In-Situ Polymerization of an Inflatable Composite Sleeve To Reline Damaged Tubing and Shut Off Perforations
- J.L. Saltel (Drillflex) | J.R.N. Leighton (Drillflex) | A.M. Faure (Shell Research) | Thijs Baaijens (Shell E&P)
- Document ID
- Society of Petroleum Engineers
- SPE Drilling & Completion
- Publication Date
- June 1999
- Document Type
- Journal Paper
- 115 - 122
- 1999. Society of Petroleum Engineers
- 4.2.3 Materials and Corrosion, 2.2.2 Perforating, 5.4.2 Gas Injection Methods, 4.3.4 Scale, 4.1.5 Processing Equipment, 5.2 Reservoir Fluid Dynamics, 3 Production and Well Operations, 1.6 Drilling Operations, 4.1.2 Separation and Treating
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Finding an effective solution to seal-off perforations, whether it be to reduce gas flow, reduce water cut, or to modify injection profiles, has long been a subject of concern. Several solutions for through tubing shut-off have been tried with a varying level of success.
After several years of testing a new technology has been developed to manufacture a composite sleeve using elastomers, fibers, and thermosetting resins. The sleeve is run-in on electric wireline, inflated to push the composite against the inside of the casing, then heated to polymerize the resins. The running equipment is extracted to leave a pressure resistant inner lining in place. There is little diameter loss, leaning access to the well below, and opening up applications for tubing repair. Following successful field trials commercial operations have begun.
The technology has been used not only for water and gas shut-off, but also for repairing damaged casings and tubings. This paper introduces the technology, describes the equipment used, and runs through the development and testing phases prior to beginning field operations. Typical examples of jobs carried out are cited, and some case histories are developed in greater detail.
Composite material are generally composed of reinforced fibers such as glass, carbon, or steel bedded in a matrix. The fibers generally provide the majority of the strength and the matrix serves to maintain them in place and to transfer the stresses to them.1
The matrices used may be soft or rigid:
- Flexible matrices can be used for deformable products. When this is the case, the matrix is mainly an elastomer. It has almost nothing to do with the mechanical strength, but acts solely as a binder for the fibers (protection, seal). Among other applications, some examples are various types of seals, car tires, membranes, etc.
- Rigid matrices form products that are not deformable and provide a degree of strength to the composite material, especially in the crosswise direction of the fibers.
Fiberglass boats, fiberglass casing, are common examples.
Very generally, a product is used either in a flexible and hence deformable state or else in a rigid and hence undeformable state.
Using the deformability properties of a composite material with a thermosetting matrix in its unpolymerized state, while preserving its great mechanical properties obtained after polymerization has several advantages. The crosslinking of the resin occurs directly at the place where the end product will be used, and not during manufacturing as it is usually the case. This means the composite can be shaped to the desired form in the well, and opens up a multitude of potential applications. The first available application of this technology is the PatchFlex, designed for remedial applications. A short composite tube manufactured with thermosetting resins is run on electric wireline opposite the zone to be treated. It is inflated and polymerized to leave a self-supporting cylindrical lining (Fig. 1).2
Product and Equipment.
Run-in and set-in electric wireline (Fig. 1). The PatchFlex itself is composed of two principle parts.
- A PatchFlex sleeve which will remain downhole. This is made up of an outer skin in elastomer and a body of fibers and resins.
- An Inflatable Setting Element connected to the running tool, is built inside the PatchFlex sleeve, and contains integrated electrical resistances for heating the resins. At the end of the job it is separated from the PatchFlex sleeve and pulled out of hole.
The running equipment can be divided into three groups.
- Downhole equipment. A specialized running tool is connected to the wireline rope socket and is controlled from surface (Fig. 1A). It contains an electromagnetic CCL for positioning the PatchFlex, a pump to inflate with downhole fluid, several temperature, and pressure sensors along with electronics for the heating and the telemetry system to monitor the operation.
- Specialized surface equipment. This is composed of transformers, to supply the required tension, and a power module for controlling the operation which is piloted from a portable computer (Fig. 1).
- Wireline unit. The equipment is designed to be run on seven conductor open-hole logging cables. Lubricators and a grease tube are necessary for running into wells under pressure.
Running-in and Setting.
The PatchFlex is made up onto the running tool, and the running tool is connected to the rope socket on the seven conductor cables. A surface cable connects the power module directly to the collector on the wireline drum, by-passing the control cabin computer (Fig. 1). A separate cable from the power module will transmit the CCL signal to the wireline unit computer for depth correlation.
When opposite the zone to be treated, the pump in the running tool is activated to start inflating the PatchFlex (Fig. 1A). The lower zone (?1 m) will inflate first to anchor the product in place (Fig. 1B). Inflation will then be progressively from the bottom upwards to flush out fluid in the annulus and ensure a good seal along the entire length (Figs. 1B, 1C, 1D).
When the product is fully inflated, the PatchFlex sleeve is pressurized against the inside surface of the tubing or casing to be treated. The inflation pressure is maintained while polymerization takes place. Electric power is used to heat electric resistances built into the body of the Inflatable Setting Element. Full power is used to raise the temperature in the resin, then reduced power is used to maintain polymerization temperature for the full cycle.
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