US2310397A - Method of packing wells - Google Patents

Description

Feb. 9, 1943. c. J. coal-:RLY

METHOD OF PACKING WELLS originalv Filed Jap. 24; 1938 Y a 6 .7 C M SM M M 0 y HA RR/J, 'ff/5CH, F o.: TER a HARR/J Y' atented Feb. 9, 1943 2,310,397 Mirrnop oF PACKING WELLS Clarence J. Coberly,

Los Angeles, Calif., assignor to Kobe, Inc. Huntington Park, Calif., a corporation of California originall application January 24, 193s, sei-iai No.

186,597. Divided and this application February 10, 1940, Serial No. 318,300

i claims.' (ci. liss-26) This appiicatidh isa division of my applicationV Serial No. 186,597, led January 24, 1938, for "Gravel packing for wells, now Patent No. 2,217,- 215, granted Oct. 8, 1940.

This invention generally relates to the well art and more particularly to a method of packing a well so as to prevent sand from the well formation from entering the bore of the well. Although the invention has a wide range of uses, it has particular utility in the oil well pumping art, and, accordingly, the preferred embodiment will be described in connection therewith for the purpose of illustration.

In many oil iields, the oil producing zone is l comprised in part at least of relatively flne sand,

which, during normal pumping of a well therein, tends to beme detached from the formation and to pass through the pump and associated production equipment, causing excessive wear and requiring frequent shut-downs for equipment repairs and replacements. -Thus, pumps, tubing,

- pack the well formation ,with gravel, sometimes regas traps, and other production equipment which are operated under such conditions have -an extremely short life, and the annual cost of replacement and repairs for such equipment due to such production of sand in the oil is a substantial burden on the oil industry. Another major diiliculty encountered under such pumping' conditionsV is the tendency for the pumping equipment and tubing to become filled with sand, or sandedup, so that the equipment. cannot be operated. This always requires a thorough cleaning of the tubing and pumping equipment, which usually necessitates removal of the pump and an extended lbailing of the tubing, both of which interrupt the production from the well, causing great economic waste and loss to the operators. Therefore, it is a primary object of this invention to provide a method of treating a well so asto' prevent the above-stated difficulties now commonly experienced in the art.

For the purpose of this speciflcation, the term ""sand is defined as meaning any undesirable substance formed of discrete particles normally.

found in a well and which it may be desired to of the well,l such as. for example, truef sand, shale, mica, or other similar substances.

ness of the sand, producing conditie .low bottom-hole pressures, or other factors, been possible. to set a liner which will properly control and prevent the production of. sand. The usual dlmculty is that Where merely a ilne perforation liner is. used, the formation sand packs therearound to form a bed of sand of low permeability, with an attendant pressure drop therethrough, greatly decreasing the maximum production from thel Well. I n addition, a liner having a ne mesh perforation will readily clog to further reduce the production. It is, therefore, another object of my invention to provide a method for so treating a well that a liner having perforations of relatively large mesh may be employed.

Attempts have been the space between made in the prior art to the perforated liner and ferred to as gravel-packing, for the purpose of forming a bedof gravel therebetween substantially impervious to the now of'sand therethrough but permitting oil to flow into the pump through the liner. Such attempts at gravel-packing have not vproved satisfactory because ofthe lack of knowledge of the factors involved and a proper method of application thereof and .apparatus therefor. Accordingly, it is another. object of this invention to provide a method for packing a 'well .with a substance comprised of discrete particles, such as, for example, gravel, in which the previously indeterminate factors are given anovel solution. I

Although gravel is al cheap-and satisfactory substance for use in my invention, it will be understood that any suitable substance comprised of discrete particles may be substituted therefor without departing from the spirit ofV my invention. f

. By testing ou wens in the onahoma city Field,

near-Oklahoma City, Oklahoma, in which considerable trouble has been experienced as a result of sand in the pumped oil, I have established a exclude from entering the production equipment 'In the prior art, attempts have been made to z overcome the .above-stated diiliculties by setting a perforated liner at the bottom ofthe well, having perforations of the'prop'er mesh to prevent the entry of the formation sand therethrough. These attempts have not been successful, however, because in many oil fields, due to the finetion,

number of relevant facts. For example, in some wells in this iield the producing-zone is almost continuous sand from top to bottom, the 'sand occurring in layers of varying hardness, due to different binders,' different amounts of binder, different degrees of compaotlon'of the well formaand other conditions. Furthermore, in most of the' older wells of this ileld, large cavities have formed in the well formation throughoutv the length of the 4.producing zone as a result'of the formation sand becoming detached and being produced with the oil during the flowing and gas it has vnot -has formed around the well,

` bridges between the gravel grains.

left stages of production of the wells. Many of the Wells in this field are now being pumped, or are soon to be placed on the pump, but sand diiilculties continue during the pumping, the magnitude of which depend on the age of the Well, its present production, length of period of natural iiow, length of period of gas lift, gas-oil ratio, Well location, and any other factors which have affected or may still affect the size of the cavities between the well and the producing zone formation and the ability of the oil to carry sand from the present producing zone to the bore of the well. In some of the newer wells of this eld which are being pumped but in which only a small cavity it has been found that if such a-well is shut down for as short a period as a quarter of a minute, the pump becomes sanded-in due to settling of the large percentage of sand carried by the oil in the production tubing. Some or all of these conditions may be found in other oil fields.

In packing gravel around a well base, there are three principal problems presented: (l) selection of the proper mesh gravel to prevent travel of substantial quantities of formation sand therethrough with the oil to be pumped; (2) proper placement of the gravel; and (3) the selection of 'a liner having perforations of a proper mesh to prevent the gravel from passing therethrough. The latter problem is readily disposed of after selection of gravel of the proper size, as a liner perforation of twice the grain size at the ten percentile may be employed if an assorted size.

gravel is used, or a perforation twice the width of the grain size of the individual grains may be employed if a closely graded grave1 is used.

'Ihe selection of the proper size or mesh gravel" to screen the formation sand is more diiiicult. Using sand grains taken from a typical oil well having bad sand conditions and passing them through a bed of gravel, I have discovered that 1 stable bridging of the sand grains over the spaces between the .gravel grains occurs when the diameter of an imaginary circle inscribed in the space between the gravel grains is not over two times the diameter of the ten percentile sand grain size. The gravel size may also be stated as: the diameter of the largest gravel grains in a singie classified gravel (Tyler scale) suitable for gravel packing is approximately thirteen times the effective sand grain size at the ten percentile. The se conclusions are stated for gravel grains oi the maximum size that can be used to forme.: stable sand bridge therebetween, although gravel grains of one or possibly two screen sizes (Tyler scale) smaller would provide an additional factor of safety in insuring the formation of stable sand Accordingly, it is a further object of my invention to provide a substance comprised of discrete particles, such as, for example, a gravel, for packing an oil well which bears the above-stated size relation to the size of the formation sand therein.'

Regarding the placement of the gravel in an oil well, I have found that the gravel should be transported to the point of placement in such a manner that the possibility of clogging of the gravel during placement is reduced to a minimum. Furthermore, the angle of repose of the gravel must be small so that the gravel may fill all crevices and pockets in the well formation as fully as possible. Also, the method of placing thegravel should be such that if any interruption occurs, placing of the gravel may be resumed without serious difliculty. Further, any material' mixed with the gravel to facilitate placement thereof should be readily removable by washing, natural ow of the oil, or otherwise, and preferably should be soluble in or miscible with the produced oil. Also, provision should be made for the placing of additional gravel in the well at some later time in case of settling of the original gravel bed or incomplete lling of the formation cavities. Furthermore, the gravel should preferably be placed from below; that is, the iiow of the gravel should be from the bottom of the hole upward, in order to reduce to a minimum the caving of the formation Walls during'placement of the gravel and to reduce the possibility of a portion of the well hole remaining filled with original formation sand. Therefore, it is another object of this invention to provide a method and composition of matter capable of accomplishing the foregoing desired conditions.

'Ihe conditions set forth in the preceding paragraph are best fulfilled by mixing the discrete particles, such as gravel, with a viscous fluid and placing it in a state of pressure-mobile mixture in the well cavity, and, accordingly, this is still another object of the invention. This mixture, being pressure-mobile, will also have the advantage that it may be handled as a iiuid, i. e., pumped through tubing in much the same manner that mud is pumped.

Another object of the invention is to'provide a novel composition of matter comprised of a substance made up of discrete particles having the size characteristics stated hereinabove, for use in packing a well.

Likewise, it is an object of the invention to provide a pressure-mobile mixture of a substance formed of discrete particles and a viscous fluid.

I provide an apparatus for pumping a well comprising a tubing in the well having a perforated liner at the lower end thereof, and a check valve connected to the bottom of the liner permitting a material to be expelled from the tubing into the well but preventing the material from passing from the well through the valve and into the liner.

I provide an apparatus for use in a well, comprising a tubing in the Well, having a plurality of valves spaced along the length of such tubing, and means for selectively passing a substance out of the tubing and into the well through any one of the valves as desired.

Another object of the invention is to provide a method for packing a well in which discrete particles are pumped into the Well from the lower end of a tubing, the pumping pressure values being utilized to indicate completion of the packing operation.

Although the principal object of the invenmay' be advantageously applied to wells having little or no sand diiiiculties. In many wells, a1- though little sand diiiiculty is experienced, considerable trouble is had with soft portions of the formation, such as clay, for example, caving or heaving to shift the bore of the well or to pinch off the liner or other tubing therein. This is due to the fact that there is always a substantial space in a well-around the production tubing. By packing this space as describedherein, these diiculties may be, in part at least, obviated. and, iaccordingly, this is another object of the invenion.

Other objects and advantages of my invention will be evident from the following specication, which is for the purpose of illustration only, the claims, and the drawing in which:

Fig. 1 is a diagrammatic sectional view of a well having my preferred form of apparatus therein.

Fig. 2 is an enlarged sectional view of the lower end of the apparatus of my invention.

Secured in the lower end of the water tubing II,V

as by a` suitable combination packer and hanger I2, is a permanently set outer tubing I3 at the lower end of which is secured by a suitable coupling a liner I4 having perforations I5 in the walls thereof. It will be recognized, however, that the outer tubing I3 and liner I4 may be formed integrally in one piece, by merely perforating the lower end of the outer tubing; As shown in detail in- Fig. 2, a valve shoe I6 is threadedto the lower end of the liner I4 and is provided with-an internally threaded central bore I1 and a seat I8 therearound. The central bore I1 communicates with a vertical passage I9 having a counterbore 20 internally threaded \to receive a threaded plug 2l. Radial passages 22 communicate between the counterbore20 and the exterior of the valve shoe I6. A ball valve member 23 is held in upwardly seating engagement with the 4vertical passage I9 by means of a compression spring 24 bearing against the threaded plug 2|. The valve shoe I6 and the mechanism therein thus provide a valve means adapted to permit materials to pass outwardly through the vertical passage I9 and the radial passages 22, forcing the ball valve member 23 downwardly against the action of the compression spring 24, but prevent materials from passing inwardly from the well through the radial passages and the vertical passage into the central bore. Threadedly received in the. central bore I1 is the lower end of a wash tube 25, which may be extended through the water tubing II, the outer tubing I3, and the liner I4 into uid-tight seating relation on the seat I8.

As shown in Fig. 1, the lower end of the wall I may have one or more relatively large cavities 30 extending back from the well bore into the 1miducing formation of the well. As pointed ou hereinabove, lthese cavitiesv 3II are normally formed during the natural flow, gas lift, or pumping stages of yproduction from the well, and are caused byv relatively soft portions of the well' formation, including considerable quantities of iine sand, becoming detached therefrom by the flow of oil inwardly froin the .formation to the bore of the well. l The depth and'cross-,sectional area of th'e cavities 30 depend largely` upon the history of the well and the flow and pumping conditions therein, and may vary from a foot or. two in length to many feet in length. A s indicated, it is the primary purpose ofthe present invention to flll the cavities 30 andthe space between the liner I4 and the well formation with va bodyof discrete particles, such as gravel, so as to form a screen preventing the passage of substantial quantities of formation sand `therethrough' and through the perforations I5 into the liner and outer tubing I3.

Adapted to be connected to the upper end of the water tube 25 by means of a coupling 32 is a supply pipe 33 having a suitable pumping mecha- Vnism 34 in the line thereof, the pipe 33 being connected to a closed supply tank 35 which'acts as a r'eservoir for the material to be used for packing the Well.

In operation, and prior to the setting of the outer tubing I3 in the lower end of the water tubing II, the lower end ofth'e well I0 is cleaned by hailing, or otherwise, so as to remove substantially all of the sand and other foreign materials which may have accumulated in the bottom of the well during prior operations in producing from the well. Such hailing or cleaning is a common expedient` in the art and will be familiar to those versed in the industry. When the bot-- -tom of the well I0 has been thoroughly cleaned of sand -and other foreign materials, the outer tubing I3, with the packer and hanger I2, the liner I4, and the valve shoe I6 attached thereto, is run inthe well tosubstantially the position shown in Fig. 1 by any means well known in the art, such as a string of tubing connected to the upper end of the outer tubing (not shown), and the packer and hanger is then utilized to hold the outer tubing in place at the bottom of the well.'

As ,will be noted, the packer I2 forms a seal between the outer tubing I3 and the Water tubing I I, which is utilized for a purpose to be describedl hereinafter. Although I have sh'own a well III in whichthe water tubing II has been inserted in accordance with the usual well practice, it will be recognized that in some wells no water tubing is provided at the lbottom of the well and that the packer and hangerv I2 may be positioned in direct engagement with th'e walls of the well without departing from the present invention.' When the outer tubing I3 is set in position in the well I0, as`

described, the wash tube 25 is then run intothe well through the water tubing II and the outer tubing I3 until the lower end thereof seats on the seat I8 of the valve shoe I6, at which time thev outer tubing I3 into the position shown in Fig. 1,

in which case the wash tube is threaded into the valve shoe prior to insertion in the welll and only one operation is required thereby'.v A

When the outer tubing I3 and the wash tube 25 are in position, as shown in Fig. l', the supply pipe 33 is connected to the wash tube by means of .a coupling such as 32, so as to connect the wash tube with the supply tank 35'through the pump` ing mechanism 34. The supply tank 35 is then filled with the substance with which it is desired to pack the well IU, and, as described hereinabove,

for this purpose I prefer to use a pressure-mobile mixture of discrete particles, such as gravel, and

a viscous fluid, such as a hydrocarbon derivative obtained from the same type of oil as is to be produced from the well. This mixture is mixed in the supply tank 35 and is then pumped there-A from by the pumping mechanism 34 through the pressure-mobile mixture flows upwardly in the well I0, fllling the cavities 30 and the space between the formation and the liner I4 until it reaches the packer and hanger I 2, at which time the pumping pressure on the pumping mechanism 34 rises to indicate that the bed 3| has been completely formed. When this material rise in pressure occurs, the operation of the pumping mechanism 34 is stopped, the supply pipe 33 and coupling 32 are disconnected from the wash tube 25, and the wash tube is then unscrewed from the valve shoe I6 and removed from the well. 'I'he interior of the liner I4 and outer tubing I3 is then hailed to remove any gravel from the wash tube therein, any suitable type of pumping mechanism may then be lowered through'the well I0 into pumping position with relation to the liner I4, and pumping of the well may then be cornmenced. During pumping, oil or other well uid flows from the formation through' the bed 3| comprised of discrete particles, such as gravel, cws through the perforations I5 of the liner I4 and may then be pumped to the surface of the ground. Due to proper selection of the size of the discrete particles with reference to the size of the formation sand, and the proper selection of the size of perforations I5, the discrete particles are substantially prevented from entering the liner I4 through the perforations I5 thereof, and the formation sandl is prevented from passing through the bed 3| of discrete particles. By the selection of discrete particles of the proper size relative to the size of the formation sand, as pointed out herein, a substantial quantity of the sand is effectively screened from entry into the liner I4 without decreasing the normal ow of oil or other well fluid through the bed 3|. By using a. viscous fluid for the pressure-mobile mixture, the mixture may be pumped as a fluid through the tubing and valve shoe I6 and will readily flow into the desired position in the well. By using a viscous fluid which is miscible or soluble in the oil or other fluid to be produced from the well, the viscous uid will be quickly washed out of the bed 3| by the well uid passing therethrough upon commencement of the normal pumping operation.

Although the invention has been primarily described in connection with a. well in which a pump is to be installed, it will be appreciated that I do not intend to have the invention limited to packing a well to be pumped, since the invention is equally applicable to a well that is in the natural flow or gas lift stages.

It will also be understood that when the packing operation is commenced, there is ordinarily a considerable head of oil accumulated in the bottom of the well IIJ, and particularly below the packer and hanger I2, and that as the pressure-mobile mixturer is passed upwardly in the well around the liner I4 this head of oil must be displaced. To prevent the oil from being forced back into the well formation, the perforations I 5 are preferably continued up the liner I4 to a point adjacent the packer and hanger I2, so that as the pressure-mobile mixture is introduced into the bottom of the well I 0 and upwardly therein, `the oil thereabove may ow into the liner through the perforations I5, thus preventing a high back-pressure from being built up on the producing zone formation.

It is sometimes desirable, however, to provide a special solvent for removing the viscous uid from the bed 3| prior to commencement of the pumping operation. In such cases, I prefer to empty the closed tank 35 of its pressure-mobile mixture, replacing it with a viscous fluid solvent or other substance which will effectively cut the viscosity of the viscous fluid, such as distillate in the case where a viscous hydrocarbon is employed as the carrying agent for the discrete particles, which is then pumped through the supply pipe 33 and the wash tube 25 and into the well as described, from which it flows through the bed 3| so as to decrease the viscosity of the viscous fluid therein. This may be regarded as a modied form of my process, and can also be performed by means of a standard perforation washer, as is well known in the art.

Also, in some installations, I have found it desirable to precede the packing operation by pumping a quantity of the viscous fluid to be used into the bottom of the well without any discrete particles therein, so as to form a layer of heavy fiuid at the bottom of the well, the purpose of which is to protect the viscous fluid in the pressure-mobile mixture from contamination by mixture with the oil or other well fluid from the formation. This operation will normally be carried out prior to pumping of the pressure-mobile mixture into the well as described.

In Fig. 3 I show a modified form of apparatus which may be used in connection with the apparatus shown in Fig. 1 to carry out a modied method of packing a well. Similar parts are given similar indicating numerals with the suiilx a added thereto. The device shown in Fig. 3, and the method employed therewith, are frequently preferable where the producing zone of the well is extremely long and where a long liner 4a is required, or where there are alternate blank and perforated zones in the liner. In such cases, the liner |4a is divided into a plurality of sections joined together by couplings 36, each of the couplings having inwardly closing valves 31 therein comprised of openings 38 in the wall of the coupling provided with seats 39 adapted to receive an `inwardly faced valve member 40 resiliently held in engagement with the seat 39 by a spring arm 4| suitably secured to the coupling as by rivets 42. Although only one coupling 36 is shown in Fig. 3, it will be understood that as many of such couplings as desired may be utilized. The valves 31 thus permit the pressuremobile mixture to be forced out of the liner into the well |0a at various points along the length ,of the liner. In this form of the invention the Wash tube 25a is provided with a fitting 45 adapted to be secured to the lower end thereof having basket packers 46 at opposite ends thereof and radial openings 41 therein. In'operation of the device shown in Fig. 3, the liner I4a is iirst set in the well as described with relation to Fig. 1, and the wash tube 25a is run into the tubing as described with relation to Fig. 1, and the pressure-mobile mixture is pumped therethrough and into the well as heretofore described. Due to the long length of the liner I4a, the pressuremobile mixture cannot satisfactorily be pumped from the bottom of the inlet shoe I6 above a certain distance above the inlet shoe due to the Weight of the pressure-mobile mixture and packing thereof in the cavities 30. When the bed of discrete particles 3| is thus formed to a certain height, such as represented by the line C-C, pumping of the pressure-mobile mixture is discontinued, the wash tube 25a. is removed from the well, and the fitting 45 is attached to the bottom thereof as `shown in Fig. 3. The

top' thereof The f obtain wash tube 25a is then run into the well to a pition in which the basket packers 46 straddle any one of the couplings 36, preferably the lowest coupling through which it is possible to place the mixture, and the pressure-'mobile mixture is then pumped downwardly through the wash tube 25a and outwardly through the opening 41, forcing the valve member 40 outwardly against the resilient action'of the spring arm 4I to permit the pressure-mobile mixture to be pumped outwardly through the liner I4a into the well above the bed 3| previously formed. Pumping is then continued as desired or until the pressure re` quired therefor rises substantially, and the pumping is then discontinued, the wash tube 25a is then moved until the basket packers 46 straddle another coupling v36, preferably the nextv higher in the liner Ma through which the mix ture can be placed, and pumping may then be resumed to force Vvthe pressure-mobile mixture. outwardly into the well through the inwardly closing valve 31 above that iirst used. This may be continued as desired until the entire well is suitablypacked with a bed or beds 3l of discrete particles formed The wash tube a may then be withdrawn from the well, the well bailed, a well pump inby the pressure-mobile mixture.y

apparatus and method disclosed herein may be used without departing from the spirit of the invention, and, accordingly, I do not desire to be limited by the foregoing specication but intend to be granted the full scope of the following claims.

I claim -as my invention:

l. A method of removing sand grains from the production ow of a well, including the steps of: forming a single classied body of discrete particles in which thediameters of the largest particles are approximately thirteen times the size Yof the sand grains in the well at the' ten percentile; l disposing said body of discrete particles in the well in the path of the production flow' therefrom; and passing said production iiowthrough said body of discrete particles.

2. A method of removing sand grains from the production fiow of a well, including the steps of:

forming a single classiiied body of discrete particles in which the diameter of a circle inscribed in the spaces between the largestparticles is approximately two times the size of the sand grains serted, or production otherwise commenced as described in connection with Fig. 1. In the apparatus shown in Fig-3, the perforations 15a should be selected of a mesh such that no discrete particles will be able to enter the perforations fromnthe inside of the liner I4; otherwise, when the basket packers 46 with the pressure- 'mobile mixture therebetween are being moved through the liner, the perforations will become plugged. Liners with fine-meshed slots may be set without aiecting the wellproduction, due to the high permeability of the bed 3l, and thus it will be possible in most cases to select a liner` having perforations which will n'ot plug with discrete particles when the pressure-mobile mixture is in engagement liner l4a.

After a well has been pumped or otherwise produced for some time with a packing bed 3| therein, the bed may settle, making it desirable to add an additional layer of discrete particles on the inwardly closing valves 31 of the liner |4a may be utilized in such cases to increase the depth of the bed 3|, without disturbing the bottom portion ofthe bed, and this is another modified use of the invention.

Although the invention has been described in I connection with a well in which cavities 3|) have already been formed during the past history of the well by prior flow conditions, it will be evident that extensive cavities around the perforated liner will increase thenatural production of the well by increasing the formation area draining into the well, provided the formation sand can be held in place. It will therefore be evident that in new wells where no such cavities have been formed during the history of the Well,'it may be advantageous to create such cavities by any means well known in the art, such as underreaming the'well hole prior to the packing operation.

Although it is old in the art to underream a well to increase the production thereof, and although this does not play any part in the present invention, it will be recognized that underreaming in conjunction with the present invention may be distinctly advantageous in new wells so as to maximum production therefrom.

It will be understoodl that modifications of the with the inside of the in the well at the ten percentile; disposing said body of discrete particles in the well in the path of the production flow therefrom; and-passing said production ow through said body of discrete particles. A

3. A method for packing a well having substantial quantities of sand in the well formation of the producing zones thereof, including the steps of: permanently setting a liner in a well opposite to a production zone of the well; forming a bed of discrete particles around a portion of said liner, said bed being substantially impervious to sand in the well; extending a tubing downwardly into said liner to a first position adjacent the top of said bed; and passing additional discrete particles downwardly through said tubing and out through said liner at a point above said'bed so as to form an additional layer of said particles around said liner on the top of said bed.,V

4. A method-'for packing a well having substantial quantities 'of sand inthe well formation of the producing zones thereof, including the steps of permanently setting va liner in a well opposite to a production zone of the well; forming a bed of discrete particles around a portion of said liner, said bed being substantially im pervious to sand in the welk-extending altubing downwardly into said liner t'o a rst position adjacent the top of said bed; passing additional discretefparticles downwardly through said tubing and outI through said liner at a point above said bed so as to,form an additional layer of said particles around said liner on the top of said bed;

raising said tubing upwardly to a second position in said well adjacent the top of said additional layer without moving said liner; and passing additional discrete particles downwardly through said tubing and out through said liner at a point above said additional layer so as to form a'further layer of said particles around said liner on top of said additional layer.

5. A method for packing a well'having a perforated liner permanently set therein, including the steps of:` forming a rst bed of discrete-parl ticles around a portion of said liner, said bed being substantially impervious tosand inthe I well; extending a tubing downwardly into said liner Ato aposition above the top of said first bed;

and passing additional discrete particles down'-,

wardly through said tubing and out throughthe walls of said liner to form a second bed of said particles around said-liner'- abov'e said irst downwardly through said liner and out through 10 the walls thereof at a point above the top of said iirst bed to form a second bed oi said particles around said liner above said rst bed.

7. A method for packing a wellhaving a perforated liner permanently set therein, including 15 the steps of: setting a tubing in a tirst position in the hner; passing a stream of discrete particles downwardly through said tubing and outwardly through the walls of said liner to form a iirst bed of discrete particles around said liner, said iirst bed being substantially impervious to sand in the well; raising said tubing to a second position in said liner without moving said liner; and passing additional discrete particles downwardly through said tubing and outwardly through the walls of said liner to form a second bed of discrete particles around said liner above said rst bed, said second bed being substantially impervious to sand in the well.

CLARENCE J. COBERLY.

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