US3038541A - Well packer - Google Patents

Description

Jun 12, 1962 F. n sPRAGUE 3,038,541

WELL PACKER Filed Jan. 13, 1960 INVENTOR.

. BY Frank Sprague z/waw, mwa( M ATTORNEYS 3,038,541 WELL PACKER Frank D. Sprague, Wooster, hio, assigner of one-half to Frank D. Sprague, Jr., and 'one-hait to Gary D. Sprague, both of Wooster, Ohio Filed Jan. 13, 1960, Ser. No, 2,184 1 Claim. (Cl. 16d-196) The invention relates to a well packer for cementing Wells. More particularly it pertains to apparatus for providing a cemented well casing at the lower end portion of the well bore.

Oil or gas wells are usually drilled through varying str-ata of earth formations which release Water from subterranean channels. If the water and resulting mud are permitted to drain into the lower end of a well the water and mud will contaminate the oil or gas reservoir below the channels. In order to prevent such contamination a well is usually provided with a cement casing that seals the water in place and prevents its draining into the oil or gas reservoir.

Various methods and apparatus for providing a cement casing in a well have been developed. A device usually usedfor providing a cement casing is known as a well packer. Most well packers of prior construction have been use to provide a temporary seal for the water and mud and to provide a lower support for the cement during the time required to permit the cement to set. Other Well packers have been provided with internal valves and other means to facilitate not only the preliminary cernenting operation but subsequent pumping of oil or gas through the well packer which remains permanently intact once the cement ycasing is installed.

Most well packers are irretrievable when a well u-ltimately turns out to be non-productive. The expense of the cement operation and some of the well casing above the well packer to which the packer is attached are also lost where a well is sealed by concrete before it is ultimately determined whether the well is productive or nofnproductive.

The device of the present invention provides a well packer that permits the `final drilling of the well to its ultimate `depth and the determination of whether a well is productive without first providing a cement casing for sealing off subterranean water or mud. With the device of the present invention, if it is determined that a well is non-productive, the well packer as Well as all of the metal casing is retrieved and the well is abandoned with a minimum Iof expense and without the casting of a cement casing.

If, on the other hand, the well is productive, the cement easing is cast in order to provide a seal `against the contaminating effects of subterranean water and mud.

Unlike well packers of prior construction, the device of the present invention has an internal diameter substantially equal to the diameter of the steel casing of the well. There are no internal barriers such as valves to prevent subsequent drilling and pumping operations as in well packers of prior construction. The device is provided only with a small internal shoulder adapted to support a temporary plug that is used as an internal support for the cement if it is found that the well is productive. Thereafter the plug is removed by a drill bit extending down through the casing and well packer to re-open the 2 casing and packer to their original diameters prior to the cementing operation.

Accordingly, it is a general object of this invention to provide a well packer for a gas or oil well which may be completely retrieved where a well is non-productive,

It is another object of this invention Ito, provide a well packer ywhich has a central open bore substantially equal to the diameter of the well casing.

It is another object of this invention to provide a well packer having an internal shoulder for the support of a frangible plug for the cementing operation and which is easily removed by a drill bit Within the well casing.

It is another object of this invention to provide a well packer which temporarily seals subterranean water and mud from entering the oil or gas reservoir at the bottom of a Well during determination of the question of productiveness of the well.

Finally, it is an object of this invention to provide a well packer having a minimum of parts lost where the well is non-productive and having a mini-mum number of permanent parts.

These and other objects and advantages apparent to those skilled in the -art from the following description and claim may be obtained, the stated results achieved, and the described difficulties overcome by the discoveries, principles, apparatus, parts, elements, combinations, and sube combinations which comprise the present invention, the nat-ure of which is set forth in the following general statement, a preferred embodiment of which-illustratiye of the best mode in which applicant has contemplated applying the principles-is -set forth in the following decription and shown in the drawing, and which is particularly and distinctly pointed out and set forth in the `appended claim forming part hereof.

The well packer of the present invention may be used in conjunction with a detachable plug for providing a cement casing in wells and includes generally a tube having a radially outturned shoulder forming a reduced upper portion and having la radially inturned plug-receiving shoulder, the upper portion of the tube having a pair of oppositely `disposed longitudinal slots and also having a threaded aperture, a collar telescopically mounted over the upper reduced portion of the tube and having one end facing the outturned shoulder of the tube, the collar having a pair of pins extending through the elongated slots, the collar being movable to and from the outturned shoulder, the ycollar also having a plurality of radial apertures, a plug in each radial aperture and composed of a material that is fnacturable at a predetermined hydrostatic pressure, the collar also having a second threaded aperture alignable with the threaded aperture in the tube when the collar is in a remote position from t-he outturned shoulder of the tube, a shear pin extending through the aligned threaded apertures of the collar and tube which pin is fracturable at a predetermined pressure applied at opposite ends of the well packer, an elastic sleeve mounted on the tube with one extremity abutting the outturned shoulder and the other extremity abutting the end of the collar, and the sleeve being expandable om a cylindrical position on the outer surface of the tube to an expanded position with the upper and lower ends disposed between the shoulder `and the collar upon movement of the end of the collar toward the tube shoulder.

Referring to the drawing, in which a preferred embodiment of the invention is shown by way of example:

FIGURE 1 is a vertical sectional view of a well packer disposed at the lower end of a casing in the unexpanded position in a well;

FIG. 2 is a vertical sectional view showing the well packer in the expanded position and showing a plug within the well packer;

FIG. 3 is a horizontal sectional view taken on the line 3 3 of FIG. 2; and

FIG. 4 is a vertical sectional view showing a well packer disposed in position for use after a cement casing has been installed.

Similar numerals refer to similar parts throughout the various views of the drawing.

In FIG. 1 a well packer is generally indicated at 1 at the llower end of a casing 2 within a well 3. The well packer 1 includes a tube 4, a collar 5, and an elastic sleeve 6.

The tube 4 is preferably a cylindrical member, the outer diameter of which is preferably equal to the outer diameter of the metal casing 2 which extends throughout the greater length of the well 3. As shown in FIG. 1, both the casing 2 and the well packer including all of its parts are of substantially less diameter than the well 3, leaving an annular space 7 between the casing and well packer on one side and the well on the outer side. The internal diameter of the tube 4 is equal to the inner diameter of the elongated casing 2 with ythe exception of a slightly reduced portion `8 which provides a shoulder 9 extending radially inwardly from the inner wall of the well packer and the purpose of which is to provide means by which a plug 10 (FIG. 2) is securely seated within the well packer. However, the reduced portion 8 of the tube 4 including the shoulder 9 is not suflicient to interfere with subsequent drilling and pumping operations which may occur after the well packer is permanently installed.

In addition, the tube 4 includes -a reduced upper portion 11 which provides an upturned shoulder 12 extending radially outwardly from the reduced portion 11. The lower end of the tube 4 includes a threaded portion A13 by which an annular shoe 14 having a corresponding threaded portion may be attached to the well packer 1. The purpose of the shoe 14 is to serve as ya base on which the well packer 1 and the elongated casing 2 therezbove may rest on a temporary bottom 15 of the Well As shown in FIG. 1, the collar 5 is provided with an upper internally threaded portion 16 for engagement with a corresponding portion at the lower end of the casing 2. 'Ihe collar 5 has an internal shoulder 17 extending radially outwardly from an inner surface 18 of the colvlar 5 and thereby provides an annular portion 19 of reduced thickness which tits telescopically over lthe reduced upper portion 11 of the tube 4 and is slidable longitudinally therewith. A lower end 20 of the `annular portion 19 faces `and is spaced from the shoulder 12 of the tube 4. As shown in FIG. 1, the elastic sleeve 6 is disposed around the reduced upper portion 11 of the tube 4 and between the shoulder 12 and the end 20 of the members 4 and 5 and remains in a snugly fitting position when the well packer is disposed in the expanded position as shown in FIG. 2. The elastic sleeve 6 is preferably composed of rubber.

In addition to the foregoing, a tube 4 land collar 5 are provided with interconnecting means generally indicated at 21 by which they are held together in the inoperative position such `as when the well packer 1 is being lowered into the well '3. 'Ihe interconnecting means Z1 includes at least one and preferably `a pair of longitudinal slots 22 disposed on opposite sides of the upper end of the reduced upper portion 11 and includes a pair of pins 23 the outer ends of which are secured in the annular portion 19 of the collar 5 and the inner ends of which extend into the slots 22 and are slidable along the slots when the tube 4 and the collar 5 are moved longitudinally with respect to each other. Finally, the interconnecting means 21 includes `a shear pin 24 that extends through a pair of threaded apertures 25 and 26 (FIGS. 1 and 2) in the tube 4 and collar 5, respectively. The apertures 25 and 26 are aligned when the well packer 1 is in the inoperative position `as shown in FIG. l.

The pin 24 is composed of a frangible material which is intended to 'be fractured at a predetermined pressure of say 600 pounds when the shoe 14 is seated upon the bottom 15 of the well (FIG. 2) and supports the elongated casing 2, the weight of which exceeds the predetermined pressure of 600 pounds.

As shown in FIG. 1, the collar 5 is provided with two or more apertures .27 through which fluid cement 28 (FIG. 4) is forced under pressure into the space 7 when it is determined that a well 3 is productive. During preliminary operations, however, prior to the cementing step the apertures 27 `are preferably filled with threaded plugs 29 which may be composed of frangible material that can be `fractured at a predetermined pressure of say 1200 to 1500 pounds developed by a hydrostatic head of uid within the elongated casing 2.

Operation In operation, a well 3 is drilled to the temporary level 15 which usually is the upper side of a deposit 30 of socalled Clinton sand which is a gas or oil bearing reservoir. At that level the drilling bit is removed from the well 43 and a casing composed of many sections of metal casing members 2 is lowered into the well 3 with the well packer 1 secured at the lower end of the lowermost casing 2 until the shoe 14 strikes the bottom 15 of the well. At that moment the lower portion of the packer 1 including the shoe 14 and the tube 4 stop moving but the casing 2 above the packer continues to move through the relatively short distance of the slots 22 until the upper end 31 of the reduced upper portion 11 of the tube 4 strikes the internal shoulder 17 of the collar 5 as shown in FIG. 2.

When the lower end of the shoe comes to rest on the bottom of the well the frangible shear pin 24 is broken due to the force of the weight of the casing 2 bearing down on the collar 5. During the short travel of the collar 5 on the tube 4, the rubber sleeve 6 is expanded outwardly from its snug-fitting position on the portion 11 of the tube 4 and extends outwardly through the space 7 into contact with the wall of the well 3 and provides a tightly tting peripheral seal 32 therewith. Thereafter any migrant water or mud flowing down the sides of the well 3 are stopped at the upper side of the expanded rubber sleeve 6 and are prevented from passing therebelow into the lower end of the Well 3 and into a subsequent bore 33 (FIG. 4) having a diameter substantially equal to that of the inner diameter of the casing and well packer and extending into the Clinton sand deposit 30.

After the well packer 1 is lowered to the position shown in FIG. 2 a drill bit is lowered through the casing and well packer (in the absence of the plug 10) and the bore 33 is drilled to the desired depth into the Clinton sand. Thereafter the drill bit is removed and tests are made to determine whether or not the well will be productive and therefore justify the provision of a cement casing 28 as shown in FIG. 4. If tests indicate that the well is not productive the casing 2, as well as the packer 1, may be removed from the well without the loss of any parts except the elastic sleeve 6 and the shear pin 24.

One advantage of the well packer 1 that differs from well packers of prior construction is that all parts of the casing and well packer except the sleeve 6 and shear pin 24 are recoverable if it turns out that the well is not productive. With well packers of prior construction, it had been necessary to irst provide a concrete casing similar to the casing 28 before the bore 33 could be drilled and tests made. If then the well was found non-productive, the expense of the well packer and the lower part of the casing, as Well as 400 to a thousand feet of cement, were lost when the well was abandoned. Because of the unique construction of the Well packer 1 it can be used repeatedly until it is used in a Well which a preliminary test reveals is productive, in which case the expense of the well packer, the steel casing 2, and the cement casing 3l are justified.

If the tests reveal that the Well is productive, the plug 10 is lowered on a line 3S to the position shown in FIG. 2. 'Ihe line 3S is then severed near the plug 10 by means of a so-called go-devil that is dropped on the line from the top of the well. The force of the go-devil striking the plug 10E severs Ithe line, whereupon the line and go-devil are pulled out. As vshown in FIG. 2, the plug 10 has an outer diameter substantially equal to the inner diameter of the casing 2 and the packer 1 and the plug is provided with a shoulder 36 which is adapted for abutment with the shoulder 9 of the tube 4. -In addition, the plug 10 may be provided with various means such as outwardly spring-biased members 37 having prongs 38 adapted to bite into the inner surface of the tube 4 and thereby prevent any subsequent pressure from below the plug raising the plug 10 out of its position on the shoulder 9. Thus the plug 10 remains seated in a substantially fluid-tight position within the well packer until it is subsequently removed by a drill bit.

With the plug 10 in place as shown in FIG. 2, a column of water is poured into the casing 2 where it is supported at its underside by the plug. Hydrostatic force is then applied to the Water with sufcient pressure to 'blow out the plugs 2.9` in the apertures 27.

Thereafter cement is poured into the casing 2 to a predetermined level and a hydrostatic force is again applied to the iluid cement, the pressure of which drives most of the cement out of the casing and into the annular space 7 between the walls of the Well 3 and the casing 2. The lower end of the annular column of cement is supported by the expanded sleeve 6 as shown in FIG. 4.

When the cement has set, after a period of say 72 hours, a drill bit is again lowered into the casing to remove the excess cement as Well as the plug 10. The plug 10, being composed of an eas-ily frangible material, disintegrates after a few turns of .the drill bit and drops into the bottom of the bore 33 where it is harmless. The well is then ready for operation with a straight, unblocked passage extending from the top of the bore 33 to the top of the well 3.

During the drilling of the bore "33' and the subsequent cementing operation, the well packer 1 Aand casing 2 are supported primarily by contact of 4the shoe 14 in the deposit 30 as well as by contact of a radially outwardly extending shoulder 39 on the outer surface of the tube 4 in contact with an upper portion of the deposit 30. The casing is also supported by the expanded sleeve 6 engaging the side of the well 3 at 32. After the cement 28 is set it anchors the casing 2 securely in place and serves as a permanent seal 'for preventing contamination of the gas or oil by migrant water.

As shown in FIG. 4, when the well is ultimately ready for pumping, the packer 1, having -a substantially straight inner diameter equal t the inner ydiameter of the casing Z, lbecomes a part of the casing and ceases to operate as a packer.

All well packers of prior construction have included inner structure for various purposes, which structure greatly reduced the inner diameter of the casing to such an extent that it was not thereafter possible to lower a drill bit through the well packer in order to provide the bore 33. Heretofore it had been necessary to irst provide the cement casing, after which the inner structure of Well packers of prior construction had no further function and could then be drilled through by a drill bit. However, as was pointed out above, all Well packers of prior construction were irretrievable when well tests indicated their non-productivity because the packers and casing having Ia length of 400 to a thousand feet were sacrificed. In other Words, with well packers of prior construction it was not possible to test the well before providing the cement casing.

The device of the present invention has an acknowledged advantage over Well packers of prior construction because it permits the testing of a well before providing a cement casing. The advantage of that procedure permits the well operator who drills a non-productive well to retrieve the entire casing and the well packer with resulting great savings of expense and time. Moreover, the well packer 1 has no inner structure which substantially reduces the inner diameter which is an operational advantage and permits the use of the entire inner cross section of the casing 2.

At the same time the well packer 1 has an inner shoulder for temporary use for plugging the lower end of the casing while providing the cement casing 28.

Finally, the welll packer 1 provides an elastic sleeve 6 which is expanded into contact with the wall of the well to seal olf old Water and mud created during the drilling operation and thereby prevent the water and mud from contaminating the productive oil or gas deposit which is subsequently drilled.

In the foregoing description, cer-tain terms have been used for brevity, clearness and understanding; but no unnecessary limitations are to be implied therefrom beyond the requirements of the prior art, because such terms are utilized for descriptive purposes herein and not for the purpose of limitation and are intended to be broadly construed.

Moreover, the description of the improvements is by way `of example and the scope of the present invention is not limited vto the exact details illustrated, or to the specific mechanisms shown.

Having now described the features, discoveries and principles of the invention, the construction, operation and use of the improved mechanisms and the advantageous, new and useful results obtained thereby; the new and useful parts, elements, constructions, mechanisms, combinations, subcombinations, and arrangements, and mechanical equivalents obvious to those skilled in the art, are set forth in the appended claim.

I claim:

A Well packer for preliminarily testing the productiveness of a well and for subsequently providing a cement casing in -a well bore, the packer including a tube having an outturned shoulder forming a reduced upper portion, the tube `also having an inturned plug-receiving shoulder on the inner surface thereof, the reduced outer portion of the tube having -a pair of oppositely disposed longitudinal slots and having a iirst aperture, a collar telescopically mounted over the upper reduced portion and having one end facing the outturned shoulder, the collar having a pair of pins extending through the elongated slots, the collar lbeing movable to and from lthe outturned shoulder, the collar also having a plurality of radial apertures, a plug for each radial aperture and removable from the aperture -at a predetermined hydrostatic pressure applied within the well packer, the collar also having a second aperture alignable with the iirst aperture when the collar is in a position remote from the outturned shoulder, a shear pin extending through the aligned rst Iand second apertures, which pin is fracturable at a predetermined pressure applied at opposite ends of the well packer, an elastic sleeve mounted on the tube between the outturned shoulder and the end of the collar, the sleeve being expandable from a cylindrical position on the reduced upper portion of the tube to a radially expanded position against a bore of a well and between the outturned shoulder and the collar when the collar is moved toward the outturned shoulder, a detachable plug composed of fracturable material seated on the plugreceiving shoulder, which detachable plug provides a fluid-tight partition between the upper and lower sides of thetube, and the tube and collar having an open cross section with substantially parallel internal walls extending throughout the length of the packer, whereby the packer may be used for preliminarily testing the productiveness of -a well by expanding the elastic sleeve against the bore of a well and for preventing drainage of water into a productive well reserve below a well bore, whereby the well packer may be entirely removed from the well in the event of negative test results, whereby a detachable frangible plug seated on the inturned shoulder of the tube provides a fluid-tight bottom in the tube to support a deposit of uid cement for applying a cement casing to a well bore in an annular space between the packer and the bore and above the expanded sleeve, and

whereby excess solidified cement and the frangible plug may be subsequently removed from the tube by the use of a drill bit applied thereto.

References Cited in the tile of this patent UNITED STATES PATENTS 2,021,206 Spang Nov. 19, 1935 2,249,511 Westal'l July 15, 1941 2,633,199 Reed Mar. 3l, 1953 FOREIGN PATENTS 99,559 Germany Jan. 28, 1898 487 Great Britain Feb. 5, 1877

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