Nearshore Studies
One of the most important pieces of equipment needed to perform geotechnical surveys at sea and nearshore is the Jack-Up Vessel. This device is responsible for transferring drilling, sampling and in-situ testing equipment and tools to the borehole location.
Baran Khak va Pay Consulting Engineers Company, by utilizing its specialists, has launched the BKP drilling Jack-Up and so far has performed numerous nearshore and offshore geotechnical studies in the Persian Gulf, Sea of Oman and Caspian Sea using this vessel. This device has the capability to perform geotechnical operations in waters up to 20 meters deep and is fully owned by this consulting engineers’ company. This device consists of three main parts: deck, legs and spud cans. The deck of this device has a triangular layout, and in its center, there is a moon pool opening through which all drilling and in-situ testing operations are performed. Also, its three legs and spud cans are used to transfer the jack-up and equipment load on it to the seabed.
The Jack-Up used by this consulting engineers company is designed with optimum dimensions and has acceptable seaworthiness. Due to this distinctive feature, this device has the capability to perform required geotechnical operations in two modes of self-elevating platform (Jack-Up) and floating platform, so one of these modes can be selected based on project conditions:
- In Jack-Up mode, the spud cans and legs are placed on the seabed and then the deck is raised to a safe height and then the desired geotechnical operations are performed through the moon pool opening. An image of these geotechnical operations is shown below.
- In floating platform mode, the device is stationed at the desired location using installed anchors and winches, and the required geotechnical operations are performed through the moon pool opening on the deck. An image of these operations is shown in Figure 2.
It should be noted that:
At the survey design stage, required equipment and tools are located on the jack-up deck and calculations of buoyancy, stability and yaw anchors are performed considering the weight of equipment on deck and their layout, and after ensuring adequate safety, the equipment is installed on the device for offshore geotechnical operations and transferred to the project site.
The location of exploratory boreholes in offshore geotechnical operations is first implemented using the Google Earth satellite system and the exact coordinates of each exploratory borehole are recorded, and then the offshore team leader accurately determines borehole locations using GPS, and then the jack-up is towed to that location and stationed.
Figure 1: BKP’s Jack up Vessel
Figure 2: Nearshore Geotechnical Investigation in Jack up mode.
Figure 3: Nearshore Geotechnical Investigation in floating mode.