Dalian University of Technology

Congcong Han

Jun Liu

Yuxia Hu

Xu Wang

The present invention relates to a hybrid dynamically installed anchor with a folding shank and a control method to keep the verticality of the hybrid anchor during free fall in the seawater, which can be applied to the field of offshore engineering. The hybrid anchor comprises a folding-shank plate anchor, a ballast shaft, an extension rod, a plurality of rear fins, and a recovery hole from the front to the tail. The folding shank is not only useful in reducing the water and soil resistance during installation, but also beneficial in improving the directional stability of the hybrid anchor during free fall in the seawater. The re-used shaft can significantly increase the penetration depth of the folding-shank plate anchor and reduce the installation cost at the same time. The control method keeping the verticality of the hybrid anchor can improve the success rate during anchor installation.

Hybrid dynamically installed anchor with a folding shank and control method for keep anchor verticality during free fall in water

The present invention relates to a free-sliding seabed mudmat foundation, which belongs to the fields of offshore and ocean engineering. The mudmat comprises a base foundation, an upper foundation, and a cover plate. The base foundation sits on the seabed to support dead weights of the mudmat itself and the subsea production system fixed on the mudmat. The upper foundation, with a plurality of universal rolling ball bearing being attached to the bottom, can slide on the base foundation when it is subjected to a horizontal push force generated by the pipeline during operation. Therefore, the axial load on the pipeline during operation due to heating and pressurization is released and the buckling failure risk is then reduced. The mudmat disclosed has smaller size and lighter weight, which is beneficial in reducing fabrication costs and reducing requirements for cranes on the pipeline laying vessel.

Free-sliding seabed mudmat foundation

An anchor booster is designed to increase the final penetration depth of the gravity installed plate anchor. Moreover, the booster can also improve the directional stability of the gravity installed plate anchor during its free fall in water. After installation, the booster is retrieved by pulling its retrieval line up and can be used for the subsequent installation. The booster is comprised of a cylindrical shaft with three rear fins. The shaft is designed with an ellipsoidal tip and a contracted rear. The shaft rear is set with three slots thus the rear fins can be inserted into the slots to improve the directional stability of the hybrid anchor (i.e. the gravity installed plate anchor with a booster). The booster tip is fabricated with a cylindrical slot and the anchor tail has a compatible bar, such that the booster can be connected to the anchor tail by a shear pin.

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Liaoning, China

Congcong Han