US2776011A - Borehole gravel packing - Google Patents

Description

Jan. 1, 1957 w. A. CLARK 2,7 1

BOREIHOLE GRAVEIL PACKING Filed June 30, 1953 2 Sheets-Sheet l i I F Jan. 1, 1957 w. A. CLARK 2,776,011

BOREIHOLE GRAVEL. PACKING Filed June 30, 1953 2 Sheets-Sheet 2 United States Patent 2,776,011 BOREHOLE GRAVEL PAGKING William A. Clark, Larchmont, N. Y., assignor to The Texas Company, New York, N. Y., a corporation of Delaware Application June 30, 19.53, Serial No. 365,146

6 Claims, (01. 166-51) This invention relates to bore hole gravel packing and more particularly to a method and an apparatus for placing a gravel filter pack in the well cavity of a bore hole opposite. a producing formation, in Which method the gravelis first placed around aperforated liner or screen at the surface and is then run into the well cavity along with the screen. 'lhe principal object of the invention is the provision of a method and apparatus of this type in which the gravel or granular material can be placed conveniently in the well. cavity and without the necessity of using any carrier fluid or complicated equipment with Which to circulate the gravel downwardly into the hole.

As is well known, the gravel packing of well bore holes is being used extensively and has many advantages in the completion of a well. The mass of gravel, when properly placed in the well cavity around the-perforated screen-member or liner serves as a filter to keep back the sand ;which would otherwise tend to pass into the screen with the oil and which frequently ab'rades or cuts away the metal. of the screen. This gravel mass also supports the walls of the formation and keeps the formation material from sloughing oil into the cavity where it frequently packs tightly around the screen to prevent the oil from passing into that member.

One of the more commonly used methods of .gravel packing is sometimes called the reverse circulation method. In this method the screen is attached to the I'owere'nd of a flow tubing and placed in position within the. well cavity. The gravel in a carrier fluid such as oil or'drilling mud is pumped downwardly through the annular space between the. tubing and the casing and the gravel collects and builds up in thecavity around the screen while the carrier fluid passes inwardly through the screen perforations and then back to the surface through the tubing. While this :method has proven quite successful-there are times when it is desired to place the gravel without the use of the carrier fluid or, in other Words, without circulating it into the cavity around-a previously placed screen.

in accordance with the present invention, an annular disc or plate of steel or the like is disposed around the lower end of-the screen member, and the screen is lowered into the casing for a short distance. The gravel is then poured into the annular space between the casing and the'screen and'rests upontheannular plate or disc. When a "sufiicient amount of gravel has been so :placed, the graveland screen are run into the-casing for 'axshort distance, and an additional amount of gravelis placed in the annular space. This is continued'until an amount of gravel has been poured in which will be sutficient 'to fill the cavity around the screen when the latter is-at the'bottom of the hole. Thescreen and'gravel are then lowered through 'the hole .on the lower end of a string of tubing into the well cavity, and the gravel flows downwardly out-of :the bottdrnof the casinginto the cavitywhere it fills the space around thescreen. If desired, a packer member then may 'be placed be'tween theupp'enend of the screen and the inner surface of the casing, the tubing H ice removed and the well produced through the casing, or, if desired, the tubing may remain connected to the screen and the well produced through the tubing.

In a modification, where the casing is in stepped form, that is, where several strings of casing of diiferent diameter are used, two or more of the annular plates of different sizes may be placed in the manner described, the gravel poured in on top of the upper plate and the tubing and gravel run into the hole, In this case, the annular plates will be of progressively larger diameters from the bot-tom to the top in such manner that when the screen has been lowered to a section of smaller diameter casing, the smallest annular plate will pass downwardly into the smaller casing While the larger diameter plate will remain on the shoulder between the larger and the, smaller casing sections. The larger diameter plate will prevent the gravel from flowing downwardly below the screen While the screen is within the large diameter casing, and the smaller plate will hold the gravel while it is passing downwardly .through the smaller casing, as has been described.

For a better understanding of the invention reference may be had to the accompanying drawing .in which Figure l is a vertical sectional elevation through a portion of a well bore hole showing the gravel around the screen near the surface;

Figure 2 is a view somewhat similar to Figure 1, but showing the gravel surrounding the screen which has been lowered to the well cavity;

Figure 3 is a plan view of one of the annular ringshaped discs ;or plates for supporting the gravel as it is lowered through the hole, and

Figure 4 is a view similar to Figure -1 but showing a modification in which a stepped casing lines the bore hole.

Referringto Figure 1 of the drawing, a well bore hole 10 is shown :as terminating at its lower end in a cavity 12 in a producing formation or sand. The bore hole is lined with a casing 14 cemented in place as indicated diagrammatically at 16. A conventional perforated screen member or strainer 18 having a perforated nipple or plug 20 at its lower end is shown as positioned in the upper end of the casing 14. At the lower end of the screen portion 18 a plurality of shear pins 22 are attached so-as :to project outwardlya short distance from the screen. Resting upon these shear pins is an annular disc or plate 24 of steel or the like slightly smaller in outside diameter than the interior of the casing 14. Directly above the plate 24 is a somewhat cup-shaped annular disc or washer 26 of a flexible material such as rubber or leather adapted to contact the inner surface of the casing 14. As is shown in Figure 3, both the plate 24 and the annular washer 26 are provided with a plurality of perforations 28 of about 4 inch in diameter, the purpose of these holes orper'forations 28 being to permit fluid in the'bore hole'to'pass upwardly through the plate, washer and gravel -whilethe assembly is being lowered into the hole.

As illustrated in Figure '1, 'a quantity of granular material or gravel 30 has beenpoured into-the aimular space 32 between the screen 18and-thecasing '14. This gravel rests upon the leather waher' 26wyhich in turn issupported by the steel disc "-24 'on the shear pins 22. A caliper log or other measurement of the diameter of the lower portion of the borehole and the cavity .12 will preferably be made previously andth'e bperator'can determine from these measurements the amount of 'the gravel '30which willbe required tofill the space between the screen and the 'walls of the formation after the' screen has reached the bottom of the hole. -From the positionishown in Figure t1, :thesscreen 1 8 and the gravel 30 are lowered downwardly into the casing for a predetermined distance and more of the gravel 30 is poured into the annular space 32. This is continued until a suflicient amount of gravel has been placed in the annular space when the assembly will be lowered through the casing until the bottom of the nipple 20 rests upon or is close to the bottom of the well cavity 12, as is indicated in Figure 2. In this position the annular members 24 and 26 will have passed down below the bottom of the casing 14 and the gravel will have passed downwardly into the cavity 12. A sufficient amount of the gravel is used so as to provide a surplus which will fill a portion of the space between the upper end of the screen 18 and the lower portion of the casing 14 so that if there is any settling of the grave] in the well cavity, the surplus gravel will move downwardly to maintain the cavity full of the granular material. If desired, a packer or slipon adapter 34 may be placed between the upper end of the screen 18 and the inner surface of the casing 14 and the well may then be produced through the casing. In other words, oil from the formation will pass through the gravel 12, through the perforations in the screen 18 and upwardly to the surface through the casing. 011 the other hand, if desired, the tubing string may be left attached to the upper end of the screen 18, and the well may be produced through the tubing. In case it should subsequently be found necessary to pull the screen from the hole, the pins 22 can be sheared off and the plates 24 and 26 dropped in the hole.

In Figure 4 a modification is shown in which the bore hole 10 is provided with a stepped casing, that is, a section of small diameter casing 14 serves to line the lower portion of the bore hole, and a section of larger diameter casing 36 is used to line the upper portion of the hole. A shoulder 38 will exist, of course, between the upper end of the casing 14 and the lower end of the larger casing 36. In this case the shear pins 22, small diameter annular plate 24, and the leather plate or disc 26 will be assembled as in the case of Figure 1. A slightly larger perforated steel annular plate 40 will rest upon the leather disc 26 and resting upon this plate 40 is a larger diameter leather washer 42. As shown in Figure 4, the diameter of the center holes in plate 40 and washer 42 is slightly smaller than the outer diameters of plate 24 and washer 26 so that in the position illustrated with plate 40 resting upon shoulder 38, an annular space will exist between the periphery of the center hole in plate 40 and the external surface of screen 18. Thus, in the position shown gravel will pass through this annular space from space 44 into the space 32. As stated hereinbefore, all of the annular members 24, 26, 40, and 42 will be provided with the holes or perforations 23, as shown in Figure 3.

In the operation of the modified form shown in Figure 4, when the screen 18 is lowered into the upper end of the casing 36, all of the members 24, 26, 40, and 42, in that order from bottom to top, rest upon the shear pins 22. Gravel is then poured into the annular space 44, and this gravel will rest upon the larger leather disc 42. The screen and gravel are lowered, as described above, by increments, and additional gravel is poured into the space 44 until a sufiicient amount has been so positioned to fill the cavity 12 around the screen 18 when it has reached the bottom of the hole. While the assembly is being lowered through the larger casing 36, the parts will remain as described but, as soon as the lower portion of the screen passes into the upper end of the smaller casing 14, the steel plate 40 and the leather disc 42 will remain on top of the shoulder 38 while the smaller disc 24 and leather washer 26 will pass downwardly into the smaller casing in the position shown in Figure 4. The gravel will pass downwardly from the space 44 into the space 32 by gravity, as shown by the arrows, and will then continue downwardly around the screen 18 until the plate 24 and washer 26 pass out of the bottom of the casing. As has been described with reference to Figure 1, the gravel will then pass downwardly so as to fill the annular space around the screen, i. e., between the screen and the walls of the cavity. It is to be understood that if more than two sections of casing are used in the hole, that is, if there are three or four or even more sections of casing of progressively larger diameters, the method of the invention can be carried on in the same manner. In this case additional pairs of the steel plates 40 and leather discs 42 will be used, each pair being of a larger diameter than the pair below it. The largest diameter pair will remain at the shoulder at the bottom of the largest casing section, and so on.

Summarizing, it is to be understood that the method of the invention comprises essentially the placing and holding of a quantity of granular material around a well screen while the screen is in the upper portion of the well and then lowering the screen and the mass of granular material together to the well cavity where the granular material settles to fill the annular space between the screen and the walls of the cavity. While one type of apparatus has been described for use in carrying out this method, it is to be understood that other forms of apparatus can be used. For example, the granular material could be placed in an elongated bag or the like, attached to and around the screen while at the surface and then lowered with the screen to the well cavity. The abrasion of the bag on its way down through the casing would tend to weaken it so that when the screen passes downwardly below the lower end of the casing, the gravel would pass outwardly to fill the annular space in the well cavity. The action of the fluid in the well would also tend to rot the bag so that it would not interfere with the passage of oil into the screen and upwardly to the surface.

While the screen or strainer member has been described as being run into the well on the lower end of a string of tubing, it is to be understood that, if desired, the screen can be lowered through the well while suspended from a wire line. With the screen on bottom, the packer 34 can be set to seal the space between the upper end of the screen and the lower portion of the casing or, if desired, a string of tubing can be lowered through the well and connected to the upper end of the screen so that the well can be produced through the tubing.

Obviously, many other modifications and variations of the invention, as hereinbefore, set forth, may be made without departing from the spirit and scope thereof, but only such limitations should be imposed as are indicated in the appended claims.

I claim:

1. A bottom-hole assembly for use in completing a well with a gravel pack, said well having a casing extending downwardly to a cavity in a producing formation, comprising a well screen member, and a perforated annular plate attached to and around the lower end of said member, said plate being slightly smaller in diameter than the interior of said casing and adapted, when positioned within said casing, to support a mass of gravel between the screen and the inner surface of the casing, the arrangement being such that when the screen and plate are lowered through the casing, the gravel will remain supported around the screen and when the screen and plate pass into the cavity below the bottom of the casing, the gravel will flow downwardly around the plate to fill the space between the screen and the walls of the said producing formation.

2. An assembly as described in claim 1 in which a flexible, annular perforated washer member is supported on said annular plate, said washer member being sutficiently large in external diameter to contact the inner surface of said casing.

3. An assembly as described in claim 1 in which said annular plate is supported on at least one shear pin projecting laterally from said screen member.

4. An assembly as described in claim 1 in which an annular packer surrounds the upper portion of said screen member for sealing the space between the screen and the lower portion of the casing.

5. An assembly for use in completing a well with a gravel pack, said well having a stepped casing made of portions of progressively smaller diameter extending downwardly to a cavity in a producing formation so as to provide shoulders between adjacent casing portions of different diameters, comprising a well screen member and a plurality of perforated annular plates supported around the lower end of said member, each one of said plates being slightly smaller in outside diameter than the inside diameter of a respective portion of said casing and the plates being disposed around said screen with the plates having progressively larger outside diameters arranged from bottom to top, at least one shear pin projecting laterally from said screen near its lower end to support the bottom-most of said plates, said bottom-most plate having an inside diameter such that the plate has snug engagement with the outer surface of said screen and each plate above said bottom-most plate having an inside diameter larger than the external diameter of said screen and smaller than the external diameter of the casing portion forming the shoulder next below its respective casing portion, said plates being adapted, when positioned one on top of another and within the upper casing portion,

to support a mass of gravel between the screen and the inner surface of the casing so that when the screen and plates are lowered through the upper casing portion the gravel will remain supported on the plates around the screen until the screen and the smaller plates pass into the next smaller casing portion, the largest plate then remaining on the shoulder between the largest and next smallest casing portions, the gravel passing downwardly through the annular space between the largest plate and the screen and into the annular space between the screen and said next smaller casing portion, and so on until the screen and bottom plate pass into the cavity below the bottom of the casing, the gravel then flowing downwardly around the bottom plate to fill the space between the screen and the walls of the said producing formation.

6. An assembly as described in claim 5 in which a flexible annular perforated washer member is supported on each annular plate, each washer member being slightly larger in external diameter than the plate upon which it is supported.

References Cited in the file of this patent UNITED STATES PATENTS 1,518,390 Cater Dec. 9, 1924 1,608,654 Harmon Nov. 30, 1926 2,011,448 Kelly Aug. 13, 1935

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