Here are the most frequent questions our mooring experts get asked. Keep asking and dig deeper to get answers that are specific to your project.

  • Why do I need Preset Mooring Lines?

Preset mooring lines greatly improve the safety and feasibility of an installation. Preset lines are necessary when conventional moorings are not strong enough to meet the minimum safety factor requirements. Presets can also provide installation flexibility in a crowded field whereas a conventional system is more suitable in an undeveloped field. Lastly, presets can be used to quickly install or disconnect a rig from the field, in case of impending weather, allowing for the moorings to remain in the field when the rig returns.

  • What type of anchor do I need for my well location?

The most commonly used anchor for temporary mooring operations are drag embedment anchors, however more specialized anchors (i.e. vertically loaded anchors (VLAs), Suction Embedded PLate Anchors (SEPLAs), and suction piles) can be used for complex locations. The necessary anchor depends on the field and rig characteristics such as installation limitations, sediment characteristics, holding capacity requirements, the presence of vertical loads on the anchor, and range of the mooring line’s heading.

  • How could hiring more than one installation vessel save me money?

While it may seem contradictory, utilizing two (2) anchor handling vessels (AHV’s) for a rig move can have a lower cost than if only one (1) AHV is used. Simply put, a rig move is completed faster when two AHV’s are working simultaneously. The savings in time from utilizing two (2) AHV’s in parallel return savings in rig costs that offset the additional vessel costs.

  • What type of mooring analysis do I need to pass API standards?

The mooring analysis required to pass API standards is dependent on the type of mooring system being installed. A temporary (<2 years) mooring installation will typically be analyzed using a frequency domain analysis, while longer campaigns necessitate a more in-depth study and are expected to require time domain analysis. Frequency domain analyses are implicitly simulated using separate and independent calculations to estimate motions. Time domain analyses explicitly simulates vessel movement by solving the equations of motion for the entire six degrees of freedom.