Brown & Root, Inc.

Other

Joe C Lochridge

Avadhesh N Srivastav

Herman F Boehme

William A Morgan

Thomas R Schmitz

An apparatus and method for trenching beneath an elongated member lying on the bottom of a body of water are disclosed. The apparatus has a movable frame member, at least one cutting assembly, an assembly support means connected to the frame member for supporting each cutting assembly and for moving each cutting assembly at least in a laterally directed plane, and a spoil removal system. Each cutting assembly comprises at least two actuatable cutting tools which are driven for cutting movement relative to cutting tool axes. The cutting tool axes, for each cutting assembly, define an assembly cutting plane and means are provided for rotating the assembly cutting plane relative to the laterally directed plane, thereby, varying the cutting swath of the associated cutting assembly. In one aspect the method of the invention is directed to trenching from both sides of and beneath the elongated member to be buried. In another aspect, the method is directed to trenching from one side only, or from one side of and then from the other side of and beneath the elongated member to be buried.

Trenching apparatus and method

A method and apparatus for entrenching an elongated pipeline and the like uses a trenching apparatus having a trench cutting assembly which is detachably connected to a sled base. A floating vessel has means to control positioning of the trenching apparatus, including means to raise and lower, and to connect and disconnect, the trench cutting assembly and the sled base. Several methods and apparatus are disclosed for raising and lowering the trench cutting assembly while leaving the sled base positioned on the bottom of the body of water, straddling the elongated pipeline. In each embodiment, the cutting means may be lifted on board the vessel for maintenance and/or repair, leaving the sled base in position relative to the pipeline. Means are provided for abandoning the sled base at the entrenching site and returning later to lower the trench cutting assembly into its operational relationship with the sled base.

Separable trenching apparatus

A method of installing a riser to provide a continuous flow path from a relatively rigid pipeline lying on the bottom of a body of water to an above water connection on an offshore apparatus is disclosed. The riser according to one aspect of the invention is a tubular flexible conduit and in a second aspect is a rigid member connected to the pipeline by a flexible section. The method of the invention for installing the riser uses available equipment, relatively small lifting forces and avoids the deformation of rigid pipe. In one particular embodiment, the pipeline-riser combination is laid on the bottom of the body of water and according to the method, the riser member is thereafter raised to a vertical orientation with respect to the offshore platform. The method provides a riser which does not undergo deformation at the bending zone wherein fluid flow changes between the horizontal and vertical directions.

Method of installing a flexible riser

A process for starting and laying a submergible elongate structure, such as a pipeline, upon the bed of a body of water from a marine vessel, while controlling the bending configuration thereof. The method includes the steps of tensioning a flexible cable between a marine vessel and a submerged hook-up facility, progressively suspending portions of a pipeline from the tensioned cable by means of spaced hangers, and extending the pipeline toward the submerged facility. The process may be employed solely to initially start to lay a submergible elongate structure or the process may be employed to both start to lay a submergible elongate structure and to subsequently lay a submergible elongate structure.

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Houston, TX, United States of America

Joe C Lochridge