US3034912A - Elimination of abrasion of well tubing by production fluid containing abrasive material - Google Patents

Description

INVENTOR. R.L. FLOWERS WM 3 A T TORNE Ks y 1962 R. L. FLOWERS ELIMINATION OF ABRASION OF WELL TUBING BY PRODUCTION FLUID CONTAINING ABRASIVE MATERIAL Filed Dec. 29, 1958 3,034,912 ELIMINATION OF ABRASIQN F WELL TUBWG BY PRODUCTIDN FLUID CQNTAINING ABRA- SIVE MATERIAL Richard L. Flowers, Houston, Tex, assiguor to Phillips Petroleum Company, a corporation of Delaware Filed Dec. 29, B58, Ser. No. 783,448 14 Claims. (Q1. 166-243) This invention relates to fluid production from a deep well. In one aspect, it relates to protection of a production tubing adjacent an upper producing formation of a dually completed well in which the fluid entering the well bore from the upper formation at high velocity contains an abrasive and abrades or erodes the tubing through which fluid from the lower formation is produced.

:In wells which are completed in more than one formation, it is necessary to place one or more joints of tubing opposite the upper producing formation. In a dually completed well, production tubingextending to a lower producing formation sometimes becomes abraded or eroded at the level of the perforations of the upper producing formation. This tubing erosion results from the presence of abrasive material in the fluid produced from the upper formation. In case a tubing, which is produc ing fluid from the lower of two formations, becomes abraded to such an extent that an opening is produced, fluid from the upper formation enters the tubing through the opening and is produced in the tubing along with fluid from the lower formation. As is known, it is necessary to produce fluid from several formations separately because in some instances fluid pressure from one formation may be sufficiently higher than the fluid pressure from the second formation that fluid from the first formation enters the second formation thereby preventing fluid production from the second and lower pressure formation. Failures of production tubing at the level of the upper producing formation have occurred. Pulling of well tubings and replacing of the damaged sections of tubings are expensive operations. Various attempts have been made to solvethis erosion problem. Joints of tubings which are to be positioned at the level of the upper fluid producing formation have been coated with solid coatings such as rubber, neoprene, lead, ceramic material, etc., with varying degrees of success. The erosion is particularly severe in cases when nearly all of the perforations of the casing adjacent the upper formationbecome plugged thereby causing the remaining unplugged perforations to admit fluid pressure under extremely high velocity. Fluid containing such abrasive material as sand from the formation entering the well bore through a small number of easing perforations enters at a much higher velocity than if there is a larger num- 7 her of open perforations.

The present invention is directed to a more feasible solution of this erosion problem than the provision of the solid coating materials mentioned hereinabove being disposed on the well tubing. This solution involves use of a series of loosely fitting rings disposed around the joint of production tubing at the level of the perforations of the upper of two fluid producing formations. The outer faces of these loosely fitting rings are provided with curved surfaces or vanes so arranged that fluid impinging against the vanes will rotate these loosely fittings rings around the well tubing. The fluid containing abrasive material entering the well bore gives up a portion of its kinetic energy in rotating these rings thereby reducing the velocity of the fluid and simultaneously reducing the abrading action of the fluid. The rings are held in place by upsets or couplings of the tubing.

An object of this invention is to provide relatively inexpensive means and methods for the elimination of abraassists Patented May I5, 1962 sion or erosion of a well tubing adjacent an upper producing high pressure formation in a dually completed well in which the fluid from the upper formations contains an abrasive. tion will be realized upon reading the following description which, taken with the attached drawing, forms apart of this specification.

In the drawing, FIGURE 1 illustrates the installation of the apparatus of my invention in a dually completed well. FIGURE 2 is a view taken on the line 2-2 of FIGURE 1. FIGURE 3 is a view, partly in section, taken on the line 33 of FIGURE 2. FIGURES 4, S, 6,.7 and 8 illustrate additional embodiments of my invention. FIGURE 9 is a view taken along the line 99 of FIGURE 8. FIGURE 9a is a sectional view of a portion of another embodiment of the invention. FIGURE 10 is a sectional view taken along the line 10-16 of FIGURE 9a.

In reference to the drawing and specifically to FIGURE 1, reference numeral lll'identifies the well bore provided with a casing 12. This well bore and casing extend through two fluid producing formations 13 and 14. The casing adjacent the upper of the two producing formutions is provided with perforations l5 and is provided with perforations 16 adjacent the lower producing formation. A packer 20 seals formation 14 from formation 13 so that fluid from one of the formations cannot enter or be mixed with fluid from the other of the formations. A production tubing 17 is disposed in the well as illustrated. Near the lower end of this production tubing 17 is disposed a ring assembly 25 of my invention. The lower end of the tubing extends through packer 20 in such a manner that the ring assembly 25 does not come in contact with the inner walls of the casing 12.

A second production tubing 18 is provided as illustrated for passage of fluid from the upper formation 13 to the well head. Tubingslti and 17 communicate with pipes 23 and 24, respectively, at the well head for passage of production from the two formations to such disposal as desired. Reference numeral 22 identifies the head of the casing. A second packer I9 is illustrated as sealing off the upper formation from the well head. This packer also holds tubings 17 and I8 rigidly in place. On reference to FlGURE 2, which is a view taken on the line 2-2 of FIGURE 1, it is seen that the outer periphery of ring 26 is made of vanes 27, which are herein more accurately described or termed as deflector vanes. The sides of vanes 27 are curved deflector side surfaces 28 and these side surfaces are so shaped that fluid entering well bore 11 through casing perforations 15 causes the rings 26 to rotate in one direction or the other. These curved surfaces act to rotate these rings in a manner more or less similar to the action of buckets on water wheels such as the Pelton type water wheel. It is realized that fluid passing at a high velocity through perforations 15 can enter the casing as a jet stream, or it may spread out more or less in the form of a cone. The particular form that the fluid acquires on entering the casing depends at least in part on the shape and the orientation of the perforations 15. However, the fluid which enters the casing enters at a high velocity and this high velocity is reduced by impinging on the curved surfaces 28 thereby causing the rings 26 to rotate. Some of these rings may rotate in one direction while others may rotate in the same direction or in the reverse direction. The annulus inside casing 12 at the level of the upper producing formation 13 is identified in FIGURE 1 by reference numeral 21. Reference numeral 33 identifies the upset ends of adjacent tubing joints which contain male and female threaded sections for attaching one joint of tubing to the other. This upset portion 33 serves as a collar or as a retainer to prevent downward move- Other objects and advantages of this invenment of the ring assembly 25. As illustrated in FIGURE 3, the upper and lower end surfaces of the vanes 27 terminate as curved surfaces 52a so that fluid impinging at these surfaces will be deflected and thus reduced in velocity to minimize the abrasion effect of the incoming fluid. However, fluid impinging against surfaces 52a does not assist in rotation of the rings 26. In the embodiment illustrated in FIGURE 3, the rings 26 are constructed of a polyethylene material. The inner diameter of rings 26 is made greater than the outer diameter of tubing 17 with the provision of an annulus 29 therebetween so that the ring can rotate freely around the tubing. In one instance, a polyethylene ring 26 or a ring made of other suitable plastic, such as Teflon, a polymeric fluorocarbon, is split at 32 so that the rings can be spread somewhat and raised upward over the upset portion 33 of the tubing prior to running of this tubing into the well.

In FIGURE 8 is illustrated rings 46 also made of a plastic material. These rings illustrated in this figure are not provided with the curved top and bottom surfaces corresponding to surfaces 52a of FIGURE 3 but they are merely square shouldered. Such rings are, if desired, split as the ring illustrated in FIGURE 4 for sliding over the upset ends of a joint of tubing. Ring 46 is provided with a beveled surface 47 to bear against a beveled surface 48 of a joint of tubing to prevent the assembly of rings from sliding downward on the tubing. These rings are also provided with a flange 50, as illustrated, for assisting in preventing abrasive material from finding its way through the joint at which an upper ring contacts a lower ring. Abrasive material which would find its way to the annulus 49 between rings 46 and tubing 17 would certainly abrade the tubing as the rings rotate. This annulus provides for free rotation of the rings around the tubing. As mentioned hereinabove, rings 46 may all rotate in one direction or some may rotate in one direction and the remainder in the opposite direction. Rings 46 are provided with curved side surfaces 53 similar ot side surfaces 28 of FIGURE 2 for causing rotation of the rings of the assembly. These side surfaces 53 are illustrated in FIGURE 9. The rings 46 of FIGURES 9 and are also made of such a plastic material as mentioned hereinabove. In FIGURE 5 is illustrated another embodiment of deflector ring of my invention more or less similar to the ring 46 of FIGURE 8 but rings 31 of FIGURE 5 are provided with upper and lower curved surfaces 52b. These curved surfaces 52b serve the same purpose as curved surfaces 52a of FIGURE 3. Ring 31 is provided with beveled surface 34 which contacts with beveled surface 35 on the tubing 17 to support the ring assembly. As illustrated in FIGURE 5, a threaded section 36 is provided for joining one joint of tubing with another.

In FIGURE 6is illustrated another embodiment of deflector ring of my invention in which the outer portion of the ring is composed of a metal such as steel while the inner portion of the ring is made of a plastic material such as a polyethylene 38. This material 38 on the inside of the ring serves as a hearing or bushing for rotation of the ring around tubing 17. Since a portion of this combination metal and plastic ring is not expandable for sliding upward and over an upset section as section 33 of FIGURE 5, the rings are placed around the tubing 17 and then a metal ring 39 is placed as illustrated in FIGURE 6 and attached by welds 40. The plastic ring 38 is sufficiently larger in inside diameter than the outer diameter of tubing 17 to provide an annulus 51 for free rotation of the ring around the tubing. The steel portion 37 of this ring is provided with upper and lower curved surfaces 52 and side curved surfaces similar to surfaces 28 of FIGURES 2 and 3 for deflection of the incoming fluid containing abrasive. In FIGURE 7 is illustrated a combination deflector ring more or less similar to that illustrated in FIGURE 6. In this figure,

a pair of adjoining rings is shown to illustrate the positioning of one ring against another ring when the rings are made of the outer metal and the inner plastic. The metal portionis provided with shaped deflector veins 42 which have top and bottom curved surfaces 520 as well as side curved surfaces similar to those illustrated in FIG- URES 2, 3, 9 and 9a. In FIGURE 7, it is intended that upper plastic bushing 43 bear snugly against the lower plastic bushing 43 so that if these two rings rotate in opposite directions or at different rotational rates in the same direction the main bearing surface is that between the two plastic bushings. However, the lower surface of the upper metal deflector vane 42 and the upper surface of the lower metal vane 42 may fit rather snugly so that solid material cannot easily find its way between these two metal surfaces. Metal flanges 45' are positioned with respect to the bushings 43 as illustrated. As will be realized by those skilled in the art the flange 44 of plastic when Wet with well fluid permits the upper bushing 43 along with its ring to rotate rather freely. The inner diameters of bushings 43 are made slightly larger than the outer diameter of the tubing 17 so that the rings easily rotate therearound. Reference numeral 41 identifies this clearance or annulus.

In FIGURES 9a and 10 are illustrated an embodiment of deflector ring in which the ring is made entirely of metal. In these figures reference numeral 54 identifies the metal ring While reference numeral 55 identifies the protruding vane having curved deflector side surfaces 56 similar to those of the other embodiments of this invention.

I find that a plastic material which is suitable for production of the deflector vanes and also for the ring bearings or bushings is a high density polyolefin, such as a polyethylene. This polyethylene which is suitable for the production of these apparatus parts has a molecular weight in the range of 25,000 to 200,000 or higher, a density of from 0.940 to 0.980 gram per cubic centimeter and a crystallinity of at least percent. A full description of the method for preparation of this plastic material is given in U.S. Patent 2,825,721. Briefly, this process involves polymerizing ethylene at a polymerization temperature in the range of to 500 F., with a catalyst active for such polymerization and consisting essentially of chromium oxide supported on at least one material selected from the group consisting of silica, alumina, zirconia and thoria, at least part of the chromium being in the hexavalent state at the initial contacting of hydrocarbon with said catalyst, and recovering a resulting solid polymer. After production of the solid polyethylene, the rings, bearings and any other apparatus parts desired to be made of this material are extrusion molded into the proper shapes.

As stated, the density of this polyethylene material is between about 0.940 and 0.980 gram per cubic centimeter and the density is ordinarily determined on a sample of the mass polyethylene in non-filamentary form. The sample is prepared for the determination of density by compression molding of the polyethylene at a temperature of 340 F. in a mold provided with a water jacket through which water can be circulated. The sample is maintained at about 340 F. until it is completely molded. It is then cooled from 340 to 200 F. at the rate of approximately 10 Fahrenheit degrees per minute. Water is then circulated through the mold to continue the cooling to F., the rate not exceeding 20 Fahrenheit degrees per minute. The polyethylene is then removed from the mold and cooled to room temperature. A small piece of the solidified polyethylene is cut from the compression molded sample and inspected to make sure that it is free of voids and that it has a sufiiciently smooth surface to prevent the trapping of air bubbles on its surface. The small sample is placed in a 50 ml. glass stoppered graduate. Carbon tetrachloride and methylcyclohexane are then allowed to run into the graduate from separate burettes in such proportions that the sample is suspended in the mixed solution, i.e., it neither floats nor sinks. The graduate is shaken during the addition of the liquid in order that the two liquids mix thoroughly. A total liquid volume of to ml. is required. After the liquids have been so proportioned that the polyethylene is suspended therein without sinking or floating, the density of the liquid mixture is equal to the density of a solid polyethylene. The polyethylene is then removed from the liquid and a portion of the liquid mixture of carbon tetrachloride and methylcyclohexane is transferred to a Westphal balance and the specific gravity of the liquid is measured at a temperature in the range of 73 to 78 F. This specific gravity is equal to the specific gravity of the polyethylene. For most practical purposes, the specific gravity is considered identical to the density. However, if a precise conversion to actual density units, grams per cubic centimeter, is desired, this is readily referable to water at 4 F. by calculations which will readily be evident to those skilled in the art. The precision of a single specific gravity determination is ordinarily within i.0002. The molecular weight is determined by measuring the .time required for a filtered solution of 0.1000 gram of the polyethylene in 50 ml. of tetralin (measured at room temperature, that is, about 75 F.) to run through the marked length on a size 50 (0.8-3.0 centistokes) Ostwald-Fenske viscosimeter at a temperature of 130 C. (the viscosimeter being immersed in a thermostatically controlled oil bath) and measuring also the time required for an equal volume of tetralin containing no polyethylene to run through the same distance on the same viscosimeter. The molecular weight is calculated in accordance with the following formula:

where K equals 24,450, C equals 0.183, Vr equals time, in seconds, required for solution to run through the viscosimeter divided by the corresponding time required the polymer-free tetralin, both at 130 C. A single determination of molecular weight originally has a precision of $1,000 molecular weight units.

The crystallinity of this polyethylene is determined by nuclear magnetic resonance. The percentage crystallinity represents the percentage by weight of the total polymer which is crystalline rather than amorphous.

The deflector rings of my invention are made of such metal as will withstand abrasion at least reasonably well. The rate or mass of these rotatable ring should be so selected that the rings are rather easily rotated by the jetting well fluid yet they must be sufficiently heavy to absorb at least a considerable portion of the kinetic energy of the stream or streams of well fluid entering through the casing perforations. When these rings are too light they rotate too easily under the influence of the inflowing well fluid and do not absorb much kinetic energy nor reduce the velocity of the inflowing fluid and in this manner actually they do not serve the intended purpose. When the rings are too heavy they rotate with difficulty and are more or less equivalent to merely a stationary tubing and continued jetting of the well fluid through the perforations onto the fins of the rings with the rings not rotating will in due time abrade the fins, the rings then merely acting as mechanical protectors of the tubing. Upon continued use in this manner, the rings wear or are abraded and ultimately the tubing will be damaged by the incoming well fluid. The rings in this case serve little purpose.

The rings should fit loosely around the tubing so that there will not be unwarranted abrasion between the plastic ring, or inner ring and the metal tubing as the ring rotates. Clearances of the order of 0.05 to 0.1 inch or greater are usually ample for free rotation of the ring around the tubing. In some instances, clearances, i.e., the inside diameter of the ring minus the outside diameter of the 6 tubing, are greater than 0.1. inch, and in other instances less than 0.05 inch.

Other polyolefins suitable for production of the deflector vanes herein disclosed possess densities of about 0.90 to 0.92, crystallinities of at least about percent, and molecular weights in the range of about 25,000 to 200,000. A method for preparation of polyolefin plastic material is given in Belgian Patents 533,362 and 538,782.

While certain embodiments of the invention have been described for illustrative purposes, the invention obviously is not limited thereto.

I claim:

1. An apparatus for minimizing erosion of a portion of a deep well fluid production assembly disposed in a well through a high pressure fluid producing formation, said formation being adapted to inject fluid containing an abrasive into said well at high velocity comprising, in combination, a well production tubing extending from the head of said well through a high pressure fluid producing formation to a level below said formation, said tubing being adapted for production of well fluid from a formation below the aforesaid formation, a packer set in said Well intermediate said formations, at least one ring disposed concentrically and rotatably around said tubing throughout the area exposed to said high pressure fluid of the first mentioned formation, a plurality of vanes disposed at spaced intervals on the outer periphery of said ring and extending outward therefrom, the longitudinal axes of said vanes being parallel to the axis of said tubing, said vanes having inwardly curved side surfaces in such a manner as to absorb energy from said well fluid containing abrasive on being injected into said well at high velocity, the absorbed energy being transformed into rotational energy of said ring thereby reducing abrasion of said tubing by the high velocity fluid containing abrasive, and means retaining said ring at the level of the first mentioned formation.

2. An apparatus for minimizing erosion of a portion of a deep well fluid production assembly disposed in a well through a high pressure fluid producing formation, said formation being adapted to inject fluid containing an abrasive into said well at high velocity comprising, in combination, a well production tubing extending from the head of said well through a high pressure fluid producing formation to a level below said formation, said tubing being adapted for production of well fluid from a formation below the aforesaid formation, a packer set in said well intermediate said formations, a plurality of rings disposed concentrically and rotatably around said tubing throughout the area exposed to said high pressure fluid of the first mentioned formation, a plurality of vanes disposed at spaced intervals on the outer periphery of each of said rings and extending outward therefrom, the longitudinal axes of said vanes being parallel to the axis of said tubing, said vanes having inwardly curved side surfaces in such a manner as to absorb energy from said well fluid containing abrasive on being injected into said well at high velocity, the absorbed energy being transformed into rotational energy of said rings thereby reducing abrasion of said tubing by the high velocity fluid containing abrasive, and means retaining said rings at the level of the first mentioned formation.

3. The apparatus of claim 2 wherein said plurality of rings extend a distance along said tubing approximately equal to the thickness of said high pressure fluid producing formation.

4. An apparatus for minimizing erosion of a portion of a deep well fluid production assembly disposed in a well through a high pressure fluid producing formation, said formation being adapted to produce fluid containing an abrasive comprising in combination, a casing disposed in said well, a well production tubing in said casing extending from the well head through said high pressure fluid producing formation to a level below said formation, said tubing being adapted for production of well 7 fluid from a formation below the aforesaid formation, a packer set in said casing intermediate said formations, said casing containing perforations at the level of said high pressure formation, a plurality of rings disposed concentrically and rotatably around said tubing throughout the area exposed to said high pressure fluid injected through said perforations, a plurality of vanes disposed at spaced intervals on the outer periphery of each of said rings and extending outward therefrom, the longitudinal axes of said vanes being parallel to the axis of said tubing, said vanes having inwardly curved side surfaces in such a manner as to absorb energy from said well fluid containing abrasive on being injected into said casing through at least one perforation of said plurality of perforations at high velocity, the absorbed energy being transformed into rotational energy of said rings thereby reducing abrasion of said tubing by the high velocity of fluid containing abrasive, and means supported by said tubing retaining said rings at the level of said perforations.

5. The apparatus of claim 4 wherein said plurality of rings extend from a level below the lowermost of said perforations to a level above the uppermost of said perforations.

6. The apparatus of claim 1 wherein said ring is a ring of plastic material.

7. The apparatus of claim 1 wherein said ring is a metal ring.

8. The apparatus of claim 1 wherein said ring comprises a pair of mutually nonrotatable concentric rings, the inner ring of said pair of rings being a bearing of a plastic and the outer ring of said pair being of a metal.

9. The apparatus of claim 6 wherein said plastic material comprises a polyethylene having a molecular weight in the range of 25,000 to 200,000, a density of from 0.940 to 0.980 grams per cubic centimeter and a crystallinity of at least 90 percent.

10. The apparatus of claim 1 wherein the rings comprise a plastic material and said plastic material comprises a polyethylenehaving a molecular weight in the range of 25,000 to 200,000, a density of from 0.940 to 0.980 grams per cubic centimeter and a crystallinity of at least 90 percent.

11. The apparatus of claim 8 wherein said plastic comprises a polyethylene having a molecular Weight in the range of 25,000 to 200,000, a density of from 0.940 to 0.980 gram per cubic centimeter and a crystallinity of at least 90 percent.

12. An apparatus for minimizing erosion of a portion of a deep well fluid production assembly disposed in a well through a high pressure fluid producing formation,

said formation being adapted to produce fluid containing an abrasive comprising in combination, a casing disposed in said well, a well production tubing in said casing extending from the well head through said high pressure fluid producing formation to a level below said formation, said tubing being adapted for production of well fluid from a formation below the aforesaid formation, a packer set in said casing intermediate said formations, said casing containing at least one perforation at the level of said high pressure formation, at least one ring disposed concentrically and rotatably around said tubing throughout the area exposed to said high pressure fluid injected through said perforation, a plurality of vanes disposed at spaced intervals on the outer periphery of said ring and extending outwardly therefrom, the longitudinal axes of said vanes being parallel to the axis of said tubing, said vanes having inwardly curved side surfaces in such a manner as to absorb energy from said well fluid containing abrasive on being injected into said casing through said perforation at high velocity, the absorbed energy being transformed into rotational energy of said ring thereby reducing abrasion of said tubing by the high velocity fluid containing abrasive, and means supported by said tubing retaining said ring at the area exposed to said high pressure fluid.

13. The apparatus of claim 5 wherein said rings are rings of plastic material and said plastic material comprises a polyethylene having a molecular weight in the range of 25,000 to 200,000, a density of from 0.940 to 0.980 gram per cubic centimeter and a crystallinity of at least percent.

14-. The apparatus of claim 12 wherein said ring is a ring of plastic material and said plastic material comprises a polyethylene having a molecular weight in the range of 25,000 to 200,000, a density of from 0.940 to 0.980 gram per cubic centimeter and a crystallinity of at least 90 percent.

References Cited in the file of this patent UNITED STATES PATENTS 1,272,253 Green July 9, 1918 1,716,015 Tuthill June 4, 1929 2,005,767 Zublin June 25, 1935 2,552,716 Holland May 15, 1951 2,857,931 Lawton Oct. 28, 1958 2,925,097 Duesterberg Feb. 16, 1960 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,034,912 May 15 1962 Richard L. Flowers It is hereby certified that error appears in the above numbered patters Patent should read as ent requiring correction and that the said Let corrected below.

4 Column 8 line 27, for the claim reference numeral "5" read Signed and sealed this 2nd day of October (SEAL) Attest:

DAVID L. LADD ERNEST W. SWIDER Attesting Officer Commissioner of Patents

Claims (1)

1. AN APPARATUS FOR MINIMIZING EROSION OF A PORTION OF A DEEP WELL FLUID PRODUCTION ASSEMBLY DISPOSED IN A WELL THROUGH A HIGH PRESSURE FLUID PRODUCING FORMATION, SAID FORMATION BEING ADAPTED TO INJECT FLUID CONTAINING AN ABRASIVE INTO SAID WELL AT HIGH VELOCITY COMPRISING, IN COMBINATION, A WELL PRODUCTION TUBING EXTENDING FROM THE HEAD OF SAID WELL THROUGH A HIGH PRESSURE FLUID PRODUCING FORMATION TO A LEVEL BELOW SAID FORMATION, SAID TUBING BEING ADAPTED FOR PRODUCTION OF WELL FLUID FROM A FORMATION BELOW THE AFORESAID FORMATION, A PACKER SET IN SAID WELL INTERMEDIATE SAID FORMATION, AT LEAST ONE RING DISPOSED CONCENTRICALLY AND ROTATABLY AROUND SAID TUBING THROUGHOUT THE AREA EXPOSED TO SAID HIGH PRESSURE FLUID OF

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