US2837165A - Permanent well completion apparatus - Google Patents

Description

June 3, 1958 A. P. ROBERTS PERMANENT WELL COMPLETION APPARATUS set 4 1954 FIG. 2.

Fii i w ms w n M a T r R a R n m A United States Patent 9 2,837,165 PERMANENT WELL CONIPLETION APPARATUS Alan P. Roberts, Jim Hogg County, Tex., assignor, by mesne assignments, to Esso Research and Engineering Company, Elizabeth,N. J., a corporation of Delaware Applicationoctober l, 1954, Serial No. 460,114

1 Claim. Cl. 166114) The present invention is directed to apparatus for servicing a well. Briefly, the invention concerns apparatus for conducting treating operations in a cased well having a tubing arranged therein, the lower open end of which is positioned above a productive interval; the apparatus comprising a packer positioned adjacent the lower end of the tubing for sealing off the annulus between the casing and tubing, a tubular extension member arranged within the tubing and having sealing means sealingly engaging the tubing above the packer and extending to adjacent the productive interval, fluid passage means positioned in the tubing above and adjacent to the packer and below said tubular extension sealing means adapted to fluidly communicate the casing-tubing annulus and the interior of the tubing, and valve means in thefluid passage means opena-ble when the fluid pressure in the annulus and the tubing is below a selected pressure to permit flow through the passage means and closa'ble to seal off fluid communication between the annulus and the tubing when the pressure in the annulus and the tubing is greater than the above selected pressure.

The apparatus of the present invention may be -em ployed in fracturing impermeable formations and the like or otherwise opening up fractures or cavities inthe formation, sand, or the stratum. The invention may be also used in cementing or acidizing-operations in which acid is introduced into the formation to cause dissolution and increase or cause flow of oil from a formation into the wellbore.

The invention may also housed in sealing oil formations or sealing perforations in a perforated casing and the like.

When the invention is employed in fracturing formations a fracturing fluid such as oil and other similar fracturing fluids containing bodying and/or weighting agents, such as sand, may be used. As an example of a suitable fracturing fluid, the type described in French Patent No. 987,352 published August 18, 1951, may be used. However, it is unnecessary to employ a fracturing fluid containing bodying or weighting agents and it may be desirable to use an oil such as crude oil, distillates, and fractions of crude oil, and the like.

When the invention is used in acidizin-g or fracturing in which acid is forced into formations, the acid may suitably be a mineral acid such as hydrochloric acid, sulphuric acid, nitric acid, hydrofluoric acid, and the like. Preferably hydrochloric acid is used, and this acid may be used in the form of an acid gel, as it is known to the market. There are many acid gels available on the market and the acid gel desired may be used as a fracturing fluid if desired. When the fluid is a cement slurry, it is preferred and desirable but not necessary to employ a cement of the modified type having a low fluid loss.

Neat cement may also be used satisfactorily even though ithas a high water loss.

As examples of these cements, the cement slurry may be prepared in accordance with the patent to Salathiel,

U. S. 2,482,459. Other modified types of cement havinglow fluid loss such as oil-emulsion cements, oil slurries of cement, and the like, may suitably be used.

The present invention will be further illustrated by reference to the drawings in which:

Figures 1 through 6 include a step-wise application of the invention; and,

Figure 7 is a sectional view of a valve suitable for use in Figures 1 through 6.

Referring now to the drawings in which identical numerals will be employed to designate identical parts,

numeral 11 designates a wellbore drilled from the earths surface, not shown, and extending through at least one or through a plurality of formations, strata, or productive intervals A and B, which may be separated by an impervious formation or interval such as C. Arranged in the wellbore 11 is a casing 12 which may extend from the top to the bottom of the wellbore 11 but which may extend only the reater length of the wellbore. Stating this otherwise, there may be an open hole below the casing 12. The casing 12 is cemented in place with primary cement 13 to hold the casing securely in place and to seal off strata or formations, such as water, oil, and/ or gas-bearing strata, and the like.

Arranged in the casing 12 is a tubing string 14 which extends to the earths surface to the wellhead, also not shown.

Arranged in the tubing 14 may be a plurality of gas lift mandrels provided with ports 16 and 17 communicating the annulus 18 with tubing 14. Tubing 1-4 is arranged above the uppermost of the productive intervals A and B with the lower open end 19 of the tubing 14 arranged just above the interval A. A packer 20, such as illustrated on page 942 of the 1952-53 edition of the Composite Catalog of Oil Field and Pipeline Equipment isolates the annulus 18 adjacent the lower end 19 of the tubing 14. Arranged in the upper mandrel 15 is a gas lift valve 21 which may be employed to close port 16. This gas l'iift valve is a valve such as illustrated in the Composite Catalogue (1952-53 edition) supra at page 1059 and is used only when gas lift is required.

The port 17 in the lower of the'mandrels 15 maybe opened and closed by a valve such as 21 or a valve such as 22 which is shown in more detail in Figure 7. For the purpose of this description in Figure l, the port 17 is provided with a valve such as 21.

In Figure 1 the casing 12 has been perforated in interval B and perforations 22a opened up to allow production, such as hydrocarbons, from the formation B up the casing 12 into the lower open end 19 and up the tubing 14 to the earths surface. The perforations 22a may have been formed by lowering a tubing gun perforator through the tubing 14 on a wire line or on an electric conductor cable and firing same into the interval B to open up production.

After the hydrocarbons or other desirable fluids have been produced to exhaustion or substantial depletion from productive interval B or invasion by water and/ or gas has caused a decline in production of the desirable well fluids, it may be desirable to obtain production from another interval such as A. *It may also be desirable to attempt to reestablish production from interval B, if for some reason production may have ceased before this zone was depleted. The valve, such as 21, is removed from the lower of the mandrels 15 by means of a wire line tool using a tool such as described at page 1059 of the Composite Catalogue (1952-53 edition) supra and replaced by a valve such as valve 22. This valve is normally open and is closed under a pressure which may be predetermined. Thereafter, there is'lowered through tubing 14 and supported, secured and/ or anchored in a landing nipple, such as 23, a tubular member 2 4 which serves to lengthen or vary the effective length of the tubing 14. The tubular extension 24 provides a passageway 25 which allows fluid to be conducted to the in terval B in the region of perforations 22a.

The landing nipple 23 may be of the type described in the Composite Catalog (1952-53 edition) supra at page 4063. Anchoring and/or securing means, such as pipe engaging mean-s as, for example, slips, latching dogs, and the like, not shown, may 'be provided on tubular member 24 for releasably'securing member 24 to landing nipple 23. Arranged adjacent the upper end of the tubular extension 24 for sealing engagement with the landing nipple 23 is a sealing means such as chevron packing 26.

The tubular member 24 is provided with a fishing neck 27 which allows the tubular member 24 to be lowered through the tubing 14 and retrieved therefrom by means of a fishing tool attached to a wire line and the like.

In the showing of Figure 2 flow is established down the tubing 14 through the tubular extension member 24 and thence back up the tubing through the valve 22 and port 17 into the annulus 18 in the flow pattern shown by the arrows.

Thereafter, a cement slurry, such as 28, which may be a modified cement of the type referred to supra, is deposited in the region of the perforations 22a as shown in Figure 3. The casing valve, not shown, at the wellhead is then closed and pressure allowed to build up in the tubing 14 and the annulus 18 until the pressure is suflicient to close the valve 22, the operation of which will be described in more detail hereinafter.

Pres-sure is then exerted on the cement slurry 28 through the tubing 14 and passageway 25 in tubular extension member 24 to seal the perforations 22a with the cement and to form a filter cake of cement in perforations 22a as illustrated by the buttons or rivet heads 29 shown more clearly in Figure 4. Thereafter, the casing valve at the wellhead, not shown, is opened and the pressure on the annulus 18 and tubing 14 released, which causes the valve 22 to be opened and allows communication between the annulus 18 and the tubing 14. Fluid is then flowed down the annulus 18 to the open end 19 of the tubing 14 and upwardly through the extension member 24 through passageway 25 and up the tubing 14 to the earths surface. This allows the fluid cement or other fluid material in the casing 12 below the open end 19 be of the shaped charge or bullet gun type, is lowered on wire line 32 through the open end 19 of the tubing 14 until the perforator 31 is opposite the interval A. For purposes of this description and for illustrative purposes only the gun perforator 31 is considered to be one of the shaped charge type which may contain a power pack for firing same or may receive electric energy through a conductor cable, extending to the cart s surface, which would replace the wire line 32.

In any event, the gun perforator 31 is fired to form perforations in the casing 12, such as 34, and allow production to be obtained from the interval A with the flow being in the direction indicated by the arrows. This is shown in Figure 6. In Figure 6 the valve 22 has been replaced by the valve 21 to close ofl port 17. It is to 'be noted that the operations in Figures 1 and 6 are substantially identical except for flow in Figure 6 which is from an interval vertically displaced from Figure l.

The apparatus of the invention may be used also in 4 operations in an open hole below the casing seat which may allow the treatment of the open hole for fracturing a formation to render a formation more permeable than it was before and to increase the flow of desirable fluid therefrom.

A formation penetrated by the open hole may suitably be treated with acid on which pressure is imposed to cause dissolving or dissolution of acid reactive materials.

It is also contemplated that such fracturing and acid treating operations may be conducted through perforations in the casing by forcing the fluid into an interval or formation penetrated by the well casing and perforations in the formation to be drilled or fractured.

The valve, the use of which is described in Figures 2 through 5, is shown more clearly in Figure 7 and is generally indicated by the numeral 22. The valve 22 comprises an elongated body member 40 provided with spaced apart packers 41 and 42 between which is arranged a flow port 43. This flow port 43 communicates with the port 17 in the mandrel 15 and allows flow from and to the annulus 18 and the tubing 14.

Arranged in the body member 40 is a bellows member 44 to which is attached a piston 45 connected to valve stem 46. On the free end of the valve stem 46 is a valve member 47 provided with a sealing means such as O-ring 48 arranged in a recess 48a therein.

The valve 47 serves to close off the chamber 49 which is in communication with the port 43. The chamber 49 communicates with the annulus 18 through the port 50. The piston 45 has an annular shoulder 51 arranged thereon. Embraceably arranged on the piston 45 is a biasing means, such as a helical coil spring 52 which normally urges the valve 47 away from the seat 53; thus the valve generally indicated by numeral 22 is normally in an open position until a predetermined pressure exerted on the valve 47 overcomes the spring 52 and the bellows 44 causing the collapse of the bellows 44 and thus closes the valve 47 on the seat 53 which prevents flow from the port 50 to port 43 or from the port 17 through the port 43 and thence through port 50. Thus, when pressure is built up in the tubing and easing by closing oh the casing valve at the wellhead, this pressure causes the valve 47 to seat on seat 53.

The pressure at which the valve 22 will be closed may be predetermined by the size and strength of spring 52 and/or by the charge pressure of bellows 44. Thus, adjustment of spring tension or bellows charge pressure with the latter preferred may be employed or a combination of both may be used. It will be desired to have the valve 22 close at a predetermined pressure less than the safe working pressure of the casing. With the valve 22 closed off the pressure imposed on the fluid, such as cement slurry and the like, below the lower open end of the tubing may exceed the safe working pressure of the casing above the packer 20. From the foregoing description of the invention taken with the drawing, it may be seen that the invention involves forcing fluid down the tubing 14 and the member 24. Thereafter, pressure is built up in the annulus 18 and the tubing 14 which closes off a valve 22. Pressure in excess of the safe working pressure of the casing 12 above the packer 20 is then exerted below the open end of the tubing through the tubing. This pressure is higher than ordinarily possible to exert on such fluids since in the operation the annulus is isolated.

After the cement has been forced in the perforations, or the fluid has been forced into the formation, pressure is released from the annulus 18 and tubing 14 which opens up communication between the annulus 18 and the tubing 14 re-establishing a flow pattern as has been indicated. Thereafter, excess fluid such as fluid cement and the like is reversed out from the annulus 18 up the member 24 to the wellhead. An interval or formation vertically displaced from the treated formation may, if desired, be

perforated by running in a tubing gun perforator after member 24 is withdrawn.

While I have described the use of the present invention with respect to what amounts to reverse circulation for removing undesirable fluids from the completion interval, it is to be understood that undesirable materials may be removed by circulating the long-way, that is, down through the tubing and tubular member 24 into the annulus 18 through the valve, such as 22, and up the annulus 18 to the earths surface. It is advantageous to employ the socalled long-way circulation since in the reverse circulation method it may be necessary to replace the gas lift valves and to seal the gas lift mandrels to prevent circulation of fluid through the gas lift valves from the annulus to the tubing. In the long-way circulation, replacement of the gas lift valves may be desirable but is not necessary since gas lift valves, such as referred to, are provided with check valves to prevent flow from the tubing to the annulus.

Likewise, the use of the invention, while described with respect to a plurality of productive intervals, may be used with only one productive interval where the tubing is set above the interval on which the work is to be performed.

When pressure is imposed upon the tubing, the safeworking pressure of the casing below the packer 1s not exceeded because of the following considerations:

Current practice in designing casing string utilizes casing having varied physical properties. Normally casing having the greater strength is placed on the bottom and top of the string, while casing having lesser strength is placed in the center of the string. Thus, if a packer were set below the casing having the lesser strength, isolation of the annulus would allow application of higher pressure below the packer than could safely be placed upon the entire length of easing.

Cement is normally employed to seal off all productive formations behind the casing. If the tubing packer were set below the top of the cement, greater pressures could conceivably be safely placed on the casing below the tubing, since this section of easing would be reinforced to some degree with the cement.

In the Gulf Coast area, for example, weighted mud is normally in the hole when the casing string is set, and remains behind the casing after the well is completed. Normally workovers, particularly where permanent completion methods are used, employ salt water as the workover fluid. Since the static pressure gradient of the fluid behind the casing is normally greater than that of the salt water inside the'casing and since this differential pressure which tends to collapse the casing increases with depth, it is conceivable that greater pressures may be 6 safely applied inside the casing near the bottom of the hole than at the top of the hole.

In some instances it is conceivable that pressure applied inside the casing may be transmitted to some extent through casing perforations to fluid behind the casing for some distance above the perforations; thus, the differential pressure tending to burst the casing may be lessened in sections near the casing perforations.

Any one or a combination of the several mentioned factors may operate to allow the present invention to be employed when pressures exceeding what is normally considered safe-working pressure of the casing below the packer are placed on the tubing.

The present invention allows many advantages to be obtained, principally the use of pressures in conducting operations, which heretofore were not possible since the safe working pressure of the casing ordinarily would be exceeded.

The nature and objects of the present invention having been completely described and illustrated, what I wish to claim as new and useful and secure by Letters Patent Apparatus for conducting treating operations in a cased well having a tubing arranged therein, the lower open end of which tubing is positioned above a productive interval, said apparatus comprising a packer positioned adjacent the lower end of said tubing for sealing off the annulus between said casing and tubing, a tubular extension member arranged within said tubing and having sealing means sealingly engaging said tubing above said packer and extending to adjacent said productive interval, and fluid passage means positioned in said tubing above and adjacent to said packer and below said tubular extension sealing means adapted to fluidly communicate said casing-tubing annulus and the interior of said tubing, valve means in said fluid passage means .openable when the fluid pressure in said annulus and said tubing is below a selected pressure to permit flow through said passage means and closable to seal off fluid communication between said annulus and said tubing when the pressure in said annulus and said tubing is greater than said above selected pressure.

References Cited in the file of this patent UNITED STATES PATENTS 1,050,244 Smith Jan. 14, 1913 2,087,297 Pew July 20, 1937 2,360,311 Ausburn et al. Oct. 17, 1944 2,675,880 Baker Apr. 20, 1954 2,716,454 Abendroth Aug. 30, 1955 2,749,989 Huber June 12, 1956 2,760,578 Tausch Aug. 28, 1956

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