Stationmar's revolutionary technology will let all semi-submersible vessels be unaffected by the ocean waves. This means the system will neutralize the vertical movements on the vessel that are normally caused by ocean waves. This is done without introducing any energy in the forms of electrical, hydraulic, mechanical or other types. The mere design itself will neutralize the energy of the ocean waves.
A drilling rig without any heave (vertical) movement from waves may be taut moored using fiber ropes. The list of benefits with this new technology is long.
For drilling operations, you don't need a sub-sea BOP. A smaller and lighter dry BOP placed on-board the rig saves time and money. A simpler mooring system that is faster and cheaper to lay out. No need for heave compensation equipment that are heavy and costs a lot of money. No need for slip-joint and marine riser.
For work-over rigs that perform light or heavy interventions the benefits are many. In rough sea areas you may extend the operational window from today being 3-4 months of the year to a year round operation. That alone represents enormous savings for the oil company as well as the contractor. The safety of the rig will also be increased when helicopters may land in any type of weather condition due to the fact that the rig is not moving.
For a Dynamically Position semi-submersible rig with no mooring we have a special system built into the rig that allows the Dynamically Position rig not only to be horizontally kept in place, but also be vertically kept in place due to the Heave Neutralization system. This will be very beneficial for deep water drilling and interventions. As the rig will be kept in place in a 3D perspective. This has never been done before.
This is how the technology works…..
Introducing Heave Movement Neutralization for Semi-submersible platforms
At Stationmar AS we have developed a (patent pending) technology that neutralizes all vertical movements due to ocean waves in a semi-submersed structure. This is done through the design of a purpose-built rise cannister connected to a trapped air container system that is being built into the columns of the semi-submersible structure.
The Stationmar Heave Movement Neutralization (HMN) technology requires no electrical system, no hydraulic system, nor any moving parts to operate. Simply by the special design of the riser cannister and the trapped air container will the vertical energy be neutralized.
This is how it works: In the column, below the lowest water level, a rise canister is built in. The water level in the riser canister is balanced by a pressurized air volume in the hull above the water table. As a wave passes by, the water level rises around the column, which means that more of the column will be submerged. This increased submerged volume increases buoyancy to the hull which will tend to lift the hull in relation to the seabed. The increased water level height ads hydrostatic pressure to the trapped air volume above the water in the riser canister below. The added hydrostatic pressure compresses the air which allows increased water level in the riser canister. This reduces buoyancy of the hull exactly correspondingly to the added buoyancy by the column above. The volume of the air and the shape of the riser canister ensures that the multiple of pressure and volume – p x V – is constant, thus the system is energy neutral.
Please double-click on the video below for a simplified viewing of how the system works.