EXPLORATION/DRILLING/FIELD SERVICES 25
ROV utilisation for varied subsea grouting operations
R S Miles and H W Lee have for more than 25 years involved with working with ROV operators and designing systems to execute subsea grouting projects using the ROV as a method of executing the service of injecting grout into a specific location or area.
T
he types of solutions where grout is required to be injected, and a remotely operated vehicles (ROV) is used as the method of placing, and injecting the
hardening medium are many and varied. They include:
o Pipeline supports. o Pre-lay pipe sleepers. o Central crossing supports for pipelines or cables. o Stabilisation to pipelines or cables. o Pipeline protection. o Under base grouting; valve box protection. o Structural grouting to offshore platforms or piles. o Template grouting. o Clamp or brace grouting.
An understanding of ROV operation of what can and cannot be done by the ROV is paramount in
preparing the solution to be installed and injected using the ROV as the method of installation. The aim is to keep the operations simple with use of one manipulator, which is a twist or push/pull operation.
Metholdolog of design
Visual ability to evaluate all attachments and or aspects of the solution in its final position pre/post injection must be one of the main considerations when considering the methodology of design for ROV utilisation.
In other words we design for the work to be carried out by ROV; we do not adapt an existing design or solution for ROV installation. ROV grouted solutions have been used worldwide to 1000 metre water depth for structural grouting to offshore structures and pipelines
How to make the installation method user friendly for ROV installation. Example: Free span correction. The sketches’ below are an illustration of the depth of thought that has to be gone into to achieve a total package. You will note the additional aids to the structure
to, retain, ensure shape is maintained and the item is easily handled to ensure the ROV can manoeuvre around for ease of placing. Note the means of cutting the grout flow line is easyand in a location that is very ROV friendly.
Structural grouting
The technique to permit grouting of piles by ROV was initially developed and presented to industry during the mid 80s; today this is a documented procedure that industry accepts as a normal procedure.
The ROV has to interface with the section of hose to connect to the location or connection where the grout hose has to be inserted or connected. It is therefore critical
Fig. 1. The deployment basket is located on the seabed. The remotely operated vehicle is waiting to open it.
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for the grouting contractor to provide the correct information at fabrication stage of the structure, and to consider how the ROV is
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