US3858648A

US3858648A - Dual string hydraulically actuated oil well packer

Info

Publication number: US3858648A
Application number: US412221A
Authority: US
Inventors: Marion Barney Jett
Original assignee: Dresser Industries Inc
Current assignee: Dresser Industries Inc
Priority date: 1973-11-02
Filing date: 1973-11-02
Publication date: 1975-01-07
Anticipated expiration: 1992-01-07

Abstract

A simplified and efficient dual string hydraulically actuated packer assembly is disclosed which utilizes unitary tubular anchor means, compressible packer elements, and spring-loaded, shearable, ratcheting packer lock means.

Description

llnite Patent 1 .llett 1 DUAL STRING HYDRAULICALLY ACTUATED 01L WELL PACKER [75] Inventor: Marion Barney Jett, Seagoville, Tex. [73] Assignee: Dresser Industries, Inc., Dallas, Tex. [22] Filed: Nov. 2, 1973 [21] Appl. N0.: 412,221

[52] US. Cl 166/120, 166/134, 166/237 [51] Int. Cl. E21b 23/06, E21b 33/122 [58] Field of Search 166/120122,

[56] References Cited UNITED STATES PATENTS 1/1965 Sizer ..166/120 6/1965 Cochran 166/120 1610 16Gb I60 I68 ,lan.7,1975

3,211,226 10/1965 Myers et a1. 166/120 3,288,218 11/1966 Young 166/120 X 3,381,752 5/1968 Elliston 166/120 3,548,936 12/1970 Kilgore et a1. 166/121 3,714,984 2/1973 Read 166/206 X 3,731,740 5/1973 D0uglass.... 166/120 3,779,314 12/1973 Read 166/216 3,804,164 4/1974 Ellis 166/120 Primary Examiner-David H. Brown Attorney, Agent, or Firm-Michael J. Caddell [57] ABSTRACT A simplified and efficient dual string hydraulically actuated packer assembly is disclosed which utilizes unitary tubular anchor means, compressible packer elements, and spring-loaded, shearable, ratcheting packer lock means.

10 Claims, 36 Drawing Figures PATENIED JAN T1975 SHEET 01 0f 13 PATENTED JAN 7375 SHEET 02 8F 13 PATENTED JAN 7 i 5 SHEET 030F113 PATENTEU JAN 7 L975 saw on or 13 FIG. 8

PATENTED '7l975 3,858,648

FIG. 7

FIG. 7A

PATENTED JAN 7 I975 SHEET OB 0F 13 PATENTED 3,858,648

sum OBGF 13 FIG. II'D FIG. HE

F e. I F

FIG.I3

FIG. l4

PATENTEDJAN #1915 a. 858,648

SHEU IUUF 13 FIG. I5A FIG. I5B

PATENTEU 71975 I $858,648

SHEET llUF 13 FIG. I6A

FIG. I6B' DUAL STRING HYDRAULICALLY ACTUATIED OIL WELL PACKER BACKGROUND OF THE INVENTION Often during the producing life of an oil well it becomes desirable or necessary to produce from two or more different underground formations penetrated by the wellbore. This is commonly achieved through the use of packer assemblies containing two or more strings of conduit passing therethrough.

An example of such apparatus is shown in U.S. Pat. No. 2,965,173 in which a packer apparatus having dual conduit strings passing side-by-side therethrough has located on its outer surface resilient sealing cups having outwardly flared ends which are moved into sealing engagement by fluid pressure differentials above and below the cups.

Other types of multi-string packers include the inflatable or bladder type such as disclosed in U.S. Pat. No. 2,991,833 and the hydraulically actuated, compressible element, multistring packer such as disclosed in U.S. Pat. No. 3,167,127. All known multi-string packers using mechanical anchors to lock the assembly to the casing wall utilize the wedge-type slip segments having teeth which are cammed or wedged into contact with the casing wall by the action of a wedging mandrel being forced inside the slip segments forcing them outwardly into contact with the casing. Other known types of slips include the hydraluic button type which are spring-retained radial pistons slidably located in the wall of the packer body and actuated outwardly against the spring retainer by hydraulic force applied from inside the packer assembly. An example of the button type slips is shown in U.S. Pat. No. 3,311,169.

The dual-string or dual-conduit packers normally are used with a standard single string packer located on the tubing string below the dual-packer, which tubing string communicates with a lower formation below the standard packer and is connected to one conduit in the dual packer and from there to a tubing string passing to the surface. The second formation is normally located between the standard packer and the dual packer and can be produced through the second conduit passing through the dual packer and communicating with a second tubing string extending to the surface.

The disadvantages of the prior art dual string packers are their complexity, extended length, and the tendency of the wedge-type slips to become disengaged by shifting or stretching of the tubing and/or casing during the production life of the packer.

These and other disadvantages of prior devices are overcome by the present invention which comprises a dual string packer having simplified design, shortened length, and highly efficient tubular unitary slip means.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a top view of the dual packer assembly;

FIGS. 2A and 23 comprise a lateral cross-sectional view of the assembly taken at line 2-2 of FIG. 1;

FIGS. 3A and 3B comprise a lateral cross-sectional view of the assembly along line 3-3 of FIG. 1;

FIGS. 4A and 48 comprise a lateral cross-sectional view of the assembly taken along line 4-4 of FIG. 1;

FIG. 5, shows an axial cross-sectional view of the assembly taken at line 5-5 of FIG. 2;

FIG. 6 is a cross-section side view of the improved unitary tubular slip;

FIG. 7 is a top view of the improved unitary slip;

FIG. 7a is a side view of the improved unitary slip;

FIG. 8 illustrates a cross-sectional view of the apparatus in its engaged position;

FIG. 9 illustrates the top view of an alternate embodiment of the apparatus;

FIGS. 10A through 10C comprise a cross-sectional view of the embodiment of FIG. 9 taken at line 10-10 in FIG. 8; 7

FIGS. 11a through 11c are cross-sectional views of the embodiment of FIG. 9 taken at line 11-11;

FIG. 11d is a cross-sectional axial view of a key retaining sleeve;

FIG. He is a side cross-sectional view ofa key retaining sleeve;

FIG. 11f is an axial end view of a retaining key;

FIGS. 12A through 12C comprise a cross-sectional view of the embodiment of FIG. 9 taken at line 12-12 of FIG. 9;

FIG. 13 is an isometric view of the shearable ratchet pins;

FIG. 14 is an isometric view of one of the setting cylinder releasing keys in the piston assembly;

FIGS. 15a and 15b are schematic cross-sectional views of the gripping teeth on the anchor slip;

FIGS. 16a and 16b show axial and radial crosssectional views of the wedge-cone heads dissassembled from the apparatus;

FIG. 17 illustrates a cross-sectional view of the slip of the second embodiment;

FIG. 18 shows a side view of the slip of FIG. 17;

FIG. 19 is an axial cross-sectional view of a mandrel locking assembly;

FIG. 20 is a lateral cross-sectional side view of the mechanism of FIG. 19 taken at line 20-20;

FIG. 21 is a lateral cross-sectional top view of the mechanism of FIG. 19 taken at line 21-21.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the invention is illustrated in FIGS. 1 through 5 in which a packer assembly 1 is comprised of an upper mandrel assembly head 2, resilient packer assembly 3, upper slip 4, lower slip 5, and piston assembly 6, all mounted more or less in encircling relationship about primary mandrel 7 and secondary mandrel 8.

The upper mandrel assembly head consists of an integral cylindrical mandrel head 9 having longitudinal parallel bore passages 10 and 11 passing therethrough having internal threaded sections 10a and 11a in which are threadedly engaged by cylindrical tubular

elongated mandrels

7 and 8. A receiver collar 12 is connected by bolts 13 to mandrel head 9 and has bore passages 10b and 1 1b coinciding and axially aligned with passages 10 and 11 of head 9. Collar 12 has a concave cupped upper surface 12a arranged to guide a tubing string connector 14 into bore 11b of the assembly. Mandrel head 9 further has a threaded internal section adapted to receive a section of conduit or tubing in threaded engagement therein.

Tubular mandrels

7 and 8, fixedly attached by threaded connection to head 9, extend in parallel relationship to the longitudinal axis of the packer assembly 1 and generally parallel to the well-bore and have bottom threaded sections 7a and 8a extending downward out of the piston assembly 6 whereby either or both may be threadedly engaged into a lower tubing string extending downward into the wellbore.

Slidably mounted on

mandrels

7 and 8 are, in descending order, the upper unitary slip 4, upper packer head 31, one or more resilient packer elements 32, and lower packer head 33. Upper and lower packer heads 31 and 33 are metal cylindrical plates having a cupped surface on one side and having two axial bores therethrough for receiving

mandrels

7 and 8.

Resilient packer elements 32 are made of a resilient material such as synthetic rubber and are generally cylindrical, with dual bore passages passing axially therethrough to snugly receive

mandrels

7 and 8. Packer elements 32 are located in close fitting relationship with each other and with the cupped surfaces of

plates

31 and 33. A flanged retainer ring 34 abutting an external shoulder 18 on mandrel 8 limits downward movement of the resilient packer assembly 3 on the mandrels by also abutting the lower surface of lower head 33.

Lower unitary slip 5 is located on the mandrels in encircling relationship about the mandrels and slidably mounted thereon; slip 5 is similar to slip 4 but is mounted on the mandrels in an inverted orientation to slip 4.

Piston assembly 6 is mounted on

mandrels

7 and 8 in encircling relationship and consists of cylindrical setting piston 61 and cylindrical setting cylinder 62. Setting piston 61 is a substantially solid cylindrical piece having dual axial bore passages therethrough to receive

mandrels

7 and 8 and an upper annular space 63 around mandrel 8. Referring to FIG. 5, setting piston 61, as shown in cross-section, has a plurality of transverse lateral cylindrical bore passages 64 intersecting the longitudinal axis of bore passage 11 and having internal helical threads. Shearable cylindrical ratchet pins 65 are slidably located in passages 64 and are urged into engagement with mandrel 8 by the expansive forces ofleaf, helical, or belleville springs 66 which are held in compression against pins 65 by abutting engagement with threaded plugs 67 which are snugly secured into threaded passages 64.

Pins 65 (see FIGS. 5 and 13) have a reduced section 65a designed to shear at a predetermined load and a toothed ratchet head 65b having a curved face adapted to match the curvature of mandrel 8, with a plurality of cammed teeth 65c thereon designed to match and engage external annular teeth 8b formed on mandrel 8. FIG. 13 illustrates a second view of the shearable ratchet pins showing the relationship of the teeth 650 on ratchet head 65b. The teeth 8b and those on head 65b are arranged to allow upward movement of the pins on mandrel 8 but prevent downward movement of the pins and thus prevent downward movement of piston 61. The cammed faces of teeth 8b and 650 allow the piston 61 to move upward by camming the pins back against the springs 66, compressing them and allowing the ratchet teeth to slide over one another. Upon attempted downward movement of piston 61 on mandrel 8 the perpendicular faces of teeth 65c abut the perpendicular faces of teeth 8b and prevent the backward motion. Further operation and function of the ratcheting arrangement will be described in connection with operation of the entire packer assembly.

Setting cylinder 62 is a cylindrical element having a substantially solid lower section 62a and an upwardly 4 extending outer collar 62b passing exteriorly around piston 61. Lower section 6211 is solid except for two longitudinal bore passages therethrough which receive in snug slidable relationship the

mandrels

7 and 8. Cylinder 62 is temporarily attached to piston 61 by means of a plurality of shear pins 68 passing through upper collar 62b in threaded engagement therewith and seating in exterior channel 610 passing circumferentially around piston 61.

Setting cylinder 62 is temporarily attached to mandrel 8 by means ofa plurality of curved locking keys 69 having inwardly projecting shoulder 69a thereon for engaging a matching exterior channel in mandrel 8. Keys 69 are held inward by overlapping abutment of annular shoulder 61b on the lower end of piston 61. The keys, by abutment with the grooved channel in mandrel 8, the lower end of piston 61, and the upper end of solid end 62a of cylinder 62 temporarily prevent any sliding motion of the piston assembly 6 with respect to

mandrels

7 and 8. One or more ports located through the wall of mandrel 8 to communicate with the area between piston 61 and cylinder end 62a from bore 11 to release keys 69 in a manner which will be more fully described in relation to the operation of this tool.

At the lower end of mandrel 8 on external threaded end 8a is a standard threaded collar 19 attached thereto containing a valve seat 21 for receiving a fluid valve member such as a ball or plug, arranged to selectively close passage 11 to fluid flow through mandrel 8 and allow fluidic pressure to be applied through ports 80.

Referring specifically to FIGS. 2 and 4, the tubing string connector 14 is more particularly described as a cylindrical tubular upper sleeve having internal threads 14a for engaging a standard conduit section and an annular external depression 14b for receiving a seal carrier ring 15. A lower spring collet sleeve 16 is threadedly attached at 16a to the upper sleeve 14c and has collar 16b thereon for abutting and retaining carrier ring 15 which has a plurality of circular seals 17 thereon for sealing engagement between connector 14 and head 9.

Collet sleeve 16 is temporarily restrained in head 9 by the abutment of annular exterior shoulder with interior annular projection 9a in head 9. Removal of shoulder 16c upward past projection 9a can be accomplished by application of a predetermined lifting force which causes inward deflection of the shoulder 16c and allows it to move upward past projection 90. Deflection inward of shoulder 16c is made possible by the forming of several longitudinal slots 16d in collet sleeve 16 thereby lending flexibility to the metal remaining in the areas between the slots. The amount of lifting force required to move collet sleeve 16 out of head 9 can be adjusted as desired by the number and/or width of slots 16d and/or the angle of engagement between 160 and 9a.

Referring now to FIGS. 6, 7, 7a, 15a, and 15b, a more detailed description of the improved unitary slip members can be given. Each

slip

4 and 5 comprises a generally cylindrical gripping unit having on the extended outer reaches of opposing sides a plurality of teeth 41 curved about the slip body with an axis of curvature at an angle to the central longitudinal axis of the slip member. The teeth are also arranged so that the intersection of a plane passing through the slip longitudinal axis with the teeth extreme outer tips would circumscribe a curve as shown in FIGS. a and 15b. This is to allow the use of this apparatus in casings having varying inner diameters and obviates the need for a separate set of unitary slips for each weight rating of casing. In smaller ID casings, as shown in FIG. 15a, i.e., those of heavier weight, the two sets of teeth near the center of the slip, having the shortest distance between them will contact the casing wall with greatest area contact; while in larger ID, lighter weight casing as shown in FIG. 115b, the teeth at the two outer ends of the slip will contact the casing due to the greater distance between the upper outer teeth and the lower outer teeth.

The curved boundary tooth profile as shown in FIGS. 15a and 15b allows this versatility of use by providing greater tooth-casing wall contact area regardless of which teeth are called upon to anchor the packer assembly.

Looking at FIGS. 6, 7 and 7a, it is clear that each unitary slip has a dual-axis bore passage for each mandrel to pass therethrough. One axis of each bore passage generally parallels the central longitudinal axis of the slip and the other axis is located at an angle thereto in the same plane.

In FIG. 6, the intersecting bore passages are illustrated more clearly and their longitudinal axes are designated as XX and Y-Y. This view is taken from the side with the two mandrels lying in line with one another so that only one can be seen in cross-section. The axis XX defines bore passages 43 which are shown by the dashed lines in the figure. When the slip is oriented so that the mandrels occupy these bore passages, the gripping teeth are at their innermost orientation, out of contact with the casing wall.

When the slip has been rotated to bring the passages M into fitting relationship with the mandrels, then the gripping teeth are at their outermost extension from the mandrels and can engage the casing wall. Bore passages M are shown by the solid lines in the figure.

The angle between axes XX and YY can be from five degrees up to about 35 degrees but preferably is around 18 to 20 degrees.

Referring specifically to FIG. 6, a significant improvement in the unitary anchor slip 5 is illustrated in the cross-sectional view which shows the abutment surface 51. This surface is at the opposite end of the slip from abutment edge 52 and provides a dual purpose surface on the slip.

Rotation of the slip into casing engagement is achieved by moving an abutment means such as piston 61 against compound surface 511 which moves the slip along the mandrel until abutment edge 52 encounters an opposing abutment surface. The resultant effect in a rotational moment established in the slip from the reactant force on edge 52. This is aided by abutment forces introduced into the slip from surface 51.

Surface 51 has been termed a dual or compound surface. This is because of the flat portion 511a and the tangentially curved section Slb joining the flat surface. The curve of surface 51b is preferably on a radius R substantially equivalent to VzL where L is the axial length of the slip along axis XX. The curved surface is tangential to flat surface 51a at the point where axis XX intersects the end of the slip at surface 51.

The slip is arranged to pivot about a point C located at the intersection of axes XX and YY at a distance of approximately one-half of the slip length L from surface 51.

A phantom line P is drawn on the slip at the edge containing surface 51b to indicate the construction of the prior art slip means. Such a slip is disclosed in US. pat. No. 3,739,849 to Robert B. Meripol. While the slip of that disclosure is a significant improvement over the art, the existence of the extended shoulder P requires significant additional apparatus in the packer on which it is used.

Primarily a significant clearance must be maintained with the prior art slip between the slip in its unset position and the lower abutment means to allow pivoting of the slip into casing engagement position. This is because the radius Rp is considerably greater than the distance /2L and therefore a minimum clearance equivalent to Rp R must be maintained below the flat surface of the prior art slip to allow it to rotate into the set position.

To maintain the clearance and also to support the slip in a rotatable position and allow a moment force to be applied to abutment surface 52 without driving the slip downward on the abutment surface, the prior art slip was necessarily supported by pivot pins at C which passed through the slip and were engaged in an inner support sleeve. The downward force at 52 was countered by the oppositely reacting upward force of the pins on the slip which set up the desired rotational moment. The inner sleeve and the pins also served to hold the slip up off of the lower abutment means so that it could be pivoted. The inner sleeve and pivot support pins are illustrated in FIG. I of the aforementioned Meripol patent and designated therein as 20 and 34 respectively. The clearance under the slip is not illustrated in that figure since the slip has been rotated to the engaging position.

The improvedslip of this invention eliminates the need for the supporting sleeve, the pivot pins, and the pivot clearance necessary to the prior art device.

Since the radius of the curvature of surface 51b about the pivot center C is equivalent to the distance of surface Sla from C, it is obvious that the slip 5 can be pivoted about C in the same space as that occupied by the slip in the unset position. This eliminates the need for the support sleeve, the pins, and the clearance below surface Sll. Furthermore surface 511 may remain in constant abutment with adjacent abutment means to provide the necessary rotational moment from forces on surface 52 which further obviates the need for support pins at C.

Another advantage of the improved slip is in the guaranteed setting of the slip. In the aforementioned patented slip, should the clearance below the slip ever be decreased due to stretching of the parts, accumulated debris in the clearance area, failure of one or more of the parts, or incorrect assembly of the tool during manufacture, to the point where the clearance is substantially less than the amount Rp-wzL, it is clear that edge P will abut the lower surface or the debris in opposition to the setting forces at edge 52 and the desired rotational moment about C will be cancelled.

This situation is non-existent since the slip can rotate without the needed clearance and due to the simplicity of having no pins, nor sleeves; and incorrect assembly and part failure are almost absolutely eliminated.

One further advantage of the improved slip is that, when used as the lower slip, should it become lodged in the casing to the point that the releasing spring 49b hereinafter described is insufficient to rotate it out of engagement, dislodgement can be accomplished by merely bumping upward on the slip with the lower abutment means. Since some point on the curved surface lb will be located directly below C and will receive the upward abutment is is clear that no rotational moment will be introduced into the slip, and the simple upward driving force, in addition to the disengaging force of the releasing spring 49b will dislodge the slip from the casing. The upper surface 52 will of course be free from abutment during this releasing step.

Although the slip 5 has been described above, it is emphasized that slip 4 is identical to slip 5 and operates in the same manner, and the above description appertains thereto as well. Thus it can be seen that these two side-by-side dual bore passages and the compound curved-fiat abutment surface 51 allow the unitary slip to pivot about the two

parallel mandrels

7 and 8 from a non-engaging position to a casing contact position without any interference between the slips and the mandrels.

Each slip also has a releasing slot 46 as shown in FIG. 3 which runs partially the length of the slip and passes through the wall thereof in a plane perpendicular to the plane of the two dual-axis bore passages and the central slip axis. A third bore passage 47 passes from the inner terminal wall 46a of the slot 46 through the slip to the opposite end. The cross-sectional view of FIG. 3 reveals the purpose of slot 46 and passage 47 to be for the location of the threaded L-shaped releasing lug 48 and release spring 48a in the upper slip 4; and in the lower slip 5, retaining bolt 49, flanged bolt collar 49a, and coil spring 49b. A spring cavity 49c is formed in each slip and a spring cavity 48b is formed in the L-shaped bolt to receive coil spring 48a. Lug 48 passes through passage 47 and is threadedly secured into the lower end of head 9. Likewise, bolt 49 passes through passage 47 of the lower slip 5 and is threadedly secured to the upper end of setting piston 61.

In FIGS. 2 through 5 the packer assembly is illustrated in its unset orientation with the

mandrels

7 and 8 lying in bore passages 43 parallel to the central longitudinal axis. In FIG. 8 the packer apparatus has been activated and expanded into sealing and anchoring engagement with the casing wall. In this position, the slips have been rotated to bring the mandrels into the second bore passages 44 at the angle to the longitudinal bore passages 43 mentioned above.

OPERATION OF THE PREFERRED EMBODIMENT In a typical use of the described apparatus in a dual zone formation the apparatus is interconnected into a tubing production string by threaded connection of threads 10c and 7a to mating threads of standard tubing sections. The string will have a standard packer located in the string below this apparatus capable of sealing off the annulus between the tubing and the casing at the predetermined desired time.

The tubing string with the standard packer and the packer apparatus 1 is lowered into the well until the lower packer passes the upper producing formation and is situated between the two subject formations. The packer apparatus 1 will be located above the upper producing formation.

By appropriate means, such as manipulation of the tubing or hydraulic pressure applications, the lower packer is set in the casing. Alternately, the lower packer may be set by wireline or other means before the primary and secondary tubing strings are lowered into the hole and then the primary string can be strung into the lower packer. The second production string may then be lowered down the well with the connector sleeve 14 threadedly attached at the lower end. When the string has been lowered sufficiently, the sleeve 14 will engage head 9 and snap into place. The second string will then be sealingly communicating with mandrel 8 via bore 11 of head 9.

A sealing ball or plug 20 is dropped run in on a wireline, or pumped into the secondary tubing string to seal on seat 21 and allow fluid pressure to be applied to the fluid in the secondary string and act through bore 11 and ports against the lower end of the setting piston 61. When sufficient pressure has been reached in bore 11, piston 61 will shear pins 68 and move upward against the lower edge 51 of lower slip 5 sliding the slip upward until upper abutment edge 52 of the slip contacts the lower edge of lower head 33. Movement upward of piston 61 on mandrel 8 is allowed by the ratcheting action of ratchet pins 65 over mandrel teeth 8b which ratchet mechanism simultaneously prevents downward movement of piston 61 on mandrel 8 under normal operating conditions.

As piston 61 moves upward in response to hydraulic pressure acting upward, the upward force is transferred to lower slip 5, and from slip 5 to packer elements 3 and into the upper slip 4. This abutment of the slips with the packer assembly serves to rotate the slips into contact with the casing simultaneously with compression of the packer elements 32. Thus, continued application of hydraulic pressure of sufficient magnitude for a short period of time will set the two unitary slips into the casing and will expand the resilient packer elements outward into sealing engagement with the casing as shown in FIG. 8.

Upon release of hydraulic pressure in bore 11, the resilient packer elements will attempt to expand longitudinally and contract radially. This will provide a constant upward force on slip 4 and a constant downward force on slip 5 maintaining them engaged in the casing. Also, ratchet pins 65 will maintain mandrel 8 telescoped within piston 61 thereby preventing the packer from unsetting should mandrel 8 try to move upward in the wellbore for any reason.

Should it become desirable to unseat the packer apparatus 1, this can be done selectively by applying an upward force on mandrel 7 and thus on mandrel 8 sufficient to shear pins 65 through their reduced area 65a. In order to prevent a bending or collapsing of shear head 65b along the gap at 65a, a relatively soft filler material such as lead or plastic can be filled in the gap at 6511 to absorb the bending moment and insure proper shearing of the pins.

Upon shearing pins 65

mandrels

7 and 8 move upward with respect to the

slips

4 and 5 and packer assembly 3. Releasing lug 48 will move upward and work through spring 48a to pivot upper slip 4 back to its nonengaging position, also pulling it upward off of the packer assembly 3, allowing the resilient packer elements to contract to their normal unseated orientation. Continued upward movement of the

mandrels

7 and 8 will disengage the lower head 33 from abutment shoulder 52 of slip 5 allowing disengagement of the lower slip from the casing. Coil spring 49b will then expand against slip 5, thereby pivoting slip into its retraccted position. The packer assembly 1 is now completely unset and may be removed from the hole. The secondary tubing string may be removed from passage 11 before or after unsetting the packer assembly 1, or may be removed from the hole with the primary string if desirable.

MANDREL LOCKING MEANS FOR HIGH WELL PRESSURES Occasionally the apparatus of this invention must be used in a well having extremely high formation pressures or used in treatments of wells whereby fluids under high pressure must be pumped into the well formations through this apparatus.

For instance, pressures below the above described packer assembly may reach the range of 5,000 PSI or higher, and in this range a considerable upward force is exerted by the fluid upon the conduit strings in the wellbore, creating a buoyancy effect on the packer mandrels tending to drive them upward through the packer assembly resulting in unsetting of the slips and consequently the packer elements. This bouyancy effect is termed the piston or end area effect.

To avoid this tendency towards disengagement of the slips caused by the pipe bouyancy, a special locking mechanism is provided which is actuated by pressure below the packer elements and serves to lock the mandrels in the packer assembly.

Referring to FIGS. 19, 20, and 21 the locking mechanism is illustrated. FIG. 19 is an axial view in crosssection taken at line 1919 of FIG. 20. In the modified embodiment, the packer assembly 3 of FIGS. 1-4 is replaced by the modified locking packer assembly 203. Packer assembly 203 consists essentially of an upper head 231, resilient packer elements 232 and lower head 233, all encircling mandrel 7 and modified mandrel 208.

Modified mandrel 200 is substantially similar to mandrel 8 except for the existence of a plurality of tooth ridges 210 formed in the outer surface of the mandrel. Each ridge 210 has an abrupt upper face 210a and a sloping lower face 21012. The angle that face 210a makes with a plane normal to the tubular axis of mandrel 208 is preferably about ten degrees but may vary from 1 to 40 degrees depending upon the amount of restraining force desired. The angle of face 21% with face 210a may be from 130 degrees to about 50 degrees with a preferable angle of around 90 degrees. Ridges 210 preferably circle mandrel 200 entirely but this is not absolutely essential.

The packer assembly 203 contains two fluid bore

passages

204 and 205 passing through lower head 233, resilient packer elements 232, and part of the way into upper head 231. The bore passages generally run parallel to the

mandrels

7 and 208 and communicate with the formation annular area below the packer assembly 203.

Rigid tubes

206 and 207 line the bores through the resilient elements 232 to prevent collapse and closure of the passages upon compression and deformation of the resilient packer elements.

The

bore passages

204 and 205 intersect

pin channels

211 and 212 passing from the longitudinal bore passages 209 in head 231 containing mandrel 200, going radially outward from mandrel 208 through head 231 and through the outer surface of the head.

The

radial passages

211 and 212 contain outer threaded

portions

211a and 212a and smooth piston sections 21% and 212b. The radial passages preferably are of a cylindrical configuration for ease and convenience of manufacture but may be of any reasonable configuration.

Located slidably in piston sections 2111) and 21212 of the radial passages are locking

pistons

213 and 214 having curved toothed faces 213a and 214a. The teeth on these faces match and complement the teeth of mandrel 208 so that full surface contact between the two sets of teeth will occur. The radius of curvature of

faces

213a and 214a is substantially equal to that of the outer surface of mandrel 208.

Threaded

sections

211a and 212a contain threaded

plugs

215 and 216 snugly engaged therein in sealing contact, which plugs, in conjunction with

pistons

213 and 214, serve to form

hydraulic expansion chambers

217 and 218 in each radial passage. Circular seals 219 and 220 in the outer wall of

pistons

213 and 214 serve to prevent leakage of fluid from the expansion chambers into the mandrel bore passage 209.

Operation of the locking mechanism is automatic when this modified embodiment of packer mechanism 203 is installed in the previously described packer apparatus l, and consists of hydraulic pressure from the annular area below the packer mechanism 203 communicating through

bores

204 and 205 and into

pressure actuation chambers

217 and 218. The pressure is prevented from moving radially outward by

plugs

215 and 216 and therefore it acts inwardly against the

pistons

213 and 214 driving them against the mandrel teeth 210 thereby gripping the mandrel 208 and holding it in the packer assembly 203.

Since the packer anchors 4 and 5 are normally released by pulling upward on the tubing strings and thus on the mandrels, the angle of faces 210a on the mandrel teeth should be around five to fifteen degrees to allow upward movement of the mandrels upon application of external lifting force on the mandrels. Also, the pressure area of piston faces 213 and 214 may be designed so that the gripping force of the piston teeth on the mandrel teeth is just equal to or slightly greater than the bouyant upward force on the mandrels so that little additional upward lifting of the mandrels is required to wedge the piston teeth out of engagement with the mandrel teeth when unsetting the packer to remove it from the wellbore.

It should be noted that the back or lower edges 21% of the mandrel teeth are at a relatively flat angle compared to the upper faces 210a so that movement of the upper head upward on the mandrels is hardly impeded.

In additijon to the hydraulic force on

pistons

213 and 214 it is clear that any known spring means such as coil springs could be compressed and placed in

chambers

217 and 218 to supplement the actuating pressure.

ALTERNATE EMBODIMENTS Referring now to FIGS. 9 through 12 and 16 through 18, an alternate embodiment of the invention is disclosed which utilizes a single unitary slip or anchor capable of anchoring the assembly in the casing against upward and downward forces and pressures.

The packer apparatus 101 essentially comprises upper connector assembly 102, upper head assembly 103, packer assembly 104, unitary slip 105, and piston assembly 106.

The upper connector assembly 102 features a primary tubing receiver 110 which is an elongated tubular member having external threads 110a and 110b at its upper and lower ends and containing a connector collar 111 threadedly attached to threads 110a and arranged to be interconnected into a standard tubing string. Tubing receiver 110 is threaded into upper head 112 which also receives in threaded engagement a tubular elongated secondary tubing string receiver 113. Head 112 is primarily a cylindrical member having dual bore passages passing therethrough oriented substantially parallel with the central longitudinal axis of the cylindrical member. The upper portions of the dual bore passages have internal threads 112a for receiving

tubular sections

110 and 113.

Tubular receiving member 113 has an enlarged chamber area 114 attached to a standard tubular section or neck 115 and containing an annular inwardly projecting shoulder 116. Threadedly attached to the upper end of member 113 at threads 113a and slidably encircling member 110 is upper receiver disk 117 which is a generally cylindrical section having a concave upper face 121 and

dual bore passages

119 and 120 to receive member 110 and the secondary tubing string collet sleeve 118. Collet sleeve 118 is a tubular member having an annular shoulder 123 sized to abut shoulder 116 and be retained thereby. Longitudinal slots 122 are formed through the wall to give the remainder of the sleeve flexibility and allow shoulder 123 to flex inward and traverse shoulder 116. A cylindrical, tubular seal carrier collar 124 is threadedly attached to sleeve 118 and contains seal elements 125 encircled thereon to seal against bore 114 of receiver 113. A standard length of tubing 126 can be threadedly attached into collar 124.

Upper head 112 contains inner annular abutment ridges 112b in

bore passages

130 and 131 to receive in snug fitting relationship the primary and

secondary mandrels

107 and 108 which mandrels are elongated cylindrical tubular members extending substantially through the entire tool.

Each

mandrel

107 and 108 has an annular exterior shear shoulder 107a and 108a for abutment with and selective shear means for shear screws 127 which project through the wall of head 112 and into the shear chamber 128 formed between head 112, shoulders 107a and 108a and madnrels 107 and 108.

A cylindrical abutment shell 129 is secured to head 112 by threaded bolts 132 passing through the head and threadedly engaging shell 129 as shown in the discontinuous cross-sectional view of FIG. 9. This cross section must be shown in broken or discontinuous section in order to show the bolts since a normal cross section at line -10 of FIG. 9 would not clearly show them.

Located axially within shell 129 are two parallel locking-

key retainer sleeves

133 and 134 which are relatively thin cylindrical sleeves having flats milled along diametrically opposing sides and placed side by side slidably telescoped over

mandrels

107 and 108. The milled sides are shown in cross section in FIG. 12 and the normal sides are shown in FIG. 10. FIG. 11d shows a cross-sectional axial view of one of the key-retaining

sleeves

133 and 134, and FIG. He shows a crosssectional axial view of a sleeve.

Shell 129 also consists of a thick wall area and a thin wall area as shown in FIGS. 11 and 12. The narrowed walls of shell 129 and of

sleeves

133 and 134 are to allow side by side placement of the two

mandrels

107 and 108 within the dimensions of the sleeves and the shell. shell 129 has at its lower end an inwardly projecting flange 129a through which pass locking collet sleeves 135 and packer assembly bolts 136 concentrically located within sleeves 135.

Sleeves 135 each have a small spring lip 135a on the outer edge of the upper end for engaging flange 129a and an outer abutment flange 135b at the lower end for abutment and retention of upper packer plate 137 to head 112. This prevents head 112 from floating upward on bolts 136 away from plate 137 and prematurely shearing of screws 127 while going in the hole with the tool.

Key-retaining

sleeves

133 and 134 are arranged so that slots in the sleeves are located directly over parallel, exterior

circumferential ridges

138 and 139 on

mandrels

107 and 108. Retaining keys 140 are snugly fitted within the slots and abut the mandrels between the ridges as shown in FIG. 9. This arrangement temporarily locks the mandrels to the upper head assembly 103 by means of keys 140,

ridges

138 and 139 and

sleeves

133 and 134 and allows the operator to pick up on the string and reciprocate it to dislodge sediment or other material which may be binding between the tool string and the casing while going in the hole. This protects shear pins 127 from premature shearing. Keys 140 are held within the slots in

sleeves

133 and 134 by abutment with the inner wall of the lower extending portion of head 112. FIGS. 11a 11c give views of the sleeves and keys disassembled from the apparatus for a better understanding of their structure.

The resilient packer assembly is located slidably about the

mandrels

107 and 108 below upper packer plate 137 and consists of resilient packer elements 141, rigid spacer plates 142 and lower packer plate 143.

A dual wedge-cone head 144 is abutted against lower plate 143 in encircling relationship about

mandrels

107 and 108 and wedge anchors 145. Anchors are wedge shaped inserts having a plurality of angled gripping teeth on their inner surface contacting the outer wall of the mandrels.

Movement upward of the anchor inserts 145 on the mandrels is possible because of the angle of the upper faces of the wedge teeth but movement downward on the mandrels is prevented by the' perpendicular teeth face projecting into the mandrel surface and also because of the wedging force inward imposed by the action of the wedge-cone head 144. It is clear that the angled inner surface 144a of head 144, acting on the angled outer surface 145a of the anchor 145 as the anchor moves upward, will result in a pressing inward of the anchor insert upon the mandrel it contacts thereby preventing downward movement of the mandrel. A more detailed view of the dual wedge-cone head 144 is shown in FIGS. 16a and 16b.

Guide pins 146 project through head 144 and into slots 145b formed in the outer portion of wedge inserts 145 to prevent the anchors from rotating around on the mandrel and getting out of optimum gripping position which is with each anchor diametrically opposed to another anchor about the mandrel.

A thin cylindrical retaining sleeve 147 snugly encircles head 144 and abuts lower plate 143 and cylindrical anchor cap 148 which is slidably aligned on mandrels

Claims

1. A dual string oil well packer comprising: dual elongated tubular mandrels arranged in substantially parallel orientation, each having an integral independent bore passage extending therethrough: upper body means attached to and encircling said mandrels; a unitary tubular anchor slip encircling said dual mandrels and arranged on said mandrels in limited slidable and pivotable relationship; said unitary slip having a plurality of teeth formed on diametrically opposite sides at opposite ends thereof, said teeth adapted to engage said grip the inner wall of the well casing; said anchor slip further having two sets of dual parallel bore passages therethrough each capable of receiving said mandrels, said one set of dual passages intersecting said other set at an angle of about five degrees up to about thirtyfive degrees, whereby said anchor slip can be rotated from casing engaging position to nonengaging position on said mandrels; packer means comprising a plurality of resilient annular packer elements and rigid containing means adjacent said resilient elements, said packer means encircling said mandrels in a partially slidable relationship thereon and arranged to abut said anchor slip; hydraulic actuation means located on said mandrels and comprising piston means and cylinder means, said piston means slidably engaging said cylinder means, and said piston means and said cylinder means each containing inner annular differential pressure area surfaces arranged to communicate with post means through the wall of one of said mandrels; said differential pressure surfaces adapted to receive fluid pressure through said port means and force said piston means out of said cylinder means into abutment with said anchor slip thereby rotating said anchor slip and compressing said resilient packer elements into engagement with the well casing; locking means on said mandrels for engaging said mandrel and maintaining said said anchor slip in said rotated position and said packer means in said compressed position; shear means preselectively shearable to allow said anchor slip and said packer means to be released from said locking means at a predetermined desired time; releasing means in said packer arranged to abut said rotated engaged anchor slip and selectively rotate said anchor slip out of the engagement with said well casing; and, wherein said locking means further comprises a dual conical wedging collar slidably mounted on said mandrels and attached to said cylinder means, and a plurality of toothed wedge inserts located within said wedging collar between a conical inner wall in said collar and said mandrels, said inserts arranged to be wedged against said mandrels by the conical inner wall of said wedging collar to force the toothed portion of said inserts into engagement with the mandrels, said toothed portions having cammed teeth thereon arranged to allow said inserts to move in only one direction on said mandrels.

2. The well packer of claim 1 wherein said locking means further comprises a second dual conical wedging collar slidably mounted on said mandrels, said second collar being attached to said packer means and containing a plurality of wedge inserts in a dual conical cavity therein between said wedging collar and said mandrels, said inserts having cammed gripping teeth thereon in abutment with said mandrels and arranged to allow movement in one onE direction on said mandrels.

3. The well packer of claim 2 wherein said releasing means comprises an elongated releasing member attached to said packer means, extending through said unitary slip, and having abutment means thereon arranged upon upward movement of said packer means to abut one side of said slip and rotate said slip out of engagement with the casing wall; said slip being shearably and temporarily attached to said releasing member in a non-engaging position in the casing by a shearable screw passing through said slip and into said releasing member.

4. The well packer of claim 3 wherein said shear means further comprises shearable pins within said packer means in abutting relationship with said mandrels; and said packer means further comprises an upper cylindrical packer head attached to the upper side of said rigid containing means and encircling said mandrels; a retainer key sleeve means located concentrically between said packer head and said mandrels, said key sleeve means having key retaining slots formed therein; retainer keys located in said slots and projecting radially inward through said slots; and, annular abutment ridges on said mandrels for receiving said projecting keys in longitudinal axial abutment, and internal, annular retention abutment shoulder means within said packer head arranged to abut said keys and maintain them engaged in said abutment ridges; said packer head further having an enlarged inner bore area adjacent said internal shoulder means adapted to receive said retainer keys upon upward movement of said packer head with respect to said retainer key sleeve means; said retainer key sleeve means arranged to abut said rigid containing means and said packer head and transfer downward axial forces from said tubing string to said packer means and to transfer downward forces acting on said mandrels to said packer means, and further arranged to allow shearing of said shearable pins and release of said packer means and anchor slip upon application of upward force on said tubing string.

5. A multistring well packer assembly capable of isolating a plurality of annular areas in an oil well, said well packer assembly comprising: a plurality of tubular, cylindrical elongated mandrels arranged in generally parallel, longitudinal alignment and adapted to be inserted longitudinally into an oil well; packer assembly means slidably and concentrically located telescopically about said mandrels and containing a plurality of resilient compressible packer elements therein; releasing assembly means attached to said packer assembly means and releasably connected to said mandrels; one or more elongated tubular receiving conduits securedly attached to said releasing assembly means and communicating coaxially with said mandrels; cupped cylindrical upper connector means attached to one or more of said receiving conduits and adapted to receive therein in yieldable connection, additional tubular conduits from above; a first gripping assembly located slidably and concentrically on said mandrels below and attached to said packer assembly means and arranged to allow longitudinal movement of said packer assembly in one direction on said mandrels and to selectively retard said longitudinal movement in the opposite direction; unitary tubular anchor means mounted partially rotatably and slidably on said mandrels below said gripping assembly and arranged to abut said gripping assembly and rotate it into gripping engagement with the oil well casing; piston and cylinder means located below said anchor means in slidable concentric attachment on said mandrels, said piston and cylinder means having a piston securedly attached to said mandrels and a cylinder slidably mounted on said mandrels and said piston; said cylinder arranged to move upward on said mandrels toward said anchor means; one or more ports through the wall of at least one of said mandrels communicating with a differential pressure area between said piston and Cylinder, said differential pressure area arranged to drive said cylinder from said piston in response to hydraulic pressure communicating through said ports; and, a second gripping assembly attached to said cylinder and arranged to allow upward movement of said cylinder on said mandrels while retarding downward movement of said cylinder on said mandrels, and further arranged upon upward movement to abut said anchor means and further rotate said anchor means into engagement with the oil well casing.

6. The well packer assembly of claim 5 further comprising: anchor release means attached to said first gripping assembly and arranged to abut said anchor means upon upward movement of said gripping assembly, said release means abutment occurring at one side of said anchor means thereby providing selective rotation of said anchor means out of engagement with the oil well casing; first shear means between said piston and said cylinder arranged to secure said piston to said cylinder until sufficient hydraulic pressure through said ports forces said cylinder from said piston by shearing said first shear means; and, second shear means between said anchor means and said release means arranged to prevent engagement of said anchor means with the well casing until rotative force sufficient to shear said second shear means has been applied to said anchor means.

7. The well packer assembly of claim 5 wherein said releasing assembly means further comprises an upper head, an intermediate tubular abutment collar, and a releasing key sleeve located concentrically within said head and said abutment collar and abuting said packer assembly means, said sleeve having a plurality of key slots through the wall thereof and a plurality of retaining keys located in said key slots and projecting inwardly through said wall of said sleeve and abutting said mandrels, said mandrels having parallel circumferential annular ridges thereon arranged to receive said keys therebetween in close fitting relationship, said keys and ridges temporarily restraining longitudinal relative movement between said sleeve and said mandrels; said upper tubular head having a lower projecting skirt arranged to abut the outer surfaces of said keys and maintain them engaged in said parallel ridges; said abutment collar having an inner annular space between said collar and said sleeve arranged to receive said keys from said slots and allow disengagement of said sleeve from said mandrels upon upward movement of said head lower skirt from abutment with said keys; and said upper head being shearably attached to said mandrels by shear means passing through said head and abutting said mandrels above said parallel ridges and directly below a third annular ridge on said mandrels; said third ridge having a shear edge thereon arranged to shear said shear means passing through said head.

8. The well packer assembly of claim 5 further comprising: collected sleeve means passing through and yieldably abutting said releasing assembly means and said packer assembly means and arranged to yieldably connect said releasing assembly means to said packer assembly means.

9. The well packer assembly of claim 5 wherein said anchor means comprises a generally cylindrical gripping member having a dual-axis bore passage therethrough for each mandrel of said well packer assembly, said each bore passage comprising two generally cylinderical intersecting bores passing longitudinally through said gripping member, with the axes of said intersecting bores having an angle of intersection of from about five degrees up to about 35 degrees, said dual axis bore passages arranged to allow said member to pivot about said mandrels from a non-engaging position to a gripping position in the well casing; said gripping member having a plurality of peripheral ridges formed at diametrically opposite sides and at opposite ends of said member, said ridges adapted to engage said well casing upon rotation of said anchor means.

10. THe well packer assembly of claim 9 wherein said first and second gripping assemblies generally comprise a multiple passage, inner conical surface wedging collar encircling said mandrels and forming an annular conical space therebetween; and a plurality of conical shaped toothed wedge inserts located in said conical space and in contact with said collar and said mandrels; said teeth on said inserts arranged to cam over said mandrels in one direction of movement therebetween, and to engage said mandrel upon attempted movement in the opposite direction.