Preparation work

Before installing deepwater borewell casing pipe, sufficient preparation work is required. First, the size and length of the casing pipe, as borewell as the depth and diameter of the wellbore need to be determined. Then the appropriate casing pipe material and connection method need to be selected, and necessary acceptance and inspection need to be carried out.

Transportation of casing pipe

When transporting casing pipe, care should be taken to prevent casing pipe deformation and damage. Special transportation equipment can be used for transportation to avoid excessive extrusion and friction of the casing pipe. At the same time, it is necessary to store it in accordance with the prescribed stacking method to avoid safety problems such as lateral tilting and unstable stacking of the casing pipe.

Pre-installation

Before the actual installation of the casing pipe, pre-installation is required. During pre-installation, the casing pipe needs to be assembled in a predetermined order at the wellhead, and then the casing pipe is suspended in the air by a cable, and the hanging point is fixed to the steel pipe at the wellhead. Safety issues need to be paid attention to during pre-installation, and tools such as plumb lines and tension ropes need to be firmly connected and strictly inspected.

Installation

When the actual installation of the casing pipe is carried out, it needs to be carried out according to the pre-designed installation method. First, the casing pipe should be placed from the pre-installed state to the lower conveyor, and then gradually lowered to the wellhead until the top of the casing pipe enters the wellbore. During the installation process, special attention should be paid to parameters such as casing pipe diameter, wall thickness and strength, and appropriate tools and equipment should be used for adjustment and calibration.

1. Install casing pipe by riser method

The riser method is a common method for installing casing pipe in deepwater wells, mainly installing casing pipe on the sea surface. This method can ensure the positioning accuracy of the casing pipe and can be adjusted during the installation process.

Installation steps

First, pile driving construction should be carried out after underwater survey. This ensures that the casing pipe can be stably placed on the seabed.

Then, use a crane or a lifting ship to place the casing pipe within the steel pipe length and accuracy control range of the pile driver. The vertical positioning of the casing pipe can be achieved by controlling the length of the steel pipe.

When the casing pipe is completely placed on the seabed, the pipe fittings are connected and the seals between the casing pipe and the wellbore are handled.

Finally, filling is carried out to minimize the buoyancy difference inside and outside the well.

Advantages: It can ensure the positioning accuracy of the casing pipe and facilitate adjustment.

Disadvantages: Pile construction is required, which increases the difficulty and cost of the work.

2. Floating method to install casing pipe

The floating method is a relatively new casing pipe installation method, which is suitable for shallow waters. This method places the casing pipe on a buoy and then transports and installs it by ship.

Installation steps

First, place the buoy at the location where the casing pipe needs to be installed.

Then place the casing pipe on the buoy through the lifting device, and ensure that there is no collision between them.

When the casing pipe and the buoy are firmly connected, the ship can be used for backlog connection, and the seal between the casing pipe and the wellbore is handled.

Finally, the filling operation is performed to reduce the buoyancy difference inside and outside the well.

Advantages: Compared with the riser method, the piling construction step is omitted, which reduces the difficulty and cost of the work.

Disadvantages: Not accurate enough, and the position of the casing pipe cannot be adjusted.

Fixing of casing pipe

After installing the casing pipe, it needs to be fixed to the borewell wall. Common fixing methods include cement slurry filling method, Mason hook method and Vam anti-drop hook method. Different fixing methods have different advantages and scope of application, and need to be selected according to actual conditions and needs.

Safety issues

When installing deepwater borewell casing pipe, safety must be kept in mind first. During the operation, attention should be paid to preventing safety issues such as steel pipe falling and sliding, and strictly abide by safety regulations and operating procedures.

Summary

There are two ways to install deepwater borewell casing pipe: riser method and floating method. Choosing the right method requires considering specific conditions and needs. At the same time, during the installation of casing pipe, some issues need to be paid attention to, such as the diameter of the wellbore and the length of the casing pipe. During the installation of casing pipe, special attention should be paid to safety issues to ensure construction safety and the normal operation of the casing pipe.