Title:
Method and apparatus for completing wells
United States Patent 2312862


Abstract:
to tne completion of a well in wlic. a Fo ,gravel or other granular'material is placed around a perforated liner or scree in the well cavity. 5 The principal object of the invention is to provide a method and means whereby a liner may be used which is larger in diameter than could normally...



Inventors:
Bermingham Jr., James A.
Application Number:
US31566840A
Publication Date:
03/02/1943
Filing Date:
01/26/1940
Assignee:
TEXAS CO
Primary Class:
Other Classes:
166/115, 166/123, 166/158, 166/180, 166/228
International Classes:
E21B43/04
View Patent Images:



Description:

to tne completion of a well in wlic. a Fo ,gravel or other granular'material is placed around a perforated liner or scree in the well cavity. 5 The principal object of the invention is to provide a method and means whereby a liner may be used which is larger in diameter than could normally be used with a given size of casing while still providing sufficient space around the liner 1 to accommodate a suitable gravel pack. Another object is to provide means for suspending the liner from the well casing after the gravel has been placed in the well.

It is more or less common in the graveling of a 1 well to circulate the gravel or other granular material with a carrier fluid downwardly in the space between the casing and a tubing string, the gravel remaining around a screen or perforated liner at the bottom of the hole and the 2 carrier fluid passing into the liner or screen and upwardly to the surface through the tubing. It is usually necessary to use a liner considerably smaller in diameter than the casing so as to provide sufficient annular space around the upper  portion of the liner through which the gravel may pass downwardly to the well cavity. Moreover, the gravel usually extends upwardly in the annular space between the lower portion of the * casing and the upper portion of the liner since it is frequently not known exactly when the right amount of gravel has been placed to reach just to the top of the cavity. Obviously, if a liner were used but slightly smaller in diameter than the casting, it might still be possible to run the liner down through the casing but there would be little, if any, space left between the liner and the casing to provide passage for the gravel. It is naturally an advantage to use as large a perforated liner or screen as possible since with a large diameter liner there is a larger peripheral area and there are more perforations per foot. Furthermore, the larger the liner, the larger the pump which may be used.

In accordance with the invention a method has been provided which consists of attaching to the lower end of the main casing one or more joints of casing larger in diameter than that used in the main casing string so as to provide a comparatively large annular clearance space between the inside surface of the larger section of casing and the outside of the liner or screen, thereby permitting a larger size liner or screen to be used for a given size of the main casing. A liner or screen but slightly smaller in diameter than the inside diameter of the nmain casing is run into the well cavity and the upper part of the liner will extend up within the section of larger casing. Thus, in this manner the liner used may be nearly as large in diameter as the main casing string, while at the same time sufficient annular space will be provided around the upper portion of the liner to allow passage of the gravel and to accommodate the upper portion of the gravel 0 pack. Means are also provided whereby, after the tubing string is withdrawn from the bore the liner may be hung or suspended from the main casing while the lower or screen portion of the liner remains surrounded by gravel in the well cavity.

For a better description of the invention reference may be had to the accompanying drawing in which Figure 1 is a vertical sectional view through 0 the lower portion of the well before the gravel is placed, while Figure 2 is a sectional view somewhat similar to Figure 1 but showing the method of suspending the liner after the gravel has been positioned.

25 With reference to the drawing, the lower end of a hole or bore 10 has been shown as having been drilled through a producing formation 12.

In order to describe the invention more clearly certain typical dimensions will be given, although 30 these dimensions do not, of course, form a part of the invention. The portion of the hole ,10 shown in the upper part of Figure 1 may be, say, 124 inches in diameter. After the hole has been drilled and the desired location of the setting 35 point of the casing has been determined a portion 14 of the hole is then underreamed or scraped to a diameter of, say, 151/2 inches and this underreamed portion may extend for a suitable distance such as 60 feet above the point 16 at which 40 the lower end of the casing is to be set. Starting about 5 feet below the setting point 16 of the casing hole is then underreamed to a diameter of 19 inches and this second underreamed portion 18 will extend to the bottom of the hole, i. e., through 4the producing formation 12.

After the hole 10 with the two underreamed or stepped portions 14 and 18 has been prepared, a casing string 20 of joints of 8%" casing will be made up in the usual manner with the exception 50 that a 40 foot joint 22 of 9% inch casing will be suitably secured on the bottom of the main or 8% inch string. A float collar (not shown) could be inserted in the string directly above the junction of the 8% inch and 9% inch sections. The 55 9% inch casing section 22 would have a clearance of 1.31 inches in the 121/4 inch hole and no unusual difficulty should arise in running the string into the hole.

It will be observed with reference to Figure 1 that the string of casing is positioned in the hole with the bottom of the larger section 22 at the setting point 16 and the enlarged casing oprtinn 22 exftnringlr iunfrl rAlr n!thin th-n uinAnrreamed hole portion 14. The string of casing is then cemented in the hole in any suitable manner, a portion of the cement being shown at 24. After the cement has set sufficiently the casing string will preferably be cleaned out thoroughly. If desired, the casing string can be set prior to the operation of underreaming the lower portion 18 of the hole.

A liner 26 having a lower perforated portion or screen 28 and having an external diameter of, say, 6% inches is then run into the hole on a string of tubing 30. Resilient casing guides 32 are preferably secured to the upper portion of the liner before the latter is run in the hole and these guides will serve to center the top of the liner within the larger section of casing 22. It will be observed that the width of the annular space between the 6% inch liner and the 9% inch casing is 1.05 inches, which provides sufficient clearance for the passage of gravel in the gravel packing operation. The lower end of the liner or screen may be provided with a transverse plate 34 which will engage the formation at the bottom of the hole to prevent rotation of the liner after it has been positioned.

In order to secure the liner 26 to the tubing during the operation of running the liner into the hole, the lower end of the tubing string may be provided with left hand threads 36 adapted to be threaded into a boss formed on a plate 38 secured as by welding to the inside of the liner 26. The plate 38 is provided with a center opening in alignment with the tubing 30. If desired, a portion of the screen 28 below the plate 38 may be previously filled with a quantity of gravel 40 held in place by means of a slotted or perforated plate 42.

In order to center the upper end of the liner 26 around the tubing 30 and to prevent gravel, when passing downwardly through the casing, from entering the upper end of the liner, a closure member 44 is secured as by welding to the tubing 30 and is provided with a downwardly extending interior boss portion 46 adapted to fit within the upper end of the liner.. The method of securing the liner 26 to the tubing 30 by means of the threaded section 36 and the provision of the closure member 44 does not form a part of this invention, and are thoroughly described and illustrated in the Patent Number 2,198,573, granted April 23, 1940, to E. L. Davis, H. S. Cole, Jr., W. E. Larson and N. C. Wells.

After the liner has been placed in the hole in the manner illustrated in Figure. 1, a quantity of granular material such as gravel 48 is circulated into the hole through the space between the casing and the liner 30. The gravel may be circulated into the hole by means of a carrier liquid such as oil or mud, the carrier liquid entering the lower portion of the screen 28 below the plate 38 and passing upwardly to the surface through the opening in the plate 38 and the tubing 30. Although this is the preferred method of placing the gravel in the hole, other methods may be used without departing from the scope of the invention.

In Figure 2 the gravel 48 is shown filling the annular space in the underreamed hole portion 18 and sufficient gravel will be used so that it will extend upwardly in the annular space between the casing section 22 and the upper portion of the liner 26. After the gravel has been placed the tubing 30 is rotated so as to unscrew the connection 36, after which the tubing string can be withdrawn from the hole. A joint of 6% inch casing or other pipe 50 having a slip type casing bowl 52 on the bottom is then run into the hole on drill pipe or tubing.

After the casing bowl has engaged and surrounded the upper end of the liner 26, the liner is preferably pulled upwardly one or two feet so as to pack off the space between the inside of the bowl 52 and the upper end of the liner 26. The liner is then hung in tension from the casing 20 by means of any suitable type of liner hanger 54. The drill pipe or tubing will then be removed from the casing section 50 in the usual manner and when this operation has been completed, the well will be ready to be placed on production.

It will be observed that with the method of completing a well such as has been described, a liner can be used which is considerably larger than could otherwise be used within a given size hole and casing. The stepped or enlarged casing section 22 will provide sufficient annular space for the gravel to extend upwardly around the upper portion of the liner 26.

As has been pointed out hereinbefore, although dimensions have been given for the sizes of the main hole 10, the enlarged portions 14 and 18, the main casing 20, the casing section 22 and the liner 26, these have been given for purposes of illustration only and may be considered to illustrate one example or installation such as may be made in carrying out the invention. Other dimensions may be used, the principal point to be borne in mind being that the liner must naturally be smaller in diameter than the inside diameter of the main casing, but only sufficiently smaller so that the liner can be run freely through the casing.

Obviously many modifications and variations of ' the invention as before set forth may be made : without departing from the spirit and scope thereof, and therefore only such limitations should be ' imposed as are indicated by the appended claims.

I claim: 1. A method of completing a well having a well bore extending into a producing formation, which comprises underreaming a portion of the bore above the producing formation to form a chamber, underreaming another portion of said bore to form a cavity below said chamber, the diameter of said cavity being greater than that of said chamber, placing in the bore a liner-screen assembly slightly smaller in diameter than the main bore and with the lower or screen portion of the assembly in said cavity and the upper or liner portion within said chamber, the diameter of said liner-screen being only sufficiently smaller than the diameter of the main bore to permit lowering of the liner through said main bore, and placing a quantity of granular material around said linerscreen assembly within said cavity and said chamber.

2. In a bottom hole assembly for a well bore provided with a casing and an enlarged cavity in a producing formation, a casing section larger in diameter than said first mentioned casing and 7i depending therefrom to the top of said cavity, and a perforated liner within said cavity and extending up within said enlarged casing section, said liner being but slightly smaller in diameter than the first mentioned casing.

3. A bottom hole assembly for a well bore having an enlarged cavity in a producing formation and a chamber above the cavity, the chamber being larger in diameter than the bore but smaller than the cavity, comprising a casing in said bore extending downwardly to the top of said chamber, a second casing section depending from said first casing and disposed within said chamber, said casing section being larger in diameter than said first casing, a liner-screen assembly positioned in said cavity and chamber and having an outside diameter slightly smaller than the inside diameter of said first mentioned casing, the upper portion of said assembly being disposed within said casing section, and the arrangement being such that space is provided around said assembly for accommodating granular material both within said cavity and between the upper portion of the assembly and said casing section.

4. In a bore hole assembly for a well bore provided with a casing and an enlarged cavity in a producing formation, a casing section larger in diameter than said first mentioned casing and depending therefrom substantially to the top of said cavity, a perforated liner within said cavity and extending up within said enlarged casing section, said liner being but slightly smaller in diameter than the first mentioned casing, and means for sealing the space between the upper end of the liner and said first mentioned casing.

JAMES A. BERMINGHAM, JR.

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