GB2403744A - A means of isolating / sealing a part of a well - Google Patents

Abstract

A means of sealing a part of a well (3, figure 2) comprises a tool 2 with a packer 30. The packer 30 comprises two inflatable packer elements 31, 32 that are expanded by mixing two part resins / epoxy / rubber 13, 14 that react with each other to form an expanded seal. The two part resins 13, 14 are stored in their respective chambers 6, 18, and are discharged into the packer elements 31, 32 by pistons 11. In another embodiment, only one packer (60, figure 8) is utilised, and the tool 2 is secured on a casing (22, figure 1) by grippers (62, figure 8).

Description

Well Treatment System It has been common practice for many years to use

one or more inflatable packers that are expanded by fluid under pressure to isolate a zone in a well for what ever reason, be it to perform a drill stem test, to perform a selective chemical treatment, else to isolate a zone for the remainder of the selective chemical treatment, else to isolate a zone for remainder of the wells productive live.

There are two common types of inflatable packers in current use.

One has a multi layered construction comprising an elastomeric inner bladder, a sheath of wire or fabric which is arranged in parallel sets that are woven over and under one another with their ends secured to the end fittings by an epoxy potting process that is disclosed in US patent no. 3,003,798 issued Oct. 10, 1961, finally covered in an outer elastomeric boot which forms the hydraulic seal on the casing or open hole surface it is expanded to contact. The other common type of inflatable packer has again a multi layered construction comprising an elastomeric inner bladder, completely surrounded and secured relative to a plurality of peripherally overlapping, resilient, reinforcing slats or ribs. The medium portions of the reinforcing ribs are surrounded and bonded to an outer annular elastomeric to again perform the external hydraulic sealing function. A structure of this type is shown in US patent no. 3,160,211 reinforcing slats or ribs. In both cases, these packers are deployed on coiled tubing (a continuous seam welded self supporting steel tube) or on self supporting jointed tubing, and fluid is pumped down the deployment tube.

It is an objective of this invention to provide a sealing system that is straightforward and efficient to deploy and use.

According to the present invention there is provided a method of sealing at least part of a well, at a position remote from the surface, comprising a gettable sealing material, said well comprising a casing or wall, characterised in that the gettable material is contained in a discharge chamber and is dischargeable from the chamber by a discharge means to set in the form a seal at the required position.

Ideally, the gettable material is discharged into an expandable sealing chamber to form the seal.

The gettable material is generally deployed on a hybrid braided wire line which has a small hydraulic flow path integral with its construction.

The packer's pressure containment capability in the well is significantly increased by filling it with a 2 component silicone rubber which cures.

Embodiments of the present invention provide down hole accumulators to accept fluid from the surface via the small hydraulic path and allow controlled volumes to be pumped either between two packer elements of below a single packer element.

Electrical sensors to measure all the vital parameters during the well operation and allow surface corrections may be provided.

Figure 1 shows a longitudinal view of a well; Figure 2 shows an overview of the whole system; Figure 3a shows a section through a tool suspended on the hybrid wire line; Figure 3b shows one embodiment of the hybrid wire line; Figure 3c shows a further embodiment of the hybrid wire line; Figures 4 and 6 to show steps in the operation of the tool shown in figure 3a Figures 7 to 9 steps in the operation of another embodiment of the tool Figures 10 to 13 steps in the operation of another embodiment of the tool Referring to figure 1, a well is lined with a casing 22 with perforations 28, 29 at the lower end of the casing. A production tube is sealed at its lower end by production packer 24. During the life of a well the lower perforations 29 often begin to produce more water due to coning of the water-oil contact profile. As more water flows into the well, the production potential is reduced from the upper oil producing perforations 28. It is desirable to seal off this water production in the most efficient manner possible so that oil can be efficiently produced from the upper perforations.

Now referring in more detail to figure 2 and 3a, 3b and 3c, a surface winch unit and hybrid reel 1 can be used to convey the tool 2 upon a braided wire line 4 via a conventional sheaf wheel and pressure lubricator (if deployed in a live well) into the well 3. The braided wire line 4 is adapted in that it includes a small hydraulic flow path 5, so it will not be primarily used to pump directly into the formations, but will be used to fill down hole chambers in the tool 6 in a manner discussed in more detail below. The braided wire line 4 has thin wall hydraulic tube 15, reinforced on the outside by braided wire 16. Typically, the cable could be 3/4 inch in diameter. Referring to figure 3c the hybrid braided wire line 4 could also have electrical cables 7 included in its construction to power sensors, carry telemetry and operate valves in the tool. Some embodiments of the tool (such as that shown in Figure 9) may though be lowered on a simple slickline, that is a cable (usually steel wire) having no telemetry of fluid pumping capability.

Figures 4 to 6 shows an operation of one embodiment of tool and its operation. The tool 2 is deployed in the well. It has an upper part 10 and a lower part 20. In the upper part is a chamber 6, which contains Belleville washers 12 under compression, below which is a piston with seal 11 separating the Belleville washers 12 from one part of a two component silicone rubber 13, which fills the remainder of the chamber 6. The lower part 20 similarly includes a container 18 containing Belleville washers 12, a piston with seal 11 and above the washers, and the other component 14 of the two component silicone rubber. A two component silicone rubber such as GE silicones (RTV 11, RTV21 and RTV41) with an appropriate curing agent can be used. RTV11, RT21 and RTV41 are general purpose two-part silicone elastomers which are supplied by GE Silicones, ready-to-use with a base compound and a standard curing agent such as [) 131 (dibutyl till dialurate). Other curing agents, such as STO (stannous tin octoate) can be used to facilitate deep section curing, faster curing and automated mixing.

A packer 30 comprising an two inflatable seal packer elements 31, 32 is located in the middle of the tool. Once at the required location in the well, fluid pressure in the hydraulic tube 15 (or a cable may be provided to allow an electrical signal to activate the Belleville washers) initiates the Belleville washers to move the pistons 11. The two components of the silicone rubber mix as they enter the packer 30 and so as the packer is filled it both inflates to its expanded shape and after a period of time the internal contents of between the packer becomes a solid mass of silicone rubber, as shown in figure 5. Referring to figure 5, as the two packer elements 31, 32 are inflated, a small gap 50 is formed between the packer elements, this being gap being located at the zone which is to receive the treatment fluid.

The treatment fluid 48 then pumped down the hydraulic path 5, and fills the chambers 6. As the chambers fill, the Belleville washers are compressed.

Referring to figure 6, once full, a sequence valve (not shown) or an electronically controlled valve (not shown) opens to allow the Belleville washers to discharge the fluid 48 into the formation isolated by the packers.

This operation is repeated as often as required.

It will be seen that this arrangement both seals off the lower portion of a well, and allows treatment fluid to be applied at the upper region of that lower portion. It will also be seen that a the packer tool could be adapted, for example with the provision of a controllable valve or an additional Towpath communicating with the region beneath the lower bladder 32, to seal off only the region between the upper and lower bladders 31, 32 (i.e. retaining a flow path between the lower portion of the well and the upper portion and/or surface).

The following embodiments use a single bladder to seal the lower portion of a well, without creating any intermediate region.

Referring to figures 7 to 9, a single inflatable element 60 is conveyed into the well on a similar tool as shown in figure 3 to 7. In this example the tool is lowered into position and the packer element 60 filled with two component silicone 13, 14 as shown in figure 8, and left until it is set hard.

The running tool 70 is disconnected and removed from the well 71 as shown in figure 9. Before inflating the packer element 60, or simultaneously with inflating the packer, a gripper 62 comprising pairs of pivoted arms 63, 64 is actuated, each pair of arms operating in a scissor fashion. The distal ends of the arms bear against the inner surface of the casing, and a toothed surface 66 provided on the distal ends engage with the casing, securing the tool.

Figure 10 shows another embodiment of the packing system. A slick line 72 conveys a battery powered 2 tool into the well. The tool also has a built in clock and associated control circuitry 73 to allow the operation to be commenced at a predetermined time after leaving surface. In the tool is a small electric motor which linearly displaces a shaft 85 using a screw thread engagement.

Referring to figure 11, the when the tool is in the correct position, the electric motor operates to turn shaft 85 and drive a piston head 86 down through cylinder 92 to urge a resin mixture through a tube 81.

The resin mixture could for example comprise Therma-Set) resin available from WellCem AS. The setting time of this resin can be varied by incorporating different quantities of initiator and inhibitor into the resin.

The components of the resin mixture are mixed at the surface and loaded into the packing tool. After passing through tube 81, the mixture them passes through a check valve 82 and into the expandable packer skin 83.

Referring to figure 11, the resin mixture 78 expands the bladder 83 until it contacts the casing wall 22, a separate by-pass 90 prevents the resin filled bladder being subjected to differential pressure until it is cured.

As for the previously described embodiment, a gripper 63, 64 is provided upon the static mixer tube 81 to secure the tool in the correct position. Alternative or additional slip / anchor arrangements could of course be provided.

Referring to figure 12, the running tool can disconnect at the completion of its filling operation and be recovered back to surface.

Referring to figure 13, when the resin in the bladder 83 has suitably cured and the packer can withstand the differential pressure applied to it from the lower perforations, the non return valve 82 closes the by pass 90 through the packer to seal the lower section.

The embodiment shown in figure 10 can be adapted to receive two separate components of a silicone or similar gettable mixture, and store them separately until the bladder is to be filled. For example, the cylinder can be divided into a inner cylindrical compartment and a surrounding annular compartment. The piston means may then comprise a central piston head upon a central shaft, and an annular piston head upon an annular shaft coaxial with the central shaft. The central shaft may then be secured to the annular shaft at the top, and the electric motor engage with the outer annular shaft to depress both shafts and both piston heads through the separated compartments. In order to thoroughly mix the two components, tube 81 incorporates a static mixer.

Although principally described here as a tool and method for isolating a lower region of a well, it will be appreciated that the principles disclosed here could also be used to isolate one or more zones in a well, particularly if flowpaths are incorporated.

Claims (10)

1. Claims 1. A method of sealing at least part of a well, at a position

   remote from the surface, comprising a gettable sealing material, said well comprising a casing or wall, characterised in that the gettable material is contained in a discharge chamber and is dischargeable from the chamber by a discharge means to set in the form a seal at the required position.
2. 2. A method according to any previous claim, characterised in that the gettable material is discharged into an expandable sealing chamber to form the seal.
3. 3. A method according to any previous claim, characterised in that discharge chamber is cylindrical and the discharge means is in the form of a correspondingly shaped piston.
4. 4. An apparatus according to any previous claim, characterised in that the discharge chamber may be lowered into the well to a position proximate to the location of the expandable sealing chamber.
5. 5. An apparatus according to claim 3, characterised in that the expandable sealing chamber is expanded to seal perforations in the well by pressing against the perforation region of the casing of the well.
6. 6. An apparatus according to any previous claim characterised in that a closable by-pass passage is provided through the seal to prevent the ' build up of any pressure difference either side of the seal until the seal is set.
7. 7. An apparatus according to any of claims 2 to 6, characterized in that the discharge chamber and discharge means are provided on a wire line or coiled tubing together with the expandable sealing chamber for lowering to the desired position in the well.
8. 8. An apparatus according to claim 7, characterized in that the discharge chamber is releasable from the expandable sealing chamber and the discharge chamber remains attached to the wire line or coiled tubing and is retrievable back to the top of the well.
9. 9. An apparatus according to any previous claim, characterized in that the discharge means is electrically powered.
10. 10. An apparatus according to claim 8, characterized in that the electric power is provided by means of a battery mounted for deployment with the discharge chamber.