Method and Apparatus for Subsea Installations

摘要

There is provided a method and apparatus for lowering and/or raising a load or structure to or from the bed of a body of water. The apparatus comprises a buoyancy apparatus configured to be coupled to a load, and having positive buoyancy sufficient to lift the load. At least one receptacle is provided on the apparatus for receiving a control weight lowered from a vessel to lower or raise the assembly. The lowering method includes forming an assembly from a buoyancy apparatus and a load and submerging the assembly to a position at a first height above the bed. In a preferred embodiment the assembly is submerged by a clump weight tow system. A control weight is deployed from a vessel to the assembly to overcome the positive buoyancy of the assembly and thereby lower the load from the first height to the bed. The raising method reverses the steps of the lowering method.

主权项

1. A method of raising a payload from a bed of a body of water, the method comprising:
coupling the payload on a bed to a buoyancy apparatus to form an assembly, wherein the buoyancy apparatus has sufficient buoyancy to lift the payload; retaining the assembly on the bed using a control weight; using a vessel to retrieve the control weight from the assembly to render the assembly positively buoyant, thereby raising the assembly from the bed.