Coil Spring Supported Sealing Element and Device

1. Field of the Invention:

This invention relates to improvements in sealing devices useful in flow conductors. More specifically, the invention relates to sealing devices or packers for wells, which may be positioned in a well flow conductor and operated to compress and expand an improved resilient sealing element carried on the device, into sealing engagement with the flow conductor. When sealingly engaged, the expanded sealing element functions as a cup type sealing element or packer

2. Description of Related Art

The following U.S. patents, all to J. W. Tamplen and incorporated herein for reference, disclose sealing devices using sealing elements provided with anti-extrusion members in the form of coil springs, molded into the elements at each end, to prevent pressure extrusion of the resilient sealing material and enable the sealing element and device to seal against higher pressures:

U.S. Pat. No. 3,215,208 patented Nov. 2, 1965

U.S. Pat. No. 3,227,462 patented Jan. 4, 1966

U.S. Pat. No. 3,278,192 patented Oct. 11, 1966

An U.S. Pat. No. 3,278,219, which issued to T. L. Elliston Oct. 11, 1966, discloses the use of a sealing element, having coil springs molded into each end to prevent extrusion, on a well tool for retrieving objects from a well.

Another U.S. Pat. No. 3,118,682, to John V. Fredd issued Jan. 21, 1964. This patent discloses the use of an expandable metal backup member at one end of an elastic seal member.

Another U.S. Pat. No. 2,988,148 issued June 13, 1961 to Martin B. Conrad and John F. Muse, discloses a packing element that when expanded into sealing engagement with a well conduit functions as a cup type seal or packer as an increase in pressure sealed causes the cup type seal to seal tighter. The cup type seal disclosed in this patent does not utilize coil springs in both ends to prevent extrusion of the sealing material.

The use of coil springs in the ends of expandable resilient sealing elements, to prevent pressure extrusion of the sealing material, has enabled sealing elements which function as cup packers when sealing to continue to seal when subjected to pressures high enough to cause failure of sealing elements having no coil springs.

Failure of sealing elements, which function as cup type seals and utilize coil springs to prevent pressure extrusion, have occurred in deep, hot hydrocarbon wells where the resilient sealing material has been softened by high earth temperatures and the pressure holding capabilities of these sealing elements have been exceeded. These failures cause loss of well production and could cause loss of well pressure control resulting in well blowout with possible damage to the well and well equipment and danger to property and lives.

Analysis of prior sealing elements which failed in wells and tests of this type sealing element to failure revealed the coils of the springs used in the element ends to prevent pressure extrusion are tilted or were forced to lay in a more tangential direction from a radial direction when the sealing element ends expand because expansion and spring elongation creates clearances between coils into which the coils may tilt. Localized tilting or flattening of coils is caused by the sealing device not being centered in the flow conductor when the seal element is expanded to seal.

The diameter of the end spring coils are purposely made greater than the annular clearance between the sealing device and the inside of the flow conductor, so when the coils are more radially directed, the coil diameter bridges the annular clearance to effectively prevent extrusion of the resilient seal material. When pressure forces tending to extrude resilient material through the annular clearance are high enough, the already tilted coils are forced into the annular clearance and tilted more toward a tangential direction, further reducing their bridging height and resistance to resilient material extrusion.

This invention provides a means of centralizing the sealing element and a means of limiting the tangential tilt of the coils in the end springs, both of which provide greater seal end support and resistance to extrusion of the sealing element material at the ends, which enables the sealing element and device to seal greater pressures.

One object of this invention is to provide a sealing element for a sealing device having improved expandable end supports.

Another object of this invention is to provide a sealing device utilizing the improved sealing element and having means for compressing and expanding the element to seal in a flow conductor.

Also an object of this invention is to provide a sealing device useful for sealing in a flow conductor, which utilizes the improved sealing element and includes means limiting the compression setting stroke to control expansion of the sealing element, releasable means locking the device in limited stroke position and centralizing means which centralize the sealing device automatically when operated to seal in the flow conductor.

FIG. 1 is a half sectioned drawing of the sealing device of this invention having an improved sealing element of this invention.

FIG. 2 is a half sectioned drawing of the sealing device of FIG. 1 which has been positioned and operated to seal in a flow conductor.

FIG. 3 is a drawing of a cross section of the improved seal element of this invention, along line 3--3 of FIG. 1, showing a single strand of reinforcing wire in the element end supporting coil spring and the spring ends connected by a threaded connector.

FIG. 4 is the same as FIG. 3 except the wire has been cut into sections.

FIG. 5 is the same as FIG. 3 except the wire has more than one strand.

FIG. 6 is the same as FIG. 3 except the stranded wire has been cut into sections.

FIG. 7 is a drawing of a cross section of the improved seal element of this invention, along line 3--3 of FIG. 1, showing a single strand of reinforcing wire in the element end supporting coil spring and the spring ends connected by welding.

FIG. 8 is the same as FIG. 7 except the wire has been cut into sections.

FIG. 9 is the same as FIG. 7 except the ends of the wire have been cut to overlap.

FIG. 10 is a drawing in section of the seal element of this invention showing a layer of softer resilient material on the outside.

The invention sealing device is shown in FIG. 1 ready to be positioned in a well flow conductor. The device has an internal fishing neck 10 which is releasably connectable to a running tool. The fishing neck is connected to sleeve 12 with thread 11. There are a number of slots 12a in the sleeve and a radially slidable centralizing lug 13 is positioned in each slot. The sleeve is slidably disposed around a mandrel 14 and has a bore 12b, a camming surface 12c and a recess 12d in bore 12b. The mandrel has camming surfaces 14a and 14c and outside surface 14b. There is an upper expander 15 slidably mounted on and sealed to the mandrel with resilient seal 16. This expander has a frusto-conical end surface 15a, a number of collet fingers 15b and each finger has a camming surface 15c. Disposed around the mandrel between camming surfaces 12c and 15c are arcuate wire segments 17. Also around the mandrel is an improved expandable sealing element 18 of this invention. This sealing element has a resilient material body 19 and improved expandable end supports 20, which are formed by inserting a wire or wires 21 into a solid wound coil spring 22 and connecting the spring ends. The body 19 has an internal recess 19a and at least one lateral opening 19b communicating recess 19 a with the exterior of the element body. Body 19 also has internal frusto-conical surfaces 19c, which are sealingly engageable with the outside of mandrel 14 and frusto-conical end surfaces 19d.

Around mandrel 14 below the sealing element is a lower expander 23, which is sealed to the mandrel with resilient seal 24 and has a frusto-conical end surface 23a. Element end surfaces 19d are sealingly engageable with upper expander surface 15a and lower expander surface 23a.

Connected to the lower end of the mandrel by thread 25 and sealed by resilient seal 26 is a connector 27. The connector has a thread 28 for connecting the sealing device to other well tools used in flow conductors.

To use the sealing device of FIG. 1, a well tool is connected to connector 27 and the sealing device fish neck 10 is releasably connected to a running tool. If the flow conductor is known to have a rough inside surface, a sealing element 18 of the type shown in FIG. 10 should be used on the sealing device. The running tool and sealing device are then lowered to the desired level in the flow conductor at which the connected tool is set in the flow conductor or lands on a support so the sealing device fish neck may be jarred down or weight applied to it through the running tool, moving fish neck 10 downwardly. Downward movement of fish neck 10 moves sleeve 12 with surface 12c slightly downward over mandrel 14 to contact wire segment 17 and move it into contact with surface 15c on upper expander 15.

Further downward movement of the sleeve moves centralizer lugs 13 along mandrel surface 14a, camming them outwardly until they are moved over mandrel surface 14b. At the same time upper expander 15 was moved down through surface 12c, wire segments 17 and surface 15c sliding seal 16 along the outside of mandrel 14. Also, sealing element 18 was compressed between expanders 15 and 23 and expanded until wire segments 17 are cammed inwardly by surface 12c to mandrel surface 14c. The sealing element has expanded and is sealingly engaging the inside of the flow conductor, element surfaces 19c are sealingly engaged around mandrel 14 and element end surfaces 19d are sealingly engaged with expander surfaces 15a and 23a. Now further down travel of sleeve 12 moves sleeve bore 12b down over wire segments 17, locking them under mandrel surface 14c and locking upper expander 15 in a limited stroke position which retains sealing element 18 expanded in sealing engagement. Final downward travel of sleeve 12 moves surface 12c to contact collet finger cam surfaces 15c and cam collet fingers 15b inwardly until sleeve bore 12b can pass over the collet fingers to retain them cammed in under wire segments 17 as shown in FIG. 2. The running tool is then released from the sealing device and removed from the flow conductor.

To retrieve the sealing device from the flow conductor, an appropriate pulling tool is lowered to engage fish neck 10. On lifting the engaged pulling tool, sleeve 12 is moved upwardly over mandrel 14 permitting the collet fingers 15b to move outwardly into sleeve recess 12d and pulling the collet fingers and upper expander 15 upwardly. The collet fingers push wire segments 17 up surface 14c which cams them outwardly to be pushed along mandrel surface 14b, until sleeve 12 returns to its full upward position as shown in FIG. 1. The sealing element is now free to extend and contract from sealing engagement with the flow conductor, expanders and mandrel and lugs 13 are free to move inwardly. Continued lifting of the pulling tool will remove the sealing device and connected tool from the flow conductor.

The sealing element 18 (FIGS. 1 and 10) of this invention has improved end supports 20 which utilize a threaded connector or welding to connect the ends of body end supporting coil springs 22 after inserting a single or multistrand reinforcing wire 21 in the coil springs. FIGS. 3, 4, 5 and 6 show the use of a threaded connector 29, which has been threaded with a half wire diameter plus profile and on a helix angle equal to that of the coils in the solid wound coil spring. FIG. 3 shows a single strand of wire 30 which has been cut once and inserted into coil spring 22. Each end of the coil spring has been twisted a few unscrewing turns so when each end is brought in contact with the threaded connector and released it will screw itself halfway on to the connector. End supports 20, assembled as described, are positioned in a resilient material mold cavity and are molded into the ends of element body 19 as it is formed.

FIG. 4 shows the single wire has been cut more than once into sections to facilitate twisting to unscrew and screwing the coil spring ends on to the connector.

FIG. 5 shows use of a wire (or cable) 31 having more than one strand and cut once, in coil spring 22.

FIG. 6 shows the use of a multistrand wire 31, cut more than once into sections, in coil spring 22 whose ends are connected by threaded connector 29.

FIG. 7 shows a single wire 30 which has been cut once and inserted into a coil spring 22, the ends of which have been connected by weld 32.

FIG. 8 shows use of a single strand of wire 30, cut more than once into sections and inserted into the coil spring before connecting the ends by welding.

FIG. 9 shows a single strand of wire 30, with ends cut to overlap, inserted into coil spring 22 whose ends have been connected by welding.

FIG. 10 shows improved sealing element 18 of this invention having an outer layer of softer resilient material 33 on body 19.