US2238533A - Tubing attached reinforcing trapping strainer - Google Patents

Description

April 15, 1941. E. H. MQCLEASE 2,238,533

TUBING ATTACHED REINFORCING TRAPPING STRAINEB Filed Dec. 17 1938 2 sheets shet 2 Patented Apr. 15, 1941 UNITED STATE s PATENT OFFICE TUBING ATTACHED BEINFORCING TRAPPING STRAINEK Ervin H. McClease, Bakersfield, Califl Application December 17, 1938, Serial No. 246,421

24 Claims.

This invention is a sand trapping, channelforming, reinforcing strainer for deep well liners, or for sole use in hard well holes or wells without a first liner,

An object of the invention is to provide an apparatus to largely control or eliminate the entry of earthy solids from the well formation into the Y A further purpose is to provide a substantial trapping reinforcement to give much added resistance to formation pres'sure, as from heaving, caving, shifting, and gas and fluid pressures, and to greatly reduce the hazard of collapsing or buckling of the main liner.

' An additional object is to provide a sand trapping strainer which will give a substantiallynormal rate of flow from the well; that is will prevent complete sand bridging in the liner and will afford ample interstitial structure for the well liquids to maintain channels of normal flow volume. Especially it is an object to provide sub-passageways to enable the stream to move at a rate to carry along a; suitable amount of solid particles from the formation to keep the formation orifices open fortheir normal flow in a manner not possible in liners in which the sand can pack or bridge as a seal to block the sometimes small spring orifices from which the fluids leave the formation at the face of the well bore. A fast moving liquid will act as a vehicle to lift the solids through the tubing foot to a level well above the spring face of the formation.

Also a purpose of the invention is to provide for the ready removal of the loaded, sand trapping to provide elongate trapping means toobtain and show at the different levels the nature of the incoming well product or the lack of inflow, and to provide for keeping formation grains or suspended solids from settling to a lower level than at which they come in, and still provide for the ascent with the moving liquid of as much of In other words, an

the fine solids as is possible. object is to Provide a method and a means in the form of a sand trap and strainer and remover of a length equal to or greater than the depth of the tapped formation or producing zone in the well to obtain a faithful, production-level log or indicator for a given well.

It is a further object to provide a tubing-attached and handled strainer which may be readily ping strainer; to provide a trapping strainer strainer or reinforcement; asit may be called if used as a secondary device in the first or main liner, at such times as the well may determine without need of recourse to very costly and hazardous bailing operations with a special tool.

An important object of the invention is to provide means by which to receive and trap formation grains at about the level, in a formation face, from which they flow into the hole with the spring liquid, as oil or water, and also provide for the trapping of specimens of the products at their inflow level to provide a true level-indication formation tester at each period the trapping strainer is pulled for clean-out, or, if d i iormation test. More specifically, an object is consisting of slack-jointed sections to successively stack on a main liner shoe or otherwise formed support and which sections will successively, from topmost downwardly, separate to a limited degree upwardly when the attached tube, orother well string to which the strainer is applied, is pulled either merely to open the section, relatively for bridge breaking, or for pulling the loaded stand of sections for formation testing or for well clean-out. Also, an object is to provide a'variety of sections making up a strainer assembly, in which assembly the sections superpose in normally spaced relation and have provision for vertical travel of liquid and at the same time to entrap local level formation grains to keep a log.

An additional object is to provide for a brushing or wiping of the orifices of the main liner at the same time that the strainer sections are activated or jostled by vertical vibration to smash possible bridges.

This well liner orifice brushing or. wiping function is also done when the strainer is pulled from the liner proper for any reason, or when it is set back into the main liner in telescoped operative position.

An object, also, is 'to provide a safety-joint,-inner strainer combination, with a tubing especially,

or other appropriate string, so that in the event i of the lower end of the, string becoming sanded or jammed from any cause, the upper string and the. associated strainer may be loosened off the lower part and used as a means to free the sand stuck part so that it would not. belost and could be pulled from the hole. And a further object is to provide safety-break points along the inner strainer to enable recovery of as much apparatus as possible above collapsed or otherwise frozen bottom portion of the assembly.

The invention consists of certain advancements in this art as will be set forth in the ensuing disclosure and having, with the above, additional objects and advantages as hereinafter developed and whose construction, combination and details of means will be made manifest in the de-. scription of the herewith illustrative embodiments; it being understood that modifications, variations and adaptations may be resorted to within the spirit, scope and principle of the invention as ismore directly claimed herebelow.

Figure 1 is an elevational axial section of the upper portion of the strainer assembly and Figure 2 is a like section of its lower portion, both in a well liner; the assembly parts being in normal-flow, landed position on a liner shoe.

Figure 3 is a sectional plan of the coupling saddle ring on a tubing collar on line 33, Fig. 1.

Fi ure 4 is a cross-section of the coupling body on line 4-4, Fig. 1.

Figure 5 is a sectional plan of an upper cup unit of the assembly, showing associated connection parts in section on line 5-5, Fig. 1.

Figure 6 is a cross-section on line 6-6 of Fig. 2; showing attached, offset buckets.

Figure 7 is a detail broken elevation of a form of side-hang bucket.

Figure 8 is a sectional elevation of a nesting, modified form of trap bucket unit as being set into position.

Figure 9 is a top'plan of Fig. 10, and

Figure 10 is a sectional elevation of a tube receiving cup unit with parts of hangers of ,a supraadjacent unit in lowering position.

A well casing L is shown as surrounding and extending below an adapter A carrying a lower reduced size liner 'Lw with wall perforation P, for any desired height, permitting formation flow into the liners above the bottom shoe S. As here adapted the strainer is mounted on a string of tubing T of any desired length, and the lower end of the tubing T beingshown in Fig. 2 as positioned well above the shoe S to leave a. space I of any desired length in the liner La: between the tubing and the shoe.

This space above the shoe tends to pack up with fine well solids and the present invention includes means attached to the tubing T to reduce or retard this packing tendency and also means to remove the sand pack, thereby cleaning the liner.

As here shown a top saddle ring 2 is fitted on the tubing to seat downwardly on its lowermost collar C. Slidably mounted in this saddle is a set of coupling rods 3 slidably passing through a washer 4 which is thrust upwardly against collar C by strong springs 5, on rods 3.

The rods 3 are solidly fixed by nuts 6 to the upper flange 'I'of a coupling sleeve or body 8 slidably fitting around the given inserted tubing T. To the lower end of the body 8 there is firmly attached, as by bolt-shanks 9,-a suitable packer III, of any well known and adaptable construction which serves to seal off the casing L and space thereabove about the tubing T. The packer units are successively picked up from collapsed or stacked positionto extended position.

The object of the washing process is to clear the cup-like units of any packed solid or semi-' solid materials, which may be about their inner or outer sides.

Now in some cases, wells mayhave a very low fiuid level, and for this reason there will be no fluid above the packer 10. In such wells, the fluid should be supplied from some outside source. That is, the fluid should be dumped or pumped in at the well head, within the well casing L but outside the tubing T. Since the object of the That is, the fluid should be dumped or pumped fluid washing is to eliminate friction about the sides of the various strainer units, a lubricating fluid should be used for this purpose. In water The means to trap formation grainsand provide flow channels includes divers forms of cups or traps. Above the adapter A, and below the packer l0, there is considerable annular space about the tubing T and this space is reduced in diameter as it extends into the lesser bore of the well liner Lm. Below the packer a plurality of trap units I5 is provided each having an outer cup wall [6 quite loosely fitting in the casing L to leave an annular flow channel I! at the adjacent bore surface of the casing, and each unit is provided with an inner concentric wall l8 loosely slidable about the pump-tubing T to provide for fluid fiow thereabout. There is thus formed an annular sand pocket IS in the cup between the walls l6 and I8.

Various ,telescopic or slidable means may be provided to afford attachment between the top unit I 5 and the superjacent packer In or such other device as may be associatedin the string set-up, and as here shown the lower element of the packer has a series of parallel, depending shanks 20 preferably tubular to provide up-flow ducts 2| for fluid which may accumulate in the next lower cup unit. The wall structure l6 and I8 of each cup device as IE or others so desired, is vertically slotted at 22 to receive a hitch device such asa radial cross pin or screw 23 passing through a relative intruded shank 20 from the bottom of the next upper element as packer In. These cup units have like shanks 24 likewise hitched by pins 23 to next lower cups in the assembly, in which there may be any desired number of cups under the set packer I0. There is thus provided a lost motion or slack type of hitch or connection by the pins 23 and slots 22 in walls of the several cups I5 and the packer.

While the cup string is being lowered into the well with the assembly hung by the saddle ring 2 on collar C on the tubing T, the cups are in open or spaced position in relation to each other and suspended from the tops of their slots 22 on the cross pins or, screws 23 of the next higher string element. When the assembly is landed or bottomed, as later set forth, the cups close down on each other to a degree determined by the length of the slack slots 22; the top edges of the various cups being suitably vertically spaced from the bottom of the next higher element.

When the assembly is bottomed on a given foot and the springs 5 which provide a desired cushion reaction to the tubing setting on the washer 4 are compressed; the rods 3 sliding up in the saddle ring 2 during such relative downward movement of the tubing. 1

A second important function of the assembled coupling device, consisting of saddle ring 2, cou pling rods 3, washer 4, springs 5, nuts 6, upperf lange 1, body 8, and bolt shanks'9, is to provide a vertical play of considerable length between body 8 and saddle 2 to allow for the placing of all cup units in collapsed position; to yieldably hold them so placed, and to have sufiicient up and down slack to allow for the setting of a tubing catcher.

To further explain this function, an operator is running a completely assembled strainer into a well on a string of tubing T. Now in time the bushing 36 seats within the well liner shoe S; next, the anchor block 34 settles into place, after whicheach higher cup unit or other element 'is in turn lowered or collapsed into standing or arrested position; then eventually the packer l settles to the stack of arrested parts. Now at the time the packer is arrested the operator continues to lower the tubing string thereby compressing the springs 5, until they are completely compressed, at which time the tubing string begins to apply some dead weight to the coupling device 8, packer Ill, and all units and assembly sections thereunder. Now at this time, the operator at the well head, notes this loss of weight on the weight indicator, and naturally assumes that the complete strainer assembly is bottomed, collapsed and properly in functioning position. However the tubing catcher is not yet set. Assuming that the operator knows that there is three feet difference between the fully compressed and fully extended positions of the springs 5, he proceeds to set the tubing catcher, by raising the tubing approximately 34 inches, then dropping it sharply two feet or other required amount extra. This two feet drop sets the tubing catcher simultaneously, without disturbing any of thelower strainer assembly, which is alreadyin operative position.

Note that in the position of parts as just described there is no dead weight of the tubing T applied to any part of the-assemblybelow the springs 5, that the springs lack approximately ten inches of being fully compressed, that the springs 5 exert a powerful downward pressure on the packer l0 and all lower units of the strainer, therebyholding these parts in their collapsed position, despite the' upsurge .of liquids and gas tending to raise them. In the position of parts are described justabove, the foot end of the tuhing T will not rest in its cup seat 21, but will hang approximately ten inches above it.

At this point it may be explained that should the tubing or other string in its stead below the collar C become frozen or trapped in .the well hole it is an important feature of this invention that the lower tubing string may be disconnected at the collar C to enable all'ofthe tubing string above and connected to the upper end of the collar to be lifted, to successively pull up one cup 15 after the other with the purpose of breaking up a sand pack that may have formed'and be holdin of the collar. To provide for the disconnection of the collar C from the tubing section in the lower end of the collar such lower end is provided with a left hand thread 25 to take a like thread on the upper end of the inserted, next lower tubing section. It is only necessary therefore to give the upper string of tubing several right hand turns in order to unscrew thread -joint at 25 and permit the upper string to be gradually lifted to successively pick up the hitched cups l5, and other hitched parts therebelow. When the upper tubing and the attached strainer assembly are lifted the separate, slackly hitched strainer members are, from the top downwardly, successively lifted along the lower frozen tubing until the frozen part is entirely free, whereupon it is engaged and lifted by the seat 21.

This may be repeated until the sand bridge or bridges are opened up either to re-establish well flow, or as suggested, to free the stuck tubing foot section if possible. If it is thus freed, the distended assembly can be pulled by the upper string of tubing and bring with it the fished part of the lower tubing; thus the assembly of trapping units becomes a practical fishing tool.

Somewhat above the level of the adapter A the cup units are of a reduced outside diameter so that they may be extended down in a collapsed stack of suitable length into the reducing adapter bore; the reduced cups being indicated at l5.-

As shown in Fig. 5 the annular space of the cups l5l5' may be provided with small wells 26 about each of the hitching shanks 24 so as to provide an up-flow channel from and around each shank. These wells 26 and tubular shanks 24 are preferably perforated with minute or pin sized holes 24, so as to form sub-upflow channels for liquids, gas and only the smallest of grains of sand, silt and other solid materials. Such perforations are shown in the tubular shanks, 24 and wells of Fig. 10.

These separate sub-passages will continue to receive liquids, gas and small solid particles long after all larger outside spaces of the strainer and well liner have become bridged and choked off by the coarse sands, shales and gravel often entering passages for weeks or months after it has other? wise bridged over'; and would have been off of production but for the flow, through the subchannels.

Another function of this strainer is its tend-- ency to conserve gas, in fluid and gas producing wells, and at the same time raise the normal fluid level of the well. 'This function'is accomplished by the strainer greatly reducing the flow I area upward through the well liner proper. This reduction of the flow area causes a given amount of gas to lift a greater amount of oil or other the tubing section extending from the lower end 7 liquid up to a given point or to a higher point in a well. In other words it causes an increase in the ratio of oil to gas raised to the point where it enters the gas anchor or other perforated tubing.

' This liquid raising functionfis obviously still more'pronounced when the how is 'further replained. The speeding up of the sub-passage stream, causes the gas to boost the liquid ahead of it, instead of breaking through the liquid and dissipating itself in large bubbles as it would in a large slow moving stream.

The lowermost of the adapter string or stack of cups l5' is provided with a seat or socket 2'! to receive the point of the tubing, and if the upper string is pulled up as a fishing tool as above described, the foot end of the tube will stand on the cup seat 21 as in Fig. 2, which is provided with ascent ducts 28 for flow upward into the duct 2| and well 26 of the strainer unit l5.

There may be provided at any suitable point in the assembly a means to brush or wipe the adjacent bore surface of the casing or liner Lm, and such means here includes a circular brush device 29 attached by pins or bolts 30 to a crossed arm 3! which is hitched to the next cup l5 as by tubular shanks 24, as above. This function of brushing the well liner and its slotted perforations might .be as well accomplished by constructing any of the strainer elements with a considerably reduced diameter,

then studding the outer walls with numerous stiff wires for brushing, thus forming a combined brush and cup unit.

Since the part of the liner La: below the foot of the tubing T is unobstructed, above the shoe S other forms of stacking, sand trap cup devices may be employed. One such form 'is shown in Figs. 2, 6 and '7, as being a semicylindrical element 32 designed to loosely circumferentially fit the bore of the liner Lx. A series of these half cups is built up to given length and their contiguous corners are aligned with the cups in alternately staggered relation to form staggered open spaces 0 on each side of the axis of the strainer assembly. These half cups are slidably mounted, on one side of the assembly, on corner pins or bolts 33, fixed in the corners of the half cups on the opposite side of .the string or assembly.

Below the lowermost cup element 32 there is attached thereto an anchor block 34, the connection being made as by a slack hitch or sliding pin or bolt means 35 which allows the next above parts to settle at rest on the anchor. This anchor is in turn slackly connected to a bottoming guide or bushing 36 by a pin or bolt 31.

When the made-up, strainer assembly, in the form for instance as above set forth, is lowered and set in a well with and by means of the pump tubing T, the bushing 36' finally comes to rest and centers on the liner shoe S and then all of the slackly hitched elements of the assembly settle one after the other on each other. They center thetubing and steady it, and they constitute a firm reinforcement for the surrounding liner means La: and casing L or a naked formation well. The function of breaking and scattering packs of well solids or brldges (which may have formed below the bottom of the upper, tub-' ing T) may be accomplished by lifting the upperv tubing T and the attached strainers until the assembly isfully extended and slightly lifted from the well bottom. However, if such sand packs or bridges are formed along and about the lower tubing T it may be frozen and unpullable. If this is the condition it will be necessary to disconnect theupper tubing T from the lower tubing at the joint 25 and vertically move the upper tubing T whereby to effectively separate the said strainers and shift them along the lower tubing thereby freeing the lower tubing 'I' and breaking stricted .to the sub-channels as previously ex- 'the solid and semi-solid'materials are packed, and bridged in the well liner and strainer, below' the foot of tubing T. In such cases the tubing is left free and clear of all binding influences and can be raised as one unit. Then, as each receptacle unit is moved, it breaks up the surrounding bridge, scattering it downward by gravity, or scattering it upward by combined gas and liquid force; and also a portion of the finer solids of the packs and bridges are taken into the subpassages and carried by the way of these passages and the well tubingto the head of the well, and thence out.

Naturally, after a successful bridge breaking operation, the tubing, the strainer and all parts carrying production, may be re-set in their normal flow position and the well put on production, with its normal flow re-established.

This bridge scattering operation can be repeated from timeto time as necessary until such time as it is found to be ineffective; in which case, thestrainer should be pulled from the well, dumped, cleaned, inspected, repaired if necessary, then reset as previously explained.

At this point it is appropriate to describe the pulling of a tubing attached strainer. To render the description of this pulling operation more comprehensible it may bef-assumed that in this case the tubing T is free and clear from sand packs, bridges, or any other binding force. Also assume that each receptacle unit or other unit below the packer- III has a one inch slack space from its fully telescoped position to its fully ex- I theirfully telescoped position.

Now in the actual operation of pulling the tubing and strainer assembly, the operator at the well head prepares for tube pulling in the usual manner, then begins to lift the tubing with a steady slow motion. When he moves the tubing at the well head, the entire string of tubing to its very bottom; moves as a unit. Now as the tubing is moved upward, the saddle ring 2, the washer 4 and the top of springs 5 move in exact unison. As yet there has been no movement of the lower parts of the coupling device, the packer, or any part of assembly below the packer. Upon further movement upward of the tubing string, the springs 5 become fully. extended, at which time the saddle ring 2 contacts upper nuts 6'. This contact sets in motion the upper nuts 6',

the rods 3, and all parts of the coupling device down to and including the packer III and shanks 20. Now with the entire string. of tubing, all parts of the coupling device and the packer in free upward motion, no parts of lower assembly have as yet been moved'. However, upon a further upward movementof one 1) inch, the topmost cup-like unit I5 is contacted and set in an upward motion. Another one (1)- inch upward motion picks up a second cup-like unit and so this action continues, each successive onev (1) inch upward motion, picking up another unit, until at last the bottom bushing'l'mit 351s picked up and set in upward motion. Since these units are liquid washed as theyare successively picked up, it may be assumed that'they are fairly free the sand bridges along the assembly. The sevfrom friction, once they are all in motion and the .cups l5". Any of the several forms of trapping cups shown may be provided with side wall orifices 42 for fluid flow into the cups. The tapered form or pot shaped cups l5" give a larger side clearance than the cylindrical forms, enable if bridgesshould form.

In large diameter well holes a more capacious cup element may be utilized, and in Figs. 9 and 10 the shank wells are shown as separate cylinders 45 around which the well product may settle or flow in the cup chamber.

If desired the connecting pins 23 or the shanks 24 may be made of differential breaking strength at levels along the assembly so that should sections or trapping elements thereof be stuck clue to liner collapse and not pullable, then only that portion of the sections below the topmost frozen section would be lost since the next above weakest connection point would shear or break and allow the upper assembly, that is the free portion, to be recovered by pulling the tubing string,

, faster up-flow and also are easier to break away sand-packed or frozen.

In reference to the units of. this device variously referred to as cup-like, -flower-pot shape, and semicylindrical-each of these different types may be considered as a special design to serve a special purpose in a well liner The special function or well production zone. of each type has previously been fully described.

However, these four different types of units'are of'two distinct models. l

I The first model is so shaped as to fit the well liner proper or casing, and to surround. and fit the well tubing; It will hereafter be referred to as a washer model.

The second model fits the main well liner or casing with no provision made for'passing the tubing through it, and .will be referred to as a disk model. y

In further reference to the packer II), as shown and previously described as a part of the assembled strainer, it may be said that the prime object a pling device to a pointsafely above the possibility of a sand pack.

run the tubing below a point less than 500 feet from bottom in such a well--these sorts of wells are usually abandoned.

By using the strainer assembly as here shown and described, with the packer l0 and about 100 feet of uni-ts surrounding the tubing in their closed position, the owner or operator of such wells may safely run the well tubing within a few inches of the well bottom, if he so wish'es. In this particular case, the socket unit 21 is placed in the assembled strainer just above the bottom bushing 36, and while any type or types of units or elements may be used at all higher points, they must be constructed as washer models.

In an opposite situationwith a well having a very high fluid level, the tubing can be correspondingly raised in relation to all other parts of the strainer. This may be worked out by using only a short tubing or gas anchor bullplug below the lowermost'collar .C. The length of the bull-plug so measured that only the lower few inches will extend below the packer I0, when the complete strainer assembly is in its closed position. In this case, only the few inches of the bull-plug extending below the packer will be perforated, This arrangement naturally eliminates the possibility of any tubing becoming Therefore, the socket unit 21, may be dispensed with and also the left hand thread 25. Only disk model units or elements of any type or types would be used in this particular arrangement.

In those cases where 100 feet or more tubing joint tubing exclusively below the lowermost collar C.

In case no packer is used as a part of the strainer assembly and no tubing catch-er is used anywhere along the tubing string, any suitable coupling may be used between the upper tubing The special function of the. tubing attached.

strainer, to act as a fishing tool by freeing and recovering a --sand-packed and frozen" gas anchor, or any part of the tubing below the packer I0, is of much importance, because, there are a great many oil wells which have a very low fluid level-100 feet or less. These same wells may occasionally-heave foreign material into the well liner and casing, to a height of 500 feet or Since a gas anchor or other perforated tubing mustbe extended within the oil, inorder to pump oil, and, since it is obviously unsafe to and thestrainer assembly. In this instance, a

reasonable amount of the tubing dead weight may be applied to the coupling device and all assembled units below.

Among novel features and advantages of this device as a well sand receiver, retainer and remover arezthat it may simultaneously trap sand from all well levels along the length of the assembly; that be'ing a pullable device it may safely hold trapped solids over a lorig period of time without pulling; that it traps well solids laterally adjacent to their point of entry and retains the solids as separate samples; that it de-sands a well by removing practically all trapped solids by the simple, safe and fast operation of pulling the well tubing and the attached assembly and that its use requires the use of noadditional well tools or equipment.

It is well to bear in mind'that the tubing attachedstrainer is, in its practical application to a producing well, of a permanent or semi-permanent nature. It may remain in operative position 'in a well for months, years or possibly for the life ofthe well, In this respect it differs radically from the many single function tools and devices used in fluid well production-most such tools and devices being used only temporarily.

make the assembled coupling device, packer I and cup, units l5, as here shown, of a reduced diameter, to fit the blank pipe. With this change made, the entire strainer assembly may be moved into the blank pipe and liner.

It is not the intention of this invention, as conceived, to be limited to the exact arrangement and position of the various elements I, 21, 29, 32 and others as shown.

They are rather considered as interchangeable,

- to be placed in a strainer assembly, singly, or in any combination of two or more types.

It is also conceived to construct either of the four types, as a washer model or as a disk model as well. When thus constructed any given type maybe positioned at any point within a well or well liner, regardless of the low or high position of the attached tubing.

For the purpose of running two or more types and models in combination, a. suitable slack .slidable fastening devices of all the various types and models of strainer unitsfs o that they will stack in contact with each other, leaving no space between.

The semi-cylindrical type unit 32, may also be supplied with a. sub-channel similar .to other units, but located at its axis and separate from its slidable fastening devices.

Also with the exception of unit 32, any other type of unit made as a disk model may be equipped with one combined sub-channel and fastening device at its axis.

The broadest possible conception of this invention, as practically applied to producing fluid wells; with its many functions and adaptations,

would be to consider it as a new system of'con-- trolling the fluid, solid and semi-solid and gas production of a well.

It is considered within the spirit and scope of this invention to.use all the many variations,

adaptations, combinations and modifications as previously shown and explained, to dispense with certain parts as described and to use any suitable material inthe constructionof these and other parts.

In those cases in which a well has a heaving and caving condition only in upper part of the primary liner,a false well bottom may be created in combination with the tubing and the assembly of strainer elements by use of a conventional bridge as used in cementing with a bailer.

What is claimed is: 1. A device of the class described, including, a series of sand trapping elements connected together by slack joints for relative end motion tensible assembly of sand trapping bowls connected by slack joint connections endwise thereof.

3. The combination comprising a desired string of tubing, an assembly of slack jointed sand trapping elements, means for attaching the head of the assembly to the string for local vibration of the bottomed assembly if and when sand bridged, and the tubing having a left-hand thread to break tubing joint at said attachment for use of the assembly as a fishing tool for the lower part of the disconnected string.

4. A direct or auxiliary well re-inforcing device comprising a series of cup sections movably attached one to another to be installed as a unit in a naked or lined well for permanent or temporary production function; said cup sections including tube-like, interengaging channels .to form a continuous, reduced, fluid conduit throughout the device.

5. In a well strainer and formation materials trap, a connected series of flower-pot shaped elements telescopic in a. well bore or its liner and relatively telescopic one in another.

6. A well strainer to telescopically receive a sectional, separable tubing and including movably connected sections in train along the tubing and means for attaching the strainer to the tubing; said attached strainer having means to engage a frozen section of the tubing to free and recover said frozen section of the tubing when the latter is disconnected from an upper section of the sectional tubing.

'7. A liner or well wall reinforcing strainer for a well hole, including an assembly of slack jointed strainer elements, and means for attaching the assembly to a tubular part or string for production installation and pulling thereby; the said elements relatively closing in stack arrangement when taking a seat on an obstruction.

8. Well apparatus for lining a bore face as a reinforcement, including an assembly of alined or coaxial strainer elements for use with a given string, hitch means connecting the elements for axial slackness and for stacking when set in a well and means for attaching the upper end of the assembly to a given section of the string for lowering and pulling operations with and by the pumping 'well, including a collapsible and ex- 7 string, and. for production set with and by the string; and said assembly including an element to forma seat for the lower end of the string, when the apparatus is to be used as a fishing tool to recover said lower end of the string.

9. A well bore or well liner strainer of a length to extend from the bottom of the producing zone of a well to a given higher level; the strainer including a series of relatively, collapsible, differentiated, relatively movably attached sections in suitable kind arrangement and including sections having sub-flow channels having restrictive flow orifices.

10. A strainer for the producing zone of a well, including a device attachable to a well tubing to support the strainer, and a packer connected to the lower end-of the device, and said strainer including a plurality of slackly connected strainer elements suspended from said packer to strain well fluid' to the tubing.

11. In a well strainer and desander, a tubing handled assembly including a plurality of slackly articulated trappingfstrainers to be installed and operative to catch sand in the producing zone of a well and whereby the well maybe desanded in one. operation by pulling the tubing and strainer at any time in one handling operation.

18. In a sand trapping and desanding appara- V tus for producing wells, an assembly of separate I sand traps each of a semi-cylindrical form.

19. A pullable well apparatus including slack- 1y connected sections in an assembly of suitable vice; said device including units telescopic along and each girdling the lower portion of the tub ing, other units extending below the tubing and stacking on the well bottom, and means by which the tubing is secured to the device at the point of entry of the tubing into the device.

14. A well strainer for cooperation with a conventional well tubing, and means for coupling the strainer to a given tubing, said means including a coupling which is collapsible and extensible endwise and including an endwise expansion spring, and the strainer including a series of straining and trapping elements, and couplings connecting said elements for limited sliding, end motion.

15. An apparatus for producing wells, comprising the combination of a tubing attached, loosely-linked section, sand trapping strainer assembly, and a well packer telescopic on the tubing above the strainer and forming a connective unit for the strainer and the tubing and whereby well formation solids from below the assembly are prevented from heaving above the packer and into the space between the tubing and an imperforate well pipe, or a well wall, when the apparatus is in a well.

- 16. The combination comprising a well tubing having a packer telescopic thereon, means to connect the packer to the tubing, 2. chain-like assembly of slackly connected, sand receiving strainer units suspended below the packer, and the packer forming a baiiiing means to retain well solids below the packer level when the combination is operative in a producing well, and said packer having a downwardly opening valve means to allow downward drainage oi well fluids when the combination is operative within or is being pulled from a producing well.

17. A well formation testing or sampling delength for the producing zone of a given well, the assembly being collapsible and extensible throughout its length, and said sections being of a pullable length; the apparatus being installa ble, in a well, in collapsed position; whereby when the apparatus is later engaged from the top and lifted, the sections are in succession adapted to be broken away from the binding influence of engaged solids and the unitary apparatus is pullable as a whole without resort to fishing operations.

20. A pullable well tubing having a non-rigid,

sectional well"apparatus. including a series of slackly articulated, sand trapping strainers to be installed in closed relation in a well, and later to be pulled by the tubing to separately break the top and each succeeding strainer from a sand pack; if any; whereby the apparatus is pullable intact and without injury in extremely extensive lengths of. the apparatus.

21. A pullable well producing, structure com posed of pullable, slackly linked sections and being pullable to a greater degree and pullable in longer lengths than other known well producing structures; said sections operating to facilitate such pullability.

22.'In a device of the class described, an as-;

sembly of slackly hitched strainers.

23. Apparatus for a well, comprising the combination of: a well tubing terminating in'periorated, lower sections, means for attaching the perforated tubing sections to the upper part of the tubing and being detachable by manipulating the upper tubing at the well head when the lower tubing is immovable, an elongate coupling body secured to the tubing above and extending below said means; said coupling body being end- I wise collapsible and extensible and having an vice including a plurality of separate, relativelymovable, suspended sand traps which will, when installed in a producing well, each receive and retain samples of wellsolids coming from the laterally adjacent well level at which it stands; the trapped samples showing the formation along the device when the device is pulled and in-,

endwise expanding spring device, a well packer secured to the lower part of said body and tele;

scoping about the lower tubing and having'downwardly opening, self-closing valves, and a series of loosely linked, fluid straining elements carried by and below the packer. I

'24. A combined strainer and trapping device for wells including a chain of slackly connected sand receiving cups having parts which are perforated for infiltration of well fluid.

' ERVIN n. MQCIEASE.

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