CAN Complete – from quote to installation
In this article the process from quote to a CAN-ductor installed and ready for spud is explained. Through years of experience, Neodrill offers our clients a lean full-service Engineering, Procurement, Construction, and Installation solution. This to provide a low cost, reduced CO2 emissions, safe and cost-effective turnkey solution for the subsea wellhead foundation to our clients.
The first step of the process is to know the seabed conditions of the area you want to have a CAN-ductor installed. The exact well location does not have to be decided, but geotechnical soil data from the area is necessary.
Our geotechnical experts require Cone Penetration Test (CPT) and well loads data to determine the length of the CAN. The CAN’s have been installed in various seabed conditions in clay, sand, and mixed clay/sand layers.
Neodrill offers subsea well foundations for exploration and production wells. Rental CAN’s are used for exploration well applications, and Neodrill carries a stock of CAN units that can be adjusted and prepared for installation in a short period of time, typically with 4-6 weeks of lead time. The rental CAN’s are re-used to keep the exploration well cost at a minimum. For production wells the CAN’s are built to fit the specific well. We are proud to provide the industry with low cost and low emissions alternative to conventional conductors.
Fabrication phase for production wells CAN-ductors
The CAN units can be built at suitable fabrication yards worldwide, close to the area of application. The Neodrill team will follow up and plan the fabrication, conduct quality assurance, and the coordinate logistics at the yard.
The materials used for CAN fabrication are standard steel qualities, hence the lead time and costs are kept to a minimum. The CAN design is well suited for both one-off and serial fabrication, with module prefabrication adapted to the project (quantity and timeline) and the facilities at the chosen fabrication yard.
The conductor is client supplied and integrated towards the end of the CAN fabrication stage. The CAN design allows for conductors from all manufacturers and suppliers. The conductor fixation to the CAN will transfer all axial, horizontal and bending loads from the well into the CAN structure, and further into the surrounding seabed.
The final assembly can be vertical or horizontal, depending on the capabilities at the fabrication yard and the installation vessel to be used.
Through our marine vessel partners, Neodrill can provide an installation vessel suitable for the installation location and weight of the CAN. Our largest CAN units require an installation vessel with a 250 metric tons heave compensated crane capacity. Other types of vessels can be used such as an anchor handler. In this case the CAN will be horizontal sea fastened until its deployed over the stern of the vessel, see pictures below.
The planning of the installation can start in parallel with the fabrication phase. By providing a full range of services the from fabrication to installation, Neodrill is removing unnecessary interfaces and reduce the follow-up resources required from the client.
In addition to the vessel itself, Neodrill provides:
· Construction crew for installation
· Survey contractor
· Seafastening engineering
· Deployment analysis
· Provision of installation equipment such as ROV pumps and lifting equipment.
The chartered vessel is in most cases mobilized at the fabrication facility where the CAN’s are located along seaside for the vessel crane to reach. Neodrill will coordinate and prepare the base for arrival of the vessel. Once vessel has arrived, the CAN units can be lifted onboard and sea fastened to deck.
Once the CAN units are fastened to deck the transit to the well location can commence.
The CAN is lowered to the installation location using the vessel crane or winch. The first phase of the CAN installation is the self-penetration phase. The CAN penetrates the seabed up to 60% of its length under its own weight, depending on the soil properties. Once most of the CAN weight is supported in the seabed, an ROV dock onto the top of the CAN and pump it to the final position. The ROV pumps out water to create a differential pressure, and with only one bar of differential pressure, the ROV can create force equal to 288,2 metric tons. This force drives the CAN into the seabed in a controlled manner. Neodrill has a track record of more than 28 installations, with a conductor inclination of less than 1 degree off vertical.
For recovery of exploration rental CAN units, the crane is connected to the CAN and the ROV pumps water into the CAN while the crane is kept in constant tension to eject the CAN out of the seabed. Once clear of the seabed, the CAN is recovered to deck of the vessel and seafastened.
During installation a meticulous log of the installation parameters is recoded. This allows us to confirm the geotechnical calculations and verify that the required load capacity is achieved.
Neodrill also provide input to the Drilling Program to ensure that drill out procedures are considering the short conductor.