US3272517A - Casing packer - Google Patents

Description

Sept. 13, 1966 5. 3. HOWARD ETAL CASING PACKER 2 Sheets-Sheet 1 Filed July 8, 1963 I I A r ,Hr I .7 J D A d r .A 1

INVENTORS.

GEOR C. HOWARD WILL G BEARDEN WWW ATTORNEY p 13, 1966 G. c. HOWARD ETAL 3,272,517

CASING PACKER 2 Sheets-Sheet 2 Filed July 8, 1963 4f $5 f .U

INVENTORS. GEORGE C. HOWARD WILLIAM G. BEARDEN BY 7/ ATTORNEY.

United States Patent 3,272,517 CASING PACKER George C. Howard and William G. Bearden, Tulsa, Okla, assignors to Pan American Petroleum Corporation, Tulsa, Okla., a corporation of Delaware Filed July 8, 1963, Ser. No. 293,459 3 Claims. (Cl. 277-26) This invention relates to the isolation of formations in a well bore. More particularly, it relates to installing a casing packer in oil wells and the like.

In the completion of oil and gas wells, when an oilproducing formation has been determined and it is desired to make a permanent installation, it is the usual practice to set a well casing in the bore hole. Oftentimes a cement slurry is forced downwardly through the well casing and upwardly into the annular space between the well bore and the outside of the casing to secure the casing in the well and to isolate the casing from particular subsurface formations producing undesirable fluids, such. as water and the like. One purpose of the cement is to form a seal between the casing and the well bore to exclude the undesirable fluids. However, it is often difficult to maintain a tight seal between the casing and well bore, particularly in unconsolidated formations which tend to flow under differential pressures of fracturing, injection, or producing operations. Also, in conducting secondary recovery operations by underground combustion, the burning operations cause an expansion and contraction of the casing, with the associated cracking of the well cement sheath, which oftentimes results in interzone communication because of the breaking of the casing to cement seal.

It is known to employ devices, generally referred to as packers in oil wells to form a seal between tubing and the casing, or between the casing and the well bore. In general, packers may be of the mechanical type, in which a material is compressed longitudinally to increase the diameter thereof, or of the inflatable type, wherein an expandable element is inflated by internal fluid pressure to increase the diameter thereof. Such packers are often employed in temporary installations between the casing and the wall of the bore hole to exclude water from the casing. Because of the relatively limited resilience of mechanical packers, movement of the formation contacted by the packer often causes the seal to be broken and the packer loses its sealing efficiency. In the case of the inflatable packers, it is often difiicult to maintain a tight attachment of the rubber, or other such resilient material, to the fitting by which it is attached to the casing and extremely high pressures tend to rupture the packer. Also, in the instance where the above packers are used in wells upon which are practiced secondary recovery by underground combustion, the heat resulting from the burning operations oftentimes causes the resilient material employed in the packer to break down and lose its effectiveness.

An object of the present invention is a method and means for improving the efficiency of' isolating a formation in a well bore. Another object of the invention is a packer which effectively seals a casing from a well bore over a prolonged period of use. Still a further object is a method and means for setting a casing packer, which is economical and durable, while affording simple and eflicient operation. Still another object of the invention is a casing packer which may be used to maintain a tight seal in relatively plastic formations, such as Athabasca tar sands and other unconsolidated formations. Yet another object of the invention is a heat-resistant packer which may be employed in wells wherein high temperatures may 3,272,517 Patented Sept. 13, 1966 be encountered. The above objects, as well as further objects and advantages of the present invention will become apparent from the following description of a preferred embodiment of the present invention and by reference to the accompanying drawings wherein:

FIGURE 1 is a vertical view, in partial cross section, of a well in which is positioned a packer according to the invention, prior to inflation of the packer; and

FIGURE 2 is a sectional view of the packer shown in FIGURE 1, taken at line 2-2.

FIGURE 3 is a vertical view, partly in cross section, of the packer of FIGURE 1 after being inflated.

Briefly, the present invention comprises inserting into a well bore a casing string, including a packer mandrel upon which is mounted an inflatable packer opposite a location in the well bore where it is desired to effect a seal between the casing and the wall of the bore. The mandrel is provided with one or more ports extending laterally through the wall of the casing to provide flow communication between the inside of the casing and the packer enclosing the casing adjacent the location of the ports. A valve means is operatively connected to the ports to control the flow of fluid between the casing and the packer. In a preferred form, the inflatable packer comprises an inner elastic member of a temperature-resistant resilient material, such as rubber or other suitable material, and an outer insulating covering providing ther mal insulation between the well bore and the elastic member. A cement slurry is forced down the well to fill the annular space between the casing and the wall of the well, advantageously to a point several feet or more above the packer location. Typically, during the cementing operation the ports between the casing and the packer are closed, and cement is passed down the casing and upwardly through the annular space. After the annular space has been filled to the desired level, the casing valve is opened and an inflating fluid passed under pressure down the casing, through the ports to inflate the packer while the cement is still fluid, i.e., before the cement sets. Upon inflation, the packer displaces the still unset cement and expands outwardly to contact the Wall of the Well bore. Pressure is held on the packer to maintain it in its inflated position until the cement is set.

Referring now to the drawings, wherein the same numerals are employed to designate identical. parts, a cas ing string 11 is positioned in a well bore 12. Attached to the casing string to form a portion thereof is a packer mandrel 13 connected into the casing string by couplings 14. Mounted on the outside of the mandrel is an expandable sheath-like member 16 securely attached to the mandrel in a fluid-tight manner by couplings 17. The expandable member typically comprises an inner resilient member 16a so that the packer may be expanded by the application of internal fluid pressure to increase the diameter thereof and contact the wall of the well bore 12 to effect a fluid-tight seal therebetween. Enclosing the resilient member is an outer insulating sheath 16b covering the outside of the resilient member to thermally insulate the resilient member from temperatures in the well bore. The resilient member advantageously is formed of a high temperature resistant, elastomeric material, such as Viton, neoprene, or Teflon-asbestos, although other similar materials such as natural or synthetic rubbers are contemplated for certain uses. The resilient member may be reinforced with metal braid or other suitable materials. Preferably, the resilient member of the packer is formed of a material suitable for sustained use at temperatures at least as great as 400 to 500 F. The insulating member typically is formed of a material such as woven fabric,

felt or mat of asbestos, mineral wool, or the like and possesses qualities which provide suitable insulating characteristics to protect the heat-degradable resilient member from high temperatures occurring in the well bore. Normally, the insulating materials used in the construction of the packer are, in themselves not elastic and the insulating member may be formed of a fabric fitted to the packer and so woven that it expands with inflation of the packer; or it may be formed of a loose-fitting, bag-like member enclosing the resilient material. In the latter construction, the insulating member may be formed to provide folds 18, pleats, corrugations or the like which are such that when the resilient member is inflated and moves outwardly, the insulating sheath is straightened out when the packer contacts the wall of the well bore.

The mandrel 13 is provided with one or more ports 19 extending laterally through the mandrel Wall and providing flow communication between the casing and the interior of the inflatable packer. A valve member 21, preferably a sleeve type valve, is slidably positioned inside the mandrel and operatively connected to the ports to control the flow of fluid through the mandrel ports. Basically, such a valve comprises a slidable sleeve 22 positioned in the packer mandrel and sealed thereagainst with sealing rings, such as rings (not shown). The sleeve is held in the desired position by means of a shear pin or spring (not shown) so that the port is normally closed during the cementing operation. When it is desired to open the port, the sleeve is driven downward by a ball, cementing plug, or other such member passed through the casing to contact a seat on the sleeve. Sufficient pressure is applied to shear the pin and drive the sleeve downwardly past the ports into the open position. Normally the valve will thereafter remain in the open position, although a second sleeve 22a, actuated as above, or other means may be provided for closing the valve again once it has been opened. If desired, one or more check valves permitting fluid to flow through the ports in a single direction, from the casing into the packer, may be employed as an alternative valving arrangement. The above valves are well known in the art and need not be described in detail herein.

In completing the well, a cement 25 is passed downwardly through the casing and up the annular space between the casing and the well bore, preferably, to a point several feet above the top of the inflatable packer to surround the packer and to provide additional thermal insulation for the joint. The cement, preferably, is a heatresistant refractory cement, such as Lumnite, employing crushed fire brick, silica flour, or a like refractory aggregate. While Portland cement, or other standard oil well cements, may be employed in some instances, whenever it is anticipated that high temperatures will be encountered in a well, it is important that a heat-resistant cement be utilized. The cement has several functions. One is to seal the cracks and crevices in the well bore to provide a relatively smooth surface against which the inflated packer is forced by the internal pressure, so that a more effective seal is obtained against the well wall. Another function of the cement is to serve as additional thermal insulation to more fully protect the packer from high temperatures in a well, such as those that result from a burning operation. Further, after setting, the cement serves to support the inflatable packer and reduce the likelihood of rupture which allows fluid to leak from the packer.

As shown in FIGURE 1, initially the packer is installed in the deflated position, with the insulating cover member on the outside, the insulating member typically being folded, as shown in FIGURES l and 2. The cement 25 is forced upwardly in the annulus in the desired position above the packer, and while the cement is fluid, the packer is inflated as shown in FIGURE 3. In flating the packer, typically a top cementing plug is passed down the casing under pressure so that the plug contacts the valve sleeve 22 and the pressure on the plug shears pins holding the valve closed and drives the sleeve downwardly to open the valve ports. A suitable fluid is then passed down the casing and forced under pressure through the valve ports into the packer to cause it to move outwardly against the Well wall. The inflated packer displaces the fluid cement around it and forces it upwardly and/or downwardly in the casing so that substantially all of the cement is squeezed from between the outside of the packer and the well bore, except for that which may remain in cracks and crevices in the wall of the bore. Fluid pressure is maintained on the packer for at least a time adequate to permit the cement placed around the packer to set and harden, and preferably until curing is completed. The pressure fluid used to inflate the packer typically may be water, although other suitable fluids may be used. For example, it may be desirable to employ a fluid with a suitably high vapor pressure so that an increase in the well temperature will cause a further expansion of the packer to tighten the seal between the packer and the well bore. Alternatively, if desired, after expanding the packer, the valve may be closed to seal the fluid in the packer under pressure so as to maintain it in the inflated position.

As shown in FIGURE 3, the inflated packer is maintained tightly against the wall of the well to effect a fluidtight seal. During a fracturing operation, for example, it may be desirable to maintain the valve in the open position, with the fracturing fluid passed down the casing and out into the formation so that the very high pressure of the fracturing fluid is exerted against the packer to increase the pressure against the wall of the well. In this manner the pressure within the packer is always greater than or at least equal to the external pressure from the formation during the fracturing operation. Any movement of the formation or cement is compensated for by the pressure on the packer which expands the packer so that the fluid-tight seal is maintained during the fracturing operation. During producing operations, production tubing 29 may be set on a production packer 26 below the casing packer, and the annulus 27 between the tubing and the casing filled with a suitable fluid maintained under a pressure, preferably at least as great as the foimation producing pressure, to achieve the above resu t.

Although the present invention has been described with reference to preferred embodiments, it will be understood that various modifications and alterations in the manner of operation and details of construction will become apparent from the foregoing description, and as such, these fall within the spirit and scope of the invention.

We claim:

1. A well packer comprising an elongated tubular member adapted to be connected into a casing string to form a portion thereof; port means in the Wall of said tubular member; a resilient, inflatable member attached to said tubular member and enclosing said port means; a valve member operatively connected to said port means to control the flow of fluid between the inside of said tubular member and said resilient member; and a non-elastic thermal insulating member covering the outside of said resilient member and providing thermal insulation therefor, said thermal insulating member being of greater resistance to heat transfer than said inflatable member.

2. An apparatus as defined in claim 1 in which said thermal insulating member is a loose fitting bag-like member enclosing said resilient, inflatable member.

3. A well installation in which a casing string is suspended in such well which com-prises:

an elongated tubular member connected into said casing string, said tubular member having port means in the wall thereof;

a resilient inflatable member attached to said tubular member and enclosing said port means;

a valve member operatively connected to said port means to control the flow of fluid between the in- 5 6 side of said tubular member and the inside of said References Cited by the Examiner resllielnt g fi h UNITED STATES PATENTS a n0n-east1c hermalunsulatrng member coverlng t e 2,177,601 10/1939 Smith 166 187 outside of said reslhent member, a fluid within said resilient member for inflation there- 5 2765854 10/1956 Lewis 166 187 3,104,717 9/1963 Sandlin et a1. 166-187 of, said fluid having a high vapor pressure so that an increase in the well temperature will cause further CHARLES OCONNELL, P r imary Examinerexpansion of the resilient inflatable member. I. A. LEPPINK, Assistant Examiner.

Claims (1)

1. A WELL PACKER COMPRISING AN ELONGATED TUBULAR MEMBER ADAPTED TO BE CONNECTED INTO A CASING STRING TO FORM A PORTION THEREOF; PORT MEANS IN THE WALL OF SAID TUBULAR MEMBER; A RESILIENT, INFLATABLE MEMBER ATTACHED TO SAID TUBULAR MEMBER AND ENCLOSING SAID PORT MEANS; A VALVE MEMBER OPERATIVELY CONNECTED TO SAID PORT MEANS TO CONTROL THE FLOW OF FLUID BETWEEN THE INSIDE OF SAID TUBULAR MEMBER AND SAID RESILIENT MEMBER; AND A NON-ELASTIC THERMAL INSULATING MEMBER COVERING THE OUTSIDE OF SAID RESILIENT MEMBER AND PROVIDING THERMAL INSULATION THERE-

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