the well tubing 42 and through the ball valves 33 also into the mixing chamber whereupon ready mixing of the liquids results. Once in this chamber the mixture cannot flow back out through the one-way ball valves in the chamber wall 34 or up through the one-way relief valve 18 in the through passage 15 of upper tool member 11. The applied fluid pressure forces open the relief valve 18 in the bottom of A feed assembly 49 having two chamber down through the interior of the tubular seating cup 39 on through the well tubing 42 below the mixing tool 10 and out into the formation through the perforated bell shaped member 41 at the bottom of the tubing 42.

The utility of the tool of this invention is further shown by the following examples but is not meant to be limited thereto.

' Example 1 A 4.5 inch diameter well 42 feet deep was drilled into a soft limestone formation. About 40.5 feet of nominal 2 inch (I.D.) steel tubing (2% inch O.D.) was run into the open hole. For this test the 2 inch I.D. tubing served both as well casing'and well tubing. Welded to the bottom of this tubing was a 15 inch long bell-shaped member having an outside diameter of about 4 inches at the bottom and containing about 24% inch diameter holes around its periphery.

A 6 inch long thick-walled seating nipple, inside diameter about 1% inch, had been placed in the well tubing string at a point which was about 20 feet from the ground surface.

After positioning the tubing in the well, about 10 pounds of 4060 mesh sand (US. Standard Sieve Series) was poured into the hole to fill the annular space between the open hole and the tubing to a point about 0.5 foot above the top of the bell-shaped member. The remaining annular space from the top of the sand to the surface was filled with cement.

The well was hydraulically fractured following conventional procedures using about 200 gallons of a semirefined oil, viscosity about 200 cps., as is widely used for fracturing wells. The oil contained about 700 pounds of 40-60 mesh sand propping agent. For the fracturing operation, the slurry of sand and fracturing fluid was pumped into the formation at a pressure of about 350 pounds per square inch.

About 19 feet of 1 inch diameter 304 stainless steel macaroni tubing, having the tool of the invention and a seating cup affixed to the bottom of the string was run into the well, until the seating cup engaged the seating nipple in the 2 inch tubing string. The top of the macaroni string was packed off from the 2 inch tubing with a 2 x 1 inch pump stuffing box. A single feed line was attached to the 2 inch tubing and a dual feed system was joined to the top of the macaroni string.

Four gallons of 2-nitropropane (density8.34 lb./ gal.) were pumped down the annular space between the macaroni string and the 2 inch tubing, and during the same time period, 6 gallons red fuming nitric acid containing 14 percent N0 (density-l3 lb./ gal.) were pumped down the macaroni string. The 2-nitropropane passed down the annulus, through the ball-type check valves in the side of the tool and intothe mixing chamber; The fuming nitric acid passed down the macaroni string, through the conical pressure relief valve above the mixing chamher and into the chamber. The two fluids after mixing in the chamber were forced out through the conical relief valve in the bottom of the mixing chamber, down the 2 inch pipe and through the bell-shaped member out into the formation.

The two fluid components, fuming nitric acid and 2- nitropropane, by themselves, are not explosively dangerous. However, mixtures of these fluids can be readily detonated and ltherefore are somewhat dangerous to handle.

After the fluids had been mixed, 1.2 gallons additional 2-nitropropane were pumped down the annulus and at the same time 1.8 gallons 2-nitropropane were pumped down the macaroni string to flush out the fuming nitric acid. The control valve at the top of the macaroni string was then switched from the fuming nitric acid feed line to the other line containing igniter. About 4 gallon percent phosphoric acid was pumped through the igniter line followed in order by 1 gallon Z-nitropropane and by gallons of a mixture composed of 7.5 gallons furfural alcohol and 2.5 gallons aniline, the latter compound being the igniter. The phosphoric acid and Z-nitropropane were used simply as additional flush materials to help remove the fuming nitric acid from the macaroni string. The igniter passed on down the well straight through the check valves in the tool and was forced out into the formation where it contacted the mixture of 2-nitropr0pane and nitric acid detonating the same. Proof of detonation was obtained by seismic instruments positioned near the well. Since detonation of this explosive mixture by this igniter does not occur unless the components, Z-nitropropane and fuming nitric acid, have been thoroughly mixed in proper proportions, this test was evidence that good mixing had been obtained by the tool of this invention.

Example 2 The operability of the tool also was shown in surface tests using the same assembly as described for Example 1 where about 3 gallons of carbon tetrachloride (density about 1.6 grams per cubic centimeter) containing about 0.1 percent by weight of oil red dye were pumped down a 1 inch diameter macaroni pipe and into the mixing tool. At the same time, about 2 gallons of kerosene (density about 0.8 gram per cubic centimeter) were pumped down the annulus between the macaroni pipe and a 2 inch tubing and into the mixing chamber through the ball check valves in the sidewall of the tool. The fluid coming through the valve at the bottom of the mixing tool was sampled during the run. All samples as determined by direct visual observation appeared to be of homogeneous texture and color with no stratification of the two difierent density fluids.

Various modifications can be made in the present invention without departing from the spirit or scope thereof for it is understood that we limit ourselves only as defined in the appended claims.

We claim:

1. A downhole mixing tool adapted to be connected to the lower end of a small bore well tubing and slidably inserted into a second larger diameter well tubing in a well bore which comprises; a tubular member attachable to the bottom of a small bore well tubing so that the center axis of the through passage of said tubular member coincides with the center axis of said small bore well tubing when attached thereto, a second larger diameter well tubing the bottom of said tubular member being attachable through a sealing means to said second larger diameter surrounding well tubing whereby the annular space between said small bore well tubing and said second larger diameter well tubing is sealed off, said tubular member having two check valves in spaced apart relationship in said through passage, said valves defining the top and bottom of a mixing chamber, the upper of said check valves providing for the introduction of a first fluid from said small bore well tubing into said mixing chamber, a plurality of check valves mounted in the side wall of said tubular member above said sealing means and between the said tube valves defining the top and bottom of said mixing chamber in said through passage, said plurality of check valves in the side wall of said tubular member providing for the introduction of a second fluid from the annular spacing between said small bore Well tubing and said second larger diametered well tubing into said mixing chamber an the lower of said check valves defining the bottom of said mixing chamber in said through passage of said tubular member providing for the removal of the resulting mixture of said first and second fiuids through the bottom of said mixing chamber.

2. The downhole mixing tool as defined in claim 1 wherein the two check valves defining the top and bottom of the mixing chamber of said tubular member are adjustable check valves, said valves being adjusted in the through passage so as to be opened by fluid force of a given predetermined pressure.

3. A downhole mixing tool adapted to be connected to the lower end of a macaroni well tubing and slidably inserted into the tubing in a well bore which comprises; a two-member, hollow tubular unit, the top member of said unit having a threaded collar at its upper end whereby said member can be coupled to the end of said macaroni tubing, said member having a valve seat in its through passage, said valve seat accommodating a first check valve, said check valve providing for the introduction of a first fluid under pressure from said macaroni tubing into said tubular member, said top tubular member having a coupling means at its lower end, said coupling means mating with a second coupling means in the top of the lower tubular member of said tool, said lower member having a plurality of check valves in its side wall below said coupling means, said check valves in the side wall of said lower member providing for the introduction into said lower member of a second fluid from the annulus between said macaroni well tubing and the well tubing, a valve seat in the through passage of said lower tubular member below said check valves in its side wall, said valve seat in said lower member accommodating a check valve similar to said check valve in said upper member, said check valve providing for the removal of the resulting mixture of said first and second fluids through the bottom of said lower tubular member, a sealing means, and said lower member having a coupling means at its lower end for fitting said member into said sealing means, said sealing means providing a liquid restraining seal in the annulus between said macaroni tubing and said well tubing.

4. The downhole mixing tool as defined in claim 3 wherein the check valves in the through passage are adjustable check valves, said check valves thereby affording through their means of adjustment control in a predetermined manner of the pressure required to open said valves.

Crawford Nov. 17, 1959 Wilder June 26, 1962

Claims

1. A DOWNHOLD MIXING TOOL ADAPTED TO BE CONNECTED TO THE LOWER END OF A SMALL BORE WELL TUBING AND SLIDABLY INSERTED INTO A SECOND LARGER DIAMETER WELL TUBING IN A WELL BORE WHICH COMPRISES; A TUBULAR MEMBER ATTACHABLE TO THE BOTTOM OF A SMALL BORE WELL TUBING SO THAT THE CENTER AXIS OF THE THROUGH PASSAGE OF SAID TUBULAR MEMBER COINCIDES WITH THE CENTER AXIS OF SAID SMALL BORE WELL TUBING WHEN ATTACHED THERETO, A SECOND LARGER DIAMETER WELL TUBING THE BOTTOM OF SAID TUBULAR MEMBER BEING ATTACHABLE THROUGH A SEALING MEANS TO SAID SECOND LARGER DIAMETER SURROUNDING WELL TUBING WHEREBY THE ANNULAR SPACE BETWEEN SAID SMALL BORE WELL TUBING AND SAID SECOND LARGER DIAMETER WELL TUBING IS SEALED OFF, SAID TUBULAR MEMBER HAVING TWO CHECK VALVES IN SPACED APART RELATIONSHIP IN SAID THROUGH PASSAGE, SAID VALVES DEFINING THE TOP AND BOTTOM OF A MIXING CHAMBER, THE UPPER OF SAID CHECK VALVES PROVIDING FOR THE INTRODUCTION OF A FIRST FLUID FROM SAID SMALL BORE WELL TUBING INTO SAID MIXING CHAMBER, A PLURALITY OF CHECK VALVES MOUNTED IN THE SIDE WALL OF SAID TUBULAR MEMBER ABOVE SAID SEALING MEANS AND BETWEEN THE SAID TUBE VALVES DEFINING THE TOP AND BOTTOM OF SAID MIXING CHAMBER IN SAID THROUGH PASSAGE, SAID PLURALITY OF CHECK VALVES IN THE SIDE WALL OF SAID TUBULAR MEMBER PROVIDING FOR THE INTRODUCTION OF A SECOND FLUID FROM THE ANNULAR SPACING BETWEEN SAID SMALL BORE WELL TUBING AND SAID SECOND LARGER DIAMETERED WELL TUBING INTO SAID MIXING CHAMBER AN THE LOWER OF SAID CHECK VALVES DEFINING THE BOTTOM OF SAID MIXING CHAMBE IN SAID THROUGH PASSAGE OF SAID TUBULAR MEMBER PROVIDING FOR THE REMOVAL OF THE RESULTING MIXTURE OF SAID FIRST AND SECOND FLUIDS THROUGH THE BOTTOM OF SAID MIXING CHAMBER.