Ballast deployment apparatus and method for installing and retrieving said apparatus

Abstract

An apparatus for controlled deployment of ballast material onto a subsea location, preferably a subsea structure, comprising at least one chute for conveying said ballast material, said chute having a first end and a second end; at least one buoyancy element associated with the chute such that the chute may assume a generally vertical orientation in the water, supported by said buoyancy element; a support element associated with said chute and adapted for cooperation with an installation weight, said chute second end being adapted for connection to an element associated with the seabed. A method for installation of said apparatus comprising bringing the chute into a generally vertical orientation in the water above said subsea location, lowering portions of said installation weight onto said support element, causing said ballast deployment apparatus to move towards the seabed, until said apparatus has reached a desired depth in the water; connecting said chute second end to said element associated with the seabed; and withdrawing said installation weight from said support element, whereupon deployment of ballast material through said chute may commence.

Description

[0001] 1. Field of the Invention[0002] This invention relates to the field of subsea operations. More specifically, the invention relates to an apparatus for the deployment of ballast material to a subsea location, preferably onto a structure or structures on the seabed, and a method for installing and retrieving said apparatus.[0003] 2. Description of the Related Art[0004] Installation of structures on the seabed, such as for example laying of subsea pipelines in connection with exploitation of hydrocarbons, often require deployment of ballast materials onto these structures. These structures may require ballast materials, which in most cases comprise rocks or gravel, for a number of reasons, such as increasing the weight (and thus stability), preventing scour, enhancing the seabed capacity, providing a permeable layer, and / or for mitigating environmental impacts on shipping and fisheries. One particular application of ballast materials is to cover pipelines on the seabed in order ...

AI Technical Summary

Benefits of technology

"The invention is an apparatus for controlled deployment of ballast material to a subsea location, such as a subsea structure. The apparatus includes a chute for conveying the ballast material, a buoyancy element that supports the chute in a vertical orientation in the water, and a support element that cooperates with an installation weight. The method involves bringing the chute into a vertical orientation, lowering portions of the installation weight onto the support element, connecting the chute to the seabed, and withdrawing the installation weight. The apparatus can be used in combination with standard ballast deployment equipment to extend the depth of the deployment. The invention allows for controlled and safe deployment of ballast materials in deep water."

Problems solved by technology

One problem associated with deployment of ballast materials, is to accurately control that it is deposited in the desired location.

Known techniques and equipment have practical limits.

Today's chutes are not practical for very deep waters, as the chute's free end is susceptible to moving considerably due to water currents and other perturbations and due to the considerable length and weight of such chutes.

The known chute therefore limits the depth to which this method is feasible or economical.

In order to ensure accurate deployment of ballast materials in very deep waters, one of today's techniques is to lower the ballast material in large "baskets," which is a time-consuming and costly operation, and often requires a separate vessel in addition to the ballast deployment vessel.

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