Wireline Equipment

Wireline-operated pressure-control equipment is installed on top of, or as an extension of, the well’s Xmas tree. The equipment is installed with the aid of a?, and in certain cases with a spacer?, depending on access and rigging possibilities.

The rig or stack? usually consists of a specer, double blind shear BOP and Wireline valve, adequate lengths of lubricator as required for the length of the toolstring and on top of everything, a stuffing box. (It is not always possible to install the BOP directly on top of the Xmas tree).
Wireline operations

In connection with special operations such as during completion, a circulating head or flow head is installed between the well-head and the wireline safety valves. This permits circulation of the completion fluid and pressure testing of the operation equipment when this has been rigged up.

A wireline operating unit also includes a power pack and a winch/wireline operator’s cabin.

We distinguish three types of wirelines: slickline, electric line and braided line. The pressure control equipment for electric and braided lines is identical for the same wireline dimensions.

1. Stuffing Box
The stuffing box maintains the pressure from the lubricator while the wireline is being led through it and into the lubricator. During this operation, the packing unit is regulated either manually or hydraulically. In addition, all stuffing boxes incorporate a blow-out plu/valve which will close fluid flow if the wireline breaks and is blown out of the stuffing box.
Slickline Manual Stuffing Box
Before an operation we should check the stuffing box and determine whether the set of packers is in good condition. If there is any sign of wear it should be replaced with a new set of the appropriate dimension for the wireline which is to be used in the operation. We should also make sure that the blowout plug has been inserted the right way up, i.e. with it conical end pointing upwards. The stuffing box is the primary barrier during a slickline operation.

2. Lubricator
The lubricator enables us to keep the wireline string in the tubing while we equalise the pressure between the lubricator ad the well before we start the operation, and between the lubricator and atmospheric pressure during unrigging after the operation has been completed. A lubricator consists of cylidrical pipes connected by quick-release joints as needed to make up the required length.

The quick-release joints are fitted with O-ring seals. Every time the system is rigged up we should check that the O-rings are in good condition.
Slickline Pressure Control Stack

At the lower end of the lubricator we find a bleed-off port on which to mount the lubricator manifold, which normally consists of a needle valve near test the lubricator, a manometer and a needle or ball valve ( in the form of a T) for pressure venting. If we wish to pressure test the lubricator using the manifold we install a T-joint after the manometer.

It is important to install valves capable oif withstanding the same pressure as the rest of the equipment.

3. Wireline BOP
The wireline BOP is a blind ram that is located between the lubricator and the shear ram. Closing the blind ram enables us, for example, to replace packers or seals in the stuffing box or stripper, or to install (new) equipment such as a cutter.

The wireline BOP is usually hydraulically actuated. Two cylinders activate the valve assembly and close around the wire without damaging it. Each cylinder is connected to two hydraulic hoses (for opening and closing). The BOP can also be operated manually.

It is important to ensure that when the guide-shoe on the one side of the ram seal is facing upward the guide-shoe on the other is facing down. Guide-shoes that are not in the correct position can cause serious damage when the BOP is opened or closed. Similarly, it is important to ensure that the correct type of ram seal is utilised and that the outermost seal is facing upwards, as the pressure in the well helps to press the seal upwards and keep it tight.

The wireline BOP should be functionally tested before operation. Make sure that the rams are in the fully withdrawn (open) position before the start of the operation, otherwise both the equipment and the rams themselves may be damaged as the string passes through the BOP.
Wireline BOP (Manual Type)
During the operation the equalisation valve must be closed and should only be opened in connection with activation of the wireline BOP.

When braided cable is being utilised a double wireline BOP is used. In principle, this consists of two single wireline BOPs, the lower of which is turned upside down. Between these there is a port for pumping in grease which seals the valve against the well pressure. When the valves are to be closed, the upper ram is closed first, followed by the lower, after which the grease is pumped in.

4. Shear/Seal BOP
The shear/seal BOP is installed between the well’s Xmas tree and the wireline BOP. It comprises the third barrier in the wireline operated pressure control system. The Shear-seal BOP is hydraulically actuated, but it can also be operated manually.

The valve stack is equipped with a shear ram which, when closed, also functions as a seal BOP. The valve is actuated when there is a need to cut the wire at the surface, and to avoid having to utilise the Xmas tree, which might lead to damage to the valves.
PES Wireline Cutter Valve (Shear/Seal BOP)
At present, it is normal to install stacks of three-valve and even four-valve BOPs. In such stacks, the last BOP is usually the shear/seal BOP. It is also usual to put together BOP systems that are suitable for both slickline and braided cable, if both types of wireline are going to be used in the course of the operation.

5. Grease Injection Control Head
The grease injection control head has the same functions as a stuffing box when braided cable is being utilised. Grease is pumped in through the lower ?? nipple // injection port ?? and up through the wireline and the seal tubes. A minimum of three lengths of seal tubing is essential on an injection head to reduce the pressure and keep it tight with the aid of a hydraulic packer unit on the top of the injection head. The pressure is controlled from a separate panel and is usually ?? to the unit by means of an air-driven pump. The grease is withdrawn through a return nipple below the packer unit.
Grease Injection Head
Before the start of operations we should check that the sealing tubing is suitable for the dimensions of the wireline. Excessively large sealing tubing or a worn wireline will means excessive grease consumption.

We should also make sure that sufficient grease is available for the complete operation before we start working.

Safety check union/sub
The safety check union/sub is intended to retain the pressure if the wireline breaks or is pulled out of the wireline head. It is installed just below the injection head and is a check valve in the form of a ball which is pressed against a non-extrusion ring/seating. Before installation and use, the valve should be checked, and if any damage is found the ball and its brass seating should be replaced.

Following rigging of the complete wireline stack, it is usual to functionally test and pressure test the assembly.

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