RIO OIL & GAS 2014 - Pre-Installation of Conductor Casings Using a Standalone Offshore Construction Vessel

During last decade the concept of conductor casing pre-installation was introduced in the offshore oil and gas industry and proved to be an interesting choice for operators in order to save rig time during exploratory campaigns. Three projects were executed in Brazil summing 36 conductor casings with 36 and 48 inches outside diameter. The methodology discussed in this paper for conductor casing deployment includes an offshore construction vessel (OCV), an oceangoing barge with tug, a subsea hammer and a work-class ROV. These resources are able to install each conductor casing to the desired stick-up with fine accuracy. Although many benefits exist, the lead-time for full mobilization and the welding of the conductor casing is the downside with this pre-installation method, additionally multiple vessels in the field always require special attention with regards to safety.
This paper is intended to present an improvement from the previous pre-installation methodology. Conductor casing and hammer will be loaded on a single OCV, so there is no need for the oceangoing barge. Standard conductor casings with threaded connectors are horizontally assembled onshore on the mobilization quayside.
A conductor casing of 60 meters length becomes a challenge to be carried on the back deck of a regular OCV. A tailor made structure called Conductor Overboarding Platform (COP) was engineered to support up to 5  conductor casings with 36 inches diameter or similar configurations. Because the structure is modular it can be mobilized at any port on a light OCVs.
Simplicity of the presented incremental technology can support deepwater exploration and production activities in Brazil or worldwide saving considerable rig time and all associated costs. Risks are also reduced and even a last-minute decision to pre-install the conductor casing is feasible, since all consumables are off-the-shelf and the installation equipment is designed to be flexible and mobile.

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