Abstract
Heave compensator is a system that mitigates transmission of heave movement from vessels to the equipment in the vessel. In drilling industry, a heave compensator enables drilling in offshore environments. Heave compensator attenuates movement transmitted from the vessel to the drill string and drill bit ensuring security and efficiency of the offshore drilling process. Common types of heave compensators are passive, active and semi-active compensators. This article presents 4 main points. First, a bulk modulus analysis obtains a simple condition to determine if the bulk modulus can be neglected in the design of hydropneumatic passive heave compensator. Second, the methodology to design passive heave compensators with the desired frequency response. Third, four control methodologies for semi-active heave compensator are tested and compared numerically. Lastly, we show experimental results obtained from a prototype with the methodology developed to design passive heave compensator.
Highlights
Ocean waves cause the raising and sinking of floating offshore platforms
It is important to note that the methodology proposed is able to provide an experimental frequency response close to the expected theoretical response
The example designed with cutoff frequency of 0.056Hz and maximum gain of 10dB shows a direct way to implement the methodology
Summary
Ocean waves cause the raising and sinking of floating offshore platforms. This motion affects offshore drilling process, causing drill bit and drill string damage, collapse of borehole wall and well kick. Heave compensator is a device used to compensate motion of heave platform and avoid its negative effects. Compensators are subjected to significant sprung mass variations. It ranges from 150tones, at 2km depth to 350tones, at 8km from start to finish of drilling. The four categories of heave compensators; Passive Heave Compensator (PHC), SemiActive Heave Compensator (SAHC), Active Heave Compensator (AHC) and Hybrid Heave compensator (HHC)
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