Well Packer

Abstract

An open hole drill stem testing packer is disclosed wherein the packer assembly has a resilient packer element positioned between a lower anchor and a top adapter and fixedly attached to a telescoping mandrel. The packer has pressure relief means to prevent hydraulic lock between two adjacent packers and has an expanding shoe to prevent extrusion of the packer.

Description

BACKGROUND OF THE INVENTION

After drilling an oil well borehole for the production of petroleum products it usually becomes desirable to test the formation for its ability to produce the desired oil and gas products. Of the parameters tested, the most common are those of formation pressure and fluid sampling.

A preferred method of testing involves running a string of tools and piping into the borehole prior to inserting the casing and cementing. The tools and piping are commonly referred to as the drill stem testing string which preferably includes several different tools such as sampling tools, valves, and open hole packers.

Packers are primarily utilized to isolate certain areas of the formation, prevent contamination of the formation fluid from drilling fluid in the borehole, and to anchor the drill stem in the hole.

The testing procedure requires the opening of a section of the well bore to atmospheric or reduced pressure. This may be difficult to accomplish since the fluid in the wellbore, which may extend up to 30,000 feet in depth, is under extremely high hydrostatic head, usually much higher than the normal formation pressure.

Opening a section of the well bore to reduce pressure can be successfully accomplished by the use of open hole packers in the drill stem test string. The test string is lowered into the hole on drill pipe with the tester valve closed to prevent entry of well fluid into the drill pipe. When the string reaches the proper depth to test the formation desired, packers above and below the tester may be expanded into sealing contact with the wellbore, thereby isolating the formation near the tester from the high hydrostatic fluid pressure above and below it.

When using a single packer and setting the string on the bottom of the hole, the single packer is expanded to provide a seal above the zone to be tested, and when the seal is achieved, the tester valve is opened.

The packer then supports the hydrostatic pressure load of the well fluid. The formation below the packer is relieved of this pressure and is exposed through the open tester valve to the atmospheric or reduced pressure in the empty drill pipe so that its ability to produce fluid can be determined. After a specified time interval the formation is closed in to measure the rate of pressure build-up. At the end of the test the tester valve is closed and pressure of the hydrostatic fluid is equalized across the packer to permit it to be unseated.

The open hole packers disclosed in the prior art primarily comprise a sliding mandrel which passes within a resilient packer element and which, when telescoped inward applies a compressive action on the resilient sleeve, expanding it outward into sealing abutment with the wall at the borehole.

The prior art devices primarily suffer the disadvantages of being slow and difficult to unseat due to the high degree of friction between the packer element and the mandrel sliding therethrough, and the slow bleed-down of hydrostatic pressure across the packers. The prior art devices also suffer the disadvantage of being easily extruded and deteriorated under the high temperature, high forces and pressure conditions at the bottom of deep wells. The prior art packers also suffer the disadvantage of coming unseated prematurely or allowing leakage of hydrostatic fluid around them, thereby contaminating the sample run. This usually occurs when the drill stem is picked up to manipulate the tester valve, thereby removing the down weight from the packers and allowing them to partially unseat. Conversely the prior art packers are difficult to drill out of the borehole should they become lodged therein and have to be drilled out.

Another disadvantage suffered by these devices is the occurrence of a fluidic lock which occurs between the packers when two or more are used in tandem. This usually occurs when fluid is trapped between them, which fluid is highly incompressible and prevents the packers from telescoping towards each other the necessary amount to obtain complete expansion of the resilient packer element against the wellbore.

The present invention overcomes these difficulties by providing an open hole drill stem testing packer which is easily seated by setting down weight on the drill string, said packer having a resilient element which moves in unison with the mandrel upon which it is placed, a firm elastomeric expanding shoe below said resilient element to control extrusion and deterioration of the same, a piston and valving means to allow complete seating of the packer when used in multiples, preventing hydraulic lock therebetween, and allowing almost instantaneous unseating of the packers, and an interlock device to prevent rotation of the packer element and permit easy drilling out of the tool.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partial cross-sectional view of the well packer of this invention.

FIG. 2 is a cross-sectional view of the packer of FIG. 1 as it appears in the wellbore after being seated.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In FIG. 1 the well packer 1 is illustrated in a relaxed position as it appears connected in a drill string and being lowered into the wellbore. The tool 1 comprises a resilient packer element 2 which is a substantially cylindrical elastomeric sleeve positioned about the packer mandrel 3. The mandrel 3 is cylindrical tubular sleeve fixedly attached as by threads 4 to an adapter head 5. A top packer shoe 6 is located exteriorly of mandrel 3 between packer element 2 and head 5. Head 5 and packer shoe 6 are cylindrical sleeves passing circumferentially about mandrel 3 and each contain external threads 7 and 8 respectively. Head 5 has an outwardly flared bell-end 14 abutting packer sleeve 2. At their proximate edges, head 5 and shoe 6 have interlocking projections 9 which prevent rotation between the two sleeves. The projections 9 are drawn into interlocked engagement by the threading of turnbuckle 10 upon both the head 5 and the shoe 6 at their respective threaded ends. Turnbuckle 10 comprises an internally threaded cylindrical collar having internal threads matching the external threads of head 5 and shoe 6. O-ring seals 47 prevent fluid leakage between mandrel 3, head 5, and shoe 6.

Located at the opposite end of packer sleeve 2 from top packer shoe 6 is the packer support collar 11 which is comprised of a cylindrical collar portion 12 having a flared bell-end 13 in contact with packer sleeve 2. The packer support collar 11 is slidably located on mandrel 3 so that vertical movement therebetween is possible. Rotational movement between the mandrel and collar 11 is prevented by longitudinal interlocking splines 15 on the internal surface of the collar 11 and the external surface of the mandrel 3.

Located directly below the flared bell-end 13 of the packer support collar 11 is the elastomeric expanding shoe 16. This is generally a resilient sleeve located circumferentially around collar portion 12 of the support collar 11 externally thereof in fairly tight relationship. The composition of the expanding shoe sleeve 16 is preferably of a considerably firmer elastomeric material than that of the packer sleeve 2 to give support to the packer sleeve and prevent extrusion of the sleeve downward past packer support 11.

At the end of expanding shoe 16 opposite the packer support 11 is the shoe support collar 17 comprising a cylindrical externally threaded collar portion 18 at the lower end thereof and a flared bell-end 19 at the upper end thereof in abutment with the expanding shoe 16. Threaded portion 18 of the support collar 17 is slidably and circumferentially located partially about the exterior of the collar portion 12 of the packer support 11.

Opposite the flared end 19 of the shoe support 17 is a splined collar 20 contacting the other end of the shoe support. Collar 20 has internal splines 21 in interlocking engagement with external splines 22 of mandrel 3 for preventing rotation of the shoe support about the mandrel while allowing vertical movement therebetween.

Partially overlapping the splined collar 20 of shoe support 17 is a cylindrical splined housing 23. The housing 23 includes an internally threaded sleeve portion 24 at the upper end threadedly attached to the shoe support 17 at 25. At the lower end of the housing 23 is a splined sleeve 26 having internal splines 27 engaged with external splines 22 of mandrel 3 for prevention of rotation therebetween. Splined sleeve 26 has a reduced outer diameter 28 upon which is located external threads 29 which are threadedly engaged with matching internal threads 30 of a bottom sealing adapter 31.

Bottom sealing adapter 31 is a cylindrical tubular housing containing an enlarged inner diameter (ID) 32, a second enlarged inner diameter (ID) 33, slightly smaller than ID 32, and a reduced ID 34 passing through a threaded hub 35.

An equalizing piston 36 comprising an internally threaded sleeve portion 37 and a projecting shoulder portion 38 is threadedly attached to the end of mandrel 3 at the end opposite the head 5. Sleeve portion 37 of piston 36 has annular grooves 39 therein which receive O-ring seals 40; which seals, due to the external diameter of sleeve portion 37 and the ID of the bottom adapter at 32 and 33, do not engage the sealing adapter until mandrel 3 has been moved into the sealing adapter a sufficient distance to engage piston 36 with ID 33 of the bottom adapter.

In addition, porting through the walls of the splined housing and shoe support are provided at 41 and 42 respectively, which two sets of ports are located around the entire circumference of the tool and are radially aligned one set with the other to provide a flow channel from the wellbore below the expanding shoe through the area around splines 15 to the lower end of packer element 2.

A third set of radial ports 43 are located through the wall of the bottom sealing adapter 31 in circumferential orientation to provide a fluid channel from the wellbore area to the void space behind the equalizing piston when it has been expanded into sealing engagement with ID 33 of the bottom sealing adapter 31.

METHOD OF OPERATION

In typical operation one or more of the well packers 1 is inserted at the desired place in the drill stem testing string in order to obtain a test of the formation in question. It is possible to use only one of the packers when the formation is near the bottom of the borehole by placing the packer in the tool string a sufficient distance from the bottom of the string to isolate the desired formation between the packer and the bottom end of the string.

Most frequently it is desirable to run two or more packers in tandem and this situation is one in which the advantages of the present invention can best be realized and utilized. For instance, it may be desirable to use two or more packers to isolate a certain formation or zone in the wellbore, which zone may or may not be near the bottom of the well. In this situation, the multiple packers are arranged with one or two packers above the zone and one below in what is commonly termed a "straddle packer" arrangement.

Several problems were encountered with the prior art devices in this arrangement. One was in setting the two top packers which are in tandem. This was difficult to do because of the fluid lock which naturally occurred between them when they were telescoped toward each other and expanded outward. Other problems occurred when the testing was completed and it was desired to unset the packers and come out of the hole.

It will now be illustrated how these difficulties have been solved by this invention. When the desired number of packers of this invention have been inserted in the tool string, the string is lowered into the hole to isolate the formation. When the string reaches the bottom of the hole the required weight to set the packers is set down on the tools in the string, (the weight of the string may be sufficient to supply this weight).

The application of weight to the packer 1 moves it into the position as shown in FIG. 2. As the force from the weight begins to be applied to the string near the bottom, this force is transferred to the upper part of the packers 1 in the string. The resultant force downward is transmitted through the head 5 and simultaneously into both the mandrel 3, via threads 4, and the top packer shoe 6 via interlocking projections 9 and turnbuckle 10. This simultaneous application of force to shoe 6 and mandrel 3 tends to move them downward along with the packer sleeve 2, all in unison, due to the abutment of the sleeve with the shoe and the high degree of friction between the sleeve and the mandrel 3. It should be pointed out that the mandrel 3 is machined with a rough outer surface 44 to enhance this friction and the packer sleeve is snugly fitted around the mandrel to further increase friction therebetween.

Since the mandrel is relatively unhindered for telescoping movement downward into the packer support 11, shoe support 17, splined housing 23, and bottom adapter 31, this telescoping action begins to occur thereby applying a compression effect on packer sleeve 2 and expanding shoe 16.

At this point in time the packer is acting as though it consisted of three independent solid sections with two resilient elements, one each between the three solid sections. The three solid sections are free for vertical motion between each other but are all splined, as before described, to prevent angular or rotational movement. The three solid sections comprise the upper section, which primarily consists of the head 5, the shoe 6, the piston 36, and the mandrel 3; the floating section which consists of support collar 11; and the lower section, which consists of support 17, splined housing 23, and bottom adapter 31. Packer sleeve 2 is substantially located between the upper section and the floating section above described, and the expanding shoe 16 is located primarily between the floating section and the lower section.

As the upper section telescopes inwardly toward and into the lower section, the floating section comprising support collar 11, is allowed to move vertically independently of the upper or lower sections, in order to allow the sleeve 2 and the expanding shoe 16 to compress at their own natural rate of compression unhindered vertically. It should be reiterated that the resilient material of expanding shoe 16 is preferably much firmer than that of sleeve 2, thereby allowing most of the compression to be absorbed by sleeve 2.

The effect of the telescoping movement of the packer upper and lower sections is to compress the sleeve 2 and expanding shoe 16 sufficiently to swell them outwardly into sealing engagement with the uneven surface 45 of the wellbore. The further advantage gained by utilization of the comparatively firm expanding shoe 16, which extrudes partially over packer support 11 as shown in FIG. 2, to buttress the packer sleeve 2 and prevent detrimental extrusion downward and out of the packer support area. Expanding shoe 16, being of substantially firmer material than sleeve 2, provides highly beneficial support to sleeve 2, greatly prolonging the life of the packer sleeve and, in addition, forcing it outward to effect a better seal against the wellbore.

In common usage two of the packers 1 are used in tandem, with the head 5 of the lower packer being threadedly attached to the bottom adapter 31 of the top packer. Alternatively this orientation could be spaced apart by the use of a joint of tubing between the packers for a spacer.

Tandem packer arrangements are often utilized as a safety factor in deep wells where hydrostatic pressure at the bottom of the well is extremely high and the likelihood of packer failure, which could be disastrous to the testing, is greatly increased.

In such a tandem arrangement the packer of this invention is exceedingly useful due to its ability to reduce the naturally occurring hydraulic lock between the packers and its greater setting ability. As the upper sections of the two packers begin to telescope downward, expanding the packer sleeves and expanding shoes into sealing engagement with the wellbore, at the first instant they are both sealed, a certain amount of fluid is trapped between them. Since a further expansion of the packers is desired to obtain an absolute seal against the borewall this trapped fluid must be exited or relieved in some manner. Rather than allow the fluid to drain off below the packers this invention utilizes the fluid to further obtain an even better seating of the upper packer in the wellbore while simultaneously preventing the fluid lock between the packers. Referring to FIGS. 1 and 2 it can be seen that as the mandrel with the attached piston 36 telescopes downwardly, O-ring seals 40 contact inner diameter 33 of adapter 31 in sealing engagement and simultaneously a fluid tight void, differential pressure area 46 forms behind piston 36 and OD of mandrel 3 with fluid communication being provided only through ports 41, 42, and 43. Thus as the packers are telescoped and seated, fluid trapped between them is forced into piston area 46 which acts to provide an exit or relief for pressure buildup and further provides an additional downward force on the top packer by acting against the piston 36, forcing it downward and further setting the packer against leakage or premature release. Fluid passing through ports 41 and 42 communicates, via splined groove channels along splines 21, with piston area 46. Fluid passing through port 43 communicates directly with the upper face of the equalizing piston. The area of this piston can be set sufficiently large enough to "lock-down" the packer and thereafter allow vertical reciprocal manipulations of the drill pipe to operate the tester without unsetting the packers. This is particularly advantageous when using vertically reciprocable formation testing and sampling tools such as that disclosed in U.S. Pat. No. 3,358,755.

An outstanding feature of the packer of this invention includes its ease of removal from the well and almost negligible amount of deterioration and packer sleeve damage when being unseated.

In the set position as shown in FIG. 2, the downward weight of hydrostatic fluid on the annulus above the top packer results in great compressive forces on the resilient sleeve pushing it very tightly against the mandrel. In prior art devices wherein the mandrel must slide upward through the stationary packer sleeve the resultant high friction between them makes unseating of the packer slow and oftentimes destructive to the sleeve. In this invention the sleeve and mandrel move upward together in unison and the friction force is utilized to aid in unseating the packer rather than hindering it. This friction effect also aids in maintaining the packer sleeve in proper position on the mandrel above the packer support collar 11 and prevents damaging extrusion downward.

A further advantage is obtained when using tandem packers of this invention and quick unsetting is desired. Normally when prior art packers are run in tandem on a drill string and it is desired to remove them from the hole, hydrostatic pressure across the packers must be balanced and the weight on the string picked up to pull the packers loose. The hydrostatic pressure above the top packer is acting down on the top packer sleeve preventing it from being lifted and unseated. This pressure must be balanced before the packer can be removed. The normal procedure is to allow hydrostatic fluid flow into the string above the packers, which flows down the tubing and out through the testing tool below the second packer. As the weight is picked up on the drill string the pressure below the lower packer slowly seeps around the lower packer into the low pressure area between the two packers to balance across the top packer and allow the top packer to unseat. This normally may require a substantial waiting period.

In utilizing the packer of the present invention, almost instantaneous unseating of the packer is achieved by picking up on the drill string as hydrostatic fluid enters the tubing. The pressurized fluid flows down through mandrel 3 of the top packer, into the inner diameter 33 of bottom adapter 31 and against the lower face of piston 36 which thereby acts as a differential pressure area between high hydrostatic pressure in area 33 and the lower pressure void area 46. This results in pushing mandrel 3 back upwards, and simultaneously tranfers the hydrostatic pressure to trapped fluid in the annulus area between the packers through port 43, which pressure acts through ports 41 and 42, up the channels of splines 21, 22, and 15, and against the lower end of packer sleeve 2, thereby balancing pressure across sleeve 2 and further relaxing the sleeve to allow it to unseat. This entire pressure balancing sequence occurs substantially instantaneously and allows instant unsetting of the packers. This is described in conjunction with tandem packers but applies equally to straddle packer arrangements as well.

A further distinct advantage of this packer is realized in the ease of drilling out should a packer become irretrievably lodged in the wellbore.

With the prior art, packers when the annular shaped milling cutter is lowered over the tubing and descended to the packer to begin cutting it away, as the cutter removes the upper metallic part of the packer and enters the packer sleeve, the resiliency of the sleeve prevents further cutting thereof and allows the telescoping parts of the packer to rotate uncontrollably, which then acts as a bearing and prevents the cutter from traversing through the sleeve and finishing the milling of the remainder of the packer mechanism. This is further aided in the prior art devices by their polished surface of their mandrels which must be utilized to allow the mandrels to telescopic through the packer sleeve.

This invention prevents rotation of the packer elements through two features, one is the rough high friction surfaces between the mandrel and the packer sleeve, and the other feature includes the vertical interlocking splines 15, 21, and 22 which prevent rotation between any of the metallic elements of the packer.

Other distinct advantages of this design such as economical machining of parts, ease of assembly and dissembly, low maintenance requirements, and long packer life are obvious from inspection of the disclosure.

Although a specific preferred embodiment of the present invention has been described, the description is not intended to limit the invention to the particular forms or embodiments disclosed, since they are illustrative rather than restrictive and it will be readily apparent to those skilled in the art that the invention is not so limited. For example, it is possible to utilize the packer of this invention in the vertical orientation pictured in FIGS. 1 and 2 or to utilize is in the opposite vertical orientation, or alternatively to have one or more in each orientation. It is also possible from the above description to arrive at different packer sleeve lengths and configurations to fit the particular wellbore situation, or to utilize more than one sleeve and/or expanding shoe and floating section on each packer. It would also possible to form some of the parts as an integral unit instead of as individual components; for instance, the shoe support 17, splined housing 23, and bottom sealing adapter, or the head 5, mandrel 3, and piston 36 can be formed as a single integral component. Thus, the invention includes all changes and modifications of the specific example of the invention herein disclosed for purposes of illustration, which do not constitute departures from the spirit and scope of the invention.

Claims

What is claimed is:

1. An open-hole well bore packer adapted to be connected into a tubing string comprising:

a lower tubular cylindrical section adapted to be connected into a tubing string;

a cylindrical central floating tubular section adapted for vertical telescopic movement with respect to said lower section;

a cylindrical tubular upper section adapted to be connected into a tubing string and to telescope with respect to said lower section and said floating section, said upper section being connected in telescopic engagement with said lower section and said floating section;

first resilient packer means fixedly attached exteriorly to and encircling said upper section, in abutment with said floating section;

second resilient packer means snugly located exteriorly to said floating means in abutment with and located between said floating section and said lower section;

piston means attached to the lower end of said upper section and adapted to sealingly engage a portion of said lower section so that when said piston means are engaged with said lower section and fluid pressure is applied to the interior of said tubing string, the fluid pressure urges the piston means and upper section away from the lower section; and

at least one port provided in said lower section for communicating the internal portion of said lower section with the exterior thereof so that fluid pressure applied to the exterior of said lower section is communicated to said piston means and urges said piston means and the upper section towards the lower section.

2. The well packer of claim 1 further comprising means for allowing vertical reciprocating telescopic action while preventing angular rotation between said upper section, said floating section, and said lower section, and said means further allowing fluid communication therethrough.

3. The well packer of claim 1 wherein said first resilient packer means comprises an elastomeric sleeve;

said second resilient packer means comprises a second elastomeric sleeve, and said second resilient packer means is made of a substantially firmer elastomeric material than that of said first resilient packer means.

4. The well packer of claim 1 wherein said upper section comprises:

a generally cylindrical tubular head means adapted to be threadedly engaged with a section of tubing; and having an open bore passsage therethrough, external threads thereon, internal threads therein, and first interlocking lug means located at one extremity thereon;

a generally cylindrical tubular top packer shoe means having an externally threaded end thereon containing second interlocking lug means, and a flared bell-end at one end thereof opposite said externally threaded end, said bell-end adapted to abut said first resilient packer means in retaining relationship therewith;

generally cylindrical turnbuckle means having external threads therein arranged to threadedly engage said tubular head means and said top packer shoe means and further adapted to draw said head means into abutment with said top shoe means thereby interlocking said first and second lug means;

generally cylindrical extended tubular mandrel means having externally threaded section at one end and a second externally threaded section at the opposite end, and further having a roughened friction-providing external surface located partially thereon; said mandrel means being threadedly engaged by means of said first externally threaded section to said internal threads of said head means and passing through said top packer shoe means, said first and second resilient packer means, said floating section, and partially through said lower section; and

piston means having seal means thereon, said piston means threadedly attached to said mandrel means at said second externally threaded section and encircling a portion of said mandrel means, said piston means adapted to sealingly engage the inner bore of said lower tubular cylindrical section.

5. The well packer of claim 1 wherein said floating section comprises a substantially cylindrical sleeve portion to which is attached a flared bell-end portion in abutment with said first resilient packer means.

6. An open-hole well bore packer adapted to be connected into a tubing string comprising:

a lower tubular cylindrical section adapted to be connected into a tubing string, said lower section including:

cylindrical shoe support means having a flare bell-end thereon adapted for abutment with said second resilient packer means and further adapted for slidable movement about said floating section, said shoe support means further having an externally threaded central sleeve, a lower collar, and one or more ports through said central sleeve;

splined housing means having an upper outer sleeve threadedly attached to said threaded central sleeve of said shoe support means, with one or more ports therethrough, a central collar means adapted to reciprocate vertically about said upper section, and a lower inner sleeve having external threads thereon, with said ports through said outer sleeve being aligned with said ports through said central sleeve; and

bottom sealing adapter means having two or more different sized central axial inner bores therethrough, said sealing adapter means being threadedly engaged with said splined housing means at said lower inner sleeve, said sealing adapter means having one or more ports through the wall thereof, and said sealing adapter means adapted to sealingly engage said upper section and further adapted to be threadedly engaged into a section of well tubing;

a cylindrical central floating tubular section adapted for vertical telescopic movement with respect to said lower section;

a cylindrical tubular upper section adapted to telescope with respect to said lower section and said floating section and in telescopic engagement with said lower section and said floating section;

first resilient packer means fixedly attached exteriorly to and encircling said upper section, in abutment with said floating section; and

second resilient packer means snugly located exteriorly to said floating means in abutment with and located between said floating section and said lower section.

7. The well packer of claim 2 wherein said means for allowing vertical reciprocation while preventing angular rotation comprises internal splines within said lower tubular section and said floating section, and external splines on the telescoped end of said upper section, said internal splines adapted to engage and interlock with said external splines.

8. An open hole well packer comprising:

a generally cylindrical upper adapter having an open bore therethrough, and a lower downwardly flared bell-end thereon, said upper adapter arranged to be attached into a standard string of drill pipe;

an extended tubular mandrel fixedly attached to said upper adapter;

an upper resilient packer sleeve snugly encircling said mandrel and abutting the lower edge of said downwardly flared bell-end;

a floating packer support of substantially cylindrical configuration slidably encircling said mandrel and having an upwardly flared bell-end abutting the lower end of said upper resilient packer sleeve;

a lower resilient packer sleeve fixedly attached to and encircling said floating packer support and abutting said upwardly flared bell-end;

substantially cylindrical lower adapter means having two or more different diameter axial bores therethrough, two or more sets of ports through the wall thereof, an upwardly flared bell-end abutting the lower end of said lower resilient packer sleeve and slidably engaging said floating packer support, and adapted to be inserted in a standard tubing drill string; and

piston means fixedly attached to the lower end of said mandrel and adapted to sealingly engage one of said axial bores in said lower adapter in a lower position of said mandrel, and further adapted in another position to limit telescopic extension of said mandrel out of said lower adapter.

9. The well packer of claim 8 further comprising means for preventing angular rotation between said tubular mandrel, said floating packer support, and said lower adapter;

means for preventing slippage of said upper resilient packer sleeve on said mandrel;

and means for providing fluid communication between said sets of ports and the lower end of said upper packer sleeve.

10. The well packer of claim 9 wherein said lower resilient packer is made of an elastomeric material substantially harder than that of said upper resilient packer sleeve; and said means for providing fluid communication and said means for preventing angular rotation both comprise internal splines in said floating packer support and said lower adapter, and external splines on said mandrel in interlocking engagement with said internal splines.